Intercellular bridges are plasma continuities formed at the end of the cytokinesis process that facilitate intercellular mass transport between the two daughter cells. However, it remains largely unknown how the intercellular bridge mediates Ca2+ communication between postmitotic cells. In this work, we utilize BV-2 microglial cells planted on dumbbell-shaped micropatterned assemblies to resolve spatiotemporal characteristics of Ca2+ signal transfer over the intercellular bridges. With the use of such micropatterns, considerably longer and more regular intercellular bridges can be obtained than in conventional cell cultures. The initial Ca2+ signal is evoked by mechanical stimulation of one of the daughter cells. A considerable time delay is observed between the arrivals of passive Ca2+ diffusion and endogenous Ca2+ response in the intercellular-bridge-connected cell, indicating two different pathways of the Ca2+ communication. Extracellular Ca2+ and the paracrine pathway have practically no effect on the endogenous Ca2+ response, demonstrated by application of Ca2+-free medium, exogenous ATP, and P2Y13 receptor antagonist. In contrast, the endoplasmic reticulum Ca2+-ATPase inhibitor thapsigargin and inositol trisphosphate (IP3) receptor blocker 2-aminoethyl diphenylborate significantly inhibit the endogenous Ca2+ increase, which signifies involvement of IP3-sensitive calcium store release. Notably, passive Ca2+ diffusion into the connected cell can clearly be detected when IP3-sensitive calcium store release is abolished by 2-aminoethyl diphenylborate. Those observations prove that both passive Ca2+ diffusion and IP3-mediated endogenous Ca2+ response contribute to the Ca2+ increase in intercellular-bridge-connected cells. Moreover, a simulation model agreed well with the experimental observations.

中文翻译：

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细胞间桥通过 IP3 和 Ca2+ 扩散介导微图案细胞之间的 Ca2+ 信号

细胞间桥是在胞质分裂过程结束时形成的血浆连续性，可促进两个子细胞之间的细胞间质量传递。然而，细胞间桥如何介导有丝分裂后细胞之间的 Ca2+ 通讯在很大程度上仍然未知。在这项工作中，我们利用种植在哑铃形微图案组件上的 BV-2 小胶质细胞来解决细胞间桥上 Ca2+ 信号传输的时空特征。使用这种微图案，可以获得比传统细胞培养更长、更规则的细胞间桥。初始 Ca2+ 信号由子细胞之一的机械刺激引起。在细胞间桥连接细胞中，在被动 Ca2+ 扩散到达和内源性 Ca2+ 反应之间观察到相当大的时间延迟，表明 Ca2+ 通信的两种不同途径。细胞外 Ca2+ 和旁分泌途径对内源性 Ca2+ 反应几乎没有影响，通过应用无 Ca2+ 培养基、外源性 ATP 和 P2Y13 受体拮抗剂证明。相比之下，内质网 Ca2+-ATPase 抑制剂毒胡萝卜素和肌醇三磷酸 (IP3) 受体阻滞剂 2-氨基乙基二苯基硼酸盐显着抑制内源性 Ca2+ 增加，这表明 IP3 敏感钙库释放的参与。值得注意的是，当 2-氨基乙基二苯基硼酸盐消除 IP3 敏感的钙库释放时，可以清楚地检测到被动 Ca2+ 扩散到连接的细胞中。这些观察证明被动 Ca2+ 扩散和 IP3 介导的内源性 Ca2+ 反应都有助于细胞间桥连接细胞中 Ca2+ 的增加。此外，模拟模型与实验观察结果非常吻合。