Disease relevance of Gje1

• In contrast, decreases in MAG expression and severe demyelination at the soma of SG neurons were found in Cx29(-/-) mice [1].

High impact information on Gje1

• The R142W mutant protein was aberrantly localized to the Golgi, indicating that it does not traffic properly, but the molecular organization of the myelin sheath, including the localization of Cx29, another connexin expressed by myelinating Schwann cells, was not disrupted [2].
• In mature myelin-forming Schwann cells, expression of multiple connexins, i.e. connexin (Cx) 43, Cx29, Cx32, and Cx46 (after nerve injury) has been detected [3].
• The only exception to this were dorsal roots, where the expression of Cx29 was delayed four days relative to ventral roots and spinal nerves [3].
• This identifies Cx29 as a novel marker for cells of the defined Schwann cell lineage [3].
• Cx29 protein expression was absent from neural crest cells but appeared as neural crest cells generated precursors (embryonic day 12) both in vivo and in vitro [3].

Biological context of Gje1

• Our data first provide a comprehensive and detailed pattern of Cx29 gene expression in the mouse and rat cochlea [4].
• The absence of the Cx29 gene in mice (Cx29(-/-) mice), with a penetrance of approximately 50%, caused a delay in the maturation of hearing thresholds, an early loss of high-frequency sensitivities, a prolongation in latency and distortion in the wave I of the auditory brainstem responses, and elevated sensitivity to noise damages [1].
• The nerve conduction in the sciatic nerve of adult Cx29-deficient mice and the auditory brain stem response as well as visually evoked potentials in 4- to 10-week-old Cx29-deficient mice were not different from wild-type littermate controls [5].
• Using newly generated transgenic mice in which the coding region of the connexin29 (Cx29) gene was replaced by the lacZ reporter gene, we confirmed previous immunochemical results that Cx29 is expressed in Schwann cells, oligodendrocytes and Bergmann glia cells [5].
• Cx29 is expressed throughout embryonic development [6].

Anatomical context of Gje1

• Oligodendrocytes of adult rodents express three different connexins: connexin29 (Cx29), Cx32, and Cx47 [7].
• The results suggested that Cx29 in mature CNS contributes minimally to gap junctional intercellular communication in oligodendrocyte cell bodies but rather is targeted to myelin, where it, with Cx32, may contribute to connexin-mediated communication between adjacent layers of uncompacted myelin [8].
• Cx29 was enriched in subcellular fractions of myelin, and immunofluorescence for Cx29 was localized to oligodendrocytes and myelinated fibers throughout the brain and spinal cord [8].
• Immunoblotting of sciatic nerve homogenate revealed monomeric and possibly higher molecular weight forms of Cx29 [9].
• In addition, Cx29 is present in distinctive IMP arrays in the inner most layer of myelin, adjacent to internodal axonal plasma membranes, where this connexin may have previously unrecognized functions [9].

Regulatory relationships of Gje1

• Cx29 expressed in N2A cells did not induce intercellular conductances but did participate in the formation of active channels when coexpressed with Cx32 [10].

Other interactions of Gje1

• From counts of over 9000 oligodendrocytes labeled by immunofluorescence in various brain regions, virtually all of these cells were found to express Cx29, Cx32 and Cx47 [11].
• Cx29 displayed a striking coincidence with Kv1.2 K(+) channels, which are localized in the axonal membrane [10].

Analytical, diagnostic and therapeutic context of Gje1

• Immunofluorescence labeling for Cx29 in oligodendrocyte somata was intense at young ages and was dramatically shifted in localization primarily to myelinated fibers in mature CNS [8].
• We also show that Cx29 mRNA is present in spiral limbus, spiral ligament, organ of Corti, stria vascularis, and lateral wall by the method of RT-PCR [4].
• To elucidate whether the Cx29 gap junction protein epsilon 1, GJE1, is localized in the adult mouse and rat cochlea, we performed an immunohistochemistry (IHC) and reverse transcription-polymerase chain reaction (RT-PCR) analysis [4].
• While no Cx28.6 expression could be detected by whole mount in situ hybridization, expression of Cx29 was found in the developing endoderm, lateral mesoderm, liver anlage, pronephros, and proctodeum [6].

References