Alpha6beta4 integrin and dystroglycan cooperate to stabilize the myelin sheath.
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.
Nodari
Alessandro
A
Department of Biological and Technological Research, San Raffaele Scientific Institute, 20132 Milan, Italy.
Previtali
Stefano C
SC
Dati
Gabriele
G
Occhi
Simona
S
Court
Felipe A
FA
Colombelli
Cristina
C
Zambroni
Desirée
D
Dina
Giorgia
G
Del Carro
Ubaldo
U
Campbell
Kevin P
KP
Quattrini
Angelo
A
Wrabetz
Lawrence
L
Feltri
M Laura
ML
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
D039161:Integrin alpha6beta4; D049030:Dystroglycans