The tetraspanin protein, CD9, is expressed by progenitor cells committed to oligodendrogenesis and is linked to β1 integrin, CD81, and Tspan‐2

Abstract

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.

Tetraspanin Protein CD9 Is a Novel Paranodal Component Regulating Paranodal Junctional Formation

“…These mice are healthy except for sperm-egg fusion. The life span of these mutants is normal, and for the nervous system, Terada et al (2002) reported that oligodendrocyte production and myelination appear normal in this mutant. To examine the fine structure of the myelin membrane, we performed ultrastructural analyses on optic nerves from wild-type and CD9-deficient mice (Miyado et al, 2000) at 8 weeks of age.…”

“…It is possible that myelination is terminated by CD9 together with some other molecules, including integrins and extracellular matrix proteins. Because CD9 interacts with several molecules, including the ␤ 1 integrin subfamily (Nakamura et al, 1995;Berditchevski et al, 1996;Schmidt et al, 1996;Terada et al, 2002), and because Schwann cells express ␤ 1 integrin (Salzer, 1995), ␤ 1 integrin is one of the candidates for this function. The ␤ 1 integrin subfamily comprises heterodimeric transmembrane proteins that mediate cell adhesion to extracellular matrix proteins, including laminin (␣ 3 ␤ 1 , ␣ 6 ␤ 1 ), collagen (␣ 1 ␤ 1 , ␣ 2 ␤ 1 , ␣ 3 ␤ 1 ), and fibronectin (␣ 4 ␤ 1 , ␣ 5 ␤ 1 ) (Hynes, 1992).…”

Identity, developmental restriction and reactivity of extralaminar cells capping mammalian neuromuscular junctions

“…Antibody 2166 was raised in rabbits against an epitope of Tspan-2, an oligodendrocyte-specific tetraspanin protein of 25 kDa (Birling et al, 1999;Terada et al, 2002). The original intention was to use this antibody to map oligodendrocyte disposition and lineage in the brain.…”

Autophagy in Peripheral Neuropathy

“…Protein Rab GDP dissociation inhibitor alpha (GDI1), dihydropyrimidinaserelated protein 2 (DPYSL2 -CRMP-2), PLP1, thioredoxin (TXN), MAG, MBP, CD9 antigen (CD9), alpha-synuclein (SNCA), tubulin beta-3 chain (TUBB3), and protein NDRG1 (NDRG1) were found to be downregulated at proximal and distal stumps in the presence of NGF, and in the presence of rapamycin, the expression of these proteins was downregulated at distal stumps of nerves, but were normalized in the proximal stumps. These proteins regulate nervous system development, axonogenesis, glial cell differentiation, myelination, and myelin maintenance [107][108][109][110][111][112][113][114][115]. Results of ANOVA also showed that many proteins involved in apoptosis ( Figure 21) were regulated differentially in the sciatic nerve 4 weeks after injury.…”