The Experts below are selected from a list of 90531 Experts worldwide ranked by ideXlab platform
Iain M Cheeseman - One of the best experts on this subject based on the ideXlab platform.
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cortical dynein and asymmetric membrane elongation coordinately position the spindle in anaphase
Cell, 2013Co-Authors: Tomomi Kiyomitsu, Iain M CheesemanAbstract:Summary Mitotic spindle position defines the Cell-cleavage site during cytokinesis. However, the mechanisms that control spindle positioning to generate equal-sized daughter Cells remain poorly understood. Here, we demonstrate that two mechanisms act coordinately to center the spindle during anaphase in symmetrically dividing human Cells. First, the spindle is positioned directly by the microtubule-based motor dynein, which we demonstrate is targeted to the Cell Cortex by two distinct pathways: a Gαi/LGN/NuMA-dependent pathway and a 4.1G/R and NuMA-dependent, anaphase-specific pathway. Second, we find that asymmetric plasma membrane elongation occurs in response to spindle mispositioning to alter the Cellular boundaries relative to the spindle. Asymmetric membrane elongation is promoted by chromosome-derived Ran-GTP signals that locally reduce Anillin at the growing Cell Cortex. In asymmetrically elongating Cells, dynein-dependent spindle anchoring at the stationary Cell Cortex ensures proper spindle positioning. Our results reveal the anaphase-specific spindle centering systems that achieve equal-sized Cell division.
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chromosome and spindle pole derived signals generate an intrinsic code for spindle position and orientation
Nature Cell Biology, 2012Co-Authors: Tomomi Kiyomitsu, Iain M CheesemanAbstract:Spindle orientation depends on the tethering of microtubules to the Cell Cortex through LGN, NuMA and dynein/dynactin. Cheeseman and colleagues find that spindle-pole-associated Plk1 activity restricts polar dynein whereas chromosomal RanGTP negatively regulates LGN localization at the lateral Cell Cortex, thus identifying two differentially localized signals that modulate spindle positioning by acting on dynein-mediated forces.
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Chromosome- and spindle-pole-derived signals generate an intrinsic code for spindle position and orientation
Nature Cell Biology, 2012Co-Authors: Tomomi Kiyomitsu, Iain M CheesemanAbstract:Mitotic spindle positioning by cortical pulling forces^ 1 defines the Cell division axis and location^ 2 , which is critical for proper Cell division and development^ 3 . Although recent work has identified developmental and extrinsic cues that regulate spindle orientation^ 4 , 5 , 6 , the contribution of intrinsic signals to spindle positioning and orientation remains unclear. Here, we demonstrate that cortical force generation in human Cells is controlled by distinct spindle-pole- and chromosome-derived signals that regulate cytoplasmic dynein localization. First, dynein exhibits a dynamic asymmetric cortical localization that is negatively regulated by spindle-pole proximity, resulting in spindle oscillations to centre the spindle within the Cell. We find that this signal comprises the spindle-pole-localized polo-like kinase (Plk1), which regulates dynein localization by controlling the interaction between dynein–dynactin and its upstream cortical targeting factors NuMA and LGN. Second, a chromosome-derived RanGTP gradient restricts the localization of NuMA–LGN to the lateral Cell Cortex to define and maintain the spindle orientation axis. RanGTP acts in part through the nuclear localization sequence of NuMA to locally alter the ability of NuMA–LGN to associate with the Cell Cortex in the vicinity of chromosomes. We propose that these chromosome- and spindle-pole-derived gradients generate an intrinsic code to control spindle position and orientation. Spindle orientation depends on the tethering of microtubules to the Cell Cortex through LGN, NuMA and dynein/dynactin. Cheeseman and colleagues find that spindle-pole-associated Plk1 activity restricts polar dynein whereas chromosomal RanGTP negatively regulates LGN localization at the lateral Cell Cortex, thus identifying two differentially localized signals that modulate spindle positioning by acting on dynein-mediated forces.
Tomomi Kiyomitsu - One of the best experts on this subject based on the ideXlab platform.
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cortical dynein and asymmetric membrane elongation coordinately position the spindle in anaphase
Cell, 2013Co-Authors: Tomomi Kiyomitsu, Iain M CheesemanAbstract:Summary Mitotic spindle position defines the Cell-cleavage site during cytokinesis. However, the mechanisms that control spindle positioning to generate equal-sized daughter Cells remain poorly understood. Here, we demonstrate that two mechanisms act coordinately to center the spindle during anaphase in symmetrically dividing human Cells. First, the spindle is positioned directly by the microtubule-based motor dynein, which we demonstrate is targeted to the Cell Cortex by two distinct pathways: a Gαi/LGN/NuMA-dependent pathway and a 4.1G/R and NuMA-dependent, anaphase-specific pathway. Second, we find that asymmetric plasma membrane elongation occurs in response to spindle mispositioning to alter the Cellular boundaries relative to the spindle. Asymmetric membrane elongation is promoted by chromosome-derived Ran-GTP signals that locally reduce Anillin at the growing Cell Cortex. In asymmetrically elongating Cells, dynein-dependent spindle anchoring at the stationary Cell Cortex ensures proper spindle positioning. Our results reveal the anaphase-specific spindle centering systems that achieve equal-sized Cell division.
