Molecular Biology and Genetics of Human Disease Summary PDF

Molecular Biology and Genetics of Human Disease Summary BMS 532 MOLECULAR BIOLOGY AND GENETICS BLOCK 4 LECTURE 6  Objectives Overall Goal: Understand the relationship between molecular and genetic changes in the development and/or progression of human disease 1. Compare and contrast genetic mu...

Molecular Biology and Genetics of Human Disease Summary BMS 532 MOLECULAR BIOLOGY AND GENETICS BLOCK 4 LECTURE 6  Objectives Overall Goal: Understand the relationship between molecular and genetic changes in the development and/or progression of human disease 1. Compare and contrast genetic mutation in germline cells vs. somatic cells 2. Compare and contrast molecular events in human disease with genetic predisposition 3. Define the following terms or concepts: gain of function, loss of function, protooncogene, oncogene, tumor suppressor gene, fusion gene/protein, hyperplasia, dysplasia, anaplasticity, benign, and malignant 4. Evaluate the relationship between molecular biology and development or progression in the following diseases or conditions: Asthma and COPD (COX-2), Male Infertility (DAZ), Metabolic Syndrome (Insulin signaling), Marfan Syndrome (TGF-β), Congenital Immunodeficiencies (BTK example), and Neoplasms ◦ Explain the role of signaling pathways in each disease ◦ Identify consequences for changes in terms of disease development or progression for the proteins or genes described for each condition (i.e. if the mutation causes a loss of function, be able to identify consequences of loss of function or gain of function) 5. Identify specific molecular and genetic changes that correspond with the following diseases or conditions: Asthma and COPD (COX-2), Male Infertility (DAZ), Metabolic Syndrome (Insulin signaling), Marfan Syndrome (TGF-β), X-linked Agammaglobulinemia (BTK), and Neoplasms LO1 Somatic vs. Germline Somatic ◦ All cells except reproductive cells (oocytes and spermatocytes) ◦ Changes can be acquired over the lifetime of the organism that do NOT pose a risk to offspring ◦ Mitotic nondisjunction and rearrangement play a role here Germline ◦ Oocytes and spermatocytes ◦ Changes in these cells are inheritable/pose a risk to offspring ◦ Meiotic nondisjunction plays a role here but early mitotic events are also relevant (particularly those in early gestation) LO2, LO4 Molecular Biology vs. Genetics Molecular Biology of Human Disease ◦ Interactions/cellular behaviors that promote or cause disease state ◦ Can involve genetic changes/mutation that most often will not be heritable in nature ◦ Some changes might even be catastrophic if inherited yet are perpetuated somatically because of additional changes ◦ Requires evaluation of biochemical properties or cellular behaviors Genetics of Human Disease ◦ Inherited or heritable changes that pose a risk to future generations ◦ Can involve the same or similar processes/genes as those in molecular biology; however, initiating event was inherited or is found in the germline (must have developed in gametogenesis or be present in the family) ◦ Changes in genes that are inherited = Predisposition or Inherited Risk for developing a particular condition Remember, gene changes/mutation are involved in both but the Genetics (with a capital G) means that the risk or condition was INHERITED LO4 Molecular Biology of Human Disease Molecular Biology is relevant to a wide range of human diseases: ◦ Respiratory Diseases ◦ Reproductive Disorders ◦ Metabolic Disorders ◦ Circulatory Diseases ◦ Neoplastic Diseases/Cancers ◦ Opportunistic Infections ◦ Musculoskeletal Disorders ◦ Sexually Transmitted Diseases ◦ Neuropsychiatric Disorders Many of the disorders and diseases associated with these categories are a mixture of inherited predispositions and acquired changes in somatic cells that alter molecular processes LO3, LO4 Potential Changes: Terminology Molecular and genetic changes can fall into two major categories based on their activity and relationship to disease ◦ Gain of Function ◦ Acquired increases in transcription or activity for a molecule ◦ Can be associated with a loss of regulation or can be a solo event that precipitates or contributes to disease generation ◦ Loss of Function ◦ Loss in transcription or activity for a molecule ◦ Typically associated with a regulatory function that is now lost as part of disease development or progression LO3, LO4 Potential Changes: Terminology Continued Gain of Function ◦ Protooncogene vs Oncogene Loss of Function ◦ Tumor Suppressor Gene Fusion genes/proteins ◦ Associated with dysregulated activity of the fused products These changes can develop somatically or can be inherited LO4, LO5 Respiratory Diseases: Asthma and COPD Chronic inflammation of the respiratory system is associated with both asthma and chronic obstructive pulmonary disease (COPD) Although both conditions are unique in many ways, there are underlying similarities in many patients Both are related to a combination of environmental and genetic factors with microRNAs of particular interest to both in recent years (multiple clinical trials have emphasized microRNAs for therapeutic intervention) Venn Diagram of microRNAs overlap in COPD and Asthma Ray A., Oriss TB, and Wenzel SE. (2015) Emerging Molecular Phenotypes of Asthma Szymczak I., Wiesczfinska J., and Pawliczak R. 2016 https://journals.physiology.org/doi/epdf/10.1152/ajplung.00070.2014 https://www.hindawi.com/journals/bmri/2016/7802521/ LO4, LO5 Cyclooxygenase and Chronic Inflammation The cyclooxygenase pathway is promoted in response to pro-inflammatory stimuli Cyclooxygenase (Cox-2) in particular is triggered and plays a role in both asthma and COPD development/progression ◦ Part of the rate-limiting step in prostaglandin production Environmental factors such as cigarette smoke can increase Cox-2 expression Stasinopoulos et al 2013. https://www.frontiersin.org/articles/10.3389/fphar.2013.00034/full LO4, LO5 Inherited Mutations in Cox-2 Mutations that cause pathogenic variations in COX-2 are associated with inherited deficiencies with multi-system abnormalities This includes certain mitochondrial disorders, increased risk of ischemic stroke, and neurodegenerative phenotype depending on the mutation When associated with a deficiency phenotype, the disorders are inherited in an autosomal recessive manner and are frequently loss of function mutations Cox-2 variations are also associated with increased risk for a variety of cancers ◦ COX-2 mutations in colorectal cancer are associated with poorer prognosis LO4, Connecting Back to Neurogenetics: LO5 Another implication for COX-2 Cox-2 has been explored in inflammatory and degenerative brain diseases for the last several years Evidence indicates a role for COX-2 in normal synaptic activity and plasticity with connections to key proteins such as beta- amyloid ◦ Connections to Nuclear Factor Kappa B (NF-kB): signaling through NF-kB can increase COX-2 expression and increase neuroinflammatory response More recent studies support a potential role for COX-2 in the development of Alzheimer’s Disease COX-2 inhibitors show promise as therapeutic interventions and merit additional exploration LO4, LO5 Male Infertility Approximately half of the roughly 15% of couples that experience infertility are due to issues of male infertility Genetics of Male Infertility: ◦ The most common cause of male infertility are microdeletions of key genes on the Y chromosome ◦ Azoospermia Region (AZF region) ◦ Subdivided into 3 subregions (AZFa, AZFb, and AZFc) ◦ These genes are associated with spermatogenesis ◦ May result in complete inability to generate viable sperm (azoospermia) Molecular Biology of Infertility: ◦ Loss of function for key genes such as deleted-in-azoospermia (DAZ) gene LO4, LO5 DAZ Activity in Spermatogenesis Relatively evolutionarily conserved gene with activity in multiple species 3D structure of this protein is critical to function Mutations in the gene disrupt the critical domains including the RNA binding domain and tandem repeat regions Have a key role in regulation of translation in the cytoplasm ◦ Indirectly responsible for regulation of differentiation, growth, and maturation of germ cells Paronetto MP and Sette C (2010) https://onlinelibrary.wiley.com/doi/full/10.1111/j.13 65-2605.2009.00959.x LO4, LO5 Molecular Biology of Metabolic Syndrome Metabolic Syndrome = combined occurrence of several risk factors ◦ Insulin resistance, obesity, hypertension, and atherogenic dyslipidemia (elevated triglycerides, elevated LDL and decreased HDL-C) Summarizes the pathophysiology of individuals at risk for cardiovascular disease and type 2 diabetes Altered Insulin Signaling and Insulin Resistance = major players in the development or progression of multiple diseases Insulin resistance can be linked to altered receptor expression and/or downregulation of tyrosine kinase activity of the receptor but is most correlated with altered activity of downstream players including: PI3K, IRS, and even GLUT-4 Wilcox G. Insulin