title: C2PA is a nuclear protein implicated in the heat shock response.
abstract: C2PA is a protein of unknown function that is expressed in spermatocytes. PDZ-RGS3 is a signaling molecule whose PDZ domain binds Ephrin-B2 and mediates reverse signaling of this protein. C2PA and PDZ-RGS3 have identical PDZ domains. To explore the function of C2PA, we compared it with PDZ-RGS3 with respect to tissue distribution, subcellular localization, and biochemistry. C2PA is expressed only in testis, whereas PDZ-RGS3 is expressed in various tissues including brain, heart, lung, liver, spleen, kidney, small intestine, skeletal muscles, and testis. These proteins also differ in their subcellular distribution, in that PDZ-RGS3 is cytosolic while C2PA is exclusively nuclear. C2PA is distributed diffusely in the nucleus and forms a few foci at 37 degrees C. However, when cells are exposed to 42 degrees C, the number of C2PA foci is increased. These heat shock-induced foci colocalize with CREB-binding protein and heat shock factor-1. In contrast, the distribution of PDZ-RGS3 does not change during heat stress. When overexpressed, C2PA induces heat shock response element (HSE)-dependent gene transcription, whereas PDZ-RGS3 does not. These data suggest that the function of C2PA is distinct from that of PDZ-RGS3, and that C2PA may be involved in the heat shock response in testis.
authors.affiliation: Department of Medical Biochemistry, Graduate School of Medicine, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519, Japan.
authors.forename: Susumu
authors.initials: S
authors.lastname: Hirabayashi
authors.forename: Hideki
authors.initials: H
authors.lastname: Ohno
authors.forename: Junko
authors.initials: J
authors.lastname: Iida
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Hata
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D015152:Blotting, Northern; D001921:Brain / Q000378:metabolism; D019556:COS Cells; D002352:Carrier Proteins / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D019992:Databases as Topic; D036388:Ephrin-B2 / Q000378:metabolism; D005260:Female; D019204:GTP-Binding Proteins / Q000096:biosynthesis* / Q000502:physiology*; D020690:GTPase-Activating Proteins / Q000096:biosynthesis* / Q000502:physiology*; D017930:Genes, Reporter; D006367:HeLa Cells; D000076249:Heat Shock Transcription Factors; D006358:Hot Temperature; D006801:Humans; D008297:Male; D051379:Mice; D008856:Microscopy, Fluorescence; D008957:Models, Genetic; D008969:Molecular Sequence Data; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D020710:RGS Proteins; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D013347:Subcellular Fractions / Q000378:metabolism; D013696:Temperature; D013737:Testis / Q000378:metabolism; D013997:Time Factors; D014018:Tissue Distribution; D014157:Transcription Factors; D014162:Transfection
chemical_list: D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D036388:Ephrin-B2; D020690:GTPase-Activating Proteins; D000076249:Heat Shock Transcription Factors; D020710:RGS Proteins; C485898:RGS3 protein, human; C415085:Rgs3 protein, mouse; D014157:Transcription Factors; D019204:GTP-Binding Proteins