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14 Cards in this Set
- Front
- Back
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What is the basal lamina?
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A thin flexible mat of specialized ECM components that underlie all epithelial cells.
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What is a basement membrane?
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A composite of basal lamina and the underlying connective tissue to which it is tethered.
It is synthesized by the cells that rest on it. |
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What are the 4 major components of all basement membranes?
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Laminin
type VI collagen perlecan nidogen They all interact with each other. These interacts are important in function. |
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What is the function of laminin?
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Binds to other ECM molecules in the basement membrane such as type IV collagen, nidogen and perlecan
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How does the polymerization of laminin and type IV collagen come about?
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This occurs via cell surface receptors of the integrin family
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What is type IV collagen?
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Non-fibrillar collagen that forms multi-layered sheets
Triple helical regions are interrupted by non-collagenous regions that impart flexibility. |
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Describe the assembly of type IV collagen.
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Rapid head to head association of C-terminal globular domains
Lateral association of above to form sheet like mesh Slow interactions among N-termini that protrude above the below the plane of the mesh to facilitate the formation of a stacked, multi-layered mesh network of type IV collagen molecules. |
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What does a mutation in the genes for Type IV collagen cause?
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Alports syndrome
The kidney glomerular basement membrane structure is compromised because there is little or no type IV collagen to form the mesh-like network necessary for the filtration function of the kidney. Patients present with hematuria , proteinuria and end stage renal failure |
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What is perlecan?
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A heparan sulfate proteoglycan that acts as a co-receptor for basic fibroblast growth factor
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A mutation in the perlecan genes results in this
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Severe skeletal phenotypes such as dyssegmental dysplasia
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What are the two major skeletal dysplasia's caused by mutations in perlecan?
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Schwartz-jampel syndrome and Silverman-Handmaker syndrome (dyssegmental dysplasia)
These result in protein truncation SJS = some functional perlecan is present SHS = No perlecan is secreted but degraded intracellulary |
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What is Nidogen?
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A sulfated glycoprotein that forms a bond with laminin.
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What is its function?
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It serves as a bridge between laminin and collagen type IV
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Despite the widespread occurrence of the nidogen in basement membranes, the role of nidogen 1 in the formation or maintenance of basement membranes is still unclear. When nidogen 1 and 2 were knocked out, what occurred?
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resulting animals had skeletal anomalies and derangement in limb development. No diseases have been attributed to mutations in nidogen 1 or 2
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