and Insulin Resistance https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1204764/ LO4, LO5 Genetics of Metabolic Syndrome Multiple genes are likely contributing to the inherited risk of metabolic syndrome A study performed on 2,209 individuals identified 2 quantitative trait loci (QTLs) associated with the syndrome Candidate genes for inherited predisposition were found to include: ◦ Low density lipoprotein receptor (LDLR) ◦ Transforming Growth Factor Beta (TGF-β) ◦ Interleukin-6 (IL-6) ◦ Selectin E (SELE) The study that identified the 2 QTLs: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC18944/  LO4, LO5 Molecular Biology of Cardiovascular Disease Reactive oxygen species and alterations in signaling play key roles in the generation and progression of cardiovascular diseases ROS can directly increase signaling through TGF-β TGF- signaling is associated with cardiomyocyte apoptosis and cardiac hypertrophy TGF-β signaling has been associated with myocardial infarctions and ischemic injury ◦ TGF-β signaling increases in response to tissue injury with it having a role in tissue repair and scar formation TGF-β signaling leads to myofibroblast formation (transformation of fibroblasts) Liu et al. 2017. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5443237/pdf/etm-13-05- 2123.pdf LO4, LO5 Marfan Syndrome Rare, autosomal-dominant Multisystem disorder ◦ Skeletal, cardiovascular, skin, and ocular symptoms ◦ Overlaps with other connective tissue disorders Inherited Fibrillin 1 (FBN1) mutations Implications for TGF-β signaling as alterations to FBN1 lead to increased/dysregulated activation of TGF-β Human Mutation, Volume: 37, Issue: 6, Pages: 524- 531, First published: 26 February 2016, DOI: (10.1002/humu.22977) https://onlinelibrary.wiley.com/doi/epdf/10.1002/humu.22977 LO4, LO5 Congenital Immunodeficiencies Any inherited disorder in which immune system in part or entirety has improper or absent function Individually rare but collectively affect approximately 1/10,000 people worldwide ◦ Although the numbers vary greatly by region, some estimates raise this rate in the United States to 1/2,000 Updates and improvements in our understanding of these correlate with increased understanding and identification of the patient populations ◦ Physicians report an increase in both the diagnosis and treatment of primary immunodeficiencies Many of these conditions are heritable but others are not or have no clear patterns of inheritance Clinical presentations will often include multiple systems beyond the primary immune implications Given the diverse nature of these conditions, there is a wide range of clinical presentations Generally unifying themes can include: ◦ Severe/unusual infections EXAMPLE: ◦ Autoimmune and/or autoinflammatory diseases ◦ Predisposition to malignancies X-linked Agammaglobulinemia (XLA) LO4, LO5 X-linked Agammaglobulinemia (XLA) a.k.a. Bruton agammaglobulinemia X-linked recessive disorder; predominantly impacts males ◦ ~1 in 379,000 live births; 1 in 190,000 males Pathogenic mutations in the BTK gene encoding a B cell intracellular tyrosine kinase ◦ Member of the Tec Family of tyrosine kinases BTK is critical for maturation of pre-B cells into mature B cells Loss of function mutations account for the majority of pathogenic variants ◦ Over 900 variants in the gene have been identified (list continues to expand) ◦ Specific variants have been found to influence disease severity Patients become symptomatic within the first two years of life ◦ Recurrent bacterial infections ◦ Median age of diagnosis is 26 months LO4, LO5 Neoplasms/Cancer Changes in the production and behavior of key molecules are related to a wide range of neoplasms The overall themes of change were nicely summarized in a series of articles initiated by Hannahan and Weinberg (next section) Although these changes sometimes could be inherited, most were theresult of somatic changes over time = sporadic cancer The Genetics of cancer = inherited predispositions The molecular biology of cancer = molecular interactions that promote disease development and/or progression In order to fully comprehend the wide range of consequences and risks associated with cancer, a basic understanding of cancer is necessary… Check-in Questions A family is struggling with infertility and seek additional information from your clinic. Analysis of the male sperm identifies azoospermia. This indicates a loss of function mutation in DAZ associated with the AZFc region on chromosome Y. Evaluation of