Systematic analysis of myotubularins: heteromeric interactions, subcellular localisation and endosomerelated functions
Author:
Lorenzo Óscar1, Urbé Sylvie1, Clague Michael J.1
Affiliation:
1. Physiological Laboratory, University of Liverpool, Crown Street, Liverpool, L69 3BX, UK
Abstract
The myotubularins are a large family of lipid phosphatases with specificity towards PtdIns3P and PtdIns(3,5)P2. Each of the 14 family members bears a signature phosphatase domain, which is inactive in six cases due to amino acid changes at the catalytic site. Fragmentary data have indicated heteromeric interactions between myotubularins, which have hitherto paired an active family member with an inactive one. In this study we have conducted a largescale analysis of potential associations within the human myotubularin family, through directed two-hybrid screening and immunoprecipitation of epitope-tagged proteins. We have confirmed all previously reported combinations and identified novel heteromeric interactions: MTMR8 with MTMR9, and MTMR3 with MTMR4, the first such combination of enzymatically active MTMs. We also report the capacity of several family members to self-associate, including MTMR3 and MTMR4. Subcellular localisation studies reveal a unique distribution of MTMR4 to endosomal structures, the major site of substrate lipid accumulation. All active MTMs we have tested (MTM1, MTMR2-MTMR4) reduce endosomal PtdIns3P levels upon overexpression. Despite this, only MTMR4 exerts any effect on EGF receptor trafficking and degradation, which is more pronounced with a phosphatase inactive form of MTMR4 and requires an intact FYVE domain.
Publisher
The Company of Biologists
Reference30 articles.
1. Alonso, A., Sasin, J., Bottini, N., Friedberg, I., Friedberg, I., Osterman, A., Godzik, A., Hunter, T., Dixon, J. and Mustelin, T. (2004). Protein tyrosine phosphatases in the human genome. Cell117, 699-711. 2. Azzedine, H., Bolino, A., Taieb, T., Birouk, N., Di Duca, M., Bouhouche, A., Benamou, S., Mrabet, A., Hammadouche, T., Chkili, T. et al. (2003). 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 early-onset glaucoma. Am. J. Hum. Genet.72, 1141-1153. 3. Berger, P., Bonneick, S., Willi, S., Wymann, M. and Suter, U. (2002). Loss of phosphatase activity in myotubularin-related protein 2 is associated with Charcot-Marie-Tooth disease type 4B1. Hum. Mol. Genet.11, 1569-1579. 4. Berger, P., Schaffitzel, C., Berger, I., Ban, N. and Suter, U. (2003). Membrane association of myotubularin-related protein 2 is mediated by a pleckstrin homology-GRAM domain and a coiled-coil dimerization module. Proc. Natl. Acad. Sci. USA100, 12177-12182. 5. Blondeau, F., Laporte, J., Bodin, S., Superti-Furga, G., Payrastre, B. and Mandel, J.-L. (2000). Myotubularin, a phosphatase deficient in myotubular myopathy, acts on phosphatidylinositol 3-kinase and phosphatidylinositol 3-phosphate pathway. Hum. Mol. Genet.9, 2223-2229.
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