TY - JOUR
T1 - L-type calcium channel activity in osteoblast cells is regulated by the actin cytoskeleton independent of protein trafficking
AU - Li, Fangping
AU - Wang, Wenwei
AU - Gu, Ming
AU - Gyoneva, Stefka
AU - Zhang, Jie
AU - Huang, Shiying
AU - Traynelis, Stephen F.
AU - Cai, Hui
AU - Guggino, Sandra E.
AU - Zhang, Xuemei
PY - 2011/9
Y1 - 2011/9
N2 - 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.
AB - 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.
KW - Actin cytoskeleton
KW - Depolymerization
KW - Osteoblast
KW - Polymerization
KW - Voltage-dependent L-type calcium channel
UR - https://www.scopus.com/pages/publications/83155184573
U2 - 10.1007/s00774-010-0252-6
DO - 10.1007/s00774-010-0252-6
M3 - 文章
C2 - 21246227
AN - SCOPUS:83155184573
SN - 0914-8779
VL - 29
SP - 515
EP - 525
JO - Journal of Bone and Mineral Metabolism
JF - Journal of Bone and Mineral Metabolism
IS - 5
ER -