the male’s father did not indicate any issues with spermatogenesis. What could explain the mutation in the male? Increased signaling through which of the following pathways has been associated with a wide range of cardiovascular complications or diseases? A. MAP Kinase signaling B. TGF -B signaling C. Interleukin Signaling D. microRNAs The Hallmarks of Cancer MOLECULAR PROCESSES OF CANCER DEVELOPMENT AND PROGRESSION AS SUMMARIZED BY HANNAHAN AND WEINBERG Objectives 6. List and describe the hallmarks, emerging characteristics, and updated hallmarks of cancer cells 7. Explain how the hallmarks of cancer approach revolutionized modern cancer therapeutics 8. Compare and contrast the somatic mutation theory and the tissue organization field theory and explain how they relate to the limitations of the hallmarks of cancer approach 9. Assess the consequences for changes in the molecular characteristics of cells based on the specific hallmarks and genes discussed LO6 24 LO6 Emerging Hallmarks of Cancer 25 LO6, LO7 Targeting Hallmarks The hallmarks of cancer served as the foundation for much of the modern therapeutics utilized against cancer today Led to approaching cancer as a collective set of disorders with similar underlying themes that can be targeted instead of isolated diseases with unique attributes Modern personalized medicine maintains this concept and searches for specific mutations that can be targeted rather than applying generic treatments designed based on cancer type 26 LO6 UPDATE to Hallmarks (2021 and 2022 Papers) Ability of cells to “regress” ◦ DEDIFFERENTIATION ◦ Blocked Differnentiation Unlocking phenotypic plasticity Interactions from systemic cells and microorganisms (microbiome) ◦ Role of microorganisms ◦ Role of neuronal signaling Nonmutational Epigenetic Reprograming Epigenetic changes altering gene expression 27 LO8 Caveats to the Hallmarks of Cancer Relies on SOMATIC MUTATION THEORY and cell-centered variants ◦ Theory = accumulation of mutation is sole means of generating disease variations and progression Alternative theory: TISSUE ORGANIZATION FIELD THEORY ◦ Incorporates the premise that all cells exist in a state of motility and proliferation ◦ Carcinogenesis under this theory is the result of alterations in interactions between cells and their extracellular matrix ◦ Cancer = inappropriate development The reality of cancer lies somewhere in the middle ◦ The signals provided by the surrounding cells definitely contributes to disease ◦ Accumulation of mutation is essential for disease development and survival in the face of certain signals ◦ Cancer is a disease of development AND mutation accumulation 28 LO9 Linking Gene Changes to Hallmarks Each hallmark has the potential to serve as the initiating event for neoplasms; however, some hallmarks are more ubiquitous than others ◦ All cells need to achieve limitless replicative potential and there are only a few mechanisms through which this can be achieved Some chromosome level changes contribute to the activity of each hallmark ◦ How might additional copies of a chromosome contribute to cancer? ◦ How might too few copies contribute? This section will be expanded upon in the next lecture Check-in Question Which of the following hallmarks best explains a cell that no longer responds to death domain signaling induced by either intrinsic or extrinsic mechanisms? A. Self-sufficiency in growth signaling B. Limitless Replicative potential C. Insensitivity to anti-growth signals D. Evading apoptosis E. Sustained Angiogenesis Overall Summary Continuing Gene Charts… Condition/Syndrome Genes Implicated Description of Consequences/Disease Features Asthma and COPD COX-2 Male Infertility AZF regions and DAZ Metabolic Syndrome QUANTITATIVE with multiple genes LDLR, TGF-β, IL-6, SELE Marfan Syndrome FBN-1 with implications for TGF-β  Hallmark Explanation Gene Example Overall Evading Apoptosis Summary Self-sufficiency in growth signaling Insensitivity to anti-growth Hallmarks of Cancer signaling The last 2 columns will Sustained Angiogenesis be expanded upon in Limitless replicative potential future lectures Tissue Invasion and Metastasis Slide 23 contains a nice Deregulating cellular energetics summary of genes as therapeutic targets Genomic instability Avoiding immune distruction Tumor-promoting inflammation Cellular regression/de- differentiation Role of microbiome Unlocking Phenotypic Plasticity Nonmutational Epigenetic Epigenetic changes that Multiple genes Reprogramming influence gene expression