. Plasmids, A complete list of all DNA-plasmids used in this study is provided in Supplementary Data 2. N-terminally FLAG-tagged MTMR13 in a pcDNA3.1 backbone was a kind gift from Gilbert di Paoli and was transferred into a pcDNA3.1-HA backbone, removing the HA-tag, using 5?-KpnI and 3?-EcoRV restriction sites. For the construction of mCherry-MTMR13, FLAG-tag was exchanged by mCherry from pmCherryC1 using restriction sites 5?-KpnI and 3?-EcoRV For mCherry-tagged MTMR13 domains, full-length MTMR13 (FL; aa1-1848; 5547 bp) was used as a PCR template. The DENN-domain truncation mutant of MTMR13 (MTMR13?DENN) and the various MTMR13 domains were amplified using primers specified in the primer table, p.1479

, with restriction sites 5?-EcoRV and 3?-HindIII to obtain pcDNA3.1_BirA*-Rab35. pcDNA3.1_eGFP-Rab35 was generated by insertion of amplified Rab35 C-terminal to eGFP using restriction sites 5?-XhoI and 3?-EcoRI. pcDNA3.1_eGFP-Rab35CA(Q67L) and_eGFP-Rab35DN(S22N) were generated by QuickChange site-directed mutagenesis (Agilent). pEGFPC2_mCherry-MTMR5 was obtained by exchanging the Nterminal eGFP-tag for mCherry in pEGFPC2_GFP-MTMR5 (gift from Michael Clague) at restriction sites 5?-AgeI and 3?-HindIII. GST-Rab1A, -Rab5, -Rab7, and -Rab11 were a gift from Dr, PTP + coiled coil (CC) region (aa1100-1591): 1797 bp; PH domain (aa1743-1849): 324 bp. The respective PCR products were inserted into a pcDNA3.1-based mCherry-containing vector using restriction sites 5?-NotI and 3?-XbaI for MTMR13?DENN, 5?-EcoRV and 3?-NotI for DENN and PH-GRAM domains. For PTP, PTP + CC region and PH domains, pp.6-8

D. Pareyson, P. Saveri, and C. Pisciotta, New developments in Charcot-Marie-Tooth neuropathy and related diseases, Curr. Opin. Neurol, vol.30, pp.471-480, 2017.

D. Pareyson, A multicentre retrospective study of Charcot-Marie-Tooth disease type 4B (CMT4B) due to mutations in Myotubularin-related proteins (MTMRs), Ann. Neurol, vol.86, pp.55-67, 2019.

A. Bolino, Charcot-Marie-Tooth type 4B is caused by mutations in the gene encoding myotubularin-related protein-2, Nat. Genet, vol.25, pp.17-19, 2000.

H. Azzedine, Mutations in MTMR13, a new pseudophosphatase homologue of MTMR2 and Sbf1, in two families with an autosomal recessive demyelinating form of Charcot-Marie-Tooth disease associated with earlyonset glaucoma, Am. J. Hum. Genet, vol.72, pp.1141-1153, 2003.

P. Berger, S. Bonneick, S. Willi, M. Wymann, and U. Suter, Loss of phosphatase activity in myotubularin-related protein 2 is associated with Charcot-Marie-Tooth disease type 4B1, Hum. Mol. Genet, vol.11, pp.1569-1579, 2002.

S. A. Kim, G. S. Taylor, K. M. Torgersen, and J. E. Dixon, Myotubularin and MTMR2, phosphatidylinositol 3-phosphatases mutated in myotubular myopathy and type 4B Charcot-Marie-Tooth disease, J. Biol. Chem, vol.277, pp.4526-4531, 2002.

I. Vaccari, Genetic interaction between MTMR2 and FIG4 phospholipid phosphatases involved in Charcot-Marie-Tooth neuropathies, PLoS Genet, vol.7, p.1002319, 2011.
URL : https://hal.archives-ouvertes.fr/inserm-00711724

F. L. Robinson and J. E. Dixon, The phosphoinositide-3-phosphatase MTMR2 associates with MTMR13, a membrane-associated pseudophosphatase also mutated in type 4B Charcot-Marie-Tooth disease, J. Biol. Chem, vol.280, pp.31699-31707, 2005.

