Little is known about the mechanisms that establish the position of the division plane in eukaryotic cells.Wild-type fission yeast cells divide by forming a septum in the middle of the cell at the end of mitosis. Dmfl mutants complete mitosis and initiate septum formation, but the septa that form are positioned at random locations and angles in the cell, rather than in the middle. We have cloned the dmfl gene as a suppressor of the cdc7-24 mutant. The dmfl mutant is allelic with mid1. The gene encodes a novel protein containing a putative nuclear localization signal, and a carboxy-terminal PH domain. In wild-type cells, Dmflp is nuclear during interphase, and relocates to form a medial ring at the cell cortex coincident with the onset of mitosis. This relocalization occurs before formation of the actin ring and is associated with increased phosphorylation of Dmflp. The Dmflp ring can be formed in the absence of an actin ring, but depends on some of the genes required for actin ring formation. When the septum is completed and the cells separate, Dmflp staining is once again nuclear. These data implicate Dmflp as an important element in assuring correct placement of the division septum in Schizosaccharomyces pombe cells. [Key Words: dmfl/midl; S. pombe; cytokinesis]Received April 10, 1996; revised version accepted August 22, 1996.Cells must assure correct spatial and temporal coordination of mitosis with cytokinesis so that each daughter cell will receive a nucleus and an appropriate complement of cytoplasmic material following cell division. A number of studies indicate that the position of the cleavage plane is determined during mitosis, but in most systems very little is known about the nature of the signal or the proteins involved (for review, see Strome 1993). Cytokinesis requires assembly of the division apparatus at an appropriate site on the cell cortex. In higher eukaryotes, a contractile ring forms around the equator of the parent cell at the end of mitosis. The sliding of actin and myosin filaments generates a force that pulls the plasma membrane inward to create the cleavage furrow, which narrows to form the midbody as division is completed (for review, see Satterwhite and Pollard 1992;Fishkind and Wang 1995). A structure called the telophase disc, which forms prior to the appearance of the contractile ring, has been proposed to organize contractile ring formation (Margolis and Andreassen 1993).The mitotic apparatus plays a critical role in determining where cell cleavage will occur. The site of cell division is defined by the plane of the metaphase plate, and is at right angles to the long axis of the mitotic spindle.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.