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Hindawi Publishing Corporation International Journal of Genomics Volume 2016, Article ID 2405954, 14 pages http://dx.doi.org/10.1155/2016/2405954 Review Article Role of Recombinant DNA Technology to Improve Life Suliman Khan,1 Muhammad Wajid Ullah,2 Rabeea Siddique,3 Ghulam Nabi,1...

Hindawi Publishing Corporation International Journal of Genomics Volume 2016, Article ID 2405954, 14 pages http://dx.doi.org/10.1155/2016/2405954 Review Article Role of Recombinant DNA Technology to Improve Life Suliman Khan,1 Muhammad Wajid Ullah,2 Rabeea Siddique,3 Ghulam Nabi,1 Sehrish Manan,4 Muhammad Yousaf,5 and Hongwei Hou1 1 The Key Laboratory of Aquatic Biodiversity and Conservation of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei 430072, China 2 Department of Biomedical Engineering, Huazhong University of Science and Technology, Wuhan 430074, China 3 Institute of Biotechnology and Genetic Engineering, The University of Agriculture, Peshawar 25000, Pakistan 4 National Key Laboratory of Crop Genetic Improvement, College of Plant Sciences and Technology, Huazhong Agricultural University, Wuhan 430070, China 5 Center for Human Genome Research, Cardio-X Institute, Huazhong University of Science and Technology, Wuhan 430074, China Correspondence should be addressed to Hongwei Hou; [email protected] Received 10 August 2016; Revised 21 October 2016; Accepted 6 November 2016 Academic Editor: Wenqin Wang Copyright © 2016 Suliman Khan et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. In the past century, the recombinant DNA technology was just an imagination that desirable characteristics can be improved in the living bodies by controlling the expressions of target genes. However, in recent era, this field has demonstrated unique impacts in bringing advancement in human life. By virtue of this technology, crucial proteins required for health problems and dietary purposes can be produced safely, affordably, and sufficiently. This technology has multidisciplinary applications and potential to deal with important aspects of life, for instance, improving health, enhancing food resources, and resistance to divergent adverse environmental effects. Particularly in agriculture, the genetically modified plants have augmented resistance to harmful agents, enhanced product yield, and shown increased adaptability for better survival. Moreover, recombinant pharmaceuticals are now being used confidently and rapidly attaining commercial approvals. Techniques of recombinant DNA technology, gene therapy, and genetic modifications are also widely used for the purpose of bioremediation and treating serious diseases. Due to tremendous advancement and broad range of application in the field of recombinant DNA technology, this review article mainly focuses on its importance and the possible applications in daily life. 1. Introduction even below standard in the third-world countries. Rapid increase in industrialization has soared up the environmental Human life is greatly affected by three factors: deficiency of pollution and industrial wastes are directly allowed to mix food, health problems, and environmental issues. Food and with water, which has affected aquatic marines and, indirectly, health are basic human requirements beside a clean and human-beings. Therefore, these issues urge to be addressed safe environment. With increasing world’s population at through modern technologies. a greater rate, human requirements for food are rapidly Unlike tradition approaches to overcome agriculture, increasing. Humans require safe-food at reasonable price. health, and environmental issues through breeding, tradi- Several human related health issues across the globe cause tional medicines, and pollutants degradation through con- large number of deaths. Approximately 36 million people ventional techniques respectively, the genetic engineering die each year from noncommunicable and communicable utilizes modern tools and approaches, such as molecular diseases, such as cardiovascular diseases, cancer, diabetes, cloning and transformation, which are less time consuming AIDS/HIV, tuberculosis, malaria, and several others accord- and yield more reliable products. For example, compared ing to http://GlobalIssues.org/. Despite extensive efforts to conventional breeding that transfers a large number of being made, the current world food production is much both specific and nonspecific genes to the recipient, genetic lower than human requirements, and health facilities are engineering only transfers a small block of desired genes to 2 International Journal of Genomics the target through various approaches, such as biolistic and engineering and possible future directions for researchers Agrobacterium-mediated transformation. The alteration to surmount such limitations through modification in the into plant genomes is brought either by homologous recom- current genetic engineering strategies. bination dependent gene targeting or by nuclease-mediated site-specific genome modification. Recombinase mediated 2. Recombinant DNA Technology site-specific genome integration and oligonucleotide directed mutagenesis can also be used. Recombinant DNA technology comprises altering genetic Recombinant DNA technology is playing a vital role in material outside an organism to obtain enhanced and desired improving health conditions by developing new vaccines and characteristics in living organisms or as their products. This pharmaceuticals. The treatment strategies are also improved technology involves the insertion of DNA fragments from by developing diagnostic kits, monitoring devices, and new a variety of sources, having a desirable gene sequence via therapeutic approaches. Synthesis of synthetic human insulin appropriate vector. Manipulation in organism’s genome and erythropoietin by genetically modified bacteria and is carried out either through the introduction of one or production of new types of experimental mutant mice for several new genes and regulatory elements or by decreasing research purposes are one of the leading examples of genetic or blocking the expression of endogenous genes through engineering in health. Likewise, genetic engineering strate- recombining genes and elements. Enzymatic cleavage is gies have been employed to tackle the environmental issues applied to obtain different DNA fragments using restriction such as converting wastes into biofuels and bioethanol [4– endo-nucleases for specific target sequence DNA sites fol- 7], cleaning the oil spills, carbon, and other toxic wastes, and lowed by DNA ligase activity to join the fragments to fix the detecting arsenic and other contaminants in drinking water. desired gene in vector. The vector is then introduced into a The genetically modified microbes are also effectively used in host