PACSIN proteins bind tubulin and promote microtubule assembly.

PACSINs are intracellular adapter proteins involved in vesicle transport, membrane dynamics and actin reorganisation. In this study, we report a novel role for PACSIN proteins as components of the centrosome involved in microtubule dynamics. Glutathione S-transferase (GST)-tagged PACSIN proteins interacted with protein complexes containing alpha- and gamma-tubulin in brain homogenate. ...
Analysis of cell lysates showed that all three endogenous PACSINs co-immunoprecipitated dynamin, alpha-tubulin and gamma-tubulin. Furthermore, PACSINs bound only to unpolymerised tubulin, not to microtubules purified from brain. In agreement, the cellular localisation of endogenous PACSIN 2 was not affected by the microtubule depolymerising reagent nocodazole. By light microscopy, endogenous PACSIN 2 localised next to gamma-tubulin at purified centrosomes from NIH 3T3 cells. Finally, reduction of PACSIN 2 protein levels with small-interfering RNA (siRNA) resulted in impaired microtubule nucleation from centrosomes, whereas microtubule centrosome splitting was not affected, suggesting a role for PACSIN 2 in the regulation of tubulin polymerisation. These findings suggest a novel function for PACSIN proteins in dynamic microtubuli nucleation.
Mesh Terms:
Adaptor Proteins, Signal Transducing, Animals, Brain, Centrosome, Cytoskeletal Proteins, Humans, Intracellular Signaling Peptides and Proteins, Mice, Microtubules, NIH 3T3 Cells, Neuropeptides, Phosphoproteins, Protein Binding, Protein Isoforms, Proteins, RNA, Small Interfering, Tubulin
Exp. Cell Res.
Date: Jun. 10, 2008
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