Nutrient Starvation Decreases Cx43 Levels and Limits Intercellular Communication in Primary Bovine Corneal Endothelial Cells
Nutrient Starvation Decreases Cx43 Levels and Limits Intercellular Communication in Primary Bovine Corneal Endothelial Cells
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DOI：
10.1007/s00232-016-9874-5
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发表时间：
2016-06-01
影响因子：
2.4
通讯作者：
Bultynck, Geert
中科院分区：
文献类型：
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作者：
D'hondt, Catheleyne;Iyyathurai, Jegan;Bultynck, Geert
连接蛋白 (Cx) 蛋白形成大的电导通道，通过间隙连接和/或半通道充当相邻细胞之间通信的调节器。细胞间通讯对于协调组织和器官中的细胞反应至关重要，从而在信号传导、生存和死亡过程的传播中发挥重要作用。连接蛋白 43 (Cx43) 是大脑和心脏中的主要连接蛋白亚型，可快速更新。最近的研究表明，自噬是营养饥饿时诱导的一种溶酶体降解途径，可介导连接蛋白（包括 Cx43）的降解。在这里，我们研究了营养饥饿对原代牛角膜内皮细胞 (BCEC) 中内源性 Cx43 蛋白水平和内源性 Cx43 驱动的细胞间通讯的影响。 Hank 平衡盐溶液 (HBSS) 用作饥饿条件，诱导自噬流而不影响 BCEC 的存活。 BCEC 的营养饥饿导致 Cx43 蛋白水平迅速下降，无论是作为间隙连接还是作为半通道。 Cx43 蛋白水平下降的时间过程与细胞间通讯下降的时间过程一致，细胞间通讯通过暴露于单细胞机械刺激的 BCEC 中的细胞间 Ca2+ 波传播进行评估。在完全营养饥饿期间添加溶酶体抑制剂巴弗洛霉素 A1 可以防止作为间隙连接和半通道的 Cx43 蛋白水平的下降。与此一致的是，巴弗洛霉素 A1 显着减轻了细胞间 Ca2+ 波传播的减少。这项研究进一步证实了自噬作为营养缺乏期间 Cx43 蛋白的重要降解途径的重要性，从而影响细胞进行细胞间通讯的能力。
Connexin (Cx) proteins form large conductance channels which function as regulators of communication between neighboring cells via gap junctions and/or hemichannels. Intercellular communication is essential to coordinate cellular responses in tissues and organs, thereby fulfilling an essential role in the spreading of signaling, survival and death processes. Connexin 43 (Cx43), a major connexin isoform in brain and heart, is rapidly turned over. Recent studies implicated that autophagy, a lysosomal degradation pathway induced upon nutrient starvation, mediates connexins, including Cx43, degradation. Here, we examined the impact of nutrient starvation on endogenous Cx43-protein levels and endogenous Cx43-driven intercellular communication in primary bovine corneal endothelial cells (BCECs). Hank's Balanced Salt Solution (HBSS) was used as a starvation condition that induces autophagic flux without impacting the survival of the BCECs. Nutrient starvation of BCECs caused a rapid decline in Cx43-protein levels, both as gap junctions and as hemichannels. The time course of the decline in Cx43-protein levels coincided with the time course of the decline in intercellular communication, assessed as intercellular Ca2+-wave propagation in BCECs exposed to a single-cell mechanical stimulus. The decline in Cx43-protein levels, both as gap junctions and as hemichannels, could be prevented by the addition of bafilomycin A1, a lysosomal inhibitor, during the complete nutrient starvation period. Consistent with this, bafilomycin A1 significantly alleviated the decrease in intercellular Ca2+-wave propagation. This study further underpins the importance of autophagy as an important degradation pathway for Cx43 proteins during periods of nutrient deprivation, thereby impacting the ability of cells to perform intercellular communication.