Thyroid hormone regulation of alpha-myosin heavy chain promoter activity assessed by in vivo DNA transfer in rat heart.
We have studied the thyroid-hormone responsiveness of the alpha-myosin heavy chain (MHC) gene in vivo by directly injecting an expression vector containing the alpha-MHC 5' regulatory sequences (-613 to +421 base pairs) into the rat heart. In the expression vector pAM1Luc the alpha-MHC promoter elements direct the synthesis of firefly luciferase. Although thyroxine administration of both euthyroid and thyroidectomized rats for 5 days increased alpha-MHC promoter activity, the pAM1Luc gene construct did not mimic expression of the endogenous gene. These studies of direct gene transfer into mammalian myocardium suggest that additional cis-acting elements necessary for the in vivo response to thyroid hormone reside outside the -613 to +421 region.
Ojamaa
K
K
Department of Medicine, North Shore University Hospital/Cornell University Medical College, Manhasset, New York 11030.
Klein
I
I
D000818:Animals; D015500:Chloramphenicol O-Acetyltransferase / Q000096:biosynthesis / Q000235:genetics; D005786:Gene Expression Regulation / Q000187:drug effects*; D005822:Genetic Vectors; D006321:Heart / Q000502:physiology*; D008156:Luciferases / Q000096:biosynthesis / Q000235:genetics; D008297:Male; D009218:Myosins / Q000235:genetics*; D011401:Promoter Regions, Genetic; D051381:Rats; D011917:Rats, Inbred Lew; D011994:Recombinant Proteins / Q000096:biosynthesis; D012016:Reference Values; D012045:Regulatory Sequences, Nucleic Acid / Q000187:drug effects*; D013961:Thyroid Gland / Q000502:physiology*; D013965:Thyroidectomy; D013974:Thyroxine / Q000494:pharmacology*; D014162:Transfection / Q000187:drug effects
D011994:Recombinant Proteins; D008156:Luciferases; D015500:Chloramphenicol O-Acetyltransferase; D009218:Myosins; D013974:Thyroxine