CHARACTERIZATION OF THE MOUSE CYCLIN D3 GENE - EXON INTRON ORGANIZATION AND PROMOTER ACTIVITY/

The three D-type cyclins have been shown to be differentially expresse d in a number of cell types, suggesting that they play distinct roles in cell cycle regulation in particular cell lineages. We have determin ed the complete nucleotide sequence (-1681 to +6582) of the mouse cycl in D3 gene, which encodes a G1 phase cyclin. The gene consists of five exons and four introns, varying in length from 422 to 2472 bp. Primer extension analysis revealed one major transcription initiation site a t the position 107 bp 5' upstream of the translation start. The promot er region lacks both canonical ''TATA'' and ''CAAT'' boxes. It contain s, however, multiple transcription factor recognition sites, including multiple ''GC-rich'' sequences to which Spl factor binds and sequence s recognized by GATA, NF-kappa B, ATF, E2F, and TRE/AP1 transcription factors, E box binding myogenic factors, and the IL-6 induced-transcri ption factor, APRF. Promoter activity of the 1681-bp fragment upstream of the transcription initiation site was confirmed by linking it to a reporter gene and subjecting it to transient expression experiments i n various cell types. Promoter activity was high in cell lines that ex pressed high levels of endogenous D3 mRNA, as indicated by Northern bl ot analyses, and was significantly reduced when the promoter was trunc ated to -122 bp. The characterization of the mouse cyclin D3 gene and insight into its promoter region will allow further studies defining t he molecular events regulating the expression of this cyclin in prolif erating and quiescent cells. (C) 1996 Academic Press, Inc.