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STX13 regulates cargo delivery from recycling endosomes during melanosome biogenesis

Jani, Riddhi Atul and Purushothaman, Latha Kallur and Rani, Shikha and Bergam, Ptissam and Setty, Subba Rao Gangi (2015) STX13 regulates cargo delivery from recycling endosomes during melanosome biogenesis. In: JOURNAL OF CELL SCIENCE, 128 (17). pp. 3263-3276.

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Official URL: http://dx.doi.org/10.1242/jcs.171165

Abstract

Melanosomes are a class of lysosome-related organelles produced by melanocytes. Biogenesis of melanosomes requires the transport of melanin-synthesizing enzymes from tubular recycling endosomes to maturing melanosomes. The SNARE proteins involved in these transport or fusion steps have been poorly studied. We found that depletion of syntaxin 13 (STX13, also known as STX12), a recycling endosomal Qa-SNARE, inhibits pigment granule maturation in melanocytes by rerouting the melanosomal proteins such as TYR and TYRP1 to lysosomes. Furthermore, live-cell imaging and electron microscopy studies showed that STX13 co-distributed with melanosomal cargo in the tubular-vesicular endosomes that are closely associated with the maturing melanosomes. STX family proteins contain an N-terminal regulatory domain, and deletion of this domain in STX13 increases both the SNARE activity in vivo and melanosome cargo transport and pigmentation, suggesting that STX13 acts as a fusion SNARE in melanosomal trafficking pathways. In addition, STX13-dependent cargo transport requires the melanosomal R-SNARE VAMP7, and its silencing blocks the melanosome maturation, reflecting a defect in endosome-melanosome fusion. Moreover, we show mutual dependency between STX13 and VAMP7 in regulating their localization for efficient cargo delivery to melanosomes.

Item Type: Journal Article
Additional Information: Copy right for this article belongs to the COMPANY OF BIOLOGISTS LTD, BIDDER BUILDING CAMBRIDGE COMMERCIAL PARK COWLEY RD, CAMBRIDGE CB4 4DL, CAMBS, ENGLAND
Keywords: STX13; VAMP7; SNARE recycling; TYRP1; TYR; AP-3; HPS
Department/Centre: Division of Biological Sciences > Microbiology & Cell Biology
Depositing User: Id for Latest eprints
Date Deposited: 01 Oct 2015 04:49
Last Modified: 01 Oct 2015 04:49
URI: http://eprints.iisc.ac.in/id/eprint/52476

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