40 Questions
Which of the following best describes the composition of the extracellular matrix (ECM)?
A variety of specialized structures composed of secreted proteins and polysaccharides
What is the matrisome in relation to the extracellular matrix (ECM)?
The ensemble of proteins that compose the ECM itself and associated proteins that modify the ECM
In which part of the tissue are most animal cells embedded?
Extracellular matrix (ECM)
What is an example of one type of extracellular matrix (ECM) mentioned in the text?
Basal laminae (formerly called basement membranes)
Which component is crucial for tissue elasticity, especially in large arteries?
Elastin
Which proteoglycan is involved in the formation of collagen fibers and contributes to the filtration of plasma in the kidney?
Decorin
Which component forms giant complexes resembling a bottle brush under the electron microscope?
Aggrecans
Which enzyme degrades elastic fibers, releasing peptides that recruit monocytes and fibroblasts during the development of vascular diseases and cancers?
Elastase
Which component plays a role in regulating cell adhesion, embryonic development, blood clotting, and wound healing?
Fibronectin
Which factor plays a key role in the response of platelets to vascular injury by mediating thrombus formation?
Von Willebrand factor
Which component forms an elastic network to which cells and other ECM components bind in blood clots?
Fibrin
Which integral membrane proteoglycan contributes to the adhesive properties of focal contacts?
Syndecans
Which component is less abundant in tumor cells?
Fibronectin
Which component is a major ECM component of blood clots, promoting angiogenesis and thrombus formation?
Fibrin
Which enzyme mediates the dispersal process of clots by binding to fibrin?
Plasmin
Which component is involved in the response of platelets to vascular injury?
Von Willebrand factor
Which protein provides structural integrity, mechanical strength, and resilience in the extracellular matrix (ECM)?
Collagen
What is the role of matrix metalloproteinases in the extracellular matrix (ECM)?
Facilitate collagen degradation during wound healing
Which condition can result from mutations in collagen genes?
Ehlers-Danlos syndrome
What is the function of glycosaminoglycans (GAGs) in the extracellular matrix (ECM)?
Resist compressive forces
What is the role of hyaluronic acid in the extracellular matrix (ECM)?
Act as a lubricant in joints
Which component of the ECM cushions cells and binds extracellular molecules?
Proteoglycans
What effect does increased collagen cross-linking and deposition have during tumorigenesis?
Stiffens the ECM and promotes tumor progression
What is the function of the majority of extracellular matrices in adult organisms?
Slow turnover with the capacity to respond to changes such as injury
Which component of the ECM provides the basis for signals transmitted to cells by adhesion receptors?
Glycocalyx
What is the main function of elastin in the extracellular matrix (ECM)?
Contribute to tissue elasticity
What is the role of proteoglycans in the extracellular matrix (ECM)?
Cushion cells and bind extracellular molecules
Which ECM component varies in size and carbohydrate composition, with some having a molecular weight of about 3 million Da?
Proteoglycans
What is the main function of vWF in thrombus formation?
Mediating rapid thrombus formation at high shear rates
What is the role of ADAMTS13 in thrombus formation?
Cleaving vWF multimers to restrict their size and prevent excessive thrombus formation
How does vWF control angiogenesis?
By maintaining VEGF signaling at physiological levels
What influences stem cell fate in terms of differentiation?
ECM stiffness and topography
Which factor influences the division axis orientation of epithelial stem cells?
Spatial distribution of the ECM components
What happens when a stem cell has an elongated shape in terms of differentiation?
It is less likely to initiate differentiation
What is the main mediator of stem cell-ECM interactions?
Integrins
Which integrin is recognized as a marker for different cancer stem cells?
a6/ITGA6/ CD49f
What does integrin binding to basement membrane constituents promote in many stem cell types?
Asymmetric cell division
What role does integrin-mediated mechanotransduction play in stem cell responses?
Sensing biophysical cues from ECM and modulating cellular responses
What is the function of VWF in relation to VEGF signaling?
Maintaining VEGF signaling at physiological levels
What is the effect of increased collagen cross-linking and deposition during tumorigenesis?
Promotes tumor growth and metastasis
Study Notes
Extracellular Matrix: Key Components and Functions
- Glycocalyx is a polysaccharide-rich coat found on the plasma membrane of endothelial cells and the apical membrane of intestinal epithelial cells.
- The extracellular matrix (ECM) contains structural proteins, such as collagen, embedded in a gel-like polysaccharide ground, adhesion proteins, and proteoglycans that cushion cells and bind extracellular molecules.
- Collagen, the most abundant protein in the ECM, provides structural integrity, mechanical strength, and resilience.
- Mutations in collagen genes can lead to various conditions such as chondroplasia, osteogenesis imperfecta, Alport syndrome, Ehlers-Danlos syndrome, and dystrophic EB.
- Matrix metalloproteinases are involved in the necessary degradation of collagen during wound healing and remodeling.
- Increased collagen cross-linking and deposition during tumorigenesis can stiffen the ECM, disrupt tissue morphogenesis, and promote tumor progression.
- The composition and amount of ECM differ according to the function of the tissue, with bone being calcified for strength, cartilage resisting compression, and the dermis providing strength and elasticity.
- The majority of ECMs in adult organisms exhibit slow turnover, but they need to retain the capacity to respond to changes such as injury.
- The ECM is not exclusively structural; it provides the basis for signals transmitted to cells by adhesion receptors and acts as a reservoir for growth factors.
- Major bulk constituents of the ECM include glycosaminoglycans (GAGs), which are strongly negatively charged and can resist compressive forces.
- Hyaluronic acid, a nonsulphated GAG, acts as a lubricant in joints and facilitates cell migration in embryonic development and wound healing.
- Proteoglycans consist of sulphated GAGs covalently linked to a polypeptide chain and vary in size and carbohydrate composition, with some having a molecular weight of about 3 million Da.
Test your knowledge of the extracellular matrix (ECM) with this quiz. Explore key components such as collagen, proteoglycans, and glycocalyx, and learn about the functions of the ECM in tissue strength, resilience, and cellular signaling. Delve into the impact of ECM mutations and their association with various conditions, as well as the role of ECM in wound healing, tumorigenesis, and tissue morphogenesis.
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