NOVEL ZINC-FINGER PROTEINS THAT INTERACT WITH THE MOUSE GAMMA-F-CRYSTALLIN PROMOTER AND ARE EXPRESSED IN THE SCLEROTOME DURING EARLY SOMITOGENESIS

Lens-specific expression of the mouse gamma F-crystallin gene is deter mined, at least in part, by a 23-bp DNA element, the gamma F-1-binding motif, located in the promoter region of the gene. To characterize th e transcription factors that regulate gamma F-crystallin gene expressi on through this element, we have isolated three chicken cDNAs that enc ode proteins capable of binding specifically to the gamma F-1-binding motif. These three cDNAs represent differential splicing products from a single gene, gamma FBP. The protein isoforms encoded by two of thes e cDNAs differ in their ability to modulate the activity of promoters containing the gamma F-1-binding motif. Among them, gamma FBP-B functi ons as a transcriptional repressor in lens cells, and it's expression is developmentally regulated during lens development, suggesting a rol e for this isoform in the spatial regulation of gamma F-crystallin gen e expression. We also show that expression of the different mRNA trans cripts are differentially regulated in various tissues. Furthermore, g amma FBP transcripts are highly expressed in presomitic mesoderm and t hen over the entire epithelial somite. During semitic differentiation, gamma FBP expression becomes restricted to the sclerotome. These expr ession patterns suggest a regulatory role for the gamma FBP isoforms i n sclerotome specification and/or differentiation. (C) 1994 Academic P ress, Inc.