Septins are an evolutionarily conserved family of proteins that have been implicated in a multitude of cellular processes. Septin 5 is mainly expressed in the nervous system and it has been linked to regulated secretion through its binding to the SNARE protein syntaxin 1. However, the exact mechanism of septin 5 function in localized exocytosis remains unknown. Over-expression of septin 5 is known to lead to lower levels of secretion in HIT-T15 cells. Interestingly, in the current study, the knock-down of septin 5 also results in reduced levels of regulated secretion in PC12 cells, suggesting a more complex role of septin 5 that includes both negative and positive effects on exocytosis. Septin 5 knock-down data point to a possibility of septin 5 facilitating formation of a tether between the vesicles and their site of secretion.

Septins are an evolutionarily conserved family of proteins that have been implicated in a multitude of cellular processes. Septin 5 is mainly expressed in the nervous system and it has been linked to regulated secretion through its binding to the SNARE protein syntaxin 1. However, the exact mechanism of septin 5 function in localized exocytosis remains unknown. Over-expression of septin 5 is known to lead to lower levels of secretion in HIT-T15 cells. Interestingly, in the current study, the knock-down of septin 5 also results in reduced levels of regulated secretion in PC12 cells, suggesting a more complex role of septin 5 that includes both negative and positive effects on exocytosis. Septin 5 knock-down data point to a possibility of septin 5 facilitating formation of a tether between the vesicles and their site of secretion.