Nuclear translocation of the cardiac L-type calcium channel C-terminus is regulated by sex and 17β-estradiol. (August 2016)

• Record Type: Journal Article
• Authors: Mahmoodzadeh, S.; Haase, H.; Sporbert, A.; Rharass, T.; Panáková, D.; Morano, I.
• Is Part Of: Journal of molecular and cellular cardiology. Volume 97(2016:Aug.)
• Page Start: 226
• Page End: 234
• Publication Date: 2016-08
• Subjects: Cav1.2 α1C subunit Cardiac voltage-gated l-type Ca2 + channel alpha subunit (CACNA1C) -- α1C-dCT C-terminus fragment of Cav1.2 α1C subunit -- 17β-estradiol E2, estrogen -- ER estrogen receptor -- Cx31.1 connexin 31.1 -- cs-FBS charcoal stripped fetal bovine serum -- ANF atrial natriuretic factor -- ERE estrogen response elements; Ca2 + channel -- Nuclear translocation -- Cardiomyocyte -- 17β-estradiol; Cardiology -- Periodicals; Heart Diseases -- Periodicals; Molecular Biology -- Periodicals; Cardiologie -- Périodiques; Cardiology; Electronic journals; Periodicals; 616.12
• DOI: 10.1016/j.yjmcc.2016.06.004
• Languages: English
• ISSNs: 0022-2828

Abstract

Abstract: The cardiac voltage gatedl -type Ca 2 + channel (Cav 1.2) constitutes the main entrance gate for Ca 2 + that triggers cardiac contraction. Several studies showed that the distal C-terminus fragment of Cav 1.2 α1C subunit (α1C-dCT) is proteolytically cleaved and shuttles between the plasma membrane and the nucleus, which is regulated both developmentally and by Ca 2 + . However, the effects of sex and sex hormone 17β-estradiol (E2, estrogen) on α1C-dCT nuclear translocation are still unexplored. To investigate the sexual disparity in the α1C-dCT nuclear translocation, we first generated an antibody directed against a synthetic peptide (GRRASFHLE) located in α1C-dCT, and used it to probe ventricular myocytes from adult female and male mice. Immunocytochemistry of isolated mouse primary adult ventricular myocytes revealed both nuclear staining and cytosolic punctuate staining around the T-tubules. The ratio of nuclear to cytosolic intensity (Inuc /Icyt ) was significantly higher in isolated female cardiomyocytes (1.42 ± 0.05) compared to male cardiomyocytes (1.05 ± 0.02). Western blot analysis of nuclear fraction confirmed these data. Furthermore, we found a significant decrease in nuclear staining intensity of α1C-dCT in both female and male cardiomyocytes upon serum withdrawal for 18 h (Inuc /Icyt 1.05 ± 0.02 and 0.89 ± 0.02, respectively). Interestingly, subsequent E2 treatment (10 − 8 M) for 8 h normalized the intracellular distribution of α1C-dCT in male cardiomyocytes (Inuc /Icyt 1.04 ± 0.02), but not in female cardiomyocytes. Acute treatment of male cardiomyocytes with E2 for 45 min revealed a similar effect. This effect of E2 was revised by ICI indicating the involvement of ER in this signaling pathway. Taken together, our results showed that the shuttling of α1C-CT in cardiomyocytes is regulated in a sex-dependent manner, and E2-activated ER may play a role in the nuclear shuttling of α1C-dCT in male cardiomyocytes. This may explain, at least partly, the observed sex differences in the regulation of cardiac Cav 1.2 channel activity. Highlights: Distal C-terminus of Cav 1.2α1C (α1C-dCT) is shuttled into nucleus of cardiomyocytes. We observed a sexual dimorphism in α1C-dCT nuclear localization in cardiomyocytes. Female cardiomyocytes revealed higher nuclear translocation of α1C-dCT than males. Estrogen (E2) regulates the α1C-dCT nuclear shuttling only in male cardiomyocytes. E2-activated ER is needed for nuclear shuttling of α1C-dCT in male cardiomyocytes.