title: Co-regulation of the atrial natriuretic factor and cardiac myosin light chain-2 genes during alpha-adrenergic stimulation of neonatal rat ventricular cells. Identification of cis sequences within an embryonic and a constitutive contractile protein gene which mediate inducible expression.
abstract: To study the mechanisms which mediate the transcriptional activation of cardiac genes during alpha adrenergic stimulation, the present study examined the regulated expression of three cardiac genes, a ventricular embryonic gene (atrial natriuretic factor, ANF), a constitutively expressed contractile protein gene (cardiac MLC-2), and a cardiac sodium channel gene. alpha 1-Adrenergic stimulation activates the expression and release of ANF from neonatal ventricular cells. As assessed by RNase protection analyses, treatment with alpha-adrenergic agonists increases the steady-state levels of ANF mRNA by greater than 15-fold. However, a rat cardiac sodium channel gene mRNA is not induced, indicating that alpha-adrenergic stimulation does not lead to an increase in the expression of all cardiac genes. Studies employing a series of rat ANF luciferase and rat MLC-2 luciferase fusion genes identify 315- and 92-base pair cis regulatory sequences within an embryonic gene (ANF) and a constitutively expressed contractile protein gene (MLC-2), respectively, which mediate alpha-adrenergic-inducible gene expression. Transfection of various ANF luciferase reporters into neonatal rat ventricular cells demonstrated that upstream sequences which mediate tissue-specific expression (-3003 to -638) can be segregated from those responsible for inducibility. The lack of inducibility of a cardiac Na+ channel gene, and the segregation of ANF gene sequences which mediate cardiac specific from those which mediate inducible expression, provides further insight into the relationship between muscle-specific and inducible expression during cardiac myocyte hypertrophy. Based on these results, a testable model is proposed for the induction of embryonic cardiac genes and constitutively expressed contractile protein genes and the noninducibility of a subset of cardiac genes during alpha-adrenergic stimulation of neonatal rat ventricular cells.
authors.affiliation: Department of Medicine, University of California, San Diego, La Jolla 92093.
authors.forename: K U
authors.initials: KU
authors.lastname: Knowlton
authors.forename: E
authors.initials: E
authors.lastname: Baracchini
authors.forename: R S
authors.initials: RS
authors.lastname: Ross
authors.forename: A N
authors.initials: AN
authors.lastname: Harris
authors.forename: S A
authors.initials: SA
authors.lastname: Henderson
authors.forename: S M
authors.initials: SM
authors.lastname: Evans
authors.forename: C C
authors.initials: CC
authors.lastname: Glembotski
authors.forename: K R
authors.initials: KR
authors.lastname: Chien
mesh_terms: D000818:Animals; D009320:Atrial Natriuretic Factor / Q000235:genetics*; D001483:Base Sequence; D002678:Chimera; D004622:Embryo, Mammalian; D005455:Fluorescent Antibody Technique; D005786:Gene Expression Regulation; D006352:Heart Ventricles / Q000166:cytology / Q000187:drug effects*; D008156:Luciferases / Q000235:genetics; D008969:Molecular Sequence Data; D009206:Myocardium / Q000737:chemistry*; D009218:Myosins / Q000235:genetics*; D009638:Norepinephrine / Q000494:pharmacology; D012333:RNA, Messenger / Q000032:analysis / Q000096:biosynthesis; D051381:Rats; D011919:Rats, Inbred Strains; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects*; D012045:Regulatory Sequences, Nucleic Acid; D015222:Sodium Channels / Q000737:chemistry / Q000235:genetics; D014162:Transfection
chemical_list: D012333:RNA, Messenger; D011942:Receptors, Adrenergic, alpha; D015222:Sodium Channels; C472610:atrial natriuretic peptide, rat; D009320:Atrial Natriuretic Factor; D008156:Luciferases; D009218:Myosins; D009638:Norepinephrine