title: Differential expression of transforming growth factor-beta receptors in rat kidney development.
abstract: Transforming growth factor-beta 1 (TGF-beta 1) is strongly expressed during embryogenesis and in sites undergoing intense development and morphogenesis. Two receptor serine/threonine kinases (types I and II) have been identified as signal-transducing TGF-beta receptors. This study was undertaken to further explore the role of the distinct TGF-beta receptors during kidney development. The species-specific sequence information for the two T beta R-I, namely, activin receptor-like kinase-5 (ALK-5) and Tsk7L, in the rat was sought. Two full-length T beta R-I cDNAs were cloned from a neonatal rat kidney and lung libraries, and sequencing revealed that they were the rat homologs of human ALK-5 and murine Tsk7L. Both types I and II TGF-beta receptors are expressed in the kidney as determined by Northern blot analysis. T beta R-II mRNA abundance was significantly greater in the neonatal rat kidney compared with the adult rat kidney. Similarly, ALK-5 mRNA was more highly expressed in the fetal and neonatal rat kidney than the adult rat kidney. In contrast, there was no significant difference in Tsk7L mRNA abundance among the fetal, neonatal, and adult rat kidney. Thus, based on these findings, both T beta R-II and ALK-5 are developmentally regulated in the kidney. Increased expression of T beta R-II and ALK-5 proteins in the developing kidney was confirmed by immunohistochemistry. Interestingly, the two TGF-beta receptors did not entirely colocalize, raising the intriguing possibility that other TGF-beta signaling receptors may be involved.
authors.affiliation: Division of Nephrology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
authors.forename: M E
authors.initials: ME
authors.lastname: Choi
authors.forename: A
authors.initials: A
authors.lastname: Liu
authors.forename: B J
authors.initials: BJ
authors.lastname: Ballermann
mesh_terms: D030201:Activin Receptors, Type I; D000375:Aging / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D000831:Animals, Newborn; D001483:Base Sequence; D005314:Embryonic and Fetal Development; D005260:Female; D005318:Fetal Heart / Q000378:metabolism; D005333:Fetus; D018507:Gene Expression Regulation, Developmental; D005865:Gestational Age; D006321:Heart / Q000254:growth & development; D006801:Humans; D007668:Kidney / Q000196:embryology / Q000254:growth & development / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D009206:Myocardium / Q000378:metabolism; D016133:Polymerase Chain Reaction; D011247:Pregnancy; D017346:Protein Serine-Threonine Kinases / Q000096:biosynthesis / Q000737:chemistry; D051381:Rats; D017207:Rats, Sprague-Dawley; D000077293:Receptor, Transforming Growth Factor-beta Type I; D017978:Receptors, Growth Factor / Q000096:biosynthesis / Q000737:chemistry; D018125:Receptors, Transforming Growth Factor beta / Q000096:biosynthesis* / Q000737:chemistry; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity
chemical_list: D017978:Receptors, Growth Factor; D018125:Receptors, Transforming Growth Factor beta; D011994:Recombinant Proteins; D017346:Protein Serine-Threonine Kinases; D030201:Activin Receptors, Type I; D000077293:Receptor, Transforming Growth Factor-beta Type I; C000625841:TGFBR1 protein, human; C000625842:Tgfbr1 protein, mouse; C000625843:Tgfbr1 protein, rat