title: Exclusive expression of the Rab11 effector SH3TC2 in Schwann cells links integrin-α6 and myelin maintenance to Charcot-Marie-Tooth disease type 4C.
abstract: Charcot-Marie-Tooth disease type 4C (CMT4C) is one of the commonest autosomal recessive inherited peripheral neuropathies and is associated with mutations in the Rab11 effector, SH3TC2. Disruption of the SH3TC2-Rab11 interaction is the molecular abnormality underlying this disease. However, why SH3TC2 mutations cause an isolated demyelinating neuropathy remains unanswered. Here we show that SH3TC2 is an exclusive Schwann cell protein expressed late in myelination and is downregulated following denervation suggesting a functional role in myelin sheath maintenance. We support our data with an evolutionary cell biological analysis showing that the SH3TC2 gene, and its paralogue SH3TC1, are derived from an ancestral homologue, the duplication of which occurred in the common ancestor of jawed vertebrates, coincident with the appearance of Schwann cells and peripheral axon myelination. Furthermore, we report that SH3TC2 associates with integrin-α6, suggesting that aberrant Rab11-dependent endocytic trafficking of this critical laminin receptor in myelinated Schwann cells is connected to the demyelination seen in affected nerves. Our study therefore highlights the inherent evolutionary link between SH3TC2 and peripheral nerve myelination, pointing also towards a molecular mechanism underlying the specific demyelinating neuropathy that characterizes CMT4C.
authors.affiliation: Cambridge Institute for Medical Research, Department of Clinical Neurosciences, University of Cambridge, Cambridge Biomedical Campus, Cambridge CB2 0XY, UK.
authors.forename: Sauparnika
authors.initials: S
authors.lastname: Vijay
authors.affiliation: Department of Cell Biology, University of Alberta, 5-31 Medical Science Building, Edmonton, Alberta, Canada.
authors.forename: Meagan
authors.initials: M
authors.lastname: Chiu
authors.affiliation: Department of Cell Biology, University of Alberta, 5-31 Medical Science Building, Edmonton, Alberta, Canada.
authors.forename: Joel B
authors.initials: JB
authors.lastname: Dacks
authors.affiliation: Cambridge Institute for Medical Research, Department of Clinical Neurosciences, University of Cambridge, Cambridge Biomedical Campus, Cambridge CB2 0XY, UK. Electronic address: rcr20@cam.ac.uk.
authors.forename: Rhys C
authors.initials: RC
authors.lastname: Roberts
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D002607:Charcot-Marie-Tooth Disease / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D015870:Gene Expression; D006367:HeLa Cells; D006801:Humans; D039503:Integrin alpha6 / Q000378:metabolism*; D009186:Myelin Sheath / Q000378:metabolism / Q000473:pathology*; D010802:Phylogeny; D051381:Rats; D012583:Schwann Cells / Q000378:metabolism / Q000473:pathology*; D020691:rab GTP-Binding Proteins / Q000378:metabolism*; D000099193:rab11 GTP-Binding Proteins
chemical_list: D002352:Carrier Proteins; D039503:Integrin alpha6; D020691:rab GTP-Binding Proteins; D000099193:rab11 GTP-Binding Proteins; C552539:Sh3tc2 protein, rat
keywords: Charcot-Marie-Tooth disease; Peripheral neuropathy; Schwann cells