Myosin X transports Mena/VASP to the tip of filopodia.
Myosin X (M10) is a two-headed actin based motor expressed in a variety of cell types, that is thought to play a role in cargo movement in mammalian cells, but its cellular function is unknown. Here we found that M10 binds to Mena/VASP, which facilitates actin polymerization by competing with actin capping proteins. Immunocytochemistry revealed that endogenous M10 co-localized with Mena/VASP at the tip of filopodia. Consistently, both EGFP-M10 and RFP-VASP were found at the tip of filopodia. The result raises a hypothesis that M10 transports Mena/VASP towards the tip of filopodia. Supporting this idea, the amount of VASP at the tip of filopodia was proportional to that of M10. Furthermore, we directly visualized the movement of M10 and VASP in living HeLa cells under fluorescence microscope. EGFP-M10 and RFP-VASP move together from the root to the tip of the filopodia. Interestingly, the amount of M10 at the tip of filopodia was linearly related to the length of filopodia, consistent with the actin filament extending function of VASP. These results show that M10 is a specific motor carrying Mena/VASP from the root to the tip of the filopodia where extension of actin filament takes place.
Tokuo
Hiroshi
H
Department of Physiology, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, MA 01655, USA.
Ikebe
Mitsuo
M
D000199:Actins / Q000737:chemistry; D000818:Animals; D015153:Blotting, Western; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism*; D002417:Cattle; D003598:Cytoskeletal Proteins; D018076:DNA, Complementary / Q000378:metabolism; D015723:Gene Library; D049452:Green Fluorescent Proteins; D006367:HeLa Cells; D006801:Humans; D007150:Immunohistochemistry; D008164:Luminescent Proteins / Q000737:chemistry; D008840:Microfilament Proteins; D008856:Microscopy, Fluorescence; D018715:Microscopy, Video; D008954:Models, Biological; D009218:Myosins / Q000378:metabolism*; D010957:Plasmids / Q000378:metabolism; D011233:Precipitin Tests; D011485:Protein Binding; D021381:Protein Transport; D011554:Pseudopodia / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry; D000097573:Red Fluorescent Protein
D000199:Actins; D002352:Carrier Proteins; D003598:Cytoskeletal Proteins; D018076:DNA, Complementary; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins; D008840:Microfilament Proteins; D009218:Myosins; D011994:Recombinant Proteins; D000097573:Red Fluorescent Protein; C102176:Enah protein, mouse; C498718:MYO10 protein, human