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Expression of Ca2+ channel subunits during cardiac ontogeny in mice and rats: Identification of fetal alpha1C and beta subunit isoforms

Item Type:Article
Title:Expression of Ca2+ channel subunits during cardiac ontogeny in mice and rats: Identification of fetal alpha1C and beta subunit isoforms
Creators Name:Haase, H. and Pfitzmaier, B. and McEnery, M.W. and Morano, I.
Abstract:Functional cardiac L-type calcium channels are composed of the pore- forming {a1C) subunit and the regulatory {beta}2 and {alpha}2/{delta} subunits. To investigate possible developmental changes in calcium channel composition, we examined the temporal expression pattern of {alpha}(1C) and {beta}2 subunits during cardiac ontogeny in mice and rats, using sequence-specific antibodies. Fetal and neonatal hearts showed two size forms of {alpha}(1C) with 250 and 220 kDa. Quantitative immunoblotting revealed that the rat cardiac 250-kDa {alpha}(1C) subunit increased about 10-fold from fetal days 12-20 and declined during postnatal maturation, while the 220-kDa {alpha}(1C) decreased to undetectable levels. The expression profile of the 85-kDa {beta}2 subunit was completely different: {beta}2 was not detected at fetal day 12, rose in the neonatal stage, and persisted during maturation. Additional {beta}2-stained bands of 100 and 90 kDa were detected in fetal and newborn hearts, suggesting the transient expression of {beta}2 subunit variants. Furthermore, two fetal proteins with {beta04 immunoreactivity were identified in rat hearts that declined during prenatal development. In the fetal rat heart, {beta}{beta}4 gene expression was confirmed by RT-PCR. Cardiac and brain {beta}4 mRNA shared the 3 prime region, predicting identical primary sequences between amino acid residues 62-519, diverging however, at the 5 prime portion. The data indicate differential developmental changes in the expression of Ca2+ channel subunits and suggest a role of fetal {alpha}(1C) and {beta} isoforms in the assembly of Ca2+ channels in immature cardiomyocytes.
Keywords:{Alpha}(1C) Subunit, {Beta} Subunit, Calcium Channel, Heart Development, Animals, Mice, Rats
Source:Journal of Cellular Biochemistry
ISSN:0730-2312
Publisher:Wiley (U.S.A.)
Volume:76
Number:4
Page Range:695-703
Date:1 January 2000
Official Publication:http://www3.interscience.wiley.com/journal/69501932/abstract
PubMed:View item in PubMed

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