title: JAB1 enhances HAND2 transcriptional activity by regulating HAND2 DNA binding.
abstract: HAND2 (also known as dHAND) is a basic helix-loop-helix (bHLH) transcription factor essential for development of the heart, limbs, and neural crest-derived lineages. HAND2 expression is observed in a number of tissues derived from the neural crest, including components of the peripheral nervous system, where it has been shown to regulate sympathetic nervous system development. Here we show that HAND2 is expressed in both the sympathetic and the parasympathetic divisions of the autonomic nervous system (ANS). How HAND2 functions during development of these neuronal lineages is uncertain. An important mechanism involved in HAND2's function is its interactions with other proteins. To understand better the molecular interactions regulating HAND2 during ANS development, we employed a yeast two-hybrid screen to identify HAND2-interacting proteins. One protein identified in this screen, Jun activation domain-binding protein (JAB1), is involved in numerous cell processes, including regulation of transcription and protein turnover. We show that JAB1 binds directly to the HLH domain of HAND2 and increases HAND2 transcription-stimulating activity. However, JAB1 does not contain a transcriptional activation domain, nor does it recruit an activation domain to HAND2. Our data indicate that JAB1 augments HAND2 transcriptional activity by enhancing HAND2 DNA binding. We further show that enhanced HAND2 DNA binding is mediated through the HLH domain and not through the DNA binding domain. These results show that JAB1 regulates the transcriptional activity of HAND2 in a unique manner that may account, in part, for the apparent ability of this bHLH factor to regulate gene expression through numerous mechanisms.
authors.affiliation: Department of Physiology and Cellular Biophysics, Columbia University, New York, New York, USA.
authors.forename: Yan-Shan
authors.initials: YS
authors.lastname: Dai
authors.forename: Jianming
authors.initials: J
authors.lastname: Hao
authors.forename: Christopher
authors.initials: C
authors.lastname: Bonin
authors.forename: Yuka
authors.initials: Y
authors.lastname: Morikawa
authors.forename: Peter
authors.initials: P
authors.lastname: Cserjesi
mesh_terms: D000818:Animals; D001341:Autonomic Nervous System / Q000196:embryology / Q000378:metabolism; D051792:Basic Helix-Loop-Helix Proteins; D015152:Blotting, Northern / Q000379:methods; D015153:Blotting, Western / Q000379:methods; D000075686:COP9 Signalosome Complex; D002460:Cell Line; D017124:Conserved Sequence; D004247:DNA / Q000187:drug effects / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism* / Q000502:physiology*; D024202:Electrophoretic Mobility Shift Assay / Q000379:methods; D004622:Embryo, Mammalian; D017615:Enteric Nervous System / Q000196:embryology / Q000378:metabolism; D005260:Female; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D017403:In Situ Hybridization / Q000379:methods; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D010447:Peptide Hydrolases; D011233:Precipitin Tests / Q000379:methods; D011247:Pregnancy; D013997:Time Factors; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism / Q000502:physiology*; D015533:Transcriptional Activation / Q000502:physiology*; D014162:Transfection / Q000379:methods; D020798:Two-Hybrid System Techniques; D015003:Yeasts; D029961:Zebrafish Proteins
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D000075686:COP9 Signalosome Complex; D004247:DNA; D004268:DNA-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; D010447:Peptide Hydrolases; D014157:Transcription Factors; D029961:Zebrafish Proteins; C498765:HAND2 protein, human; C498766:Hand2 protein, mouse; C410915:hand2 protein, zebrafish; C501488:COPS5 protein, human; C501490:Cops5 protein, mouse