Characterization and Expression of the Laminin γ3 Chain: A Novel, Non-Basement Membrane–associated, Laminin Chain

The Cutaneous Biology Research Center, Massachusetts General Hospital, and the Department of Dermatology, Harvard Medical School, Charlestown, Massachusetts 02129, USA.
The Journal of Cell Biology (Impact Factor: 9.69). 06/1999; 145(3):605-18.
Source: PubMed

ABSTRACT Laminins are heterotrimeric molecules composed of an α, a β, and a γ chain; they have broad functional roles in development and in stabilizing epithelial structures. Here, we identified a novel laminin, composed of known α and β chains but containing a novel γ chain, γ3. We have cloned gene encoding this chain, LAMC3, which maps to chromosome 9 at q31-34. Protein and cDNA analyses demonstrate that γ3 contains all the expected domains of a γ chain, including two consensus glycosylation sites and a putative nidogen-binding site. This suggests that γ3-containing laminins are likely to exist in a stable matrix.
Studies of the tissue distribution of γ3 chain show that it is broadly expressed in: skin, heart, lung, and the reproductive tracts. In skin, γ3 protein is seen within the basement membrane of the dermal-epidermal junction at points of nerve penetration. The γ3 chain is also a prominent element of the apical surface of ciliated epithelial cells of: lung, oviduct, epididymis, ductus deferens, and seminiferous tubules. The distribution of γ3-containing laminins on the apical surfaces of a variety of epithelial tissues is novel and suggests that they are not found within ultrastructurally defined basement membranes. It seems likely that these apical laminins are important in the morphogenesis and structural stability of the ciliated processes of these cells.

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Available from: Dale D Hunter, Aug 11, 2015
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    • "In the retina, where the vascular tree can be displayed as a sheet, it was clear γ3 was deposited in the micro-vascular and venous BMs, whereas the γ1 chain is distributed homogeneously. RT-PCR studies of various tissues, demonstrate that γ3 is not ubiquitously expressed, as it would were it expressed in all blood vessels (Koch et al, 1999). In contrast, it has been long appreciated that the β2 chain is widely expressed in the vascular system and spatially segregated (Sanes et al., 1990). "
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