title: Alpha6beta4 integrin and dystroglycan cooperate to stabilize the myelin sheath.
abstract: Schwann cells integrate signals deriving from the axon and the basal lamina to myelinate peripheral nerves. Integrin alpha6beta4 is a laminin receptor synthesized by Schwann cells and displayed apposed to the basal lamina. alpha6beta4 integrin expression in Schwann cells is induced by axons at the onset of myelination, and rises in adulthood. The beta4 chain has a uniquely long cytoplasmic domain that interacts with intermediate filaments such as dystonin, important in peripheral myelination. Furthermore, alpha6beta4 integrin binds peripheral myelin protein 22, whose alteration causes the most common demyelinating hereditary neuropathy. All these data suggest a role for alpha6beta4 integrin in peripheral nerve myelination. Here we show that ablating alpha6beta4 integrin specifically in Schwann cells of transgenic mice does not affect peripheral nerve development, myelin formation, maturation, or regeneration. However, consistent with maximal expression in adult nerves, alpha6beta4 integrin-null myelin is more prone to abnormal folding with aging. When the laminin receptor dystroglycan is also ablated, major folding abnormalities occur, associated with acute demyelination in some peripheral nervous system districts. These data indicate that, similar to its role in skin, alpha6beta4 integrin confers stability to myelin in peripheral nerves.
authors.affiliation: Department of Biological and Technological Research, San Raffaele Scientific Institute, 20132 Milan, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Nodari
authors.forename: Stefano C
authors.initials: SC
authors.lastname: Previtali
authors.forename: Gabriele
authors.initials: G
authors.lastname: Dati
authors.forename: Simona
authors.initials: S
authors.lastname: Occhi
authors.forename: Felipe A
authors.initials: FA
authors.lastname: Court
authors.forename: Cristina
authors.initials: C
authors.lastname: Colombelli
authors.forename: Desirée
authors.initials: D
authors.lastname: Zambroni
authors.forename: Giorgia
authors.initials: G
authors.lastname: Dina
authors.forename: Ubaldo
authors.initials: U
authors.lastname: Del Carro
authors.forename: Kevin P
authors.initials: KP
authors.lastname: Campbell
authors.forename: Angelo
authors.initials: A
authors.lastname: Quattrini
authors.forename: Lawrence
authors.initials: L
authors.lastname: Wrabetz
authors.forename: M Laura
authors.initials: ML
authors.lastname: Feltri
mesh_terms: D000375:Aging / Q000378:metabolism / Q000473:pathology; D000818:Animals; D002454:Cell Differentiation / Q000235:genetics; D049030:Dystroglycans / Q000378:metabolism*; D039161:Integrin alpha6beta4 / Q000235:genetics* / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009186:Myelin Sheath / Q000378:metabolism*; D009413:Nerve Fibers, Myelinated / Q000378:metabolism* / Q000473:pathology; D010525:Peripheral Nerves / Q000002:abnormalities / Q000254:growth & development / Q000378:metabolism*; D017510:Protein Folding; D012583:Schwann Cells / Q000378:metabolism
chemical_list: D039161:Integrin alpha6beta4; D049030:Dystroglycans