MODULATION OF PROTEIN-SYNTHESIS BY EXTRACELLULAR-MATRIX - POTENTIAL INVOLVEMENT OF 2 NUCLEOLAR PROTEINS, NUCLEOLIN AND FIBRILLARIN

Fibroblasts cultivated in a collagen matrix exhibit a large decrease i n the synthesis of most proteins. depending on transcriptional and pos ttranscriptional controls. Wt have previously shown that ribosomal RNA content and half-life wc rr decreased in collagen lattice cultures. H ere, we cultivated human dermal fibroblasts in monolayers and in latti ces and studied by competitive RT-PCR analysis the expression of the n ucleolar proteins nucleolin and fibrillarin, two key factors in riboso me processing and association. Nucleolin expression was found increase d, and fibrillarin expression decreased, in collagen-lattice vs monola yer-cultured fibroblasts, with some variability according to the strai ns (+25 to +250% and -40 to -60%, respectively). These data suggest th at a possible trouble of the association between neosynthesized rRNA a nd nucleolar proteins is, at least partly, responsible for the inhibit ion of protein synthesis induced by the extracellular matrix. (C) 1996 Academic Press, Inc.