Yeast two-hybrid cloning of a novel zinc finger protein that interacts with the multifunctional transcription factor YY1.
Muscle-restricted transcription of sarcomeric actin genes is negatively controlled by the zinc finger protein YY1, which is down-regulated at the protein level during myogenic differentiation. To identify cellular proteins that might mediate the function/stability of YY1 in muscle cells, we screened an adult human muscle cDNA library using the yeast two-hybrid cloning system. We report the isolation and characterization of a novel protein termed YAF2 (YY1- associated factor 2) that interacts with YY1. The YAF2 cDNA encodes a 180 amino acid basic protein (pI 10.5) containing a single N-terminal C2-X10-C2 zinc finger. Lysine clusters are present that may function as a nuclear localization signal. Domain mapping analysis shows that the first and second zinc fingers of YY1 are targeted for YAF2 protein interaction. In contrast to the down-regulation of YY1, YAF2 message levels increase during in vitro differentiation of both rat skeletal and cardiac muscle cells. YAF2 appears to have a promyogenic regulatory role, since overexpression of YAF2 in C2 myoblasts stimulates myogenic promoter activity normally restricted by YY1. Co-transfection of YY1 reverses the stimulatory effect of YAF2. YAF2 also greatly potentiates proteolytic cleavage of YY1 by the calcium- activated protease m-calpain. The isolation of YAF2 may help in understanding the mechanisms through which inhibitors of myogenic transcription may be antagonized or eliminated by proteolysis during muscle development.
Kalenik
J L
JL
Department of Biochemistry, SUNY at Buffalo, NY 14214, USA.
Chen
D
D
Bradley
M E
ME
Chen
S J
SJ
Lee
T C
TC
D000199:Actins / Q000235:genetics; D000328:Adult; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002154:Calpain / Q000494:pharmacology; D002478:Cells, Cultured; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000302:isolation & purification; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism* / Q000494:pharmacology; D004357:Drug Synergism; D050981:Erythroid-Specific DNA-Binding Factors; D005822:Genetic Vectors; D006801:Humans; D006868:Hydrolysis; D008969:Molecular Sequence Data; D009124:Muscle Proteins / Q000235:genetics* / Q000378:metabolism* / Q000494:pharmacology; D018482:Muscle, Skeletal / Q000166:cytology; D009206:Myocardium / Q000378:metabolism; D011401:Promoter Regions, Genetic; D014176:Protein Biosynthesis; D017434:Protein Structure, Tertiary; D012313:RNA / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D012097:Repressor Proteins; D014157:Transcription Factors / Q000378:metabolism* / Q000494:pharmacology; D014162:Transfection; D050986:YY1 Transcription Factor; D016335:Zinc Fingers
D000199:Actins; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D050981:Erythroid-Specific DNA-Binding Factors; D009124:Muscle Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; C104531:YAF2 protein, human; D050986:YY1 Transcription Factor; C494698:YY1 protein, human; C494700:Yy1 protein, rat; D012313:RNA; D002154:Calpain