title: The TSG101 protein binds to connexins and is involved in connexin degradation.
abstract: Gap junctions mediate electrical and metabolic communication between cells in almost all tissues and are proposed to play important roles in cellular growth control, differentiation and embryonic development. Gap junctional communication and channel assembly were suggested to be regulated by interaction of connexins with different proteins including kinases and phosphatases. Here, we identified the tumor susceptibility gene 101 (TSG101) protein to bind to the carboxyterminal tail of connexin45 in a yeast two-hybrid protein interaction screen. Glutathione S-transferase pull down experiments and immunoprecipitation revealed that not only connexin45 but also connexin30.2, -36, and -43 carboxyterminal regions were associated with TSG101 protein in pull down analyses and that connexin31, -43 and -45 co-precipitate with endogenous TSG101 protein in lysates from HM1 embryonic stem cells. TSG101 has been shown to be involved in cell cycle control, transcriptional regulation and turnover of endocytosed proteins. Thus, we decided to study the functional role of this interaction. SiRNA mediated knock down of TSG101 in HM1 embryonic stem cells led to increased levels of connexin43 and -45, prolonged half life of these connexins and increased transfer of microinjected Lucifer yellow. Our results suggest that TSG101 is involved in the degradation of connexins via interaction with connexin proteins.
authors.affiliation: Institute of Genetics, Division of Molecular Genetics, University of Bonn, 53117 Bonn, Germany. tanja.auth@gmx.de
authors.forename: Tanja
authors.initials: T
authors.lastname: Auth
authors.forename: Sharazad
authors.initials: S
authors.lastname: Schlüter
authors.forename: Stephanie
authors.initials: S
authors.lastname: Urschel
authors.forename: Petra
authors.initials: P
authors.lastname: Kussmann
authors.forename: Stephan
authors.initials: S
authors.lastname: Sonntag
authors.forename: Thorsten
authors.initials: T
authors.lastname: Höher
authors.forename: Maria M
authors.initials: MM
authors.lastname: Kreuzberg
authors.forename: Radoslaw
authors.initials: R
authors.lastname: Dobrowolski
authors.forename: Klaus
authors.initials: K
authors.lastname: Willecke
mesh_terms: D000818:Animals; D002450:Cell Communication / Q000502:physiology; D002460:Cell Line; D017630:Connexins / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D056827:Endosomal Sorting Complexes Required for Transport; D017629:Gap Junctions / Q000378:metabolism*; D051379:Mice; D011485:Protein Binding; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D020798:Two-Hybrid System Techniques; D000099177:Tsg101 Protein
chemical_list: D017630:Connexins; D004268:DNA-Binding Proteins; D056827:Endosomal Sorting Complexes Required for Transport; D020033:Protein Isoforms; D034741:RNA, Small Interfering; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; D000099177:Tsg101 Protein