Abstract
The Na,K-ATPase alpha isoform (alpha 1, alpha 2, and alpha 3) and beta subunit genes exhibit a complex pattern of expression during heart development. To identify possible molecular signals that regulate the differential expression of these genes, isolated neonatal rat myocardial and non-myocardial cells were cultured in chemically defined medium and the responses of the multiple Na,K-ATPase subunit mRNAs to various hormones were tested. Myocardiocytes in control cultures express primarily alpha 1 and beta mRNAs. Triiodothyronine (T3) induced the expression of alpha 2, alpha 3, and beta mRNAs without influencing alpha 1 mRNA levels. Dexamethasone (DEX) treatment similarly induced alpha 2 mRNA levels, but the abundance of the other subunit transcripts remained unaltered. T3 and DEX together caused increases in alpha 2 and beta mRNA, increments similar to that observed with T3 alone. However, DEX specifically repressed the induction of alpha 3 mRNA by T3. Both hormones stimulated corresponding changes in the sarcolemma concentration of these Na,K-ATPase isozymes. Addition of norepinephrine to the cultures had little appreciable effect on expression of the alpha isoform and beta mRNAs. Although characterized less extensively, control cultures of non-myocardiocytes expressed alpha 1, alpha 3, and beta mRNAs, of which only the beta mRNA was stimulated by T3. These data indicate that thyroid and glucocorticoid hormones differentially regulate the expression of multiple alpha isoform and beta subunit mRNAs of Na,K-ATPase in cardiocytes in vitro and, therefore, may also be important physiological modulators in vivo.
Highlights
Subunit genes exhibit a complex pattern of expression during heart development
To identify possible molecular signals that regulate the differential expression of these genes, isolated neonatal rat myocardial and nonmyocardial cells were cultured in chemically defined medium and the responses of the multiple Na,K-ATP
The molecular signals that regutreated with concentrations of T3 ranging from lo-*’ to lo-” late the differential expression of the multiple
Summary
Biochemistry, and Microbiology, University of Cincinnati College of Medicine, The Na,K-ATPase a isoform (al, (~2, and a3) and @. DEX repressed the induction of a3 mRNA by TS Both hormones stimulated corresponding changes in the sarcolemma concentration of these Na,K-ATPase isozymes. Addition of norepinephrine to the cultures had little appreciable effect on expression of the a isoform and fi mRNAs. characterized less extensively, control cultures of nonmyocardiocytes expressed al, a3, and /3 mRNAs, of which only the j3 mRNA was stimulated by Ts. characterized less extensively, control cultures of nonmyocardiocytes expressed al, a3, and /3 mRNAs, of which only the j3 mRNA was stimulated by Ts These data indicate that thyroid and glucocorticoid hormones differentially regulate the expression of multiple a isoform and @ subunit mRNAs of Na,K-ATPase in cardiocytes in vitro and, may be important physiological modulators in vivo.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
