Dominant negative effect of connexin33 on gap junctional communication is mediated by connexin43 sequestration
Dominant negative effect of connexin33 on gap junctional communication is mediated by connexin43 sequestration
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DOI：
10.1242/jcs.01335
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发表时间：
2004-09-15
影响因子：
4
通讯作者：
Pointis, G
中科院分区：
文献类型：
--
作者：
Fiorini, C;Mograbi, B;Pointis, G
细胞间缝隙连接通讯参与调控细胞的增殖和分化。间隙连接蛋白33是缝隙连接蛋白多基因家族中的一员，注射到非洲爪哇卵母细胞中会抑制细胞间的通讯。然而，其中涉及的分子机制仍有待阐明。我们的结果表明，连接蛋白33仅在睾丸的锯齿状小管中表达。与大多数连接蛋白不同的是，连接蛋白33未被磷酸化。免疫沉淀实验表明，Cx33与Cx43在物理上相互作用，主要与Cx43的磷酸化的P1亚型相互作用，而不与Cx26和Cx32这两个在肾小管上皮细胞中表达的Cx43发生物理作用。在Sertoli细胞和COS-7细胞中，连接蛋白43位于细胞膜上，而在connein33转基因细胞中，连接蛋白33/43的特异性结合被隔离在细胞内。高分辨率荧光去卷积显微镜显示，连接蛋白33/43复合体主要存在于早期的内吞体内。连接蛋白33/43复合体的隔离与完全抑制相邻细胞之间的缝隙连接偶联有关。这些发现首次证明了一种新的机制模型，即发挥显性负效应的天然连接蛋白可以抑制缝隙连接细胞间的通讯。在睾丸中，连接蛋白33可以通过抑制连接蛋白43的调节作用而对生殖细胞的增殖起到特定的作用。
Gap junctional intercellular communication is involved in the control of cell proliferation and differentiation. Connexin33, a member of the multi-gene family of gap junction proteins, exerts an inhibitory effect on intercellular communication when injected into Xenopus oocytes. However, the molecular mechanisms involved remain to be elucidated. Our results show that connexin33 was only expressed within the serniniferous tubules in the testis. In contrast to the majority of connexins, connexin33 was unphosphorylated. Immunoprecipitation experiments revealed that connexin33 physically interacted with connexin43, mainly with the phosphorylated P1 isoform of connexin43 but not with connexin26 and connexin32, two other connexins expressed in the tubular compartment. In Sertoli cells and COS-7 cells, connexin43 was located at the plasma membrane, whereas in connein33 transfected cells, the specific association of connexin33/43 was sequestered in the intracellular compartment. High-resolution fluorescent deconvolution microscopy indicated that the connexin33/43 complex was mainly found within early endosomes. Sequestration of connexin33/43 complex was associated with a complete inhibition of the gap junctional coupling between adjacent cells. These findings provide the first evidence of a new mechanistic model by which a native connexin, exerting a dominant negative effect, can inhibit gap junctional intercellular communication. In the testis, connexin33 could exert a specific role on germ cell proliferation by suppressing the regulatory effect of connexin43.