organism, which is grown to produce multiple copies biomining and bioremediation. of the incorporated DNA fragment in culture, and finally The advent of recombinant DNA technology revolution- clones containing a relevant DNA fragment are selected ized the development in biology and led to a series of dra- and harvested. The first recombinant DNA (rDNA) matic changes. It offered new opportunities for innovations to molecules were generated in 1973 by Paul Berg, Herbert produce a wide range of therapeutic products with immediate Boyer, Annie Chang, and Stanley Cohen of Stanford Uni- effect in the medical genetics and biomedicine by modifying versity and University of California San Francisco. In 1975, microorganisms, animals, and plants to yield medically useful during “The Asilomar Conference” regulation and safe use of substances [8, 9]. Most biotechnology pharmaceuticals are rDNA technology was discussed. Paradoxically to the view recombinant in nature which plays a key role against human of scientists at the time of Asilomar, the recombinant DNA lethal diseases. The pharmaceutical products synthesized methods to foster agriculture and drug developments took through recombinant DNA technology, completely changed longer than anticipated because of unexpected difficulties and the human life in such a way that the U.S. Food and barriers to achieve the satisfactory results. However, since the Drug Administration (FDA) approved more recombinant mid-1980s, the number of products like hormones, vaccines, drugs in 1997 than in the previous several years combined, therapeutic agents, and diagnostic tools has been developed which includes anemia, AIDS, cancers (Kaposi’s sarcoma, continually to improve health. leukemia, and colorectal, kidney, and ovarian cancers), A quick approach is offered by recombinant DNA tech- hereditary disorders (cystic fibrosis, familial hypercholes- nology to scrutinize the genetic expression of the mutations terolemia, Gaucher’s disease, hemophilia A, severe combined that were introduced into eukaryote genes through cloned immunodeficiency disease, and Turnor’s syndrome), diabetic insulin genes insertion inside a simian virus fragment. foot ulcers, diphtheria, genital warts, hepatitis B, hepatitis C, In a similar way, tumor growth was inhibited by adenovi- human growth hormone deficiency, and multiple sclerosis. ral vector that encodes endostain human secretory form Considering the plants develop multigene transfer, site- through antiangiogenic effects. Antiangiogenic effect can be specific integration and specifically regulated gene expression enhanced by dl1520 through rescuing replication of Ad-Endo are crucial advanced approaches. Transcriptional regu-. Targeted gene disruption has been used to produce lation of endogenous genes, their effectiveness in the new antitumor derivatives in other hosts which were structurally locations, and the precise control of transgene expression are similar for the production pathways. Besides, longer major challenges in plant biotechnology which need further acting therapeutic proteins have been developed through developments for them to be used successfully. recombinant DNA technologies; for example, sequences Human life is greatly threatened by various factors, like containing additional glycosylation site are one of the most food limitations leading to malnutrition, different kinds of followed approaches. A new chimeric gene has been devel- lethal diseases, environmental problems caused by the dra- oped through this technique which contains the FSH 𝛽- matic industrialization and urbanization and many others. subunit coding sequences and the C-terminal peptide of the Genetic engineering has replaced the conventional strate- hCG 𝛽-subunit coding sequences. Researchers have also gies and has the greater potential to overcome such chal- developed vectors and combined vectors for gene therapy and lenges. The current review summarized the major challenges genetic modification approaches. Presently, viral vectors have encountered by humans and addresses the role of recombi- received immense consideration in clinical settings, some of nant DNA technology to overcome aforementioned issues. which have also been commercialized. In principle, viruses In line with this, we have detailed the limitations of genetic are modified to be safe for clinical purposes. They have several International Journal of Genomics 3 Therapeutic products Vaccines Genetically modified products Growth hormones Fruits Antibodies GM vegetables GM crops Vectors GM microbes Recombinant protein GM animals Anticancer drugs Recombinant DNA technology Diagnosis Energy applications Gene therapy Biohydrogen CRISPR Bioethanol Monitoring devices Biomethanol Therapeutic strategies Biobutanol Figure 1: Illustration of various applications of recombinant DNA technology. applications including treatment of severe diseases including recognized recombinant protein that can be effectively used cancer either through in vivo or gene therapy (ex vivo), in curing of anemia. Recombinant hGH was found vaccination, and protein transduction approaches. The with a great improvement in treating children lacking the production of clinical grade viral vectors improvement has ability to produce hGH in a required quantity. Clinical testing become possible due to advance manufacturing technologies approval by the FDA in December 1997 for a recombinant. At present, due to the severe adverse effects, retroviral version of the cytokine myeloid progenitor inhibitory factor- vectors are losing their importance although the viral entities 1 (MPIF-1) was an achievement to give recognition to this transfer genes quickly and correctly into a number of species. technology. With its help anticancer drug’s side effects can The simplest nonviral gene delivery system uses “naked” be mitigated whereas it has the ability to mimic the division DNA, when injected directly into certain tissues, particularly of immunologically important cells [23, 24]. The following muscles, produces significant levels of gene expression with section summarizes the most recent developments of recom- least side effects. More recently, a P1 vector has been binant DNA technology. designed to introduce the recombinant DNA into E. coli Clustered regularly interspaced short palindromic repeats through electroporation procedures. This new cloning system (CRISPR), a more recent development of recombinant DNA is used for establishing 15,000 clone library initially averagely technology, has brought out solutions to several problems 130−150 kb pairs insert size. PAC cloning system is considered in different species. This system can be used to target useful for complex genome analysis and in mapping. destruction of genes in human cells. Activation, suppression, The construction of low copy number vectors, for