核とCaシグナル

抄録

Ca²⁺ signals in the nucleus play important roles in various functions, such as gene transcription, protein transport, appoptosis, and diseased states. It has long been accepted that Ca²⁺ freely flows by diffusion through nuclear pore complex (NPC) between cytosol and nucleus. Recently, however, there are several evidences to support the existence of the independent regulation of nuclear Ca²⁺. The presence of Ca²⁺ signaling molecules in nuclear envelope (NE), Ca-ATPase Ca²⁺ pump, IP₃ receptor, IP₄ receptor and ryanodine receptor, and the existence of nucleo-cytoplasmic Ca²⁺ gradients are identified. It is indicated that nuclear envelope may serve as a barrier to cytosolic Ca²⁺ changes and function as the Ca²⁺ store to sustain the propagation of Ca²⁺ signals through the nucleoplasm. In this paper, I would like to introduce the recent studies about Ca²⁺ transporting systems of the NE, cross-talk between cytosolic and nuclear Ca²⁺ pools, and the regulation of NPC.