L-type calcium channel activity in osteoblast cells is regulated by the actin cytoskeleton independent of protein trafficking

Fangping Li, Wenwei Wang, Ming Gu, Stefka Gyoneva, Jie Zhang, Shiying Huang, Stephen F. Traynelis, Hui Cai, Sandra E. Guggino, Xuemei Zhang

Research output: Contribution to journalArticlepeer-review

Abstract

Voltage-dependent L-type calcium channels (VDCC) play important roles in many cellular processes. The interaction of the actin cytoskeleton with the channel in nonexcitable cells is less well understood. We performed whole-cell patch-clamp surface biotinylation and calcium imaging on different osteoblast cells to determine channel kinetics, amplitude, surface abundance, and intracellular calcium, respectively. Patch-clamp studies showed that actin polymerization by phalloidin increased the peak current density of I Ca, whereas actin depolymerization by cytochalasin D (CD) significantly decreased the current amplitude. This result is consistent with calcium imaging, which showed that CD significantly decreased Bay K8644-induced intracellular calcium increase. Surface biotinylation studies showed that CD is not able to affect the surface expression of the pore-forming subunit α 1C. Interestingly, application of CD caused a significantly negative shift in the steady-state inactivation kinetics of I Ca. There were decreases in the voltage at half-maximal inactivation that changed in a dosedependent manner. CD also reduced the effect of activated vitamin D 3 (1α,25-D3) on VDCC and intracellular calcium. Weconclude that in osteoblasts the actin cytoskeleton affects α 1C by altering the channel kinetic properties, instead of changing the surface expression, and it is able to regulate 1α,25-D3 signaling through VDCC. Our study provides a new insight into calcium regulation in osteoblasts, which are essential in many physiological functions of this cell.

Original languageEnglish (US)
Pages (from-to)515-525
Number of pages11
JournalJournal of Bone and Mineral Metabolism
Volume29
Issue number5
DOIs
StatePublished - Sep 2011

Keywords

  • Actin cytoskeleton
  • Depolymerization
  • Osteoblast
  • Polymerization
  • Voltage-dependent L-type calcium channel

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Orthopedics and Sports Medicine
  • Endocrinology

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