Regulation of the nuclear gene that encodes the alpha-subunit of the mitochondrial F0F1-ATP synthase complex. Activation by upstream stimulatory factor 2.
We have previously identified several positive cis-acting regulatory regions in the promoters of the bovine and human nuclear-encoded mitochondrial F0F1-ATP synthase alpha-subunit genes (ATPA). One of these cis-acting regions contains the sequence 5'-CACGTG-3' (an E-box), to which a number of transcription factors containing a basic helix-loop-helix motif can bind. This E-box element is required for maximum activity of the ATPA promoter in HeLa cells. The present study identifies the human transcription factor, upstream stimulatory factor 2 (USF2), as a nuclear factor that binds to the ATPA E-box and demonstrates that USF2 plays a critical role in the activation of the ATPA gene in vivo. Evidence includes the following. Antiserum directed against USF2 recognized factors present in HeLa nuclear extracts that interact with the ATPA promoter in mobility shift assays. Wild-type USF2 proteins synthesized from expression vectors trans-activated the ATPA promoter through the E-box, whereas truncated USF2 proteins devoid of the amino-terminal activation domains did not. Importantly, expression of a dominant-negative mutant of USF2 lacking the basic DNA binding domain but able to dimerize with endogenous USF proteins significantly reduced the level of activation of the ATPA promoter caused by ectopically coexpressed USF2, demonstrating the importance of endogenous USF2 in activation of the ATPA gene.
Breen
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GA
Department of Molecular and Cell Biology, The University of Texas at Dallas, Richardson, Texas 75083-0688, USA. breen@utdallas.edu
Jordan
E M
EM
D000818:Animals; D002417:Cattle; D015500:Chloramphenicol O-Acetyltransferase / Q000096:biosynthesis; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins; D015971:Gene Expression Regulation, Enzymologic; D006367:HeLa Cells; D018257:Helix-Loop-Helix Motifs; D006801:Humans; D046911:Macromolecular Substances; D008928:Mitochondria / Q000201:enzymology*; D009838:Oligodeoxyribonucleotides; D010957:Plasmids; D011401:Promoter Regions, Genetic; D006180:Proton-Translocating ATPases / Q000096:biosynthesis* / Q000235:genetics*; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D012045:Regulatory Sequences, Nucleic Acid; D014157:Transcription Factors / Q000302:isolation & purification / Q000378:metabolism*; D051720:Upstream Stimulatory Factors
D004268:DNA-Binding Proteins; D046911:Macromolecular Substances; D009838:Oligodeoxyribonucleotides; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; C497181:USF1 protein, human; C497184:USF2 protein, human; D051720:Upstream Stimulatory Factors; D015500:Chloramphenicol O-Acetyltransferase; D006180:Proton-Translocating ATPases