P. Berger, Multi-level regulation of myotubularin-related protein-2 phosphatase activity by myotubularin-related protein-13/set-binding factor-2, Hum. Mol. Genet, vol.15, pp.569-579, 2006.

D. Bridges, Phosphatidylinositol 3,5-bisphosphate plays a role in the activation and subcellular localization of mechanistic target of rapamycin 1, Mol. Biol. Cell, vol.23, pp.2955-2962, 2012.

Z. Hong, PtdIns3P controls mTORC1 signaling through lysosomal positioning, J. Cell Biol, vol.216, pp.4217-4233, 2017.

N. Jin, Roles for PI(3,5)P2 in nutrient sensing through TORC1, Mol. Biol. Cell, vol.25, pp.1171-1185, 2014.

A. L. Marat and V. Haucke, Phosphatidylinositol 3-phosphates-at the interface between cell signalling and membrane traffic, EMBO J, vol.35, pp.561-579, 2016.

S. Goebbels, Genetic disruption of Pten in a novel mouse model of tomaculous neuropathy, EMBO Mol. Med, vol.4, pp.486-499, 2012.

E. Domenech-estevez, Akt regulates axon wrapping and myelin sheath thickness in the PNS, J. Neurosci, vol.36, pp.4506-4521, 2016.

G. Figlia, C. Norrmen, J. A. Pereira, D. Gerber, and U. Suter, Dual function of the PI3K-Akt-mTORC1 axis in myelination of the peripheral nervous system, Elife, vol.6, p.29241, 2017.

C. Norrmen, mTORC1 controls PNS myelination along the mTORC1-RXRgamma-SREBP-lipid biosynthesis axis in Schwann cells, Cell Rep, vol.9, pp.646-660, 2014.

D. L. Sherman, Arrest of myelination and reduced axon growth when Schwann cells lack mTOR, J. Neurosci, vol.32, pp.1817-1825, 2012.
URL : https://hal.archives-ouvertes.fr/hal-02126912

G. Figlia, D. Gerber, and U. Suter, Myelination and mTOR, Glia, vol.66, pp.693-707, 2018.

M. Chaineau, M. S. Ioannou, P. S. Mcpherson, and . Rab35, GEFs, GAPs and effectors, vol.14, pp.1109-1117, 2013.

K. Klinkert and A. Echard, Rab35 GTPase: a central regulator of phosphoinositides and F-actin in endocytic recycling and beyond, Traffic, vol.17, pp.1063-1077, 2016.

V. Uytterhoeven, S. Kuenen, J. Kasprowicz, K. Miskiewicz, and P. Verstreken, Loss of skywalker reveals synaptic endosomes as sorting stations for synaptic vesicle proteins, Cell, vol.145, pp.117-132, 2011.

C. Hsu, Regulation of exosome secretion by Rab35 and its GTPaseactivating proteins TBC1D10A-C, J. Cell Biol, vol.189, pp.223-232, 2010.

K. Klinkert, M. Rocancourt, A. Houdusse, and A. Echard, Rab35 GTPase couples cell division with initiation of epithelial apico-basal polarity and lumen opening, Nat. Commun, vol.7, p.11166, 2016.
URL : https://hal.archives-ouvertes.fr/pasteur-01301777

L. Chesneau, An ARF6/Rab35 GTPase cascade for endocytic recycling and successful cytokinesis, Curr. Biol, vol.22, pp.147-153, 2012.

S. Fremont, Oxidation of F-actin controls the terminal steps of cytokinesis, Nat. Commun, vol.8, p.14528, 2017.
URL : https://hal.archives-ouvertes.fr/hal-01492528

D. B. Wheeler, R. Zoncu, D. E. Root, D. M. Sabatini, and C. L. Sawyers, Identification of an oncogenic RAB protein, Science, vol.350, pp.211-217, 2015.

