title: Myosin concentration underlies cell size-dependent scalability of actomyosin ring constriction.
abstract: In eukaryotes, cytokinesis is accomplished by an actomyosin-based contractile ring. Although in Caenorhabditis elegans embryos larger cells divide at a faster rate than smaller cells, it remains unknown whether a similar mode of scalability operates in other cells. We investigated cytokinesis in the filamentous fungus Neurospora crassa, which exhibits a wide range of hyphal circumferences. We found that N. crassa cells divide using an actomyosin ring and larger rings constricted faster than smaller rings. However, unlike in C. elegans, the total amount of myosin remained constant throughout constriction, and there was a size-dependent increase in the starting concentration of myosin in the ring. We predict that the increased number of ring-associated myosin motors in larger rings leads to the increased constriction rate. Accordingly, reduction or inhibition of ring-associated myosin slows down the rate of constriction. Because the mechanical characteristics of contractile rings are conserved, we predict that these findings will be relevant to actomyosin ring constriction in other cell types.
authors: Temasek Life Sciences Laboratory, The National University of Singapore, Singapore 117604. meredith@tll.org.sg
authors: Meredith E K
authors: ME
authors: Calvert
authors: Graham D
authors: GD
authors: Wright
authors: Fong Yew
authors: FY
authors: Leong
authors: Keng-Hwee
authors: KH
authors: Chiam
authors: Yinxiao
authors: Y
authors: Chen
authors: Gregory
authors: G
authors: Jedd
authors: Mohan K
authors: MK
authors: Balasubramanian
mesh_terms: D000199:Actins / Q000378:metabolism / Q000502:physiology; D000205:Actomyosin / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism / Q000502:physiology; D048429:Cell Size; D048749:Cytokinesis / Q000502:physiology*; D009218:Myosins / Q000235:genetics / Q000378:metabolism*; D009492:Neurospora crassa / Q000166:cytology* / Q000235:genetics / Q000502:physiology
chemical_list: D000199:Actins; D000205:Actomyosin; D009218:Myosins