Connexin43 Is Another Gap Junction Protein in the Peripheral Nervous System

Yoshimura, Teizo; Satake, Marie; Kobayashi, Takuya

doi:10.1046/j.1471-4159.1996.67031252.x

Cited by 38 publications

(15 citation statements)

References 8 publications

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“…As precedent, protein constituents of gap junctions ("connexins") are well documented in peripheral nerve Schwann cells (Bergoffen et al, 1993;Scherer et al, 1995;Yoshimura et al, 1996;Chandross et al, 1996;Mambetisaeva et al, 1999;Nagaoka et al, 1999;Zhao et al, 1999;Altevogt et al, 2002;Li et al, 2002). Immunocytochemical evidence is strong for connexin32 (Cx32) in paranodes, at Schmidt-Lanterman incisures, and along the "inner mesaxon" of the myelin sheath (Bergoffen et al, 1993;Scherer et al, 1995Scherer et al, , 1998Spray and Dermietzel, 1995).…”

Section: Introductionmentioning

confidence: 97%

Connexin32-Containing Gap Junctions in Schwann Cells at the Internodal Zone of Partial Myelin Compaction and in Schmidt–Lanterman Incisures

Meier¹,

Dermietzel²,

Davidson³

et al. 2004

J. Neurosci.

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In vertebrate peripheral nerves, the insulating myelin sheath is formed by Schwann cells, which generate flattened membrane processes that spiral around axons and form compact myelin by extrusion of cytoplasm and adhesion of apposed intracellular and extracellular membrane surfaces. Cytoplasm remains within the innermost and outermost tongues, in the paranodal loops bordering nodes of Ranvier and in Schmidt-Lanterman incisures. By immunocytochemistry, connexin32 (Cx32) protein has been demonstrated at paranodal loops and Schmidt-Lanterman incisures, and it is widely assumed that gap junctions are present in these locations, thereby providing a direct radial route for transport of ions and metabolites between cytoplasmic myelin layers. This study used freeze-fracture replica immunogold labeling to detect Cx32 in ultrastructurally defined gap junctions in Schmidt-Lanterman incisures, as well as in a novel location, between the outer two layers of internodal myelin, approximately every micrometer along the entire length of myelin, at the zone between compact myelin and noncompact myelin. Thus, these gap junctions link the partially compacted second layer of myelin to the noncompact outer tongue. Although these gap junctions are unusually small (average, 11 connexon channels), their relative abundance and regular distribution along the zone that is structurally intermediate between compact and noncompact myelin demonstrates the existence of multiple sites for unidirectional or bidirectional transport of water, ions, and small molecules between these two distinct cytoplasmic compartments, possibly to regulate or facilitate myelin compaction or to maintain the transition zone between noncompact and compact myelin.

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Section: Introductionmentioning

confidence: 97%

Connexin32-Containing Gap Junctions in Schwann Cells at the Internodal Zone of Partial Myelin Compaction and in Schmidt–Lanterman Incisures

Meier¹,

Dermietzel²,

Davidson³

et al. 2004

J. Neurosci.

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“…Presently, at least 20 connexin proteins have been identified and characterized in rodents (Bruzzon, 2001). Changes in the expression of various gap junction gene products including connexin (Cx) 26, Cx43, and Cx46 were observed during peripheral nerve recovery, following peripheral nerve injury (Yoshimura et al, 1996;Chandross et al, 1996). Colleagues reported that gap junction proteins Cx26, Cx32, and Cx43 were differentially regulated after crush injury and that occludin frequently coexisted with Cx43 in the perineurium, suggesting that the regulation of tight junction and gap junction were closely related (Nagaoka et al, 1999).…”

Section: Introductionmentioning

confidence: 99%

Expression of Tight and Gap Junctional Proteins in the Perineurial Window Model of the Rat Sciatic Nerve

Ohta

Okajima

Hirakawa

et al. 2005

International Journal of Neuroscience

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Limited perineurial injury, known as a perineurial window, can lead to neuropathic pain. This article hypothesizes that the recovery of the perineurium is associated with the intercellular junctional proteins. It analyzes the expressions of occludin, ZO-1, and connexin 43 by immunoconfocal microscopy. Seven days after injury, immunoreactivities for occludin and ZO-1 were observed, although there was no connexin 43 detected. Then, 21 days after injury, immunoreactivity for connexin 43 were observed. These results indicate that recovery of the perineurium is associated with the intercellular junctional proteins and that the recovery of gap junctions is delayed compared with that of tight junctions.

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“…Disruption of this radial pathway may be the reason that mutations in Cx32 cause X-linked Charcot-Marie-Tooth disease (CMTX), an inherited demyelinating neuropathy (Bergoffen et al 1993). Because the pathway and the rate of 5,6-carboxyfluorescein diffusion in cx32-null mice did not appear to be different than in wild-type mice (Balice-Gordon et al 1998), there appear to be functional gap junctions in the myelin sheaths formed by another connexin(s), perhaps Cx26 and/or Cx43 (Mambetisaeva et al 1999;Nagaoka et al 1999;Yoshimura et al 1996;Zhao and Spray 1998). The exis-5 Fig.…”

Section: Introductionmentioning

confidence: 99%

On the molecular architecture of myelinated fibers

Arroyo¹,

Scherer²

2000

Histochemistry

289

220

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Schwann cells and oligodendrocytes make the myelin sheaths of the PNS and CNS, respectively. Their myelin sheaths are structurally similar, consisting of multiple layers of specialized cell membrane that spiral around axons, but there are several differences. (1) CNS myelin has a "radial component" composed of a tight junction protein, claudin-11/oligodendrocyte-specific protein. (2) Schwann cells have a basal lamina and microvilli. (3) Although both CNS and PNS myelin sheaths have incisures, those in the CNS lack the structural as well as the molecular components of "reflexive" adherens junctions and gap junctions. In spite of their structural differences, the axonal membranes of the PNS and CNS are similarly organized. The nodal axolemma contains high concentrations of voltage-dependent sodium channels that are linked to the axonal cytoskeleton by ankyrin(G). The paranodal membrane contains Caspr/paranodin, which may participate in the formation of axoglial junctions. The juxtaparanodal axonal membrane contains the potassium channels Kv1.1 and Kv1.2, their associated beta2 subunit, as well as Caspr2, which is closely related to Caspr. The myelin sheath probably organizes these axonal membrane-related proteins via trans interactions.

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Connexin43 Is Another Gap Junction Protein in the Peripheral Nervous System

Cited by 38 publications

References 8 publications

Connexin32-Containing Gap Junctions in Schwann Cells at the Internodal Zone of Partial Myelin Compaction and in Schmidt–Lanterman Incisures

Connexin32-Containing Gap Junctions in Schwann Cells at the Internodal Zone of Partial Myelin Compaction and in Schmidt–Lanterman Incisures

Expression of Tight and Gap Junctional Proteins in the Perineurial Window Model of the Rat Sciatic Nerve

On the molecular architecture of myelinated fibers

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