P. D. Allaire, Interplay between Rab35 and Arf6 controls cargo recycling to coordinate cell adhesion and migration, J. Cell Sci, vol.126, pp.722-731, 2013.

S. Corallino, A RAB35-p85/PI3K axis controls oscillatory apical protrusions required for efficient chemotactic migration, Nat. Commun, vol.9, p.1475, 2018.

C. Cauvin, Rab35 GTPase triggers switch-like recruitment of the lowe syndrome lipid phosphatase OCRL on newborn endosomes, Curr. Biol, vol.26, pp.120-128, 2016.
URL : https://hal.archives-ouvertes.fr/hal-02431336

D. Dambournet, Rab35 GTPase and OCRL phosphatase remodel lipids and F-actin for successful cytokinesis, Nat. Cell Biol, vol.13, pp.981-988, 2011.

Y. Miyamoto, N. Yamamori, T. Torii, A. Tanoue, J. Yamauchi et al., acting through ACAP2 switching off Arf6, negatively regulates oligodendrocyte differentiation and myelination, Mol. Biol. Cell, vol.25, pp.1532-1542, 2014.

H. Kobayashi and M. Fukuda, Rab35 regulates Arf6 activity through centaurin-beta2 (ACAP2) during neurite outgrowth, J. Cell Sci, vol.125, pp.2235-2243, 2012.

S. Fremont, G. Romet-lemonne, A. Houdusse, and A. Echard, Emerging roles of MICAL family proteins -from actin oxidation to membrane trafficking during cytokinesis, J. Cell Sci, vol.130, pp.1509-1517, 2017.

J. Rahajeng, S. S. Giridharan, B. Cai, N. Naslavsky, and S. Caplan, MICAL-L1 is a tubular endosomal membrane hub that connects Rab35 and Arf6 with Rab8a, Traffic, vol.13, pp.82-93, 2012.

P. D. Allaire, The Connecdenn DENN domain: a GEF for Rab35 mediating cargo-specific exit from early endosomes, Mol. Cell, vol.37, pp.370-382, 2010.

R. K. Nookala, Crystal structure of folliculin reveals a hidDENN function in genetically inherited renal cancer, Open Biol, vol.2, p.120071, 2012.

J. Zheng, Folliculin interacts with Rab35 to regulate EGF-induced EGFR degradation, Front. Pharmacol, vol.8, p.688, 2017.

K. J. Roux, D. I. Kim, M. Raida, and B. Burke, A promiscuous biotin ligase fusion protein identifies proximal and interacting proteins in mammalian cells, J. Cell Biol, vol.196, pp.801-810, 2012.

A. K. Gillingham, R. Sinka, I. L. Torres, K. S. Lilley, and S. Munro, Toward a comprehensive map of the effectors of rab GTPases, Dev. Cell, vol.31, pp.358-373, 2014.

S. C. Previtali, A. Quattrini, and A. Bolino, Charcot-Marie-Tooth type 4B demyelinating neuropathy: deciphering the role of MTMR phosphatases, Expert Rev. Mol. Med, vol.9, pp.1-16, 2007.

F. L. Robinson, I. R. Niesman, K. K. Beiswenger, and J. E. Dixon, Loss of the inactive myotubularin-related phosphatase Mtmr13 leads to a Charcot-Marie-Tooth 4B2-like peripheral neuropathy in mice, Proc. Natl Acad. Sci. USA, vol.105, pp.4916-4921, 2008.

J. Senderek, Mutation of the SBF2 gene, encoding a novel member of the myotubularin family, in Charcot-Marie-Tooth neuropathy type 4B2/11p15, Hum. Mol. Genet, vol.12, pp.349-356, 2003.

M. L. Feltri, P0-Cre transgenic mice for inactivation of adhesion molecules in Schwann cells, Ann. N. Y. Acad. Sci, vol.883, pp.116-123, 1999.

