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Vertebrate oocyte maturation is an extreme form of asymmetric cell division, producing a mature egg alongside a diminutive polar body. Critical to this process is the attachment of one spindle pole to the oocyte cortex prior to anaphase. We report here that asymmetric spindle pole attachment and anaphase initiation are required for localized cortical(More)
Single cells and multicellular tissues rapidly heal wounds. These processes are considered distinct, but one mode of healing--Rho GTPase-dependent formation and closure of a purse string of actin filaments (F-actin) and myosin-2 around wounds--occurs in single cells and in epithelia. Here, we show that wounding of one cell in Xenopus embryos elicits Rho(More)
In animal cells, cytokinesis is powered by a contractile ring of actin filaments (F-actin) and myosin-2. Formation of the contractile ring is dependent on the small GTPase RhoA, which is activated in a precise zone at the cell equator. It has long been assumed that cytokinesis and other Rho-dependent processes are controlled in a sequential manner, whereby(More)
Animal cells decide where to build the cytokinetic apparatus by sensing the position of the mitotic spindle. Reflecting a long-standing presumption that a furrow-inducing stimulus travels from spindle to cortex via microtubules, debate continues about which microtubules, and in what geometry, are essential for accurate cytokinesis. We used live imaging in(More)
Animal cell cytokinesis results from patterned activation of the small GTPase Rho, which directs assembly of actomyosin in the equatorial cortex. Cytokinesis is restricted to a portion of the cell cycle following anaphase onset in which the cortex is responsive to signals from the spindle. We show that shortly after anaphase onset oocytes and embryonic(More)
Microtubules (MTs) help establish and maintain cell polarity by promoting actin-dependent membrane protrusion at the leading edge of the cell, but the molecular mechanisms that mediate cross-talk between actin and MTs during this process are unclear. We demonstrate that the Abl-related gene (Arg) nonreceptor tyrosine kinase is required for dynamic(More)
BACKGROUND The Rho GTPases-Rho, Rac, and Cdc42-regulate the dynamics of F-actin (filamentous actin) and myosin-2 with considerable subcellular precision. Consistent with this ability, active Rho and Cdc42 occupy mutually exclusive zones during single-cell wound repair and asymmetric cytokinesis, suggesting the existence of mechanisms for local crosstalk,(More)
Anillin is a scaffolding protein that organizes and stabilizes actomyosin contractile rings and was previously thought to function primarily in cytokinesis [1-10]. Using Xenopus laevis embryos as a model system to examine Anillin's role in the intact vertebrate epithelium, we find that a population of Anillin surprisingly localizes to epithelial cell-cell(More)
Historically, much of our understanding of actin filaments, microtubules and intermediate filaments has come from the study of fixed cells and tissues. But the cytoskeleton is inherently dynamic, and so developing the means to image it in living cells has proved crucial. Advances in confocal microscopy and fluorescent protein technologies have allowed us to(More)
is achieved via Rho regulators that concentrate on spindle microtubules at the cell equator. The best characterized complex of Rho regulators during cytokinesis is the centralspindlin complex, which consists of the kinesin-6 family member MKLP-1 and the GTPase-activating protein (GAP) MgcRacGAP (Figure 1). Centralspindlin interacts with the guanine(More)