Regulation of PI4KIIa retrograde transport

Tuesday, October 25, 2011 — Poster Session II
Noon – 2:00 p.m.	Natcher Conference Center	NICHD	CELLBIO-6

* FARE Award Winner

Authors

• M Jovic
• M Kean
• Z Szentpetery
• A Gingras
• J Brill
• T Balla

Abstract

Various trafficking events depend on efficient synthesis of phosphatidylinositol 4-phosphate by appropriate kinases (PI4Ks), including PI4KIIa that primarily localizes to the Golgi and endosomes. Tight membrane association of PI4KIIa through a palmitoyl moiety is suggestive of continuous cycling between endosomes and Golgi. The importance of PI4KIIa localization is underscored by its role in EGF receptor degradation, Wnt signaling and a late-onset neurodegeneration. This study was designed to address the regulation of PI4KIIa transport between Golgi and endosomes. A proteomic screen of potential binding partners of PI4KIIa identified a vesicular fusion protein VAMP-3, and this interaction was further confirmed by co-immunoprecipitation. Remarkably, expression of Tetanus toxin (TeNT), which cleaves VAMP-3 and inhibits the VAMP-3-mediated transport, resulted in accumulation of PI4KIIa on endosomes as determined by live-cell confocal microscopy. Conversly, overexpression of TeNT together with the mutant VAMP-3 resistant to TeNT recovered the Golgi localization of PI4KIIa. TeNT will, therefore, serve as a valuable method in our future kinetic studies of PI4KIIa retrograde transport. Taken together, these findings provided the first evidence of the potential mechanism regulating PI4KIIa retrograde transport, and revealed new approaches by which to study the role of PI4KIIa in cellular processes relevant to human health and disease.

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