Oligodendrocytes in Mouse Corpus Callosum are Coupled Via Gap Junction Channels Formed by Connexin47 and Connexin32

已有的超微结构研究显示,白质中的少突胶质细胞和星形胶质细胞之间存在缝隙连接,但少突胶质细胞之间不存在缝隙连接,虽然体外培养的少突胶质细胞可形成功能性缝隙连接。本文研究新生小鼠胼胝体急性脑片中的少突胶质细胞的功能性连接。以全细胞膜片钳技术用生物胞素(一种可渗透的缝隙连接示踪剂)标记少突胶质细胞。平均61个细胞为链霉亲和素-Cy3标记的生物胞素阳性。约77%的连结细胞表达少突胶质细胞标志蛋白CNPase阳性染色,9%表达星形胶质细胞标志蛋白GFAP阳性,14%为CNPase和GFAP阴性。后者的大部分表达Olig2和一些NG2(少突胶质细胞前体细胞的标志物)。少突胶质细胞表达Cx47、Cx32和Cx29,星形胶质细胞表达Cx43和Cx30。在Cx47敲除小鼠中,连结细胞的数量减少80%。单独删除Cx32或Cx29并不能显著减少连结细胞的数量,但Cx32/Cx47双缺陷小鼠中没有观察到相互连结的细胞。Cx47敲除完全消除了少突胶质细胞与星形胶质细胞间的耦联。在Cx43敲除动物中,少突胶质细胞-星形胶质细胞间连接仍然存在,但与少突胶质细胞前体细胞间的耦联没有被观察到。在Cx43/Cx30双敲除小鼠中,少突胶质细胞-星形胶质细胞连接几乎不存在。解开连结的少突胶质细胞显示为较高的膜输入电阻。本文认为,白质中的少突胶质细胞依靠Cx47和Cx32的表达形成功能性的合胞体,而星形胶质蛋白缝隙连接蛋白的表达能提升此网络的大小。

According to previously published ultrastructural studies,oligodendrocytes in white matter exhibit gap junctions with astrocytes,but not among each other,while in vitro oligodendrocytes form functional gap junctions.We have studied functional coupling among oligodendrocytes in acute slices of postnatal mouse corpus callosum.By whole-cell patch clamp we dialyzed oligodendrocytes with biocytin,a gap junction-permeable tracer.On average 61 cells were positive for biocytin detected by labeling with streptavidin-Cy3.About 77% of the coupled cells stained positively for the oligodendrocyte marker protein CNPase,9% for the astrocyte marker GFAP and 14% were negative for both CNPase and GFAP.In the latter population,the majority expressed Olig2 and some NG2,markers for oligodendrocyte precursors.Oligodendrocytes are known to express Cx47,Cx32 and Cx29,astrocytes Cx43 and Cx30.In Cx47-deficient mice,the number of coupled cells was reduced by 80%.Deletion of Cx32 or Cx29 alone did not significantly reduce the number of coupled cells,but coupling was absent in Cx32/Cx47-double-deficient mice.Cx47-ablation completely abolished coupling of oligodendrocytes to astrocytes.In Cx43-deficient animals,oligodendrocyte-astrocyte coupling was still present,but coupling to oligodendrocyte precursors was not observed.In Cx43/Cx30-double deficient mice,oligodendrocyte-to-astrocyte coupling was almost absent.Uncoupled oligodendrocytes showed a higher input resistance.We conclude that oligodendrocytes in white matter form a functional syncytium predominantly among each other dependent on Cx47 and Cx32 expression,while astrocytic connexins expression can promote the size of this network.2010Wiley-Liss,Inc. 【