example, addition, and deletion of genes in human’s cells, mice, rats, pWSK29, pWKS30, pWSK129, and pWKS130, was carried out zebrafish, bacteria, fruit flies, yeast, nematodes, and crops using PCR and recombinant DNA technology. These vectors proved the technique a promising one. Mouse models can can also be used for generating unidirectional deletions with be managed for studying human diseases with CRISPR, exonuclease, complementation analysis, DNA sequencing, where individual genes study becomes much faster and the and run-off transcription. A broad range of applications genes interactions studies become easy by changing multiple of recombinant DNA technology has been summarized in genes in cells. The CRISPR of H. hispanica genome Figure 1. is capable of getting adapted to the nonlytic viruses very efficiently. The associated Cas operon encodes the interfering 3. Current Research Progress Cas3 nucleases and other Cas proteins. The engineering of a strain is required with priming CRISPR for priming Recombinant DNA technology is a fast growing field and crRNAs production and new spacers acceptance. CRISPR-cas researchers around the globe are developing new approaches, system has to integrate new spacers into its locus for adaptive devices, and engineered products for application in different immunity generation. Recognition of foreign DNA/RNA sectors including agriculture, health, and environment. For and its cleavage is a controlled process in sequence-specific example, Lispro (Humalog), in comparison with regular manner. Information related to the intruder’s genetic material human insulin, is a well effective and fast acting recombinant is stored by the host system with the help of photo-spacer insulin. Similarly, Epoetin alfa is a novel and well- incorporation into the CRISPR system. Cas9t (gene 4 International Journal of Genomics editing tool) represents DNA endonucleases which use RNA Besides insulin, several new drugs related to recombinant molecules to recognize specific target. Class 2 CRISPR- DNA technology have undergone developmental improve- Cas system with single protein effectors can be employed for ments and a number of protein production systems have been genome editing processes. Dead Cas9 is important for histone developed. Several engineered microbial strains have been modifying enzyme’s recruitment, transcriptional repression, developed to carry out the formulation of drugs [41, 43, 44]. localization of fluorescent protein labels, and transcriptional Molecular medicine formation that is specifically based on activation. Targeting of genes involved in homozygous proteins faces serious issues including methods and biology gene knockouts isolation process is carried out by CRISPR- of the cells which function to produce medically impor- induced mutations. In this way, essential genes can be tant compounds through recombinant DNA techniques. To analyzed which in turn can be used for “potential antifungal overcome these obstacles, there is intense need to improve targets” exploration. Natural CRISPR-cas immunity quality and quantity of medicines based on a molecular exploitation has been used for generation of strains which are phenomenon. Cell factories are considered important in resistant to different types of disruptive viruses. recombinant DNA technologies, but these needed to be CRISPR-Cas, the only adaptive immune system in explored with more details and in depth as the conventional prokaryotes, contains genomic locus known as CRISPR hav- factories are not fulfilling the needs. Similarly, the ing short repetitive elements and spacers (unique sequences). endothelial growth factor and Notch signaling were used to CRISPR array is preceded by AT-rich leader sequence and engineer oncolytic adenovirus which acts as a breast cancer flanked by cas genes which encode Cas proteins [32, 33]. selective agent for the antagonist’s expression. This further, In Escherichia coli cas1 and cas2 catalases promote new through tumor angiogenesis disruption acts as anticancer spacers through complex formation. Photo-spacer adjacent agent. This decreases the total blood vessels numbers and motif (PAM) is required for interference and acquisition causes a dramatic change along with the perfused vessels because the target sequence selection is not random. The which indicates the improved efficacy against the tumor and memorization of the invader’s sequence starts after CRISPR vascular effects. Efforts have been made to modify the array transcription into long precursor crRNA. During the influenza virus genome using recombinant DNA technology final stages of immunity process, target is degraded through for development of vaccines. The modifications are based interference with invaded nucleic acids. Specific recognition on engineering of vectors to expression of foreign genes. In prevents the system from self-targeting [32, 34]. In different practical, the NS gene of the influenza virus was replaced with species of Sulfolobus, the CRISPR loci contain multiple foreign gene, commonly chloramphenicol acetyltransferase spacers whose sequence matches conjugative plasmids sig- gene. Thereafter, the RNA previously recombined is expressed nificantly while in some cases the conjugative plasmids also and packaged into virus particles after transfection with contain small CRISPR loci. Spacer acquisition is affected by purified influenza A virus in the presence of helper virus. It active viral DNA replication in Sulfolobus species whereas has been clarified that 5󸀠 terminal and the 3󸀠 terminal bases the DNA breaks formation at replication forks causes the are sufficient from influenza A virus RNA to produce signals process to be stimulated. According to the above infor- for RNA replication, RNA transcription, and RNA packaging mation, CRISPR-Cas system has obtained a unique position into influenza virus. in advanced biological systems because of its tremendous role The abovementioned new production systems enhance in the stability and enhancement of immunity. pipelines for development of various vaccines and drugs Zinc-finger nucleases (ZFNs) and transcription activator- and so forth. Production of high quality proteins depends like effector nucleases (TALENs) are chimeric nucleases com- on physiology of a cell and the conditions provided to posed of programmable, sequence-specific DNA-binding it. The expression of proteins becomes retarded if a cell modules linked to a nonspecific DNA cleavage domain. Ther- goes under stressful conditions, which may also favor the apeutic potential of ZFNs and TALENs is more specified and production in some cases. Thus, further improvements are targeted [25, 36, 37]. Similarly, recombinant protein fibroblast required for the better and safe production at genetic growth factor (FGF-1) has been developed which functions in and metabolic