ORIGINAL ARTICLE

Cell Research (2006)16:585-598
© 2006 IBCB, SIBS, CAS All rights reserved 1001-0602/06 $ 30.00
www.nature.com/cr

Visualization of bHLH transcription factor interactions in living mammalian cell nuclei and developing chicken neural tube by FRET

Chen Wang, Wei Bian, Caihong Xia, Ting Zhang, Francois Guillemot,Naihe Jing

¹Key Laboratory of Stem Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences; Graduate School of the Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai 200031, China; ²Division of Molecular Neurobiology, National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK

Correspondence: Naihe Jing Tel: 86-21-54921381; Fax: 86-21-54921011; E-mail: njing@sibs.ac.cn Received 26 Sep 2005; revised 19 Dec 2005; accepted 21 Dec 2005; published online 15 Jun 2006

Table of Contents Download as printable (PDF) file Full Text (html)file Search Medline for articles by: Naihe Jing

Members of the basic helix-loop-helix (bHLH) gene family play important roles in vertebrate neurogenesis. In this study, confocal microscopy-based fluorescence resonance energy transfer (FRET) is used to monitor bHLH protein-protein interactions under various physiological conditions. Tissue-specific bHLH activators, NeuroD1, Mash1, Neurogenin1 (Ngn1), Neurogenin2 (Ngn2), and ubiquitous expressed E47 protein are tagged with enhanced yellow fluorescence protein (EYFP) and enhanced cyan fluorescence protein (ECFP), respectively. The subcellular localization and mobility of bHLH fusion proteins are examined in HEK293 cells. By transient transfection and in ovo electroporation, four pairs of tissue-specific bHLH activators and E47 protein are over-expressed in HEK293 cells and developing chick embryo neural tube. With the acceptor photobleaching method, FRET could be detected between these bHLH protein pairs in the nuclei of transfected cells and developing neural tubes. Mash1/E47 and Ngn2/E47 FRET pairs show higher FRET efficiencies in the medial and the lateral half of chick embryo neural tube, respectively. It suggests that these bHLH protein pairs formed functional DNA-protein complexes with regulatory elements of their downstream target genes in the specific regions. This work will help one understand the behaviours of bHLH factors in vivo.

Cell Research (2006) 16:585-598. doi:10.1038/sj.cr.7310076; published online 15 June 2006

Keywords: bHLH, confocal microscopy, chick embryo neural tube, FRET, in ovo electroporation, photobleach