Oligodendrocytes in mouse corpus callosum are coupled via gap junction channels formed by connexin47 and connexin32.
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.
Maglione
Marta
M
Max-Delbrück-Center for Molecular Medicine, Cellular Neuroscience, 13092 Berlin, Germany.
Tress
Oliver
O
Haas
Brigitte
B
Karram
Khalad
K
Trotter
Jacqueline
J
Willecke
Klaus
K
Kettenmann
Helmut
H
D015087:2',3'-Cyclic-Nucleotide Phosphodiesterases / Q000378:metabolism; D000818:Animals; D000941:Antigens / Q000378:metabolism; D001253:Astrocytes / Q000502:physiology*; D051792:Basic Helix-Loop-Helix Proteins / Q000378:metabolism; D002232:Carbocyanines; D000075302:Connexin 30; D017630:Connexins / Q000235:genetics / Q000378:metabolism*; D003337:Corpus Callosum / Q000502:physiology*; D017629:Gap Junctions / Q000502:physiology*; D005904:Glial Fibrillary Acidic Protein; D066298:In Vitro Techniques; D008239:Lysine / Q000031:analogs & derivatives; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism; D000076104:Oligodendrocyte Transcription Factor 2; D009836:Oligodendroglia / Q000502:physiology*; D018408:Patch-Clamp Techniques; D011509:Proteoglycans / Q000378:metabolism; D013234:Stem Cells / Q000378:metabolism; D019809:Streptavidin; D000097002:Gap Junction beta-1 Protein; D000099216:Chondroitin Sulfate Proteoglycan 4
D015087:2',3'-Cyclic-Nucleotide Phosphodiesterases; D000941:Antigens; D051792:Basic Helix-Loop-Helix Proteins; D002232:Carbocyanines; D000075302:Connexin 30; D017630:Connexins; D005904:Glial Fibrillary Acidic Protein; D008239:Lysine; D009419:Nerve Tissue Proteins; D000076104:Oligodendrocyte Transcription Factor 2; D011509:Proteoglycans; D019809:Streptavidin; D000097002:Gap Junction beta-1 Protein; D000099216:Chondroitin Sulfate Proteoglycan 4; C100629:Gjb6 protein, mouse; C464673:Gje1 protein, mouse; C512773:Olig2 protein, mouse; C427305:connexin 47; C089187:cyanine dye 3; C528900:glial fibrillary astrocytic protein, mouse; C013411:biocytin