levels. Microorganisms are considered the inducing the formation of new blood vessels in myocardium. most convenient hosts to produce molecular medicines. Its injection (biologic bypass) into a human myocardium These cells allow the incorporation of foreign genes with cause an increased blood supply to the heart. Apligraf, an less resistant barriers and expression is easily controlled. FDA approved product, which serves as a recombinant skin Compared to plant and mammalian cells to be taken as replacer, specified for the leg ulcer’s treatment and Derma- hosts, microbial systems provide less complicated machinery Graft, is effective in the treatment of diabetic ulcers [38–40]. which ultimately enhances the performance and quality of After successful production of insulin from E. coli through proteins production. The use of common microbial species, recombinant DNA technology, currently several animals, including bacteria and yeasts, is promising but the less notably cattle and pigs, have been selected as insulin produc- common strains have also been observed promising as ing source, which however, triggered immune responses. The being cellular factories to produce recombinant molecular recombinant human insulin is identical to human porcine drugs. The increasing demands of drugs and the needs insulin and comparatively infrequently elicits immunogenic of quality can be fulfilled with better results if these cel- responses. Furthermore, it is more affordable and can sat- lular factories of microorganisms get incorporated into isfy medical needs more readily. Human growth hormone productive processes of pharmaceuticals (Table 1) [41, 45, was the first protein expressed in tobacco plants [41, 42]. 46]. International Journal of Genomics 5 Table 1: Current DNA assembly methods for the synthesis of large DNA molecules. The table has been reproduced from Nature reviews 14: 781–793, with permission from Nature Publishing Group. Overhang Scar Method Mechanism Comments Examples of applications (bp) (bp) Construction of a Type IIP restriction Sequentially assembles small numbers of functional gene expressing BioBricks 8 8 endonuclease sequences enhanced cyan fluorescent protein Construction of Uses a highly efficient and commonly used constitutively active Type IIP restriction restriction endonuclease, the recognition BglBricks 6 6 gene-expression devices endonuclease sequences of which are not blocked by the most and chimeric, multidomain common DNA methylases protein fusions Requires attachment tags at each end of fragments Assembly of a 91 kb Pairwise Type IIS restriction 65 4 to act as promoters for antibiotic resistance fragment from 1-2 kb selection endonuclease markers; rapid, as a liquid culture system is used fragments Type IIS restriction Allows large-scale assembly; ligations are done in One-step assembly of 2-3 GoldenGate 4 0 endonuclease parallel one-step assembly of 2-3 fragment fragments Usually used for Overlapping Uses overlapping primers for the PCR 1–3 kb-long fragments, for Overlap 0 0 PCR amplification of 1–3 kb-long fragments example, for gene cassette construction Uses a single polymerase for the assembly of One-step assembly of four CPEC Overlap 20–75 0 multiple inserts into any vector in a one-step 0.17–3.2 kb-long PCR reaction in vitro fragments Uses a specific recombinase for small-scale One-step assembly of three Gateway Overlap 20 0 assembly 0.8–2.3 kb-long fragments Replaces a thymidine with a uracil in the PCR One-step assembly of three USER Overlap Up to 708 0 primers, which leaves 3󸀠 overhangs for cloning 0.6–1.5 kb-long fragments after cleaving by a uracil exonuclease Uses an enzyme mix for parallel assembly through One-step assembly of three InFusion Overlap 15 0 a “chew-back-and-anneal” method 0.2–3.8 kb-long fragments (i) Uses a T4 DNA polymerase through a chew-back method in the absence of dNTPs Generation of a ten-way (ii) Uses Recombinase A∗ to stabilize the annealed assembly of SLIC Overlap >30 0 fragments and avoid in vitro ligation 300–400 bp-long PCR (iii) Allows the parallel assembly of several fragments hundred base-long fragments Uses enzymatic “cocktails” to chew back and Assembly of the 1.08 Mb Gibson Overlap 40–400 0 anneal for the parallel assembly of several Mycoplasma mycoides kilobase-long fragments JCVI-syn1.0 genome 4. Applications of Recombinant be reduced. Lysozymes are the effective agents to get rid DNA Technology of bacteria in food industries. They prevent the colonization of microbial organisms. It is suitable agent for food items 4.1. Food and Agriculture. Recombinant DNA technology has including fruits, vegetables, cheese, and meat to be stored as major uses which made the manufacturing of novel enzymes it increases their shelf life. The inhibition of food spoiling possible which are suitable in conditions for specified food- microorganisms can be carried out through immobilized processing. Several important enzymes including lipases and lysozyme in polyvinyl alcohol films and cellulose. Lysozyme amylases are available for the specific productions because impregnation of fish skin gelatin gels increase the shelf life of their particular roles and applications in food industries. of food products and inhibit different food spoiling bacterial Microbial strains production is another huge achievement growth [48–50]. Exopolysaccharides of Staphylococcus and that became possible with the help of recombinant DNA tech- E. coli can be hydrolyzed with the use of DspB which is nology. A number of microbial strains have been developed engineered from T7. This ability of DspB causes a declination which produce enzyme through specific engineering for pro- in the bacterial population. Biofilms related to food duction of proteases. Certain strains of fungi have been mod- industries can be removed by the combining activity of serine ified so that their ability of producing toxic materials could proteases and amylases. S. aureus, Salmonella infantis, 6 International Journal of Genomics Clostridium perfringens, B. cereus, Campylobacter jejuni, L. resistance to either environmental or microbial stresses. monocytogenes, Yersinia enterocolitica, and some other food Resistance to fungal and bacterial infections can be enhanced spoiling microorganisms can be inhibited by glucose oxidase. by WRKY45 gene in rice which is induced by plant activator It is also considered one of the most important enzymes in benzothiadiazole that activates innate immune system of food industry to kill wide range of foodborne pathogens. plant. The larger grain size can be achieved by inserting qSW5 Derivation of recombinant proteins being used as phar- gene. qSH1 causes the loss of seed shattering by preventing the maceuticals came into practice from first plant recently and abscission layer formation. Kala4 gene is responsible for the many