title: Heterogenous nuclear ribonucleoprotein F modulates angiotensinogen gene expression in rat kidney proximal tubular cells.
abstract: An insulin-responsive element (IRE) in the rat angiotensinogen (ANG) gene promoter that binds to two nuclear proteins with apparent molecular weights of 48 and 70 kD was identified previously from rat immortalized renal proximal tubular cells (IRPTC). The present studies aimed to identify and clone the 48-kD nuclear protein and to define its action on ANG gene expression. Nuclear proteins were isolated from IRPTC and subjected to two-dimensional electrophoresis. The 48-kD nuclear protein was detected by Southwestern blotting and subsequently identified by mass spectrometry, revealing that it was identical to 46-kD heterogeneous nuclear ribonucleoprotein F (hnRNP F), a nuclear protein that binds to TATA-binding protein and associates with RNA polymerase II and also interacts with nuclear cap-binding complex. The hnRNP F cDNA was cloned from IRPTC by reverse transcriptase-PCR. Bacterially expressed recombinant hnRNP F bound to the rat ANG-IRE, as revealed by gel mobility shift assay. The addition of polyclonal antibodies against hnRNP F yielded a supershift in gel mobility. Transient transfer of sense and antisense hnRNP F cDNA in IRPTC inhibited and enhanced ANG gene expression, respectively. High glucose stimulated and insulin inhibited hnRNP F expression in IRPTC. Expression studies indicated that hnRNP F is present in the kidney, testis, liver, lung, and brain but not in the spleen. In conclusion, these studies demonstrate that hnRNP F binds to rANG-IRE and modulates renal ANG gene expression, implicating that dysregulation of hnRNP F might affect renin-angiotensin system activation and, subsequently, kidney injury in diabetes.
authors.affiliation: Centre de recherche, Centre Hospitalier de l'Université de Montréal (CHUM), Hôtel-Dieu Pavillon Masson, 3850 Saint Urbain Street, Montreal, Quebec, Canada H2W 1T8.
authors.forename: Chih-Chang
authors.initials: CC
authors.lastname: Wei
authors.forename: Deng-Fu
authors.initials: DF
authors.lastname: Guo
authors.forename: Shao-Ling
authors.initials: SL
authors.lastname: Zhang
authors.forename: Julie R
authors.initials: JR
authors.lastname: Ingelfinger
authors.forename: John S D
authors.initials: JS
authors.lastname: Chan
mesh_terms: D000595:Amino Acid Sequence; D000808:Angiotensinogen / Q000235:genetics*; D000818:Animals; D002478:Cells, Cultured; D003001:Cloning, Molecular; D015180:Electrophoresis, Gel, Two-Dimensional; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology; D005947:Glucose / Q000494:pharmacology; D034541:Heterogeneous-Nuclear Ribonucleoprotein Group F-H / Q000235:genetics* / Q000378:metabolism*; D007004:Hypoglycemic Agents / Q000494:pharmacology; D007328:Insulin / Q000494:pharmacology; D035925:Iron-Regulatory Proteins / Q000378:metabolism; D007687:Kidney Tubules, Proximal / Q000166:cytology / Q000502:physiology*; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic / Q000502:physiology; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats
chemical_list: D034541:Heterogeneous-Nuclear Ribonucleoprotein Group F-H; D007004:Hypoglycemic Agents; D007328:Insulin; D035925:Iron-Regulatory Proteins; D012333:RNA, Messenger; D000808:Angiotensinogen; D005947:Glucose