Inhibition of BETA2/NeuroD by Id2.
Id (Inhibitor of Differentiation) proteins belong to a family of transcriptional modulators that are characterized by a helix loop helix (HLH) region but lack the basic amino acid domain. Id proteins are known to interact with basic helix-loop-helix (bHLH) transcription factors and function as their negative regulators. The negative role of Id proteins has been well demonstrated in muscle development and some in neuronal cells. In this study, we investigated the effect of Id on the function of BETA2/NeuroD, a bHLH transcription factor responsible for neuron and endocrine cell specific gene expression. cDNAs of several Id isoforms were isolated by yeast two-hybrid system using the bHLH domain of E47, a ubiquitous bHLH partner as a bait. Id proteins expressed in COS M6 cells, were found in both cytosolic and nuclear fractions. Electrophoretic mobility shift assay showed that coexpression of Id2 proteins inhibited BETA2/ NeuroD binding to its target sequence, E-box. Id2 inhibited E-box mediated gene expression in a dose dependent manner in BETA2/NeuroD expressing HIT cells. Id coexpressed with BETA2/NeuroD in HeLa cells, inhibited the stimulatory activity of BETA2/NeuroD. These results suggest that Id proteins may negatively regulate tissue specific gene expression induced by BETA2/NeuroD in neuroendocrine cells and the inhibitory role of Id proteins during differentiation may be conserved in various tissues.
Ghil
Sung-Ho
SH
Department of Anatomy, School of Medicine, Ajou University, Suwon 442-749, Korea.
Jeon
Yong-Jin
YJ
Suh-Kim
Haeyoung
H
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D051792:Basic Helix-Loop-Helix Proteins; D001665:Binding Sites; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D024721:E-Box Elements; D005786:Gene Expression Regulation / Q000502:physiology; D018257:Helix-Loop-Helix Motifs; D006801:Humans; D051797:Inhibitor of Differentiation Protein 2; D007515:Islets of Langerhans / Q000166:cytology / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D009928:Organ Specificity; D012097:Repressor Proteins; D051820:TCF Transcription Factors; D058125:Transcription Factor 7-Like 1 Protein; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D020798:Two-Hybrid System Techniques
D051792:Basic Helix-Loop-Helix Proteins; D004268:DNA-Binding Proteins; D051797:Inhibitor of Differentiation Protein 2; D009419:Nerve Tissue Proteins; D012097:Repressor Proteins; D051820:TCF Transcription Factors; D058125:Transcription Factor 7-Like 1 Protein; D014157:Transcription Factors; C497450:ID2 protein, human; C497452:Idb2 protein, mouse; C544912:TCF7L1 protein, human; C544913:Tcf7l1 protein, mouse; C093564:Neurogenic differentiation factor 1