Connexin32 Gene Expression in Rat Sciatic Nerves and Cultured Schwann Cells

Satake, Marie; Yoshimura, Teizo; Ohnishi, Akio; Kobayashi, Takuya

doi:10.1159/000111205

Cited by 13 publications

(10 citation statements)

References 23 publications

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“…In keeping with the proposed role as a candidate gene for CMTX, Cx32 is expressed at high levels in myelinating Schwann cells and is regulated in parallel to other myelin genes (Bergoffen et al, 1993;Scherer et al, 1995;Chandross et al, 1996b;Satake et al, 1997). Immunocytochemical studies have indicated that Cx32 is localized mainly in noncompacted domains of myelin, such as paranodal loops and SchmidtLanterman incisures (Bergoffen et al, 1993;Miyazaki et al, 1995;Scherer et al, 1995;Spray and Dermietzel, 1995;Chandross et al, 1996b;Nelles et al, 1996).…”

Section: Abstract: Gap Junction; Channel; Myelin; Schwann Cell; Neurmentioning

confidence: 69%

Connexin32 Mutations Associated with X-Linked Charcot–Marie–Tooth Disease Show Two Distinct Behaviors: Loss of Function and Altered Gating Properties

et al. 1998

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The X-linked form of Charcot-Marie-Tooth disease (CMTX) is associated with mutations in the gene encoding connexin32 (Cx32), which is expressed in Schwann cells. We have compared the functional properties of 11 Cx32 mutations with those of the wild-type protein by testing their ability to form intercellular channels in the paired oocyte expression system. Although seven mutations were functionally incompetent, four others were able to generate intercellular currents of the same order of magnitude as those induced by wild-type Cx32 (Cx32wt). In homotypic oocyte pairs, CMTX mutations retaining functional activity induced the development of junctional currents that exhibited changes in the sensitivity and kinetics of voltage dependence with respect to that of Cx32wt. The four mutations were also capable of interacting in heterotypic configuration with the wild-type protein, and in one case the result was a marked rectification of junctional currents in response to voltage steps of opposite polarity. In addition, the functional CMTX mutations displayed the same selective pattern of compatibility as Cx32wt, interacting with Cx26, Cx46, and Cx50 but failing to do so with Cx40. Although the functional mutations exhibited sensitivity to cytoplasmic acidification, which induced a >/=80% decrease in junctional currents, both the rate and extent of channel closure were enhanced markedly for two of them. Together, these results indicate that the functional consequences of CMTX mutations of Cx32 are of two drastically distinct kinds. The presence of a functional group of mutations suggests that a selective deficit of Cx32 channels may be sufficient to impair the homeostasis of Schwann cells and lead to the development of CMTX.

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Section: Abstract: Gap Junction; Channel; Myelin; Schwann Cell; Neurmentioning

confidence: 69%

Connexin32 Mutations Associated with X-Linked Charcot–Marie–Tooth Disease Show Two Distinct Behaviors: Loss of Function and Altered Gating Properties

et al. 1998

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“…Cx32 expression associated with adherens junctions in the paranodes and incisures has been previously described by a number of investigators (Bergoffen et al, 1993; Meier et al, 2004; Satake et al, 1997; Scherer et al, 1995; see also Arroyo and Scherer, 2000). Our observation that intense patches of IP 3 R3 ion channels are clustered in the same regions is intriguing.…”

