scholarly journals Regulation of microtubule organization and functions by septin GTPases

Cytoskeleton ◽  
2010 ◽  
pp. NA-NA ◽  
Author(s):  
Elias T. Spiliotis
Keyword(s):  
Microtubule Organization ◽  
Septin Gtpases

scholarly journals Septin GTPases spatially guide microtubule organization and plus end dynamics in polarizing epithelia

2011 ◽  
Vol 194 (2) ◽  
pp. 187-197 ◽  
Author(s):  
Jonathan R. Bowen ◽  
Daniel Hwang ◽  
Xiaobo Bai ◽  
Dheeraj Roy ◽  
Elias T. Spiliotis
Keyword(s):  
Epithelial Polarity ◽  
Microtubule Organization ◽  
Guidance Cues ◽  
Septin Gtpases

Establishment of epithelial polarity requires the reorganization of the microtubule (MT) cytoskeleton from a radial array into a network positioned along the apicobasal axis of the cell. Little is known about the mechanisms that spatially guide the remodeling of MTs during epithelial polarization. Septins are filamentous guanine triphosphatases (GTPases) that associate with MTs, but the function of septins in MT organization and dynamics is poorly understood. In this paper, we show that in polarizing epithelia, septins guide the directionality of MT plus end movement by suppressing MT catastrophe. By enabling persistent MT growth, two spatially distinct populations of septins, perinuclear and peripheral filaments, steer the growth and capture of MT plus ends. This navigation mechanism is essential for the maintenance of perinuclear MT bundles and for the orientation of peripheral MTs as well as for the apicobasal positioning of MTs. Our results suggest that septins provide the directional guidance cues necessary for polarizing the epithelial MT network.

Platelet Microtubules in Clot Structure Formation and Contractile Force Generation: Investigation of a Controversy

1986 ◽  
Vol 56 (01) ◽  
pp. 023-027 ◽  
Author(s):  
C J Jen ◽  
L V McIntire
Keyword(s):  
Network Formation ◽  
Contractile Force ◽  
Second Phase ◽  
Clot Retraction ◽  
Forming Process ◽  
Microtubule Organization ◽  
Physiological Processes ◽  
Fibrin Network ◽  
Two Parameters

SummaryWhether platelet microtubules are involved in clot retraction/ contraction has been controversial. To address this question we have simultaneously measured two clotting parameters, clot structural rigidity and isometric contractile force, using a rheological technique. For recalcified PRP clots these two parameters began rising together at about 15 min after CaCl2 addition. In the concentration range affecting microtubule organization in platelets, colchicine, vinca alkaloids and taxol demonstrated insignificant effects on both clotting parameters of a recalcified PRP clot. For PRP clots induced by adding small amounts of exogenous thrombin, the kinetic curves of clot rigidity were biphasic and without a lag time. The first phase corresponded to a platelet-independent network forming process, while the second phase corresponded to a platelet-dependent process. These PRP clots began generating contractile force at the onset of the second phase. For both rigidity and force parameters, only the second phase of clotting kinetics was retarded by microtubule affecting reagents. When PRP samples were clotted by adding a mixture of CaCl2 and thrombin, the second phase clotting was accelerated and became superimposed on the first phase. The inhibitory effects of micro tubule affecting reagents became less pronounced. Thrombin clotting of a two-component system (washed platelets/ purified fibrinogen) was also biphasic, with the second phase being microtubule-dependent. In conclusion, platelet microtubules are important in PRP clotted with low concentrations of thrombin, during which fibrin network formation precedes platelet-fibrin interactions. On the other hand they are unimportant if a PRP clot is induced by recalcification, during which the fibrin network is constructed in the presence of platelet-fibrin interactions. The latter is likely to be more analogous to physiological processes in vivo.

AtNUF2 modulates spindle microtubule organization and chromosome segregation during mitosis

2021 ◽  
Author(s):  
Jin Li ◽  
Yutao Wang ◽  
Wenxuan Zou ◽  
Liufang Jian ◽  
Ying Fu ◽  
...  
Keyword(s):  
Chromosome Segregation ◽  
Microtubule Organization ◽  
Spindle Microtubule
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