Differential expression of mRNA coding for heparin-binding growth factor type 2 in XXXX cells.

@entity1 @entity1880 @entity957 @entity189 @entity540
The proliferation of normal @entity1 fibroblasts, keratinocytes, and melanocytes in vitro can be controlled by purified polypeptide growth factors and serum. We have studied the cellular expression of the heparin-binding growth factor type 2/basic fibroblast growth factor ( @entity540 / @entity540 ) gene to determine whether these cell types synthesize mRNA for this mitogen. Our results indicate that normal @entity1 fibroblasts synthesize four distinct mRNAs of 7.0, 3.7, 2.2, and 1.5 kilobases, which hybridize to a specific @entity540 / @entity540 cDNA probe. In fibroblasts, the level of all four of these transcripts increases dramatically (more than tenfold) within 4 hours of treatment of quiescent cells with fresh fetal bovine serum. Of the purified growth factors tested, transforming growth factor type-beta also increased @entity540 / @entity540 mRNA abundance, but not to the levels attained by serum treatment. Treatment of fibroblasts with @entity1880 before and during serum treatment blocked the ability of serum to induce the expression of the @entity540 / @entity540 gene. The gene is expressed at low levels in @entity1 fibroblasts rapidly growing in serum-free medium and at higher levels in cells rapidly growing in serum-containing medium. In contrast to fibroblasts, mRNA coding for @entity540 / @entity540 is undetectable in proliferating normal @entity1 keratinocytes, melanocytes, or mammary epithelial cells. Because keratinocytes and melanocytes proliferate in response to purified @entity540 / @entity540 , our results suggest that @entity540 / @entity540 may mediate the proliferation of epidermal cells through paracrine mechanisms involving stromal fibroblasts. Moreover, we have shown that a @entity1 @entity957 cell line (SCC-25) expresses mRNA coding for @entity540 / @entity540 , suggesting that the gene may become activated in some @entity189 .
