MgcRacGAP restricts active RhoA at the cytokinetic furrow and both RhoA and Rac1 at cell–cell junctions in epithelial cells

Breznau, Elaina B.; Semack, Ansley C.; Higashi, Tomohito; Miller, Ann L.

doi:10.1091/mbc.e14-11-1553

Cited by 46 publications

(56 citation statements)

References 60 publications

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“…Given the requirement for Fmn1 in apical emergence (Sedzinski et al, 2016), we probed the role of RhoA in this process. We first measured the dynamics of RhoA activity using the active RhoA biosensor (rGBD), which has been shown previously to be effective in Xenopus (for examples, see Benink and Bement, 2005;Breznau et al, 2015;Reyes et al, 2014). We expressed GFP-rGBD in the mucociliary epithelium and found that throughout the expansion phase of the MCC apical surface, the fluorescence intensity of normalized active RhoA increased (Fig.…”

Section: Rhoa Controls the Dynamics Of MCC Apical Emergencementioning

confidence: 99%

RhoA regulates actin network dynamics during apical surface emergence in multiciliated epithelial cells

Sedzinski¹,

Hannezo²,

Tu³

et al. 2017

Development

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Homeostatic replacement of epithelial cells from basal precursors is a multistep process involving progenitor cell specification, radial intercalation and, finally, apical surface emergence. Recent data demonstrate that actin-based pushing under the control of the formin protein Fmn1 drives apical emergence in nascent multiciliated epithelial cells (MCCs), but little else is known about this actin network or the control of Fmn1. Here, we explore the role of the small GTPase RhoA in MCC apical emergence. Disruption of RhoA function reduced the rate of apical surface expansion and decreased the final size of the apical domain. Analysis of cell shapes suggests that RhoA alters the balance of forces exerted on the MCC apical surface. Finally, quantitative time-lapse imaging and fluorescence recovery after photobleaching studies argue that RhoA works in concert with Fmn1 to control assembly of the specialized apical actin network in MCCs. These data provide new molecular insights into epithelial apical surface assembly and could also shed light on mechanisms of apical lumen formation.

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Section: Rhoa Controls the Dynamics Of MCC Apical Emergencementioning

confidence: 99%

RhoA regulates actin network dynamics during apical surface emergence in multiciliated epithelial cells

Sedzinski¹,

Hannezo²,

Tu³

et al. 2017

Development

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“…Embryos were injected with MO+MgcWT or MO+MgcSxNN along with probes for F-actin (mChe-UtrCH) and DNA (mChe-H2B), and movies of dividing cells were analyzed for defects in F-actin accumulation at the equatorial cortex of dividing cells (Fig. 5B) Breznau et al, 2015;Miller and Bement, 2009). Analysis of F-actin intensity plots at an equatorial region adjacent to the cleavage furrow at 25% ingression did not reveal a change in the breadth of F-actin accumulation (Fig.…”

Section: Mutation Of the Mgcracgap Sxip Motif Disrupts Equatorial Accmentioning

confidence: 99%

“…Endogenous Mgc was knocked down with a previously characterized morpholino oligonucleotide (MO), which effectively depletes Mgc protein levels and causes strong cytokinesis defects that can be rescued by expression of WT Mgc (MgcWT) mRNA (Breznau et al, 2015;Miller and Bement, 2009). MO-resistant Mgc-3×GFP was expressed at near-endogenous levels and localized at the overlapping anti-parallel MTs of the central spindle ( Fig.…”

Section: Mgcracgap Localizes To Microtubule Plus Ends At the Equatorimentioning

confidence: 99%

“…The MgcRacGAP SxIP motif contributes to limiting and focusing RhoA-GTP and F-actin at the cell equator If Centralspindlin is not properly localized at the equatorial cortex, activation and focusing of the Rho activity zone may be perturbed (Breznau et al, 2015;Miller and Bement, 2009), which could contribute to the increased cell division failure observed in MO+MgcSxNN cells. In order to determine whether the MgcSxNN mutant affects RhoA-GTP accumulation during cytokinesis, we performed live imaging of embryos that had been injected with MO+MgcWT or MO+MgcSxNN along with a probe for active RhoA (GFP-rGBD).…”