others are through to be used for more production of black color of rice which makes the rice resistant to attacking similar medically important proteins. pathogens [59, 60]. Genetic modification is needed in facili- Wide range of recombinant proteins have been expressed tating gene by gene introduction of well-known characters. It in different plant species to be used as enzymes in industries, allows access to extended range of genes from an organism. some majorly used proteins in research are proteins present Potato, beans, eggplant, sugar beet, squash, and many other in milk which play a role in nutrition, and new polymeric plants are being developed with desirable characters, for proteins are being used in industries and medical field example, tolerance of the herbicide glyphosate, resistance. With the invention of HBV vaccine production in to insects, drought resistance, disease and salt tolerance. plants, the oral vaccination concept with edible plants has Nitrogen utilization, ripening, and nutritional versatility like gained popularity. Plants have been used to produce several characters have also been enhanced. therapeutic protein products, such as casein and lysozyme for improving health of child and polymers of protein for 4.2. Health and Diseases. Recombinant DNA technology tissue replacement and surgery. Furthermore, tobacco plants has wide spectrum of applications in treating diseases and can be engineered genetically to produce human collagen. improving health conditions. The following sections describe High yielding molecular proteins is one of the major tasks the important breakthroughs of recombinant DNA technol- under consideration in field of recombinant DNA technology ogy for the improvement of human health:. Traditional breeding and quantitative trade locus (QTL) analysis assisted in the identification of a rice variety with 4.2.1. Gene Therapy. Gene therapy is an advanced technique protein kinase known as PSTOL1 (phosphorus starvation with therapeutic potential in health services. The first success- tolerance1) help in enhancing root growth in early stages ful report in field of gene therapy to treat a genetic disease and tolerates phosphorus deficiency. Overexpression provided a more secure direction toward curing the deadliest of this enzyme enables root to uptake nutrients in suffi- genetic diseases [62, 63]. This strategy shows good response cient amount in phosphorus deficient soil which ultimately in providing treatment for adenosine deaminase-deficiency enhances the grain yield. Chloroplast genome sequences (ADA-SCID), which is a primary immunodeficiency. At the are important in plant evolution and phylogeny. Rpl22 is beginning of this technology, several challenges including considered to be transferred from chloroplast into nuclear maintenance of patients on PEGylated ADA (PEG-ADA) genome. This gene contains a peptide which plays role in during gene therapy and the targeting of gene transfer to delivery of protein from cytosol to chloroplast. A number of T-lymphocytes were the reasons for unsuccessful results important genes deleted from chloroplast have been observed [64, 65]. However, later on successful results were obtained to be transferred into nucleus, except ycf1 and ycf2, in order by targeting haematopoietic stem cells (HSCs) by using to avoid disruptions in photosynthesis and other necessary an improved gene transfer protocol and a myeloablative processes. Trans-genesis into chloroplast is considered stable conditioning regime. as the nuclear transgenic plants face the problems of lower Adrenoleukodystrophy (X-ALD) and X-linked disorder expression and transgene escape via pollen. Almost ten are is possible through the expression of specific genes thousand copies of transgenes have been incorporated into transferred by lentiviral vector, based on HIV-1. X- the genome of chloroplast [55–57]. Transgene expression is ALD protein expression indicates that gene-correction of dependent on heterologous regulatory sequences but inde- true HSCs was achieved successfully. The use of lentivi- pendent of cellular control. T7gene10 engineering against salt ral vector was made successful for the first time to treat stress has been found successful but with lower expression genetic human disease. Metastatic melanoma was treated rate into nongreen tissues. 𝛾-tmt gene insertion into chloro- through immunotherapy by enhancing the specific proteins plast genome results in multiple layer formation of the inner expression during 2006. This success in the field of health chloroplast envelope. Lycopene 𝛽-cyclase genes introduction sciences opened up new doors to extend the research to treat into the plastid genome of tomato enhances the lycopene serious death causing diseases through immunotherapy. conversion into provitamin A [57, 58]. Highly sustained levels of cells that were engineered for tumor Organ or tissue specific genes identification can be carried recognition in blood using a retrovirus encoding a T-cell out through gene expression profiles. cDNAs with full lengths receptor in two patients up to 1 year after infusion resulted are the main resources for expression profiling of genes. 44 K in regression of metastatic melanoma lesions. This strategy Agilent Oligonucleotide microarray is used for field grown was later used to treat patients with metastatic synovial cell rice transcriptome analysis. Gene expression fluctuation and carcinoma. Autologous T-cells were genetically modified transcriptome dynamics can be predicted by transcriptomic to express a Chimeric Antigen Receptors (CAR) with speci- data and meteorological information. These processes and ficity for the B-cell antigen CD19 for the treatment of chronic predictions are helpful to improve crop production and lymphocytic leukemia. Genetically modified cells undergo International Journal of Genomics 7 selective expansion for diseases such as SCID-X1 and ADA- by gene therapy. Metastatic cancer can be regressed SCID as a consequence of in vivo selection conferred by the through immunotherapy based on the adoptive transfer disease pathophysiology despite the correction of only a mod- of gene-engineered T-cells. Accurate targeting of antigens est number of progenitors. Combination of gene and drug expressed by tumors and the associated vasculature and the therapy’s potential has recently been highlighted in a trial successful use of gene engineering to retarget T-cells before seeking to confer chemoprotection on human HSCs during their transfer into the patient are mainly focused on in this chemotherapy with alkylating agents for glioblastoma. therapy. Cancer cells often make themselves almost Gene transfer to a small number of cells at anatomically “invisible” to the immune system and its microenvironment discrete sites is a targeted strategy that has the potential