The tetraspanin protein, CD9, is expressed by progenitor cells committed to oligodendrogenesis and is linked to beta1 integrin, CD81, and Tspan-2.
Previous studies identified the tetraspanin protein CD9 in myelinating oligodendrocytes. The present report extends these observations by identifying CD9 in a subpopulation of oligodendrocyte progenitor cells (OPCs) and in premyelinating oligodendrocytes in rodents. NG2-positive cells expressed CD9 in a temporal and spatial pattern during development that was consistent with CD9 expression in OPCs just prior to their differentiation into premyelinating oligodendrocytes. NG2-positive cells in mature brains were CD9-negative. CD9 expression during oligodendrocyte development in vitro supported this hypothesis, as all CD9-positive cells became O4-positive when switched to oligodendrocyte differentiating media. CD9 immunoreactivity was enriched in myelinating oligodendrocytes and their processes, and the outer aspects of myelin internodes. Immunoprecipitation of CD9 from postnatal rat cerebrum coprecipitated beta1 integrin, CD81, and Tspan-2, another tetraspanin protein recently identified in oligodendrocytes. Following surface biotinylation of oligodendrocytes in vitro, biotinylated beta1 integrin was identified in a CD9 immunoprecipitate. These data support a molecular link between surface integrins and a CD9, Tspan-2 molecular web during the differentiation of oligodendrocytes. Oligodendrocyte production and myelination appears to be normal in CD9-deficient mice. These data support the hypothesis that CD9 helps form the tetraspanin web beneath the plasma membranes of progenitor cells committed to oligodendrogenesis, but that CD9 is not essential for oligodendrogenesis and myelination.
Terada
Nobuo
N
Department of Neurosciences, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio 44195, USA.
Baracskay
Karen
K
Kinter
Mike
M
Melrose
Shona
S
Brophy
Peter J
PJ
Boucheix
Claude
C
Bjartmar
Carl
C
Kidd
Grahame
G
Trapp
Bruce D
BD
D000818:Animals; D000831:Animals, Newborn; D000941:Antigens / Q000378:metabolism; D015703:Antigens, CD / Q000378:metabolism*; D000943:Antigens, Differentiation / Q000378:metabolism; D019921:Biotinylation; D002454:Cell Differentiation / Q000235:genetics*; D019070:Cell Lineage / Q000235:genetics; D002462:Cell Membrane / Q000378:metabolism*; D002478:Cells, Cultured; D002490:Central Nervous System / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental / Q000235:genetics; D019012:Integrin beta1 / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D009186:Myelin Sheath / Q000235:genetics / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009836:Oligodendroglia / Q000166:cytology / Q000378:metabolism*; D011509:Proteoglycans / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism*; D060225:Tetraspanin 28; D060245:Tetraspanin 29; D059470:Tetraspanins; D000099216:Chondroitin Sulfate Proteoglycan 4
D000941:Antigens; D015703:Antigens, CD; D000943:Antigens, Differentiation; D019012:Integrin beta1; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D011509:Proteoglycans; D060225:Tetraspanin 28; D060245:Tetraspanin 29; D059470:Tetraspanins; D000099216:Chondroitin Sulfate Proteoglycan 4; C554799:Cd81 protein, mouse; C554797:Cd81 protein, rat; C554870:Cd9 protein, mouse; C512651:Tspan2 protein, mouse; C512652:Tspan2 protein, rat; C036505:oligodendrocyte O antigen, mouse; C488961:oligodendrocyte O antigen, rat