Septin 6 localizes to microtubules in neuronal dendrites

In neuronal dendrites, septins localize to the base of the spine, a unique position which is sandwiched between the microtubule (MT)-rich dendritic shaft and the actin filament-rich spine. Here, we provide evidence for the association of SEPT6 with MTs in cultured rat hippocampal neurons. In normal cultures, SEPT6 clusters localized to MTs, but not to actin clusters. Only MT-disrupting agents (vincristine and nocodazole), but not microfilament-disrupting one (latrunculin A), induced the redistribution of SEPT6 to the disrupted MTs. The nascent MT fibers that were recovered from vincristine or nocodazole treatments also accompanied SEPT6. Blocking MT disruption by Taxol prevented such phenomena, proving that the redistribution of SEPT6 was due to the MT disruption. Our results indicate that SEPT6 complexes at the base of the dendritic spine are associated with MTs.