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chromosome and spindle pole derived signals generate an intrinsic code for spindle position and orientation
Nature Cell Biology, 2012Co-Authors: Tomomi Kiyomitsu, Iain M CheesemanAbstract:Spindle orientation depends on the tethering of microtubules to the Cell Cortex through LGN, NuMA and dynein/dynactin. Cheeseman and colleagues find that spindle-pole-associated Plk1 activity restricts polar dynein whereas chromosomal RanGTP negatively regulates LGN localization at the lateral Cell Cortex, thus identifying two differentially localized signals that modulate spindle positioning by acting on dynein-mediated forces.
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Chromosome- and spindle-pole-derived signals generate an intrinsic code for spindle position and orientation
Nature Cell Biology, 2012Co-Authors: Tomomi Kiyomitsu, Iain M CheesemanAbstract:Mitotic spindle positioning by cortical pulling forces^ 1 defines the Cell division axis and location^ 2 , which is critical for proper Cell division and development^ 3 . Although recent work has identified developmental and extrinsic cues that regulate spindle orientation^ 4 , 5 , 6 , the contribution of intrinsic signals to spindle positioning and orientation remains unclear. Here, we demonstrate that cortical force generation in human Cells is controlled by distinct spindle-pole- and chromosome-derived signals that regulate cytoplasmic dynein localization. First, dynein exhibits a dynamic asymmetric cortical localization that is negatively regulated by spindle-pole proximity, resulting in spindle oscillations to centre the spindle within the Cell. We find that this signal comprises the spindle-pole-localized polo-like kinase (Plk1), which regulates dynein localization by controlling the interaction between dynein–dynactin and its upstream cortical targeting factors NuMA and LGN. Second, a chromosome-derived RanGTP gradient restricts the localization of NuMA–LGN to the lateral Cell Cortex to define and maintain the spindle orientation axis. RanGTP acts in part through the nuclear localization sequence of NuMA to locally alter the ability of NuMA–LGN to associate with the Cell Cortex in the vicinity of chromosomes. We propose that these chromosome- and spindle-pole-derived gradients generate an intrinsic code to control spindle position and orientation. Spindle orientation depends on the tethering of microtubules to the Cell Cortex through LGN, NuMA and dynein/dynactin. Cheeseman and colleagues find that spindle-pole-associated Plk1 activity restricts polar dynein whereas chromosomal RanGTP negatively regulates LGN localization at the lateral Cell Cortex, thus identifying two differentially localized signals that modulate spindle positioning by acting on dynein-mediated forces.
Steven C. Ley - One of the best experts on this subject based on the ideXlab platform.
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ZAP-70 Protein Tyrosine Kinase Is Constitutively Targeted to the T Cell Cortex Independently of its SH2 Domains
2016Co-Authors: Arthur Weiss, Steven C. Ley, Howard Hughes MedicalAbstract:ZAP-70 is a nonreceptor protein tyrosine ki-nase that is essential for signaling via the T Cell antigen receptor (TCR). ZAP-70 becomes phosphorylated and activated by LCK protein tyrosine kinase after interac-tion of its two NH 2-terminal SH2 domains with ty-rosine-phosphorylated subunits of the activated TCR. In this study, the localization of ZAP-70 was investi-gated by immunofluorescence and confocal micros-copy. ZAP-70 was found to be localized to the Cell cor-tex in a diffuse band under the plasma membrane in unstimulated T Cells, and this localization was not de-tectably altered by TCR stimulation. Analysis of mu-tants indicated that ZAP-70 targeting was independent of its SH2 domains but required its active kinase do-main. The specific compartmentalization of ZAP-70 suggests that it may interact with an anchoring protein in the Cell Cortex via its hinge or kinase domains. It is likely that the maintenance of high concentrations of ZAP-70 at the Cell Cortex, that only has to move a short distance to interact with phophorylated TCR subunits, facilitates rapid initiation of signaling by the TCR. In addition, as the major increase in tyrosine phosphoryla-tion induced by the TCR also occurs at the Cell corte
