title: Direct observation of dimerization between different CREB1 isoforms in a living cell.
abstract: Cyclic AMP-responsive element binding protein 1 (CREB1) plays multiple functions as a transcription factor in gene regulation. CREB1 proteins are also known to be expressed in several spliced isoforms that act as transcriptional activators or repressors. The activator isoforms, possessing the functional domains for kinase induction and for interaction with other transcriptional regulators, act as transcriptional activators. On the other hand, some isoforms, lacking those functional domains, are reported to be repressors that make heterodimers with activator isoforms. The complex and ingenious function for CREB1 arises in part from the variation in their spliced isoforms, which allows them to interact with each other. To date, however, the dimerization between the activator and repressor isoforms has not yet been proved directly in living cells. In this study, we applied fluorescence cross-correlation spectroscopy (FCCS) to demonstrate direct observation of dimerization between CREB1 activator and repressor. The FCCS is a well established spectroscopic method to determine the interaction between the different fluorescent molecules in the aqueous condition. Using differently labeled CREB1 isoforms, we successfully observed the interaction of CREB1 activator and repressor via dimerization in the nuclei of cultured cells. As a result, we confirmed the formation of heterodimer between CREB1 activator and repressor isoforms in living cells.
authors.affiliation: Laboratory of Functional Biology, Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, Sanuki, Japan. sadamotoh@kph.bunri-u.ac.jp
authors.forename: Hisayo
authors.initials: H
authors.lastname: Sadamoto
authors.forename: Kenta
authors.initials: K
authors.lastname: Saito
authors.forename: Hideki
authors.initials: H
authors.lastname: Muto
authors.forename: Masataka
authors.initials: M
authors.lastname: Kinjo
authors.forename: Etsuro
authors.initials: E
authors.lastname: Ito
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism; D002470:Cell Survival; D017362:Cyclic AMP Response Element-Binding Protein / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D008195:Lymnaea; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D055503:Protein Multimerization; D020836:Protein Structure, Quaternary; D012097:Repressor Proteins / Q000378:metabolism; D013050:Spectrometry, Fluorescence / Q000379:methods*; D015533:Transcriptional Activation
chemical_list: D017362:Cyclic AMP Response Element-Binding Protein; D020033:Protein Isoforms; D012097:Repressor Proteins