A kinesin-1 variant reveals motor-induced microtubule damage in cells

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Centrosomal ALIX regulates mitotic spindle orientation by modulating astral microtubule dynamics

The orientation of the mitotic spindle (MS) is tightly regulated, but the molecular mechanisms are incompletely understood. Here we report a novel role for the multifunctional adaptor protein ALG‐2‐interacting protein X (ALIX) in regulating MS orientation in addition to its well‐established role in cytokinesis. We show that ALIX is recruited to the pericentriolar material (PCM) of the centrosomes and promotes correct orientation of the MS in asymmetrically dividing Drosophila stem cells and epithelial cells, and symmetrically dividing Drosophila and human epithelial cells. ALIX‐deprived cells display defective formation of astral microtubules (MTs), which results in abnormal MS orientation. Specifically, ALIX is recruited to the PCM via Drosophila Spindle defective 2 (DSpd‐2)/Cep192, where ALIX promotes accumulation of γ‐tubulin and thus facilitates efficient nucleation of astral MTs. In addition, ALIX promotes MT stability by recruiting microtubule‐associated protein 1S (MAP1S), which stabilizes newly formed MTs. Altogether, our results demonstrate a novel evolutionarily conserved role of ALIX in providing robustness to the orientation of the MS by promoting astral MT formation during asymmetric and symmetric cell division.     

Molecular Cloning and Characterization of a Leishmania donovaniα-Tubulin Gene

ABSTRACT. We have isolated a cDNA for an α-tubulin mRNA from L. donovani promastigotes and determined its complete nucleotide sequence. Both nucleotide and deduced amino acid sequence analysis of this cDNA showed significant similarity with a previously reported, partial sequence of an L. enriettii α-tubulin and the complete sequence of human α-tubulin. Further, the in vitro translated L. donovania α-tubulin gene product was specifically immunoprecipitated with a monoclonal antibody against human α-tubulin. Northern blot analysis revealed that there was little change in the expression of the L. donovani α-tubulin RNA during parasite differentiation from promastigote to the in vitro grown "amastigote" form. Southern blot analysis revealed a simple genomic organization for the L. donovani α-tubulin gene with more than one copy of the α-tubulin gene in the parasite genome. To our knowledge, this is the first complete sequence of an α-tubulin for Leishmania to be reported in the literature.     

Chemical modulation of microtubule structure through the laulimalide/peloruside site

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Adenosine dialdehyde blocks the disappearance of two nerve growth factor-induced insoluble proteins

Two nonionic-detergent-insoluble proteins are induced early in the nerve growth factor (NGF)-induced neuronal differentiation of PC12 cells. The pools of these two proteins then disappear from the insoluble fraction after a few days of continued exposure of the cells to NGF. The methylation-inhibiting drug adenosine dialdehyde blocks the disappearance of these insoluble proteins, implicating a methylation-dependent step in the pathway that regulates the fate of these proteins.Abbreviations NGF nerve growth factor - PBS phosphatebuffered saline - SDS sodium dodecyl sulfate