Identification of a candidate c-mos repressor that restricts transcription of germ cell-specific genes.
The c-mos proto-oncogene is specifically expressed in female and male germ cells. Previous studies identified a negative regulatory element (NRE) upstream of the c-mos promoter that suppresses c-mos transcription in transfected NIH 3T3 cells. In this study, we used gel shift assays to detect proteins in nuclear extracts of NIH 3T3 cells that bind to the c-mos NRE in a sequence-specific manner. One protein was found to bind to a region of the NRE which was shown by site-directed mutagenesis to be required for suppression of c-mos transcription. This factor was present in nuclear extracts of several somatic cell lines and tissues but not in male germ cells in which c-mos is transcribed, suggesting that it is a somatic cell repressor of c-mos transcription. The binding site of the candidate repressor within the c-mos NRE consists of sequences related to putative NREs identified in two other male germ cell-specific genes (encoding protamine 2 and phosphoglycerate kinase 2). The c-mos repressor bound and could be UV cross-linked to these protamine 2 and phosphoglycerate kinase 2 gene sequences as a protein with an apparent molecular mass of approximately 30 kDa. The repressor binding site is also conserved in two other germ cell-specific genes (encoding testis-specific cytochrome c and heat shock-like protein 70), suggesting that the c-mos repressor may be generally involved in suppressing transcription of germ cell-specific genes in somatic cells.
Xu
W
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Division of Molecular Genetics, Dana-Farber Cancer Institute, Boston, Massachusetts 02115, USA.
Cooper
G M
GM
D016475:3T3 Cells; D000818:Animals; D001483:Base Sequence; D002457:Cell Extracts; D002467:Cell Nucleus / Q000378:metabolism; D016384:Consensus Sequence / Q000235:genetics; D003574:Cytochrome c Group / Q000235:genetics; D004247:DNA / Q000378:metabolism; D005260:Female; D016258:Genes, mos / Q000235:genetics*; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D008970:Molecular Weight; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics; D011479:Protamines / Q000235:genetics; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics*; D012097:Repressor Proteins / Q000737:chemistry / Q000378:metabolism*; D013094:Spermatozoa / Q000378:metabolism*; D014158:Transcription, Genetic / Q000235:genetics*
D002457:Cell Extracts; D003574:Cytochrome c Group; D018840:HSP70 Heat-Shock Proteins; D011479:Protamines; D012097:Repressor Proteins; C068621:protamine 2; D004247:DNA; D017853:Phosphotransferases (Alcohol Group Acceptor); C020670:glycerate kinase