basallaminaatin

Basallaminaatin is a term used in some contexts to denote the basal lamina, the specialized extracellular matrix sheet that underlies most epithelia and endothelium and contributes to the basement membrane. The basal lamina is a thin, dense layer that separates epithelial or endothelial cells from the underlying connective tissue. It provides structural support, acts as a selective barrier, and influences cell behavior, polarity, migration, and differentiation.

Composition: It is primarily composed of laminin networks anchored to a scaffold of type IV collagen, with other constituents such as nidogen (entactin) and heparan sulfate proteoglycans like perlecan. The laminin and collagen IV networks are cross-linked by nidogen and proteoglycans to form a meshwork.

Synthesis and assembly: Epithelial and other basal cells secrete laminins and collagen IV, which assemble at the cell surface into a supramolecular network. Receptors on cells, including integrins and dystroglycan, bind to basal lamina components and mediate attachment and signaling.

Functions: The basal lamina serves as a foundation for tissue architecture, influences cell adhesion, polarization, proliferation, and differentiation, and guides cell migration during development and wound repair. In kidney glomeruli, the basal lamina functions as part of the filtration barrier.

Clinical relevance: Abnormal basal lamina structure or composition is associated with diseases such as Alport syndrome, certain forms of muscular dystrophy, diabetic nephropathy, and epidermolysis bullosa. Damage to the basal lamina also contributes to tumor invasion and metastasis by altering tissue barriers.

See also: basement membrane, laminin, type IV collagen, nidogen, perlecan.