title: Genetic suppression of a phosphomimic myosin II identifies system-level factors that promote myosin II cleavage furrow accumulation.
abstract: How myosin II localizes to the cleavage furrow in Dictyostelium and metazoan cells remains largely unknown despite significant advances in understanding its regulation. We designed a genetic selection using cDNA library suppression of 3xAsp myosin II to identify factors involved in myosin cleavage furrow accumulation. The 3xAsp mutant is deficient in bipolar thick filament assembly, fails to accumulate at the cleavage furrow, cannot rescue myoII-null cytokinesis, and has impaired mechanosensitive accumulation. Eleven genes suppressed this dominant cytokinesis deficiency when 3xAsp was expressed in wild-type cells. 3xAsp myosin II's localization to the cleavage furrow was rescued by constructs encoding rcdBB, mmsdh, RMD1, actin, one novel protein, and a 14-3-3 hairpin. Further characterization showed that RMD1 is required for myosin II cleavage furrow accumulation, acting in parallel with mechanical stress. Analysis of several mutant strains revealed that different thresholds of myosin II activity are required for daughter cell symmetry than for furrow ingression dynamics. Finally, an engineered myosin II with a longer lever arm (2xELC), producing a highly mechanosensitive motor, could also partially suppress the intragenic 3xAsp. Overall, myosin II accumulation is the result of multiple parallel and partially redundant pathways that comprise a cellular contractility control system.
authors.affiliation: Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205.
authors.forename: Yixin
authors.initials: Y
authors.lastname: Ren
authors.affiliation: Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205.
authors.forename: Hoku
authors.initials: H
authors.lastname: West-Foyle
authors.affiliation: Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Surcel
authors.affiliation: Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205 Summer Academic Research Experience, Johns Hopkins University School of Medicine, Baltimore, MD 21205.
authors.forename: Christopher
authors.initials: C
authors.lastname: Miller
authors.affiliation: Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205 Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21205 Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD 21218 dnr@jhmi.edu.
authors.forename: Douglas N
authors.initials: DN
authors.lastname: Robinson
mesh_terms: D048749:Cytokinesis; D004023:Dictyostelium / Q000166:cytology / Q000235:genetics*; D018716:Molecular Mimicry; D024462:Myosin Type II / Q000235:genetics* / Q000378:metabolism*; D015800:Protozoan Proteins / Q000378:metabolism*; D013489:Suppression, Genetic
chemical_list: D015800:Protozoan Proteins; D024462:Myosin Type II