title: Monoubiquitination Inhibits the Actin Bundling Activity of Fascin.
abstract: Fascin is an actin bundling protein that cross-links individual actin filaments into straight, compact, and stiff bundles, which are crucial for the formation of filopodia, stereocillia, and other finger-like membrane protrusions. The dysregulation of fascin has been implicated in cancer metastasis, hearing loss, and blindness. Here we identified monoubiquitination as a novel mechanism that regulates fascin bundling activity and dynamics. The monoubiquitination sites were identified to be Lys247and Lys250, two residues located in a positive charge patch at the actin binding site 2 of fascin. Using a chemical ubiquitination method, we synthesized chemically monoubiquitinated fascin and determined the effects of monoubiquitination on fascin bundling activity and dynamics. Our data demonstrated that monoubiquitination decreased the fascin bundling EC50, delayed the initiation of bundle assembly, and accelerated the disassembly of existing bundles. By analyzing the electrostatic properties on the solvent-accessible surface of fascin, we proposed that monoubiquitination introduced steric hindrance to interfere with the interaction between actin filaments and the positively charged patch at actin binding site 2. We also identified Smurf1 as a E3 ligase regulating the monoubiquitination of fascin. Our findings revealed a previously unidentified regulatory mechanism for fascin, which will have important implications for the understanding of actin bundle regulation under physiological and pathological conditions.
authors.affiliation: From the Departments of Tumor Biology.
authors.forename: Shengchen
authors.initials: S
authors.lastname: Lin
authors.affiliation: From the Departments of Tumor Biology.
authors.forename: Shuang
authors.initials: S
authors.lastname: Lu
authors.affiliation: the Department of Physics and.
authors.forename: Mentor
authors.initials: M
authors.lastname: Mulaj
authors.affiliation: Proteomics, H. Lee Moffitt Cancer Center, Tampa, Florida 33612.
authors.forename: Bin
authors.initials: B
authors.lastname: Fang
authors.affiliation: From the Departments of Tumor Biology.|the Cancer Biology Ph.D. Program, University of South Florida, Tampa, Florida 33620.
authors.forename: Tyler
authors.initials: T
authors.lastname: Keeley
authors.affiliation: Molecular Oncology, and.
authors.forename: Lixin
authors.initials: L
authors.lastname: Wan
authors.affiliation: the Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Department of Pancreatic Cancer, Tianjin 300060, China.
authors.forename: Jihui
authors.initials: J
authors.lastname: Hao
authors.affiliation: Proteomics, H. Lee Moffitt Cancer Center, Tampa, Florida 33612.
authors.forename: Martin
authors.initials: M
authors.lastname: Muschol
authors.affiliation: From the Departments of Tumor Biology, jwsun@scau.edu.cn.|the College of Life Sciences, South China Agricultural University, Guangzhou 510642, China, and.
authors.forename: Jianwei
authors.initials: J
authors.lastname: Sun
authors.affiliation: From the Departments of Tumor Biology, syang2@hmc.psu.edu.
authors.forename: Shengyu
authors.initials: S
authors.lastname: Yang
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism*; D000199:Actins / Q000378:metabolism*; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D051379:Mice; D008840:Microfilament Proteins / Q000378:metabolism*; D041681:NIH 3T3 Cells; D051381:Rats; D025801:Ubiquitin / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism; D054875:Ubiquitination
chemical_list: D000199:Actins; D002352:Carrier Proteins; D008840:Microfilament Proteins; D025801:Ubiquitin; C020324:fascin; C498342:SMURF1 protein, human; D044767:Ubiquitin-Protein Ligases
keywords: actin; cell migration; cell motility; cytoskeleton; fascin; filopodia; monoubiquitination; ubiquitylation (ubiquitination)