Filopodia formation and endosome clustering induced by mutant plus-end-directed myosin VI.
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Publication Date
2017-02-14Journal Title
Proceedings of the National Academy
ISSN
0027-8424
Publisher
National Academy of Sciences
Volume
114
Issue
7
Pages
1595-1600
Language
English
Type
Article
This Version
AM
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Masters, T., & Buss, F. (2017). Filopodia formation and endosome clustering induced by mutant plus-end-directed myosin VI.. Proceedings of the National Academy, 114 (7), 1595-1600. https://doi.org/10.1073/pnas.1616941114
Abstract
Myosin VI (MYO6) is the only myosin known to move toward the minus end of actin filaments. It has roles in numerous cellular processes, including maintenance of stereocilia structure, endocytosis, and autophagosome maturation. However, the functional necessity of minus-end-directed movement along actin is unclear as the underlying architecture of the local actin network is often unknown. To address this question, we engineered a mutant of MYO6, MYO6+, which undergoes plus-end-directed movement while retaining physiological cargo interactions in the tail. Expression of this mutant motor in HeLa cells led to a dramatic reorganization of cortical actin filaments and the formation of actin-rich filopodia. MYO6 is present on peripheral adaptor protein, phosphotyrosine interacting with PH domain and leucine zipper 1 (APPL1) signaling endosomes and MYO6+ expression causes a dramatic relocalization and clustering of this endocytic compartment in the cell cortex. MYO6+ and its adaptor GAIP interacting protein, C terminus (GIPC) accumulate at the tips of these filopodia, while APPL1 endosomes accumulate at the base. A combination of MYO6+ mutagenesis and siRNA-mediated depletion of MYO6 binding partners demonstrates that motor activity and binding to endosomal membranes mediated by GIPC and PI(4,5)P$_{2}$ are crucial for filopodia formation. A similar reorganization of actin is induced by a constitutive dimer of MYO6+, indicating that multimerization of MYO6 on endosomes through binding to GIPC is required for this cellular activity and regulation of actin network structure. This unique engineered MYO6+ offers insights into both filopodia formation and MYO6 motor function at endosomes and at the plasma membrane.
Keywords
actin dynamics, endosomes, filopodia, motor–cargo complexes, unconventional myosins
Sponsorship
This work was supported by Biotechnology and Biological Sciences Research Council Project Grant BB/K001981/1 (to F.B.). The Cambridge Institute for Medical Research is supported by the Wellcome Trust with a strategic award (100140) and an equipment grant (093026).
Funder references
BBSRC (BB/K001981/1)
Wellcome Trust (100140/Z/12/Z)
Wellcome Trust (093026/Z/10/Z)
Identifiers
External DOI: https://doi.org/10.1073/pnas.1616941114
This record's URL: https://www.repository.cam.ac.uk/handle/1810/263113
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