title: Essential and nonredundant roles for Diaphanous formins in cortical microtubule capture and directed cell migration.
abstract: Formins constitute a large family of proteins that regulate the dynamics and organization of both the actin and microtubule cytoskeletons. Previously we showed that the formin mDia1 helps tether microtubules at the cell cortex, acting downstream of the ErbB2 receptor tyrosine kinase. Here we further study the contributions of mDia1 and its two most closely related formins, mDia2 and mDia3, to cortical microtubule capture and ErbB2-dependent breast carcinoma cell migration. We find that depletion of each of these three formins strongly disrupts chemotaxis without significantly affecting actin-based structures. Further, all three formins are required for formation of cortical microtubules in a nonredundant manner, and formin proteins defective in actin polymerization remain active for microtubule capture. Using affinity purification and mass spectrometry analysis, we identify differential binding partners of the formin-homology domain 2 (FH2) of mDia1, mDia2, and mDia3, which may explain their nonredundant roles in microtubule capture. The FH2 domain of mDia1 specifically interacts with Rab6-interacting protein 2 (Rab6IP2). Further, mDia1 is required for cortical localization of Rab6IP2, and concomitant depletion of Rab6IP2 and IQGAP1 severely disrupts cortical capture of microtubules, demonstrating the coinvolvement of mDia1, IQGAP1, and Rab6IP2 in microtubule tethering at the leading edge.
authors.affiliation: Centre de Recherche en Cancérologie de Marseille, INSERM U1068, 13009 Marseille, France Institut Paoli-Calmettes, 13009 Marseille, France Aix-Marseille Université, 13009 Marseille, France Centre National de la Recherche Scientifique UMR7258, 13009 Marseille, France Department of Biology, Brandeis University, Waltham, MA 02454.
authors.forename: Pascale
authors.initials: P
authors.lastname: Daou
authors.forename: Salma
authors.initials: S
authors.lastname: Hasan
authors.forename: Dennis
authors.initials: D
authors.lastname: Breitsprecher
authors.forename: Emilie
authors.initials: E
authors.lastname: Baudelet
authors.forename: Luc
authors.initials: L
authors.lastname: Camoin
authors.forename: Stéphane
authors.initials: S
authors.lastname: Audebert
authors.forename: Bruce L
authors.initials: BL
authors.lastname: Goode
authors.forename: Ali
authors.initials: A
authors.lastname: Badache
mesh_terms: D000199:Actins / Q000378:metabolism; D048868:Adaptor Proteins, Signal Transducing / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D000818:Animals; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D045744:Cell Line, Tumor; D002465:Cell Movement; D002633:Chemotaxis; D000080865:Formins; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008840:Microfilament Proteins / Q000378:metabolism; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D008870:Microtubules / Q000378:metabolism*; D019159:Nonheme Iron Proteins / Q000378:metabolism; D017434:Protein Structure, Tertiary; D011817:Rabbits; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D000199:Actins; D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D000080865:Formins; D047908:Intracellular Signaling Peptides and Proteins; D008840:Microfilament Proteins; D008869:Microtubule-Associated Proteins; D019159:Nonheme Iron Proteins; D018719:Erb-b2 Receptor Tyrosine Kinases; C108962:DIAPH1 protein, human; C491462:DIAPH2 protein, human; C095003:MACF1 protein, human; C527585:MEMO1 protein, human; C508053:ERBB2 protein, human