Section: Mutation Of the Mgcracgap Sxip Motif Disrupts Equatorial Accmentioning

confidence: 99%

“…Mgc recruits the RhoA GEF Ect2 (Mishima et al, 2004;Somers and Saint, 2003;Su et al, 2011) and, together, Centralspindlin and Ect2 localize to the equatorial cortex to regulate active RhoA (Bement et al, 2006;Miller and Bement, 2009). Mgc and Ect2 have also been shown to regulate RhoA-mediated actomyosin contractility at adherens junctions (Breznau et al, 2015;Ratheesh et al, 2012). Interestingly, the localization of Mgc and Ect2 at both locations is thought to be MT dependent, mediated by the motor activity of MKLP1 (Douglas et al, 2010;Hutterer et al, 2009;Ratheesh et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

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The MgcRacGAP SxIP motif tethers Centralspindlin to microtubule plus ends in Xenopus laevis

Breznau

Murt

Blasius

et al. 2017

Journal of Cell Science

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Centralspindlin, a complex of the kinesin-6-family member MKLP1 and MgcRacGAP (also known as Kif23 and Racgap1, respectively), is required for cytokinesis and cell-cell junctions. During anaphase, Centralspindlin accumulates at overlapping central spindle microtubules and directs contractile ring formation by recruiting the GEF Ect2 to the cell equator to activate RhoA. We found that MgcRacGAP localized to the plus ends of equatorial astral microtubules during cytokinesis in Xenopus laevis embryos. How MgcRacGAP is stabilized at microtubule plus ends is unknown. We identified an SxIP motif in X. laevis MgcRacGAP that is conserved with other proteins that bind to EB1 (also known as Mapre1), a microtubule plus-end tracking protein. Mutation of the SxIP motif in MgcRacGAP resulted in loss of MgcRacGAP tracking with EB3 (also known as Mapre3) on growing microtubule plus ends, abnormal astral microtubule organization, redistribution of MgcRacGAP from the contractile ring to the polar cell cortex, and mislocalization of RhoA and its downstream targets, which together contributed to severe cytokinesis defects. Furthermore, mutation of the MgcRacGAP SxIP motif perturbed adherens junctions. We propose that the MgcRacGAP SxIP motif is functionally important both for its role in regulating adherens junction structure during interphase and for regulating Rho GTPase activity during cytokinesis.

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Regulation of cytokinesis during corticogenesis: focus on the midbody

2017

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Development of the cerebral cortices depends on tight regulation of cell divisions. In this system, stem and progenitor cells undergo symmetric and asymmetric divisions to ultimately produce neurons that establish the layers of the cortex. Cell division culminates with the formation of the midbody, a transient organelle that establishes the site of abscission between nascent daughter cells. During cytokinetic abscission, the final stage of cell division, one daughter cell will inherit the midbody remnant, which can then maintain or expel the remnant, but mechanisms and circumstances influencing this decision are unclear. This review describes the midbody and its constituent proteins, as well as the known consequences of their manipulation during cortical development. The potential functional relevance of midbody mechanisms is discussed.

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MgcRacGAP restricts active RhoA at the cytokinetic furrow and both RhoA and Rac1 at cell–cell junctions in epithelial cells

Cited by 46 publications

References 60 publications

RhoA regulates actin network dynamics during apical surface emergence in multiciliated epithelial cells

RhoA regulates actin network dynamics during apical surface emergence in multiciliated epithelial cells

The MgcRacGAP SxIP motif tethers Centralspindlin to microtubule plus ends in Xenopus laevis

Regulation of cytokinesis during corticogenesis: focus on the midbody

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