title: Transforming growth factor-beta 1 in heart development.
abstract: Defined biochemical stimuli regulating neonatal ventricular myocyte (cardiomyocyte) development have not been established. Since cardiomyocytes stop proliferating during the first 3-5 days of age in the rodent, locally generated 'anti-proliferative' and/or differentiation signals can be hypothesized. The transforming growth factor-beta (TGF-beta) family of peptides are multifunctional regulators of proliferation and differentiation of many different cell types. We have determined in neonatal and maturing rat hearts that TGF-beta 1 gene expression occurs in pups of both normotensive (Wistar Kyoto, WKY) and hypertrophy-prone rats (spontaneously hypertensive, SHR). TGF-beta 1 transcript levels were readily apparent in total ventricular RNA from SHR pups within 1 day of age and elevated in 3-7 day old WKY and SHR hearts when cardiomyocyte proliferation indices are diminished. TGF-beta 1 transcript levels remain at a 'relatively' high level throughout maturation and into adulthood in both strains. Further, TGF-beta 1 transcripts were localized to cardiomyocytes of neonatal rat ventricular tissue sections by in situ hybridization. Immunoreactive TGF-beta was co-localized to the intracellular compartment of neonatal cardiomyocytes at the light and electron microscopic level. In vitro analysis using primary cultures of fetal and neonatal cardiomyocytes indicated that TGF-beta s inhibit mitogen stimulated DNA synthesis and thymidine incorporation. From these data, we propose that locally generated TGF-beta s may act as autocrine and/or paracrine regulators of cardiomyocyte proliferation and differentiation as intrinsic components of a multifaceted biochemical regulatory process governing heart development.
authors.affiliation: Department of Medicine, Loyola University of Chicago, Maywood, IL.
authors.forename: G L
authors.initials: GL
authors.lastname: Engelmann
authors.forename: K D
authors.initials: KD
authors.lastname: Boehm
authors.forename: M C
authors.initials: MC
authors.lastname: Birchenall-Roberts
authors.forename: F W
authors.initials: FW
authors.lastname: Ruscetti
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001483:Base Sequence; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D004261:DNA Replication / Q000187:drug effects; D015870:Gene Expression; D006321:Heart / Q000254:growth & development*; D006352:Heart Ventricles / Q000737:chemistry; D017403:In Situ Hybridization; D008969:Molecular Sequence Data; D009206:Myocardium / Q000166:cytology / Q000378:metabolism; D051381:Rats; D011918:Rats, Inbred SHR / Q000254:growth & development; D011921:Rats, Inbred WKY / Q000254:growth & development; D016212:Transforming Growth Factor beta / Q000096:biosynthesis / Q000494:pharmacology / Q000502:physiology*
chemical_list: D016212:Transforming Growth Factor beta