KIF13A mediates influenza a virus ribonucleoproteins trafficking

The deposited article version contains attached the supplementary materials within the pdf. This publication hasn't any creative commons license associated. The deposited article version is a "JCS Advance Online Article" provided by The Company of Biologists, and it is the "Accepted manuscript" posted online on 23 October 2017.Influenza A is a rapid evolving virus, successful in provoking periodic epidemics and occasional pandemics in humans. Viral assembly is complex as the virus incorporates an eight-partite segmented genome of RNA (in the form of viral ribonucleoproteins, vRNPs). Genome assembly, with implications to public health, is not completely understood. It was reported that vRNPs are transported to the cell surface on Rab11 vesicles using microtubules, but no molecular motor has been assigned to the process. Here, we have identified KIF13A, a member of the kinesin-3 family, as the first molecular motor efficiently transporting vRNP-Rab11 vesicles during IAV infection. Depletion of KIF13A resulted in reduced viral titres and less accumulation of vRNPs at the cell surface, without interfering with the levels of other viral proteins at sites of viral assembly. In addition, in overexpression conditions and using two artificial methods able to displace vRNP-Rab11 vesicles, KIF13A augmented vRNP levels at the plasma membrane. Together our results show that KIF13A is an important host factor promoting influenza A vRNP transport, which is a crucial step for viral assembly.Fundação para a Ciência e a Tecnologia grants: (PTDC/IMI-MIC/1142/2012, IF/00899/2013, SFRH/BPD/62982/2009, SFRH/BPD/94204/2013); Instituto Calouste Gulbenkian; Fundação Calouste Gulbenkian; Fondation pour la Recherche Médicale grant: (Equipe FRM DEQ20140329491 Team label); Fondation ARC pour la Recherche sur le Cancer grant: (PJA20161204965); CNRS; INSERM; Institut Curie.info:eu-repo/semantics/acceptedVersio

BLOC-1 and BLOC-3 regulate VAMP7 cycling to and from melanosomes via distinct tubular transport carriers.

Endomembrane organelle maturation requires cargo delivery via fusion with membrane transport intermediates and recycling of fusion factors to their sites of origin. Melanosomes and other lysosome-related organelles obtain cargoes from early endosomes, but the fusion machinery involved and its recycling pathway are unknown. Here, we show that the v-SNARE VAMP7 mediates fusion of melanosomes with tubular transport carriers that also carry the cargo protein TYRP1 and that require BLOC-1 for their formation. Using live-cell imaging, we identify a pathway for VAMP7 recycling from melanosomes that employs distinct tubular carriers. The recycling carriers also harbor the VAMP7-binding scaffold protein VARP and the tissue-restricted Rab GTPase RAB38. Recycling carrier formation is dependent on the RAB38 exchange factor BLOC-3. Our data suggest that VAMP7 mediates fusion of BLOC-1-dependent transport carriers with melanosomes, illuminate SNARE recycling from melanosomes as a critical BLOC-3-dependent step, and likely explain the distinct hypopigmentation phenotypes associated with BLOC-1 and BLOC-3 deficiency in Hermansky-Pudlak syndrome variants.This work was supported by grants from the National Institutes of Health, National Eye Institute (R01 EY015625, to M.S. Marks and G.  Raposo), National Institute of Arthritis and Musculoskeletal and Skin Diseases (R01 AR048155, to M.S. Marks, and F32 AR062476, to M.K. Dennis), National Institute of General Medical Sciences (R01 GM108807, to M.S. Marks); Fondation pour la Recherche Médicale (to T.  Galli); the UK Medical Research Council (G0900113, to J.P. Luzio); and the Wellcome Trust (108429, to E.V. Sviderskaya and D.C. Bennett). This work was also supported by a Canadian Institutes of Health Research Fellowship (to G.G.  Hesketh) and a Fondation pour la Recherche Médicale grant from Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, Institut Curie, and Fondation pour la Recherche Médicale (DEQ20140329491 Team label, to G. Raposo).This is the final version of the article. It first appeared from Rockefeller University Press via http://dx.doi.org/10.1083/jcb.20160509

