Laminin membranes, figure

The brain develops and functions within a strictly controlled environment resulting from the coordinated action of different cellular interfaces located between the blood and the extracellular fluids (interstitial fluid and the cerebrospinal fluid (CSF)) of the brain (Strazielle and Ghersi-Egea, 2013). The barrier between the blood and the brain or spinal cord parenchyma proper, referred to as the BBB, is formed by the endothelium of the cerebral micro vessels. Several layers exist between the blood and brain capillary endothelial cells, a basement membrane consisting of type IV collagen, fibronectin and laminin that completely cover the capillaries, pericytes embedded in the basement membrane, and glia/astrocytes that surroxmd the basement membrane (Figure 49.1). Each of these layers could potentially restrict the movement of solutes (Hawkins et al., 2006 Alvarez et al., 2013). 

While one end of the dystrophin molecule binds to actin filaments, the C-terminal domain associates with several additional proteins to form a dystrophin-glycoprotein complex (see figure)/1 k Dystrophin is linked directly to the membrane-spanning protein P-dystroglycan, which in the outer membrane surfaces associates with a glycoprotein a-dystroglycan. The latter binds to laminin-2 (Fig. 8-33), a protein that binds the cell to the basal lamina. Four... 

Figure 1. The muscle dystrophin-glycoprotein complex. The dystrophin-glycoprotein complex normally spans the plasma membrane of the skeletal muscle cell and may stabilize the sarcolemma and cytoskeleton to allow force transduction between the intracellular cytoskeleton (F-actin filaments) and the extracellular matrix. The molecules indicated are core components of the dystrophin-glycoprotein complex. Laminin 2 is the predominant laminin isoform in skeletal muscle basement membranes. Modified from McNeil and Steinhardt (2003)...

Finally, the matrix must be attached to the cell process and the canalicular wall in order for the drag force to be transmitted to the membrane and its underlying intracellular actin cytoskeleton. If such linker molecules are present, drag forces exerted on the matrix fibers will produce a tensile stress on these linker molecules that, in turn, will produce radial (hoop) strain in the intracellular actin cytoskeleton as schematically shown in Figure 6. Possible candidates for these attachment molecules are CD44, laminin, and various integrins. [64, 149],... 

Figure 2.29. Network structure of laminin in basement membranes. Basement membranes contain a laminin network that is covalently cross-linked to a type IV collagen network.

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