ldhc expression in non-germ cell nuclei is repressed by NF-I binding.
Developmental and testis-specific expression of the mouse lactate dehydrogenase C (mldhc) gene requires mechanisms for activation in germ cells and repression in somatic cells. Promoter activity restricted to the testis has been demonstrated using in vitro transcription assays with a 60-base pair promoter sequence upstream of the transcription initiation site. This promoter fragment has a TATA box and an overlapping 31-base pair palindromic sequence. Here we have explored the role of the palindrome as a silencer of the ldhc gene in somatic tissues. A gel retardation assay detected two sites within the palindrome that were important for protein binding. A member of the NF-I/CTF family was identified as the protein binding to one of the sites. In transiently transfected mouse L cells, a promoter fragment in which the NF-I site was mutated showed a 4-fold greater activity as compared with the wild-type sequence. Overexpression of the four NF-I proteins, NF-IA, -B, -C, or -X, in mouse L cells transiently transfected with an ldhc promoter-reporter construct resulted in a 20-50% decrease in activity of the wild-type promoter but had no effect when the NF-I binding element in the palindrome was mutated. These results indicate a role for the NF-I proteins in regulation of the mldhc gene.
Jethanandani
P
P
Department of Biochemistry, Molecular Biology and Cell Biology, Northwestern University, Evanston, Illinois 60208-3500, USA.
Goldberg
E
E
D000818:Animals; D001483:Base Sequence; D022762:CCAAT-Enhancer-Binding Proteins / Q000378:metabolism*; D002467:Cell Nucleus / Q000201:enzymology*; D004247:DNA; D015971:Gene Expression Regulation, Enzymologic; D005854:Germ Cells / Q000201:enzymology; D007527:Isoenzymes / Q000235:genetics*; D007770:L-Lactate Dehydrogenase / Q000235:genetics*; D008099:Liver / Q000378:metabolism; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D051839:NFI Transcription Factors; D011485:Protein Binding; D013737:Testis / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism*
D022762:CCAAT-Enhancer-Binding Proteins; C077305:CTF-1 transcription factor; D007527:Isoenzymes; D051839:NFI Transcription Factors; D014157:Transcription Factors; D004247:DNA; D007770:L-Lactate Dehydrogenase; C409673:lactate dehydrogenase C4