SNARE Protein Mimicry by an Intracellular Bacterium

Many intracellular pathogens rely on host cell membrane compartments for their survival. The strategies they have developed to subvert intracellular trafficking are often unknown, and SNARE proteins, which are essential for membrane fusion, are possible targets. The obligate intracellular bacteria Chlamydia replicate within an intracellular vacuole, termed an inclusion. A large family of bacterial proteins is inserted in the inclusion membrane, and the role of these inclusion proteins is mostly unknown. Here we identify SNARE-like motifs in the inclusion protein IncA, which are conserved among most Chlamydia species. We show that IncA can bind directly to several host SNARE proteins. A subset of SNAREs is specifically recruited to the immediate vicinity of the inclusion membrane, and their accumulation is reduced around inclusions that lack IncA, demonstrating that IncA plays a predominant role in SNARE recruitment. However, interaction with the SNARE machinery is probably not restricted to IncA as at least another inclusion protein shows similarities with SNARE motifs and can interact with SNAREs. We modelled IncA's association with host SNAREs. The analysis of intermolecular contacts showed that the IncA SNARE-like motif can make specific interactions with host SNARE motifs similar to those found in a bona fide SNARE complex. Moreover, point mutations in the central layer of IncA SNARE-like motifs resulted in the loss of binding to host SNAREs. Altogether, our data demonstrate for the first time mimicry of the SNARE motif by a bacterium

AP-1 and KIF13A coordinate endosomal sorting and positioning during melanosome biogenesis

The clathrin adaptor protein AP-1 and the motor KIF13A work together to deliver cargo into maturing melanosomes

Melanin Transfer: The Keratinocytes Are More than Gluttons

International audienceSkin pigmentation is tightly linked to the transfer of melanin from melanocytes to neighboring keratinocytes. For decades, cellular mechanisms underlying pigment transfer have remained enigmatic. Tarafder et al. identify a keratinocyte-initiated process coupling the exocytosis and endocytosis of melanin as a major pigment transfer mode in epidermis. These findings open new paths in our understanding of melanocyte-keratinocyte communication regulating pigmentation

Identification de protéines sécrétées par Chlamydia et étude fonctionnelle d'une protéine insérée dans la membrane de la vacuole, à l'interface entre les bactéries et leur hôte

Les Chlamydia sont des bactéries intracellulaires strictes dont trois espèces sont pathogènes pour l'Homme. Elles sont responsables, selon les souches, d'infections oculaires et génitales et d'infections respiratoires. Après avoir induit leur propre entrée, les bactéries se développent dans un compartiment délimité par une membrane, appelé inclusion. Au cours du cycle infectieux, les bactéries transloquent, par leur appareil de sécrétion de type trois (STT), des protéines dont certaines s'ancrent dans la membrane de l'inclusion où elles sont en contact avec le cytosol de la cellule hôte, les protéines Inc.Mon travail de thèse a porté sur les protéines bactériennes sécrétées, au cours du cycle infectieux, dans la cellule hôte. Une approche globale nous a permis d'identifier de 24 nouvelles protéines de Chlamydia sécrétées par l'appareil de STT. Ce travail a ouvert la voie à l'étude fonctionnelle de ces protéines bactériennes qui sont en contact avec l'hôte. De manière plus spécifique, nous avons étudié la fonction d'une protéine de l'inclusion, IncA, au cours du cycle infectieux. Nous avons montré que IncA présente des similitudes structurales et fonctionnelles avec les protéines eucaryotes, les SNAREs, facteurs essentiels de la fusion des membranes cellulaires. IncA interagit dans un modèle cellulaire, et in vitro, avec certaines SNAREs. De plus, dans des expériences de fusion de liposomes in vitro, la fusion membranaire induite par un complexe SNARE des endosomes tardifs est inhibée par IncA. Ce travail a permis de proposer que IncA puisse mimer les SNAREs et participer au détournement du trafic intracellulaire induit par Chlamydia.Chlamydiae are obligate intracellular pathogens of humans and animals. Depending on the species, they are responsible for ocular and genital infections, and respiratory diseases. After inducing their own entry, the bacteria develop in a membrane-bound compartment, called the inclusion. During the infectious cycle, they translocate a subset of proteins via a type three secretion (TTS) apparatus into the host cytosol. Among these, the Inc proteins remain anchored in the inclusion membrane where they face the host cytosol.My work has focused on bacterial proteins secreted into the host cell. By a global approach, we have identified 24 new proteins secreted by the TTS apparatus of Chlamydia. This work has opened the functional studies of these bacterial proteins that are in contact with the host cell cytosol. More specifically, we have studied the function of an inclusion protein, IncA. We have shown that IncA, from different chlamydial species, share structural and functional homologies with the SNARE family of eukaryotic proteins, which are essential factors for cellular membrane fusion events. We have shown that IncA interact with SNAREs in both a cellular and an in vitro model. Moreover, in liposome fusion assays, IncA inhibit membrane fusion induced by a cognate SNARE complex specific from the late endosomal compartment. We propose that IncA, by mimicking SNAREs proteins, participate in the control of the interactions between the inclusion membrane and intracellular compartments of the host cell.ORSAY-PARIS 11-BU Sciences (914712101) / SudocSudocFranceF

Par ici la sortie ! Le SARS-CoV-2 utilise les lysosomes pour sortir de la cellule infectée

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Illuminating the dark side of recycling endosomes

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