The voltage-gated calcium channel CACNB2 (β2.1) protein is required in the heart for control of cell proliferation and heart tube integrity
- Authors
- Chernyavskaya, Y., Ebert, A.M., Milligan, E., and Garrity, D.M.
- ID
- ZDB-PUB-120127-3
- Date
- 2012
- Source
- Developmental Dynamics : an official publication of the American Association of Anatomists 241(4): 648-662 (Journal)
- Registered Authors
- Chernyavskaya, Yelena, Garrity, Deborah
- Keywords
- zebrafish, cardiac development, L-type calcium channel, beta-2 subunit, cell proliferation, adhesion, adherens junctions, N-cadherin, sarcomere, cardiomyocyte morphology, MAGUK
- MeSH Terms
-
- Heart/embryology*
- Heart/physiology
- Gene Expression Regulation, Developmental
- Organogenesis/physiology
- Gene Deletion
- PubMed
- 22274990 Full text @ Dev. Dyn.
L-type calcium channels (LTCC) regulate calcium entry into cardiomyocytes. CACNB2 (β2) LTCC auxiliary subunits traffic the pore-forming CACNA subunit to the membrane and modulate channel kinetics. β2 is a Membrane Associated Guanylate Kinase (MAGUK) protein. A major role of MAGUK proteins is to scaffold cellular junctions and multi-protein complexes. To investigate developmental functions for β2.1, we depleted it in zebrafish using morpholinos. β2.1-depleted embryos developed compromised cardiac function by 48 hours post-fertilization, which was ultimately lethal. β2.1 contractility defects were mimicked by pharmacological depression of LTCC, and rescued by LTCC stimulation, suggesting β2.1 phenotypes are at least in part LTCC-dependent. Morphological studies indicated that β2.1 contributes to heart size by regulating the rate of ventricle cell proliferation, and by modulating the transition of outer curvature cells to an elongated cell shape during chamber ballooning. In addition, β2.1-depleted cardiomyocytes failed to accumulate N-cadherin at the membrane, and dissociated easily from neighboring myocytes under stress. Hence, we propose that β2.1 may also function in the heart as a MAGUK scaffolding unit to maintain N-cadherin-based adherens junctions and heart tube integrity.
