An anti-sense c-erbA clone inhibits thyroid hormone-induced expression from the alpha-myosin heavy chain promoter.
The effects of thyroid hormone on expression of cardiac myosin heavy chain genes generally are thought to be mediated by nuclear 3,5,3'-triiodo-L-thyronine (T3) receptors that have been identified as the products of the protooncogene, c-erbA. This hypothesis has been tested by transfection of cardiomyocytes in primary culture with a plasmid, pRSVhEACAT-, expressing anti-sense c-erbA mRNA. Because only a low percentage of cells (20%) could be transfected in primary culture an alpha-myosin heavy chain-chloramphenicol acetyltransferase fusion construct was used as a reporter gene. The results indicate that the anti-sense plasmid almost completely blocks T3-induced activity of the reporter gene (less than 1% control) while transfection of a similar amount of the sense construct, pRSVhEACAT+, has no effect. When the c-erbA plasmids were cotransfected with constructs containing T3-independent promoters, no effects on expression were observed. The combined use of an anti-sense construct and a report gene provides a means of studying the role of c-erbA products in intracellular signal transduction even in differentiated, nondividing cells like those of the heart.
University Heart Center, University of Arizona, Tucson 85724.
B E
BE
Markham
R W
RW
Tsika
J J
JJ
Bahl
P G
PG
Anderson
E
E
Morkin
D000818:Animals; D002478:Cells, Cultured; D003001:Cloning, Molecular; D005260:Female; D005786:Gene Expression Regulation; D005796:Genes / Q000187:drug effects*; D006801:Humans; D008285:Major Histocompatibility Complex; D009206:Myocardium / Q000378:metabolism; D015879:Myosin Subfragments / Q000235:genetics*; D010920:Placenta / Q000378:metabolism; D010957:Plasmids; D011247:Pregnancy; D011401:Promoter Regions, Genetic; D011505:Protein-Tyrosine Kinases / Q000235:genetics; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D011519:Proto-Oncogenes; D012313:RNA / Q000235:genetics*; D016372:RNA, Antisense; D012333:RNA, Messenger / Q000037:antagonists & inhibitors; D051381:Rats; D011988:Receptors, Thyroid Hormone / Q000235:genetics*; D014162:Transfection; D014284:Triiodothyronine / Q000494:pharmacology*
D015879:Myosin Subfragments; D011518:Proto-Oncogene Proteins; D016372:RNA, Antisense; D012333:RNA, Messenger; D011988:Receptors, Thyroid Hormone; D014284:Triiodothyronine; D012313:RNA; D011505:Protein-Tyrosine Kinases