title: Three GADD45 isoforms contribute to hypertonic stress phenotype of murine renal inner medullary cells.
abstract: Mammalian renal inner medullary (IM) cells routinely face and resist hypertonic stress. Such stress causes DNA damage to which IM cells respond with cell cycle arrest. We report that three growth arrest and DNA damage-inducible 45 (GADD45) isoforms (GADD45alpha, GADDD45beta, and GADD45gamma) are induced by acute hypertonicity in murine IM cells. Maximum induction occurs 16-18 h after the onset of hypertonicity. GADD45gamma is induced more strongly (7-fold) than GADD45beta (3-fold) and GADD45alpha (2-fold). GADD45alpha and GADD45beta protein induction is more pronounced and stable compared with the corresponding transcripts. Hypertonicity of various forms (NaCl, KCl, sorbitol, or mannitol) always induces GADD45 transcripts, whereas nonhypertonic hyperosmolality (urea) has no effect. Actinomycin D does not prevent hypertonic GADD45 induction, indicating that mRNA stabilization is the mechanism that mediates this induction. GADD45 induction patterns in IM cells exposed to 10 different stresses suggest isoform specificity, but similar functions, of individual isoforms during hypertonicity, heat shock, and heavy metal stress, when GADD45gamma induction is strongest (17-fold). These data associate all known GADD45 isoforms with the hypertonicity phenotype of renal IM cells.
authors.affiliation: The Whitney Laboratory, University of Florida, St. Augustine, Florida 32080, USA.
authors.forename: Devulapalli
authors.initials: D
authors.lastname: Chakravarty
authors.forename: Qi
authors.initials: Q
authors.lastname: Cai
authors.forename: Joan D
authors.initials: JD
authors.lastname: Ferraris
authors.forename: Luis
authors.initials: L
authors.lastname: Michea
authors.forename: Maurice B
authors.initials: MB
authors.lastname: Burg
authors.forename: Dietmar
authors.initials: D
authors.lastname: Kültz
mesh_terms: D000818:Animals; D000943:Antigens, Differentiation / Q000235:genetics / Q000378:metabolism*; D018797:Cell Cycle Proteins; D002478:Cells, Cultured; D004249:DNA Damage / Q000502:physiology; D005786:Gene Expression Regulation / Q000502:physiology; D006982:Hypertonic Solutions / Q000494:pharmacology; D047908:Intracellular Signaling Peptides and Proteins; D007679:Kidney Medulla / Q000166:cytology / Q000502:physiology*; D007685:Kidney Tubules, Collecting / Q000166:cytology / Q000502:physiology; D051379:Mice; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D009997:Osmotic Pressure; D010641:Phenotype; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects / Q000502:physiology; D014508:Urea / Q000494:pharmacology; D014882:Water-Electrolyte Balance / Q000502:physiology*; D000097642:GADD45 Proteins
chemical_list: D000943:Antigens, Differentiation; D018797:Cell Cycle Proteins; D006982:Hypertonic Solutions; D047908:Intracellular Signaling Peptides and Proteins; D009687:Nuclear Proteins; D011506:Proteins; D012333:RNA, Messenger; D014508:Urea; D000097642:GADD45 Proteins; C499072:Gadd45a protein, mouse; C490125:Gadd45b protein, mouse