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

Autor/innen

  • S. Mahmoodzadeh
  • H. Haase
  • A. Sporbert
  • T. Rharass
  • D. Panáková
  • I. Morano

Journal

  • Journal of Molecular and Cellular Cardiology

Quellenangabe

  • J Mol Cell Cardiol 97: 226-234

Zusammenfassung

  • The cardiac voltage gated l-type Ca2+ channel (Cav1.2) constitutes the main entrance gate for Ca2+ that triggers cardiac contraction. Several studies showed that the distal C-terminus fragment of Cav1.2 alpha1C subunit (alpha1C-dCT) is proteolytically cleaved and shuttles between the plasma membrane and the nucleus, which is regulated both developmentally and by Ca2+. However, the effects of sex and sex hormone 17beta-estradiol (E2, estrogen) on alpha1C-dCT nuclear translocation are still unexplored. To investigate the sexual disparity in the alpha1C-dCT nuclear translocation, we first generated an antibody directed against a synthetic peptide (GRRASFHLE) located in alpha1C-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 alpha1C-dCT in both female and male cardiomyocytes upon serum withdrawal for 18h (Inuc/Icyt 1.05+/-0.02 and 0.89+/-0.02, respectively). Interestingly, subsequent E2 treatment (10-8M) for 8h normalized the intracellular distribution of alpha1C-dCT in male cardiomyocytes (Inuc/Icyt 1.04+/-0.02), but not in female cardiomyocytes. Acute treatment of male cardiomyocytes with E2 for 45min 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 alpha1C-CT in cardiomyocytes is regulated in a sex-dependent manner, and E2-activated ER may play a role in the nuclear shuttling of alpha1C-dCT in male cardiomyocytes. This may explain, at least partly, the observed sex differences in the regulation of cardiac Cav1.2 channel activity.


DOI

doi:10.1016/j.yjmcc.2016.06.004