3-DIMENSIONAL COLLAGEN LATTICE INDUCES PROTEIN-KINASE C-ZETA ACTIVITY- ROLE IN ALPHA(2) INTEGRIN AND COLLAGENASE MESSENGER-RNA EXPRESSION

A three-dimensional collagen lattice can provide skin fibroblasts with a cell culture environment that simulates normal dermis. Such a colla gen matrix environment regulates interstitial collagenase (type I meta lloproteinase [MMP-1], collagenase-1) and collagen receptor alpha(2) s ubunit mRNA expression in both unstimulated or platelet-derived growth factor-stimulated dermal fibroblasts (Xu, J., and R.A.F. Clark. 1996. J. Cell Biol. 132:239-249). Here we report that the collagen gel can signal protein kinase C (PKC)-zeta activation in human dermal fibrobla sts, An in vitro kinase assay demonstrated that autophosphorylation of PKC-zeta immunoprecipitates was markedly increased by a collagen matr ix, In contrast, no alteration in PKC-zeta protein levels or intracell ular location was observed. DNA binding activity of nuclear factor KB (NF-kappa B), a downstream regulatory target of PKC-zeta, was also inc reased by fibroblasts grown in collagen gel. The composition of the NF -kappa B/Rel complexes that contained p50, was not changed, The potent ial role of PKC-zeta in collagen gel-induced mRNA expression of collag en receptor alpha(2) subunit and human fibroblast MMP-1 was assessed b y the following evidence. Increased levels of alpha(2), and MMP-1 mRNA in collagen gel-stimulated fibroblasts were abrogated by bisindolylma leimide GF 109203X and calphostin C, chemical inhibitors for PKC, but retained when cells were depleted of 12-myristate 13-acetate (PMA)-ind ucible PKC isoforms by 24 h of pre treatment with phorbol PMA. Antisen se oligonucleotides complementary to the 5' end of PKC-zeta mRNA se qu ences significantly reduced the collagen lattice-stimulated a, and MMP -1 mRNA levels. Taken together, these data indicate that PKC-zeta, a P KC isoform not inducible by PMA or diacylglycerol, is a component of c ollagen matrix stimulatory pathway for alpha(2) and MMP-1 mRNA express ion. Thus, a three-dimensional collagen lattice maintains the dermal f ibroblast phenotype, in part, through the activation of PKC-zeta.