Calcium increases endocytotic vesicle size and accelerates membrane fission in insulin-secreting INS-1 cells
Calcium increases endocytotic vesicle size and accelerates membrane fission in insulin-secreting INS-1 cells
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DOI：
10.1242/jcs.02685
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发表时间：
2005-12-15
影响因子：
4
通讯作者：
Rorsman, P
中科院分区：
文献类型：
--
作者：
MacDonald, PE;Eliasson, L;Rorsman, P
在许多细胞中，内吞膜修复被Ca 2+加速。通过测量胰岛素分泌INS-1细胞的小膜片中的电容和电导变化，研究了Ca 2+对单个内吞囊泡和裂孔动力学的影响。在完整的细胞中，通过葡萄糖刺激升高Ca 2+诱导膜内化增加1.8倍。令人惊讶的是，这是由于内吞囊泡的单位电容增加，而内吞作用的频率没有改变。葡萄糖的这种作用通过抑制L-或R-型Ca 2+通道来防止。细胞外（移液管）Ca 2+被发现以双峰方式调节胞吞囊泡电容。囊泡电容增加在中间Ca 2+（2.6 mM），但不是在高Ca 2+（10 mM）。在将100 nM和0.5 mM Ca 2+直接应用于由内而外切除的膜贴片的细胞内表面后获得了类似的结果，并且在这些实验中，钙调磷酸酶抑制剂溴氰菊酯阻止了囊泡电容的增加。在完整细胞和分离的膜贴片中，内吞裂变孔动力学均被Ca 2+加速;然而，在这种情况下，该效应既不是双峰型，也不是溴氰菊酯敏感型。因此，膜修复可以通过内吞囊泡大小的Ca 2+依赖性增加和胰岛素分泌INS-1细胞中膜分裂的加速来上调。
In many cells, endocytotic membrane retrieval is accelerated by Ca2+. The effect of Ca2+ on single endocytotic vesicles and fission pore kinetics was examined by measuring capacitance and conductance changes in small membrane patches of insulin-secreting INS-1 cells. In intact cells, elevation of Ca2+ by glucose stimulation induced a 1.8-fold increase in membrane internalisation. This surprisingly resulted from an increased unitary capacitance of endocytotic vesicles whereas the frequency of endocytosis was unaltered. This effect of glucose was prevented by inhibition of L- or R-type Ca2+ channels. Extracellular (pipette) Ca2+ was found to regulate endocytotic vesicle capacitance in a bimodal manner. Vesicle capacitance was increased at intermediate Ca2+ (2.6 mM), but not at high Ca2+ (10 mM). Similar results were obtained upon direct application of 100 nM and 0.5 mM Ca2+ to the intracellular surface of inside-out excised membrane patches, and in these experiments the increase in vesicle capacitance was prevented by the calcineurin inhibitor deltamethrin. Endocytotic fission pore kinetics were accelerated by Ca2+ in both the intact cells and isolated membrane patches; however, the effect in this case was neither bimodal nor deltamethrin sensitive. Membrane retrieval can therefore be upregulated by a Ca2+-dependent increase in endocytotic vesicle size and acceleration of membrane fission in insulin-secreting INS-1 cells.