title: Myotubularin-related proteins 3 and 4 interact with polo-like kinase 1 and centrosomal protein of 55 kDa to ensure proper abscission.
abstract: The myotubularins are a family of phosphatases that dephosphorylate the phosphatidylinositols phosphatidylinositol-3-phosphate and phosphatidylinositol-3,5-phosphate. Several family members are mutated in disease, yet the biological functions of the majority of myotubularins remain unknown. To gain insight into the roles of the individual enzymes, we have used affinity purification coupled to mass spectrometry to identify protein-protein interactions for the myotubularins. The myotubularin interactome comprises 66 high confidence (false discovery rate ≤1%) interactions, including 18 pairwise interactions between individual myotubularins. The results reveal a number of potential signaling contexts for this family of enzymes, including an intriguing, novel role for myotubularin-related protein 3 and myotubularin-related protein 4 in the regulation of abscission, the final step of mitosis in which the membrane bridge remaining between two daughter cells is cleaved. Both depletion and overexpression of either myotubularin-related protein 3 or myotubularin-related protein 4 result in abnormal midbody morphology and cytokinesis failure. Interestingly, myotubularin-related protein 3 and myotubularin-related protein 4 do not exert their effects through lipid regulation at the midbody, but regulate abscission during early mitosis, by interacting with the mitotic kinase polo-like kinase 1, and with centrosomal protein of 55 kDa (CEP55), an important regulator of abscission. Structure-function analysis reveals that, consistent with known intramyotubularin interactions, myotubularin-related protein 3 and myotubularin-related protein 4 interact through their respective coiled coil domains. The interaction between myotubularin-related protein 3 and polo-like kinase 1 relies on the divergent, nonlipid binding Fab1, YOTB, Vac1, and EEA1 domain of myotubularin-related protein 3, and myotubularin-related protein 4 interacts with CEP55 through a short GPPXXXY motif, analogous to endosomal sorting complex required for transport-I components. Disruption of any of these interactions results in abscission failure, by disrupting the proper recruitment of CEP55, and subsequently, of endosomal sorting complex required for transport-I, to the midbody. Our data suggest that myotubularin-related protein 3 and myotubularin-related protein 4 may act as a bridge between CEP55 and polo-like kinase 1, ensuring proper CEP55 phosphorylation and regulating CEP55 recruitment to the midbody. This work provides a novel role for myotubularin-related protein 3/4 heterodimers, and highlights the temporal and spatial complexity of the regulation of cytokinesis.
authors: From the ‡Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto, ON M5G 1X5, Canada;
authors: Nicole
authors: N
authors: St-Denis
authors: From the ‡Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto, ON M5G 1X5, Canada;
authors: Gagan D
authors: GD
authors: Gupta
authors: From the ‡Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto, ON M5G 1X5, Canada;
authors: Zhen Yuan
authors: ZY
authors: Lin
authors: From the ‡Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto, ON M5G 1X5, Canada;
authors: Beatriz
authors: B
authors: Gonzalez-Badillo
authors: From the ‡Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto, ON M5G 1X5, Canada; §Department of Molecular Genetics, University of Toronto, Toronto ON M5S 1A8, Canada.
authors: Laurence
authors: L
authors: Pelletier
authors: From the ‡Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto, ON M5G 1X5, Canada; §Department of Molecular Genetics, University of Toronto, Toronto ON M5S 1A8, Canada gingras@lunenfeld.ca.
authors: Anne-Claude
authors: AC
authors: Gingras
mesh_terms: D018797:Cell Cycle Proteins / Q000378:metabolism*; D045744:Cell Line, Tumor; D048749:Cytokinesis; D057809:HEK293 Cells; D006801:Humans; D050356:Lipid Metabolism; D008938:Mitosis; D009687:Nuclear Proteins / Q000378:metabolism*; D010766:Phosphorylation; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D054558:Protein Tyrosine Phosphatases, Non-Receptor / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D000097869:Polo-Like Kinase 1
chemical_list: D018797:Cell Cycle Proteins; D009687:Nuclear Proteins; D017346:Protein Serine-Threonine Kinases; D054558:Protein Tyrosine Phosphatases, Non-Receptor; D011518:Proto-Oncogene Proteins; D000097869:Polo-Like Kinase 1; C505378:Cep55 protein, human; C444436:MTMR3 protein, human; C427064:MTMR4 protein, human