Nucleotide exchange factor Rab3GEP requires DENN and non-DENN elements for activation and targeting of Rab27a

Sanz�, Paolo; Evans, Richard D.; Briggs, Deborah A.; Cantero, Marta; Montoliu, Lluis; Patel, Shyamal; Sviderskaya, Elena V.; Itzen, Aymelt; Figueiredo, Ana C.; Seabra, Miguel C.; Hume, Alistair N.

Abstract

Rab GTPases are compartment-specific molecular switches that regulate intracellular vesicular transport in eukaryotes. GDP/GTP exchange factors (GEFs) control Rab activation, and current models propose that localised and regulated GEF activity is important in targeting Rabs to specific membranes. Here we investigated the mechanism of GEF function using the Rab27a-GEF, Rab3GEP, in melanocytes as a model. We show that Rab3GEP deficient melanocytes (melan-R3GKO) manifest partial disruption of melanosome dispersion, a read-out of Rab27a activation and targeting. Using rescue of melanosome dispersion in melan-R3GKO cells and effector pull-down approaches we show that the DENN domain of Rab3GEP (conserved among RabGEFs) is necessary, but insufficient, for its cellular function and GEF activity. Finally using a mitochondrial re-targeting strategy we show that Rab3GEP can target Rab27a to specific membranes in a GEF-dependent manner. We conclude that Rab3GEP facilitates the activation and targeting of Rab27a to specific membranes, but that it differs from other DENN containing RabGEFs in requiring DENN and non-DENN elements for both of these activities and by lacking compartment-specific localisation.

Citation

Sanzà, P., Evans, R. D., Briggs, D. A., Cantero, M., Montoliu, L., Patel, S., …Hume, A. N. (2019). Nucleotide exchange factor Rab3GEP requires DENN and non-DENN elements for activation and targeting of Rab27a. Journal of Cell Science, 132(9), 1-8. https://doi.org/10.1242/jcs.212035

• Journal Article Type: Article
• Acceptance Date: Mar 11, 2019
• Online Publication Date: Mar 21, 2019
• Publication Date: Apr 30, 2019
• Deposit Date: Mar 11, 2019
• Publicly Available Date: May 7, 2019
• Journal: Journal of Cell Science
• Print ISSN: 0021-9533
• Electronic ISSN: 1477-9137
• Publisher: Company of Biologists
• Peer Reviewed: Peer Reviewed
• Volume: 132
• Issue: 9
• Article Number: jcs212035
• Pages: 1-8
• DOI: https://doi.org/10.1242/jcs.212035
• Keywords: Organelle transport; Guanine nucleotide exchange factor; Rab27a; Rab3GEP; melanocyte
• Public URL: https://nottingham-repository.worktribe.com/output/1626369
• Publisher URL: http://jcs.biologists.org/content/132/9/jcs212035
• Contract Date: Mar 11, 2019