Etude de la protéolyse dépendante du motif Dbox au cours du cycle cellulaire et du développement chez les végétaux supérieurs

STRASBOURG-Sc. et Techniques (674822102) / SudocSudocFranceF

Expression of a Nondegradable Cyclin B1 Affects Plant Development and Leads to Endomitosis by Inhibiting the Formation of a Phragmoplast

In plants after the disassembly of mitotic spindle, a specific cytokinetic structure called the phragmoplast is built, and after cytokinesis, microtubules populate the cell cortex in an organized orientation that determines cell elongation and shape. Here, we show that impaired cyclin B1 degradation, resulting from a mutation within its destruction box, leads to an isodiametric shape of epidermal cells in leaves, stems, and roots and retarded growth of seedlings. Microtubules in these misshaped cells are grossly disorganized, focused around the nucleus, whereas they were entirely missing or abnormally organized along the cell cortex. A high percentage of cells expressing nondestructible cyclin B1 had doubled DNA content as a result of undergoing endomitosis. During anaphase the cytokinesis-specific syntaxin KNOLLE could still localize to the midplane of cell division, whereas NPK1-activating kinesin-like protein 1, a cytokinetic kinesin-related protein, was unable to do so, and instead of the formation of a phragmoplast, the midzone microtubules persisted between the separated nuclei, which eventually fused. In summary, our results show that the timely degradation of mitotic cyclins in plants is required for the reorganization of mitotic microtubules to the phragmoplast and for proper cytokinesis. Subsequently, the presence of nondegradable cyclin B1 leads to a failure in organizing properly the cortical microtubules that determine cell elongation and shape

Generation of human induced pluripotent stem cell lines from three patients affected by Catecholaminergic Polymorphic ventricular tachycardia (CPVT) carrying heterozygous mutations in RYR2 gene

International audienceCatecholaminergic Polymorphic Ventricular Tachycardia (CPVT) is an exercise and emotional stress-induced life-threatening inherited heart rhythm disorder, characterized by an abnormal cellular calcium homeostasis. Most reported cases have been linked to mutations in the gene encoding the type 2 ryanodine receptor gene, RYR2. We generated induced pluripotent stem cells (hiPSCs) from peripheral blood mononuclear cells (PBMC) from three CPVT-affected patients, two of them carrying p.R4959Q mutation and one carrying p.Y2476D mutation. These generated hiPSC lines are a useful model to study pathophysiological consequences of RYR2 dysfunction in humans and the molecular basis of CPVT

A consistent arrhythmogenic trait in Brugada syndrome cellular phenotype

International audienc