DIFFERERENTIAL CYTOKINE MODULATION OF THE GENES LAMA3, LAMB3, AND LAMC2, ENCODING THE CONSTITUTIVE POLYPEPTIDES, ALPHA-3, BETA-3, AND GAMMA-2, OF HUMAN LAMININ-5 IN EPIDERMAL-KERATINOCYTES

Laminin 5, an anchoring filament protein previously known as nicein/ka linin/epiligrin, consists of three polypeptide chains, alpha 3, beta 3 , and gamma 2, encoded by the genes LAMA3, LAMB3, and LAMC2, respectiv ely. The expression of laminin 5 was detected by Northern hybridizatio n with specific cDNA probes in various epidermal keratinocyte cultures , whereas no expression of any of the three genes could be detected in foreskin fibroblast cultures, Transforming growth factor-beta (TGF-be ta) enhanced LAMA3, LAMB3, and LAMC2 gene expression in human epiderma l keratinocytes, as well as in HaCaT and Balb/K cells in culture, alth ough the extent of enhancement was greater for LAMA3 and LAMC2 genes t han for LAMB3, interestingly, tumor necrosis factor-alpha, (TNF-alpha) alone did not alter the expression of LAMB3 and LAMC2 genes in human epidermal keratinocytes, whereas it inhibited the expression of LAMA3. These results suggest that the expression of the three genes encoding the laminin 5 subunits is not coordinately regulated by the cytokines tested.