to suppresses T-cells survival and migration but genetic engi- confer therapeutic benefit. It showed impressive results for neering of T-cells is the solution to these challenges. T- incurable autosomal recessive dystrophies such as congenital cells in cancer patients can be modified by recombining the blindness and Leber congenital amaurosis (LCA). Swiss– genes responsible for cancer-specific antigens recognition, German phase I/II gene therapy clinical trial aimed to treat resistance to immunosuppression, and extending survival chronic granulomatous disease in April 2006 that came and facilitating migration to tumors. Fusion between up with success. Mobilized CD34+ cells isolated from the genes echinoderm microtubule-associated protein like peripheral blood were retrovirally transduced and infused 4 (EML4) and anaplastic lymphoma kinase (ALK) is gen- into the patient where two-thirds of the patients showed clear erated by an inversion on the short arm of chromosome benefit from this treatment. After the treatment silencing of confers sensitivity to ALK inhibitors. Vial-mediated delivery the transgene as a result of methylation of the viral promoter of the CRISPR/Cas9 system to somatic cells of adult animals caused the severity of infection that leaded to the death of induces specific chromosomal rearrangements. patient. Wnt signaling is one of the key oncogenic pathways in Many different cancers including lung, gynecological, multiple cancers. Targeting the Wnt pathway in cancer is skin, urological, neurological, and gastrointestinal tumors, an attractive therapeutic approach, where LGK974 potently as well as hematological malignancies and pediatric tumors, inhibits Wnt signaling, has strong efficacy in rodent tumor have been targeted through gene therapy. Inserting tumor models, and is well-tolerated. Head and neck cancer cell suppressor genes to immunotherapy, oncolytic virotherapy lines with loss-of-function mutations in the Notch signaling and gene directed enzyme prodrug therapy are different pathway have a high response rate to LGK974. Codon- strategies that have been used to treat different types of optimized gene, on the basis of coding sequence of the cancers. The p53, a commonly transferred tumor suppressor influenza virus hemagglutinin gene, was synthesized and gene, is a key player in cancer treating efforts. In some of the cloned into a recombinant modified vaccinia virus Ankara strategies, p53 gene transfer is combined with chemotherapy (MVA). Immunization with MVA-H7-Sh2 viral vector in or radiotherapy. The most important strategies that have been ferrets proved to be immunogenic as unprotected animals employed until now are vaccination with tumor cells engi- that were mock vaccinated developed interstitial pneumonia neered to express immunostimulatory molecules, vaccina- and loss of appetite and weight but vaccination with MVA- tion with recombinant viral vectors encoding tumor antigens H7-Sh2 protected the animals from severe disease. Viral and vaccination with host cells engineered to express tumor gene therapy is one of the leading and important therapies for antigens. New fiber chimeric oncolytic adenoviruses head and neck cancer. Tumor-associated genes are targeted vectors (Ad5/35-EGFP) offer an affective new anticancer by viruses, and p53 gene function was targeted through agent for the better cure of hepatocellular carcinoma. A such therapy at first. Cancer cells can be destroyed by demonstration of these vectors through proper assaying was oncolytic viruses through viral replication and by arming significant for transduction improvement and more progeny with therapeutic transgenes. of the virus were produced in HCC. A higher level of trans- High density lipoprotein gene ABCA1 mutation in cells genic expression was mediated and an enhanced antitumor can make the cells be differentiated into macrophages. Gene effect was observed on in vitro HCC cells while keeping the knockouts in embryonic stem cells enhance the capability of normal cells protected against cytotoxicity. Tumor growth cells to be differentiated into macrophages and specifically was also inhibited by utilizing this technology. Cancer target the desired pathogens. The allele replacements in this gene therapy has become more advanced and its efficacy has case will assist in studying protein coding changes and regu- been improved in recent years. latory variants involved in alteration of mRNA transcription Treatment of cardiovascular diseases by gene therapy is an and stability in macrophages. important strategy in health care science. In cardiovascular field, gene therapy will provide a new avenue for therapeutic 4.2.2. Production of Antibodies and Their Derivatives. Plant angiogenesis, myocardial protection, regeneration and repair, systems have been recently used for the expression and prevention of restenosis following angioplasty, prevention of development of different antibodies and their derivatives. bypass graft failure, and risk-factor management. Mutation in Most importantly, out of many antibodies and antibody gene encoding WASP, a protein regulating the cytoskeleton, derivatives, seven have reached to the satisfactory stages causes Wiskott-Aldrich Syndrome (inherited immunodefi- of requirements. Transgenic tobacco plants can be used ciency). Its treatment requires stem cells transplantation; in for the production of chimeric secretory IgA/G known as case matched donors are unavailable the treatment is carried CaroRx, CaroRx. Oral pathogen responsible for decay of a out through infusion of autologous HSPCs modified ex vivo tooth known as Streptococcus mutants, can be recognized 8 International Journal of Genomics by this antibody. A monoclonal antibody called T84.66 can 4.2.5. Chinese Medicines. As an important component of affectively function to recognize antigen carcinoembryonic, alternative medicine, traditional chines medicines play a which is still considered an affectively characterized marker crucial role in diagnostics and therapeutics. These medicines in cancers of epithelia [84, 85]. A full-length humanized associated with theories which are congruent with gene IgG1 known as anti-HSV and anti-RSV, which can function therapy principle up to some extent. These drugs might as the recognizing agent for herpes simplex virus (HSV)-2- be the sources of a carriage of therapeutic genes and as glycoprotein B, has been expressed in transgenic soybean and coadministrated drugs. Transgenic root system has valuable Chinese Hamster Ovary (CHO) cells. Antibodies from both potential for additional genes introduction along with the sources have been shown to prevent vaginal HSV-2 transmis- Ri plasmid. It is mostly carried with modified genes in sion in mice after applying topically; if worked similarly in A. rhizogenes vector systems to enhance characteristics for humans it would be considered as inexpensive and affective specific use. The cultures became a valuable tool to study prevention against diseases transmitted through sexual inter- the biochemical properties and the gene expression profile actions [86–88]. 