Myotonic Dystrophy Flashcards
What is Classical Laminin composed of?
α1 and α2 chains; β1 and β2 chains; and a γ1 chain.
What is Long Laminin composed of?
A α5 chain; β1 and β2 chains; and a γ1 chain.
Which Laminin type can self assemble?
Long Laminin.
What are the two function of Laminins?
1) They are the structural components of basement membranes.
2) They are attachment sites for cell surface receptors, such as dystroglycan and integrins.
What is the main causes Congenital Muscular Dystrophy?
Mutations of the laminin α2 chain, resulting in it’s partial or complete deficiency. Its deficiency will affect the functioning of Laminin.
How deficiencies in the α2 chain affect Laminin functioning?
The laminin will no longer be able to bind α-dystroglycan.
What is the dystrophin-glycoprotein complex (DGC)?
It is a multi-protein complex composed of dystroglycan, α, β, γ and δ sarcoglycan and sarcospan.
What does the dystrophin-glycoprotein complex (DGC) bind to?
It binds to laminin on the outside of the muscle cell and dystrophin on the inside of the cell.
What mediates the interaction of the dystrophin-glycoprotein complex (DGC) to its ligands?
β-Dystroglycan.
In some forms of Congenital muscular dystrophy, the α-dystroglycan is modified. What is the modification and what is the consequent effect?
It is hypoglycosylated, which makes it unable to bind to laminin.
What integrin type is mainly expressed in skeletal and cardiac muscle?
Integrin α7β1
A deficiency in what integrin can also give rise to Congenital Muscular Dystrophy and why?
Deficiencies in Integrin α7β1 in mice have shown to affect the myotendious junctions.
What causes Becker Muscular Dystrophy and Duchenne Muscular Dystrophy?
Dystrophin deficiency.
What is dystrophin?
A protein that connects the cytoskeleton of a muscle fibre to the extracellular matrix by binding to the actin cytoskeleton and β-Dystroglycan.
What are the three ways Muscular Dystrophies can be diagnosed?
1) Blood tests to test for Creatine kinase (CK) levels, which would be highly elevated.
2) Genetic testing to identify for faulty genes.
3) A muscle biopsy to analyse any changes in muscle histology.
