Microtubule sliding activity of a kinesin-8 promotes spindle assembly and spindle length control

Molecular motors play critical roles in the formation of mitotic spindles, either through controlling the stability of individual microtubules, or by cross-linking and sliding microtubule arrays. Kinesin-8 motors are best known for their regulatory roles in controlling microtubule dynamics. They contain microtubule-destabilizing activities, and restrict spindle length in a wide variety of cell types and organisms. Here, we report for the first time on an anti-parallel microtubule-sliding activity of the budding yeast kinesin-8, Kip3. The in vivo importance of this sliding activity was established through the identification of complementary Kip3 mutants that separate the sliding activity and microtubule destabilizing activity. In conjunction with kinesin-5/Cin8, the sliding activity of Kip3 promotes bipolar spindle assembly and the maintenance of genome stability. We propose a “slide-disassemble” model where Kip3’s sliding and destabilizing activity balance during pre-anaphase. This facilitates normal spindle assembly. However, Kip3’s destabilizing activity dominates in late anaphase, inhibiting spindle elongation and ultimately promoting spindle disassembly

Nurses' perceptions of aids and obstacles to the provision of optimal end of life care in ICU

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MAP65/Ase1 promote microtubule flexibility.

International audienceMicrotubules (MTs) are dynamic cytoskeletal elements involved in numerous cellular processes. Although they are highly rigid polymers with a persistence length of 1-8 mm, they may exhibit a curved shape at a scale of few micrometers within cells, depending on their biological functions. However, how MT flexural rigidity in cells is regulated remains poorly understood. Here we ask whether MT-associated proteins (MAPs) could locally control the mechanical properties of MTs. We show that two major cross-linkers of the conserved MAP65/PRC1/Ase1 family drastically decrease MT rigidity. Their MT-binding domain mediates this effect. Remarkably, the softening effect of MAP65 observed on single MTs is maintained when MTs are cross-linked. By reconstituting physical collisions between growing MTs/MT bundles, we further show that the decrease in MT stiffness induced by MAP65 proteins is responsible for the sharp bending deformations observed in cells when they coalign at a steep angle to create bundles. Taken together, these data provide new insights into how MAP65, by modifying MT mechanical properties, may regulate the formation of complex MT arrays

Veno-arterial extracorporeal membrane oxygenation for drug intoxications: A single center, 14-year experience

International audienceBACKGROUND AND AIM OF THE STUDY: Acute cardiovascular failure remains a leading cause of death in severe poisonings. Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) has been increasingly used as a rescue therapeutic option for those cases refractory to optimal conventional treatment. We sought to evaluate the outcomes after VA-ECMO used for drug intoxications in a single-center experience. METHODS: We performed an observational analysis of our prospective institutional database. The primary endpoint was survival to hospital discharge. RESULTS: Between January 2007 and December 2020, 32 patients (mean age: 45.4 ± 15.8 years; 62.5% female) received VA-ECMO for drug intoxication-induced refractory cardiogenic shock (n = 25) or cardiac arrest (n = 7). Seven (21.8%) patients developed lower limb ischemia during VA-ECMO support. Twenty-six (81.2%) patients were successfully weaned after a mean VA-ECMO support of 2.9 ± 1.3 days. One (3.1%) patient died after VA-ECMO weaning for multiorgan failure and survival to hospital discharge was 78.1% (n = 25). In-hospital survivors were discharged from hospital with a good neurological status. Survival to hospital discharge was not statistically different according to sex (male = 75.0% vs. female = 80.0%; p = .535), type of intoxication (single drug = 81.8% vs. multiple drugs = 76.1%; p = .544) and location of VA-ECMO implantation (within our center = 75% vs. peripheral hospital using our Mobile Unit of Mechanical Circulatory Support = 100%; p = .352). Survival to hospital discharge was significantly lower in patients receiving VA-ECMO during on-going cardiopulmonary resuscitation (42.8% vs. 88.0%; p = .026). CONCLUSIONS: VA-ECMO appears to be a feasible therapeutic option with a satisfactory survival rate and acceptable complications rate in poisonings complicated by refractory cardiogenic shock or cardiac arrest