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ZAP-70 Protein Tyrosine Kinase Is Constitutively Targeted to the T Cell Cortex Independently of its SH2 Domains
The Journal of cell biology, 1997Co-Authors: Russell D. J. Huby, Makio Iwashima, Arthur Weiss, Steven C. LeyAbstract:ZAP-70 is a nonreceptor protein tyrosine kinase that is essential for signaling via the T Cell antigen receptor (TCR). ZAP-70 becomes phosphorylated and activated by LCK protein tyrosine kinase after interaction of its two NH2-terminal SH2 domains with tyrosine-phosphorylated subunits of the activated TCR. In this study, the localization of ZAP-70 was investigated by immunofluorescence and confocal microscopy. ZAP-70 was found to be localized to the Cell Cortex in a diffuse band under the plasma membrane in unstimulated T Cells, and this localization was not detectably altered by TCR stimulation. Analysis of mutants indicated that ZAP-70 targeting was independent of its SH2 domains but required its active kinase domain. The specific compartmentalization of ZAP-70 suggests that it may interact with an anchoring protein in the Cell Cortex via its hinge or kinase domains. It is likely that the maintenance of high concentrations of ZAP-70 at the Cell Cortex, that only has to move a short distance to interact with phophorylated TCR subunits, facilitates rapid initiation of signaling by the TCR. In addition, as the major increase in tyrosine phosphorylation induced by the TCR also occurs at the Cell Cortex (Ley, S.C., M. Marsh, C.R. Bebbington, K. Proudfoot, and P. Jordan. 1994. J. Cell. Biol. 125:639–649), ZAP-70 may be localized close to its downstream targets.
Isabelle Tardieux - One of the best experts on this subject based on the ideXlab platform.
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The toxoplasma-host Cell junction is anchored to the Cell Cortex to sustain parasite invasive force
BMC Biology, 2014Co-Authors: Marion Bichet, Candie Joly, Ahmed Hadj Henni, Thomas Guilbert, Marie Xémard, Vincent Tafani, Vanessa Lagal, Guillaume Charras, Isabelle TardieuxAbstract:Background The public health threats imposed by toxoplasmosis worldwide and by malaria in sub-Saharan countries are directly associated with the capacity of their related causative agents Toxoplasma and Plasmodium, respectively, to colonize and expand inside host Cells. Therefore, deciphering how these two Apicomplexan protozoan parasites access their host Cells has been highlighted as a priority research with the perspective of designing anti-invasive molecules to prevent diseases. Central to the mechanism of invasion for both genera is mechanical force, which is thought to be applied by the parasite at the interface between the two Cells following assembly of a unique Cell-Cell junction but this model lacks direct evidence and has been challenged by recent genetic studies. In this work, using parasites expressing the fluorescent core component of this junction, we analyze characteristic features of the kinematics of penetration of more than 1,000 invasion events. Results The majority of invasion events occur with a typical forward rotational progression of the parasite through a static junction into an invaginating host Cell plasma membrane. However, if parasites encounter resistance and if the junction is not strongly anchored to the host Cell Cortex, as when parasites do not secrete the toxofilin protein and, therefore, are unable to locally remodel the cortical actin cytoskeleton, the junction travels retrogradely with the host Cell membrane along the parasite surface allowing the formation of a functional vacuole. Kinetic measurements of the invasive trajectories strongly support a similar parasite driven force in both static and capped junctions, both of which lead to successful invasion. However, about 20% of toxofilin mutants fail to enter and eventually disengage from the host Cell membrane while the secreted RhOptry Neck (RON2) molecules are posteriorally capped before being cleaved and released in the medium. By contrast in Cells characterized by low Cortex tension and high cortical actin dynamics junction capping and entry failure are drastically reduced. Conclusions This kinematic analysis newly highlights that to invade Cells parasites need to engage their motor with the junction molecular complex where force is efficiently applied only upon proper anchorage to the host Cell membrane and Cortex.
