Disruption of Mtmr2 produces CMT4B1-like neuropathy with myelin outfolding and impaired spermatogenesis.
Mutations in MTMR2, the myotubularin-related 2 gene, cause autosomal recessive Charcot-Marie-Tooth (CMT) type 4B1, a demyelinating neuropathy with myelin outfolding and azoospermia. MTMR2 encodes a ubiquitously expressed phosphatase whose preferred substrate is phosphatidylinositol (3,5)-biphosphate, a regulator of membrane homeostasis and vesicle transport. We generated Mtmr2-null mice, which develop progressive neuropathy characterized by myelin outfolding and recurrent loops, predominantly at paranodal myelin, and depletion of spermatids and spermatocytes from the seminiferous epithelium, which leads to azoospermia. Disruption of Mtmr2 in Schwann cells reproduces the myelin abnormalities. We also identified a novel physical interaction in Schwann cells, between Mtmr2 and discs large 1 (Dlg1)/synapse-associated protein 97, a scaffolding molecule that is enriched at the node/paranode region. Dlg1 homologues have been located in several types of cellular junctions and play roles in cell polarity and membrane addition. We propose that Schwann cell-autonomous loss of Mtmr2-Dlg1 interaction dysregulates membrane homeostasis in the paranodal region, thereby producing outfolding and recurrent loops of myelin.
Bolino
Alessandra
A
Dulbecco Telethon Institute, San Raffaele Scientific Institute, 20132 Milan, Italy. bolino.alessandra@hsr.it
Bolis
Annalisa
A
Previtali
Stefano Carlo
SC
Dina
Giorgia
G
Bussini
Simona
S
Dati
Gabriele
G
Amadio
Stefano
S
Del Carro
Ubaldo
U
Mruk
Dolores D
DD
Feltri
Maria Laura
ML
Cheng
C Yan
CY
Quattrini
Angelo
A
Wrabetz
Lawrence
L
D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D002607:Charcot-Marie-Tooth Disease / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D000074288:Discs Large Homolog 1 Protein; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism; D005260:Female; D051528:Guanylate Kinases; D006706:Homeostasis / Q000235:genetics; D008297:Male; D008565:Membrane Proteins; D051379:Mice; D018345:Mice, Knockout; D046529:Microscopy, Electron, Transmission; D009154:Mutation / Q000235:genetics; D009186:Myelin Sheath / Q000378:metabolism / Q000473:pathology* / Q000648:ultrastructure; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism; D009845:Oligospermia / Q000235:genetics* / Q000378:metabolism; D010525:Peripheral Nerves / Q000378:metabolism / Q000473:pathology* / Q000503:physiopathology; D018129:Phosphatidylinositol Phosphates / Q000378:metabolism; D017027:Protein Tyrosine Phosphatases / Q000172:deficiency* / Q000235:genetics; D054558:Protein Tyrosine Phosphatases, Non-Receptor; D011901:Ranvier's Nodes / Q000378:metabolism / Q000473:pathology / Q000648:ultrastructure; D012583:Schwann Cells / Q000378:metabolism / Q000473:pathology / Q000648:ultrastructure; D012671:Seminiferous Tubules / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism
D048868:Adaptor Proteins, Signal Transducing; D000074288:Discs Large Homolog 1 Protein; C000614189:Dlg1 protein, mouse; D029721:Drosophila Proteins; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D018129:Phosphatidylinositol Phosphates; D025521:Tumor Suppressor Proteins; C106336:phosphatidylinositol 3,5-diphosphate; C070350:dlg1 protein, Drosophila; D051528:Guanylate Kinases; C498717:Mtmr2 protein, mouse; D017027:Protein Tyrosine Phosphatases; D054558:Protein Tyrosine Phosphatases, Non-Receptor