VAMP4 and its cognate SNAREs are required for maintaining the ribbon structure of the Golgi apparatus

Background

The Golgi apparatus is at a crossroads between anterograde and retrograde trafficking. It exhibits a twisted ribbon-like network in the juxtanuclear region of vertebrate cells. Vesicle-associated membrane protein 4 (VAMP4) is a unique v-SNARE expressed exclusively in trans-Golgi networks (TGN), where it regulates retrograde trafficking from the early endosome to the TGN with its cognate SNARE partners Syntaxin 6, Syntaxin 16, and Vti1a.

Highlight

To examine whether VAMP4 plays a role in maintaining the Golgi ribbon structure, we depleted VAMP4 expression using a small interfering RNA. Depletion of VAMP4 led to fragmentation of the Golgi ribbon in HeLa cells. Immunohistochemical analysis showed that, in the absence of VAMP4, although the Golgi stack length was shortened, Golgi stacking was normal. Furthermore, depletion of the cognate SNARE partners of VAMP4 also disrupted the Golgi ribbon structure. Microscopy-based analyses showed that Golgi fragmentation did not impair anterograde traffic.

Conclusion

Our findings suggest that VAMP4 and its cognate SNAREs are required for maintaining the Golgi ribbon structure by balancing membrane transport between the endosome and TGN.