Section: Discussionmentioning

confidence: 79%

Signaling proteins in the axoglial apparatus of sciatic nerve nodes of Ranvier

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Weerth

et al. 2006

Glia

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During action potential conduction, the axonal specializations at the node, together with the adjacent paranodal terminations of the myelin sheath, interact with glial processes that invest the nodal gap. The nature of the mutual signals between axons and myelinating glia, however, are not well understood. Here we have characterized the distribution of inositol 1,4,5-trisphosphate receptors (IP(3)Rs) in the axoglial apparatus by immunohistochemistry, using known myelin domain-specific markers. While IP(3)R1 is not expressed in the Schwann cells or the axon, IP(3)R2 and IP(3)R3 are expressed in distinct cellular domains, suggesting distinct signaling roles for the two receptors. IP(3)R3 is the most predominant isoform in Schwann cells, and is expressed in particularly dense patches in the paranodal region. In addition to IP(3)Rs, two other members of the metabotropic Ca(2+) signaling pathway, G(alpha)q, and P(2)Y1 type of purinoceptors were also found in Schwann cells. Their pattern of expression matches the expression of their signaling partners, the IP(3)Rs. One interesting finding to emerge from this study is the expression of connexin 32 (Cx32) in close proximity with IP(3)R3. Although IP(3)R3 and Cx32 are not colocalized, their expression in the same membrane areas raises the question whether Schwann cell Ca(2+) signals either control the function of the gap junctions, or whether the gap junctional channels serve as conduits for rapid radial spread of Ca(2+) signals initiated during action potential propagation.

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“…2). Because the endogenous Cx32 mRNA is 1.6 kb (Satake et al, 1997;Yoshimura et al, 1996b), the 1.4 kb mRNA detected in Fig. 1 is thought to be the expression of the transfected genes.…”

Section: Resultsmentioning

confidence: 99%

“…In the peripheral nervous system (PNS), however, Cx32 is believed to be located in the myelin and to take part in intramyelin (intracellular) transport (Bruzzone et al 1994). Although studies of Cx32 expression in rat sciatic nerves and cultured Schwann cells showed that the pattern of Cx32 expression is similar to that of Po, a PNS myelin-specific protein (Scherer et al, 1995;Satake et al, 1997), immunoreactivity of Cx32, which is oberved at the regions of nodes of Ranvier and Schmidt-Lanterman incisures in PNS myelin (Bergofen et al, 1993;Miyazaki et al, 1995), is completely different from that of Po.…”

Section: Introductionmentioning

confidence: 99%

Mutations of connexin32 in charcot-marie-tooth disease type X interfere with cell-to-cell communication but not cell proliferation and myelin-specific gene expression

et al. 1998

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Connexin32 (Cx32) is a gap junction protein and its mutations are responsible for X-linked Charcot-Marie-Tooth disease. We examined the functional abnormality of C6 glioma cells transfected with mutant (C53S and P172R) Cx32 genes. Nontransfected C6 did not express Cx32. Northern and Western blot analyses showed Cx32 mRNA and protein in cells with the wild-type gene as well as with the mutant Cx32 genes. An immunocytochemical study of cells with the wild-type gene showed the immunoreactive spots in the cell membrane. In cells with C53S or P172R mutant gene, however, the immunoreactivity was found in the cytoplasm. The scrape-loading method produced effective dye transfer in cells with the wild-type gene but not in those with mutant genes. A cell proliferation assay showed no differences in nontransfected cells, cells with the wild-type gene and those with the mutant genes. Messenger RNA expression for proteolipid protein did not change. These findings suggest that Cx32 gene mutation results in loss of cell-to-cell communication because of failure to incorporate Cx32 protein in the cell membrane. The mutations do not, however, interfere with cell proliferation or myelin-specific gene expression, at least myelin proteolipid protein expression in C6 glioma cells.

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Connexin32 Gene Expression in Rat Sciatic Nerves and Cultured Schwann Cells

Cited by 13 publications

References 23 publications

Connexin32 Mutations Associated with X-Linked Charcot–Marie–Tooth Disease Show Two Distinct Behaviors: Loss of Function and Altered Gating Properties

Connexin32 Mutations Associated with X-Linked Charcot–Marie–Tooth Disease Show Two Distinct Behaviors: Loss of Function and Altered Gating Properties

Signaling proteins in the axoglial apparatus of sciatic nerve nodes of Ranvier

Mutations of connexin32 in charcot-marie-tooth disease type X interfere with cell-to-cell communication but not cell proliferation and myelin-specific gene expression

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