38C13 is scFv antibody based on the idiotype of metabolic pathways. The intermediates and key enzymes of malignant B lymphocytes in the well-characterized mouse involved in the biosynthesis of secondary metabolites can be lymphoma cell line 38C13. Administration of the antibody to elucidated by the turned cultures [96, 97]. mice resulted in the production of anti-idiotype antibodies that are able to recognize 38C13 cells, which help to protect 4.2.6. Medically Important Compounds in Berries. Improve- the mice against with injected lymphoma cells, is a lethal ment in nutritional values of strawberries has been carried challenge [89, 90]. Unique markers recognizing enzymes through rolC gene. This gene increases the sugar content and could be produced through this system, most affectively the antioxidant activity. Glycosylation of anthocyanins requires surface markers of a malignant B-cells to work as an effective two enzymes glycosyl-transferase and transferase. Some therapy for non-Hodgkin lymphoma like diseases in human nutrition related genes for different components in straw-. A monoclonal antibody known as PIPP is specific for berry including proanthocyanidin, l-ascorbate, flavonoid, human chorionic gonadotropin recognition. The production polyphenols, and flavonoid are important for improving of full-length monoclonal antibody and scFv and diabody the component of interest through genetic transformation. derivatives was made possible in plants through transgenesis In case of raspberry, bHLH and FRUITE4 genes control and agroinfiltration in tobacco transformed transiently. the anthocyanin components whereas ERubLRSQ072H02 is Testosterone production by stimulated hCG can be inhibited related to flavonol. By specific transformation, these genes by each of these antibodies in cells cultured by LEYDIG and can enhance the production and improve the quality. All uterine weight gain could be delayed in mice, through which these mentioned compounds have medical values. hCG activity is checked. Diagnosis and therapy of tumors can be carried out with the help of antibodies. 4.3. Environment. Genetic engineering has wide applications in solving the environmental issues. The release of genetically 4.2.3. Investigation of the Drug Metabolism. Complex sys- engineered microbes, for example, Pseudomonas fluorescens tem of drug metabolizing enzymes involved in the drug strain designated HK44, for bioremediation purposes in metabolism is crucial to be investigated for the proper efficacy the field was first practiced by University of Tennessee and and effects of drugs. Recombinant DNA approaches have Oak Ridge National Laboratory by working in collabora- recently contributed its role through heterologous expression, tion [99, 100]. The engineered strain contained naphthalene where the enzyme’s genetic information is expressed in vitro catabolic plasmid pUTK21 and a transposon-based or in vivo, through the transfer of gene [92, 93]. bioluminescence-producing lux gene fused within a pro- moter that resulted in improved naphthalene degradation 4.2.4. Development of Vaccines and Recombinant Hormones. and a coincident bioluminescent response. HK44 serves Comparatively conventional vaccines have lower efficacy and as a reporter for naphthalene bioavailability and biodegra- specificity than recombinant vaccine. A fear free and painless dation whereas its bioluminescence signaling ability makes technique to transfer adenovirus vectors encoding pathogen it able to be used as an online tool for in situ monitoring antigens is through nasal transfer which is also a rapid and of bioremediation processes. The production of biolu- protection sustaining method against mucosal pathogens. minescent signal is detectable using fiber optics and photon This acts as a drug vaccine where an anti-influenza state can counting modules. be induced through a transgene expression in the airway. In vitro production of human follicle-stimulating hor- 4.3.1. Phytoremediation and Plant Resistance Development. mone (FSH) is now possible through recombinant DNA tech- Genetic engineering has been widely used for the detection nology. FSH is considerably a complex heterodimeric protein and absorption of contaminants in drinking water and and specified cell line from eukaryotes has been selected other samples. For example, AtPHR1 gene introduction into for its expression. Assisted reproduction treatment through garden plants Torenia, Petunia, and Verbena changed their stimulating follicular development is an achievement of ability for Pi absorption. The AtPHR1 transgenic plants with recombinant DNA technology. A large number of patients enhanced Pi absorption ability can possibly facilitate effective are being treated through r-FSH. Most interestingly r-FSH phytoremediation in polluted aquatic environments. A and Luteinizing Hormone (LH) recombination was made fragment of the AtPHR1 gene was inserted into binary vector successful to enhance the ovulation and pregnancy [94, 95]. pBinPLUS, which contains an enhanced cauliflower mosaic International Journal of Genomics 9 virus 35S promoter. This plasmid was named pSPB1898 and the carbon energy sources harmless to environment. This was used for transformation in Petunia and Verbena approach has been successful for vast range of commodity using Agrobacterium tumefaciens. AtPHR1 is effective chemicals, mostly energy carriers, such as short chain and in other plant species, such as Torenia, Petunia, and Verbena medium chain alcohols. but posttranscriptional modification of the endogenous The conductive biofilms of Geobacter sulfurreducens are AtPHR1 counterpart might be inhibited by overexpression of potential sources in the field in renewable energy, bioreme- AtPHR1. diation, and bioelectronics. Deletion of PilZ genes encoding Plant metabolism processes identify their importance to proteins in G. sulfurreducens genome made the biofilm more use for remediating the environmental pollutants. Some of active as compared to wild-type. CL-1ln is specified for the chemicals are not prone to be degraded or digested. the strain in which the gene GSU1240 was deleted. Biofilm TNT is only partially digested in which the nitrogen production was enhanced along with the production of pili further reacts with oxygen to form toxic superoxide. To and exopolysaccharide. The electron acceptor CL-1 produced overcome this issue, the gene responsible for monodehy- biofilms that were 6-fold more conductive than wild-type droascorbate reductase is knocked out which increases the biofilms when they were grown with electrode. This