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BMC Biology BMC Biology The toxoplasma-host Cell junction is anchored to the Cell Cortex to sustain parasite invasive force
BMC Biology, 2014Co-Authors: Marion Bichet, Candie Joly, Ahmed Hadj Henni, Thomas Guilbert, Marie Xémard, Vincent Tafani, Vanessa Lagal, Guillaume Charras, Isabelle TardieuxAbstract:BackgroundThe public health threats imposed by toxoplasmosis worldwide and by malaria in sub-Saharan countries are directly associated with the capacity of their closely related causative agents Toxoplasma and Plasmodium, respectively to colonize and expand inside host Cells. Therefore, deciphering how these two Apicomplexan protozoan parasites access their hosting Cells has been highlighted as a high priority research with the relevant perspective of designing anti-invasive molecules to prevent diseases. Central to the mechanistic base of invasion for both genera is mechanical force, which is thought to be applied by the parasite at the interface between the two Cells following assembly of a unique Cell junction but this model lacks direct evidence and has been challenged by recent genetic and Cell biology studies. In this work, using parasites expressing the fluorescent core component of this junction, we analyse characteristic features of the kinematics of penetration of more than 1000 invasion events.ResultsThe majority of invasion events occur with a typical forward rotational progression of the parasite through a static junction into a vacuole formed from the invaginating host Cell plasma membrane, in which the parasite subsequently replicates. However, if parasites encounter resistance and if the junction is not strongly anchored to the host Cell Cortex, as when parasites do not secrete the toxofilin protein and therefore are unable to locally remodel the cortical actin cytoskeleton, the junction is capped backwards and travels retrogradely with the host Cell membrane along the parasite surface as it is enclosed within a functional vacuole. Kinetic measurements of the invasive trajectories strongly support a similar parasite driven force in both static and capped junctions, both of which lead to successful invasion. However about 20% of toxofilin mutants fail to enter and eventually disengage from the host Cell membrane while the secreted RON2 molecules are capped at the posterior pole before being cleaved and released in the medium. By contrast in Cells characterized by low Cortex tension and high cortical actin dynamics, junction capping and entry failure are drastically reduced.ConclusionThis kinematic analysis of pre-invasive and invasive T. gondii tachyzoite behaviors newly highlights that to invade Cells, parasites need to engage their motor with the junction molecular complex where force is efficiently applied only upon proper anchorage to the host Cell membrane and Cortex.
R. Zhang - One of the best experts on this subject based on the ideXlab platform.
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structural analyses of key features in the kank1 kif21a complex yield mechanistic insights into the cross talk between microtubules and the Cell Cortex
Journal of Biological Chemistry, 2018Co-Authors: Zhuangfeng Weng, Yuan Shang, R. ZhangAbstract:: The cross-talk between dynamic microtubules and the Cell Cortex plays important roles in Cell division, polarity, and migration. A critical adaptor that links the plus ends of microtubules with the Cell Cortex is the KANK N-terminal motif and ankyrin repeat domains 1 (KANK1)/kinesin family member 21A (KIF21A) complex. Genetic defects in these two proteins are associated with various cancers and developmental diseases, such as congenital fibrosis of the extraocular muscles type 1. However, the molecular mechanism governing the KANK1/KIF21A interaction and the role of the conserved ankyrin (ANK) repeats in this interaction are still unclear. In this study, we present the crystal structure of the KANK1·KIF21A complex at 2.1 A resolution. The structure, together with biochemical studies, revealed that a five-helix-bundle-capping domain immediately preceding the ANK repeats of KANK1 forms a structural and functional supramodule with its ANK repeats in binding to an evolutionarily conserved peptide located in the middle of KIF21A. We also show that several missense mutations present in cancer patients are located at the interface of the KANK1·KIF21A complex and destabilize its formation. In conclusion, our study elucidates the molecular basis underlying the KANK1/KIF21A interaction and also provides possible mechanistic explanations for the diseases caused by mutations in KANK1 and KIF21A.
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Structural analyses of key features in the KANK1·KIF21A complex yield mechanistic insights into the cross-talk between microtubules and the Cell Cortex
Journal of Biological Chemistry, 2017Co-Authors: Zhuangfeng Weng, Yuan Shang, R. ZhangAbstract:The cross-talk between dynamic microtubules and the Cell Cortex plays important roles in Cell division, polarity, and migration. A critical adaptor that links the plus ends of microtubules with the Cell Cortex is the KANK N-terminal motif and ankyrin repeat domains 1 (KANK1)/kinesin family member 21A (KIF21A) complex. Genetic defects in these two proteins are associated with various cancers and developmental diseases, such as congenital fibrosis of the extraocular muscles type 1. However, the molecular mechanism governing the KANK1/KIF21A interaction and the role of the conserved ankyrin (ANK) repeats in this interaction are still unclear. In this study, we present the crystal structure of the KANK1·KIF21A complex at 2.1 A resolution. The structure, together with biochemical studies, revealed that a five-helix-bundle-capping domain immediately preceding the ANK repeats of KANK1 forms a structural and functional supramodule with its ANK repeats in binding to an evolutionarily conserved peptide located in the middle of KIF21A. We also show that several missense mutations present in cancer patients are located at the interface of the KANK1·KIF21A complex and destabilize its formation. In conclusion, our study elucidates the molecular basis underlying the KANK1/KIF21A interaction and also provides possible mechanistic explanations for the diseases caused by mutations in KANK1 and KIF21A.