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.
Mesh Terms:
Actins, Adult, Amino Acid Sequence, Animals, Base Sequence, Calpain, Cells, Cultured, Cloning, Molecular, DNA, Complementary, DNA-Binding Proteins, Drug Synergism, Erythroid-Specific DNA-Binding Factors, Genetic Vectors, Humans, Hydrolysis, Molecular Sequence Data, Muscle Proteins, Muscle, Skeletal, Myocardium, Promoter Regions, Genetic, Protein Biosynthesis, Protein Structure, Tertiary, RNA, Rats, Rats, Sprague-Dawley, Repressor Proteins, Transcription Factors, Transfection, YY1 Transcription Factor, Zinc Fingers
Actins, Adult, Amino Acid Sequence, Animals, Base Sequence, Calpain, Cells, Cultured, Cloning, Molecular, DNA, Complementary, DNA-Binding Proteins, Drug Synergism, Erythroid-Specific DNA-Binding Factors, Genetic Vectors, Humans, Hydrolysis, Molecular Sequence Data, Muscle Proteins, Muscle, Skeletal, Myocardium, Promoter Regions, Genetic, Protein Biosynthesis, Protein Structure, Tertiary, RNA, Rats, Rats, Sprague-Dawley, Repressor Proteins, Transcription Factors, Transfection, YY1 Transcription Factor, Zinc Fingers
Nucleic Acids Res.
Date: Feb. 15, 1997
PubMed ID: 9016636
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