high fold plant tolerance against TNT. Fine-tuning enzymatic activ- conductivity lowered the potential losses in microbial fuel ity and knockout engineering together enhance the plant cells, decreasing the charge transfer resistance at the biofilm- responses to toxic metals. Phytochelatin synthase, a heavy anode surface and lowering the formal potential. Potential metal binding peptides synthesizing enzyme, revealed a energy was increased by lower losses. way to enhance tolerance against heavy metals through enzymatic activity attenuation. Recombinant DNA 5. Current Challenges and Future Prospects technology has proven to be effective in getting rid of arsenic particles that are considered as serious contaminants The fact that microbial cells are mostly used in the production in soil. PvACR3, a key arsenite [As(III)] antiporter was of recombinant pharmaceutical indicates that several obsta- expressed in Arabidopsis which showed enhanced toler- cles come into their way restricting them from producing ance to arsenic. Seeds of plants genetically engineered with functional proteins efficiently but these are handled with PvACR3 can germinate and grow in the presence of higher alterations in the cellular systems. Common obstacles which than normal quantity of arsenate [As(V)] which are generally must be dealt with are posttranslational modifications, cell lethal to wild-type seeds. Arsenic (As) is reduced by As stress responses activation, and instability of proteolytic reductase present in A. thaliana. Phytochelatins restrict the activities, low solubility, and resistance in expressing new arsenic movement in root cells and phloem companion genes. Mutations occurring in humans at genetic levels cells. OsNramp5 and OsHMA3 represent the transporters cause deficiencies in proteins production, which can be to uptake cadmium (Cd) and its retention. In plants, altered/treated by incorporation of external genes to fill the brassino-steroid (BR) is involved in regulating physiological gaps and reach the normal levels. The use of Escherichia and developmental processes. Its activity is started with coli in recombinant DNA technology acts as a biological triggering phosphorylation or dephosphorylation cascade framework that allows the producers to work in controlled. ways to technically produce the required molecules through Recent biotechnological approaches for bioremedia- affordable processes [41, 116]. tion include biosorption, phytostabilization, hyperaccumula- Recombinant DNA research shows great promise in tion, dendroremediation, biostimulation, mycoremediation, further understanding of yeast biology by making possible cyanoremediation, and genoremediation, which majorly the analysis and manipulation of yeast genes, not only in depend on enhancing or preventing specified genes activities. the test tube but also in yeast cells. Most importantly, it is However, the challenges in adopting the successful technique now possible to return to yeast by transformation with DNA cannot be ignored. and cloning the genes using a variety of selectable marker systems developed for this purpose. These technological 4.3.2. Energy Applications. Several microorganisms, specifi- advancements have combined to make feasible truly molec- cally cyanobacteria, mediate hydrogen production, which is ular as well as classical genetic manipulation and analysis in environmental friendly energy source. The specific produc- yeast. The biological problems that have been most effectively tion is maintained by utilizing the required enzymes properly addressed by recombinant DNA technology are ones that as these enzymes play a key role in the product formation. But have the structure and organization of individual genes as advanced approaches like genetic engineering, alteration in their central issue [117, 118]. Recombinant DNA technol- nutrient and growth conditions, combined culture, metabolic ogy is recently passing thorough development which has engineering, and cell-free technology [110–112] have shown brought tremendous changes in the research lines and opened positive results to increase the hydrogen production in directions for advanced and interesting ways of research for cyanobacteria and other biofuels [3, 4]. The commercial- biosynthetic pathways though genetic manipulation. Acti- ization of this energy source will keep the environment nomycetes are being used for pharmaceutical productions, clean which is not possible by using conventional energy for example, some useful compounds in health sciences and sources releasing CO2 and other hazardous chemicals. the manipulation of biosynthetic pathways for a novel drugs Also cyanobacteria can be engineered to make them able to generation. These contribute to the production of a major part convert of CO2 into reduced fuel compounds. This will make of biosynthetic compounds and thus have received immense 10 International Journal of Genomics considerations in recombinant drugs designing. Their com- plants can cross-breed with wild plants, thus spreading their pounds in clinical trials are more applicable as they have “engineered” genes into the environment, contaminating our shown high level activity against various types of bacteria biodiversity. Further, concerns exist that genetic engineering and other pathogenic microorganisms. These compounds has dangerous health implications. Thus, further extensive have also shown antitumor activity and immunosuppressant research is required in this field to overcome such issues and activity. resolve the concerns of common people. Recombinant DNA tech as a tool of gene therapy is a source of prevention and cure against acquired genetic Competing Interests disorders collectively. DNA vaccines development is a new approach to provide immunity against several diseases. In The authors declare that there is no conflict of interests this process, the DNA delivered contains genes that code for regarding the publication of this paper. pathogenic proteins. Human gene therapy is mostly aimed to treat cancer in clinical trials. Research has focused mainly on high transfection efficacy related to gene delivery system Authors’ Contributions designing. Transfection for cancer gene therapy with minimal Suliman Khan, Muhammad Wajid Ullah, and Ghulam Nabi toxicity, such as in case of brain cancer, breast cancer, lung contributed equally to this work. cancer, and prostate cancer, is still under investigation. Also renal transplantation, Gaucher disease, hemophilia, Alport syndrome, renal fibrosis, and some other diseases are under Acknowledgments consideration for gene therapy. The authors are thankful to Chinese Academy of Science and The World Academy of Science (CAS-TWAS) scholarship 6. Conclusions program. The corresponding author is thankful to Xuan H. 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