A. Bolis, Loss of Mtmr2 phosphatase in Schwann cells but not in motor neurons causes Charcot-Marie-Tooth type 4B1 neuropathy with myelin outfoldings, J. Neurosci, vol.25, pp.8567-8577, 2005.

B. Beirowski, K. M. Wong, E. Babetto, and J. Milbrandt, mTORC1 promotes proliferation of immature Schwann cells and myelin growth of differentiated Schwann cells, Proc. Natl Acad. Sci. USA, vol.114, pp.4261-4270, 2017.

Y. R. Lee, M. Chen, and P. P. Pandolfi, The functions and regulation of the PTEN tumour suppressor: new modes and prospects, Nat. Rev. Mol. Cell Biol, vol.19, pp.547-562, 2018.

A. Bolino, Niacin-mediated Tace activation ameliorates CMT neuropathies with focal hypermyelination, EMBO Mol. Med, vol.8, pp.1438-1454, 2016.

R. Bago, Characterization of VPS34-IN1, a selective inhibitor of Vps34, reveals that the phosphatidylinositol 3-phosphate-binding SGK3 protein kinase is a downstream target of class III phosphoinositide 3-kinase, Biochem. J, vol.463, pp.413-427, 2014.

B. Ronan, A highly potent and selective Vps34 inhibitor alters vesicle trafficking and autophagy, Nat. Chem. Biol, vol.10, pp.1013-1019, 2014.

S. Gayle, Identification of apilimod as a first-in-class PIKfyve kinase inhibitor for treatment of B-cell non-Hodgkin lymphoma, Blood, vol.129, pp.1768-1778, 2017.

J. Zhang, M. Fonovic, K. Suyama, M. Bogyo, and M. P. Scott, Rab35 controls actin bundling by recruiting fascin as an effector protein, Science, vol.325, pp.1250-1254, 2009.

A. L. Marat, M. S. Ioannou, and P. S. Mcpherson, Connecdenn 3/DENND1C binds actin linking Rab35 activation to the actin cytoskeleton, Mol. Biol. Cell, vol.23, pp.163-175, 2012.

L. Lin, Rab35/ACAP2 and Rab35/RUSC2 Complex Structures Reveal Molecular Basis for Effector Recognition by Rab35 GTPase, Structure, vol.27, pp.729-740, 2019.

T. Torii, Arf6 mediates Schwann cell differentiation and myelination, Biochem. Biophys. Res. Commun, vol.465, pp.450-457, 2015.

A. Bolino, Disruption of Mtmr2 produces CMT4B1-like neuropathy with myelin outfolding and impaired spermatogenesis, J. Cell Biol, vol.167, pp.711-721, 2004.

M. A. Raess, S. Friant, B. S. Cowling, and J. Laporte, WANTED -dead or alive: myotubularins, a large disease-associated protein family, Adv. Biol. Regul, vol.63, pp.49-58, 2016.
URL : https://hal.archives-ouvertes.fr/hal-02378733

K. Tersar, Mtmr13/Sbf2-deficient mice: an animal model for CMT4B2, Hum. Mol. Genet, vol.16, pp.2991-3001, 2007.

Y. A. Mironova, PI(3,5)P2 biosynthesis regulates oligodendrocyte differentiation by intrinsic and extrinsic mechanisms, Elife, vol.5, p.13023, 2016.

C. Taveggia and A. Bolino, DRG neuron/schwann cells myelinating cocultures, Methods Mol. Biol, vol.1791, pp.115-129, 2018.

A. Bolis, Dlg1, Sec8, and Mtmr2 regulate membrane homeostasis in Schwann cell myelination, J. Neurosci, vol.29, pp.8858-8870, 2009.

K. Ketel, A phosphoinositide conversion mechanism for exit from endosomes, Nature, vol.529, pp.408-412, 2016.

S. Holm, A simple sequentially rejective multiple test procedure, Scan J. Stat, vol.6, pp.65-70, 1979.