scholarly journals A new role for RINT-1 in SNARE complex assembly at the trans-Golgi network in coordination with the COG complex

2013 ◽  
Vol 24 (18) ◽  
pp. 2907-2917 ◽  
Author(s):  
Kohei Arasaki ◽  
Daichi Takagi ◽  
Akiko Furuno ◽  
Miwa Sohda ◽  
Yoshio Misumi ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Membrane Trafficking ◽  
Retrograde Transport ◽  
Snare Complex ◽  
Initial Contact ◽  
Complex Assembly ◽  
Trans Golgi Network ◽  
Cog Complex ◽  
Protein Receptor ◽  
Golgi Network

Docking and fusion of transport vesicles/carriers with the target membrane involve a tethering factor–mediated initial contact followed by soluble N-ethylmaleimide–sensitive factor attachment protein receptor (SNARE)–catalyzed membrane fusion. The multisubunit tethering CATCHR family complexes (Dsl1, COG, exocyst, and GARP complexes) share very low sequence homology among subunits despite likely evolving from a common ancestor and participate in fundamentally different membrane trafficking pathways. Yeast Tip20, as a subunit of the Dsl1 complex, has been implicated in retrograde transport from the Golgi apparatus to the endoplasmic reticulum. Our previous study showed that RINT-1, the mammalian counterpart of yeast Tip20, mediates the association of ZW10 (mammalian Dsl1) with endoplasmic reticulum–localized SNARE proteins. In the present study, we show that RINT-1 is also required for endosome-to–trans-Golgi network trafficking. RINT-1 uncomplexed with ZW10 interacts with the COG complex, another member of the CATCHR family complex, and regulates SNARE complex assembly at the trans-Golgi network. This additional role for RINT-1 may in part reflect adaptation to the demand for more diverse transport routes from endosomes to the trans-Golgi network in mammals compared with those in a unicellular organism, yeast. The present findings highlight a new role of RINT-1 in coordination with the COG complex.

scholarly journals Syntaxin 16’s Newly Deciphered Roles in Autophagy

Cells ◽  
2019 ◽  
Vol 8 (12) ◽  
pp. 1655 ◽  
Author(s):  
Bor Luen Tang
Keyword(s):  
Membrane Trafficking ◽  
Functional Redundancy ◽  
Transport Processes ◽  
Snare Complex ◽  
Dual Roles ◽  
Trans Golgi Network ◽  
Protein Receptor ◽  
Sensitive Factor ◽  
Golgi Network

Syntaxin 16, a Qa-SNARE (soluble N-ethylmaleimide-sensitive factor activating protein receptor), is involved in a number of membrane-trafficking activities, particularly transport processes at the trans-Golgi network (TGN). Recent works have now implicated syntaxin 16 in the autophagy process. In fact, syntaxin 16 appears to have dual roles, firstly in facilitating the transport of ATG9a-containing vesicles to growing autophagosomes, and secondly in autolysosome formation. The former involves a putative SNARE complex between syntaxin 16, VAMP7 and SNAP-47. The latter occurs via syntaxin 16’s recruitment by Atg8/LC3/GABARAP family proteins to autophagosomes and endo-lysosomes, where syntaxin 16 may act in a manner that bears functional redundancy with the canonical autophagosome Qa-SNARE syntaxin 17. Here, I discuss these recent findings and speculate on the mechanistic aspects of syntaxin 16’s newly found role in autophagy.

scholarly journals Identification of the Neuroblastoma-amplified Gene Product as a Component of the Syntaxin 18 Complex Implicated in Golgi-to-Endoplasmic Reticulum Retrograde Transport

2009 ◽  
Vol 20 (11) ◽  
pp. 2639-2649 ◽  
Author(s):  
Takehiro Aoki ◽  
Sarah Ichimura ◽  
Ayano Itoh ◽  
Mami Kuramoto ◽  
Takashi Shinkawa ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Retrograde Transport ◽  
Protein Glycosylation ◽  
Snare Complex ◽  
Binding Studies ◽  
Protein Receptor ◽  
Peripheral Membrane Protein ◽  
A Subunit ◽  
Membrane Components ◽  
Weak Similarity

Syntaxin 18, a soluble N-ethylmaleimide-sensitive factor (NSF) attachment protein receptor (SNARE) protein implicated in endoplasmic reticulum (ER) membrane fusion, forms a complex with other SNAREs (BNIP1, p31, and Sec22b) and several peripheral membrane components (Sly1, ZW10, and RINT-1). In the present study, we showed that a peripheral membrane protein encoded by the neuroblastoma-amplified gene (NAG) is a subunit of the syntaxin 18 complex. NAG encodes a protein of 2371 amino acids, which exhibits weak similarity to yeast Dsl3p/Sec39p, an 82-kDa component of the complex containing the yeast syntaxin 18 orthologue Ufe1p. Under conditions favoring SNARE complex disassembly, NAG was released from syntaxin 18 but remained in a p31-ZW10-RINT-1 subcomplex. Binding studies showed that the extreme N-terminal region of p31 is responsible for the interaction with NAG and that the N- and the C-terminal regions of NAG interact with p31 and ZW10-RINT-1, respectively. Knockdown of NAG resulted in a reduction in the expression of p31, confirming their intimate relationship. NAG depletion did not substantially affect Golgi morphology and protein export from the ER, but it caused redistribution of Golgi recycling proteins accompanied by a defect in protein glycosylation. These results together suggest that NAG links between p31 and ZW10-RINT-1 and is involved in Golgi-to-ER transport.

scholarly journals The COG complex interacts directly with Syntaxin 6 and positively regulates endosome-to-TGN retrograde transport

2011 ◽  
Vol 194 (3) ◽  
pp. 459-472 ◽  
Author(s):  
Orly Laufman ◽  
WanJin Hong ◽  
Sima Lev
Keyword(s):  
Steady State ◽  
State Level ◽  
Retrograde Transport ◽  
Snare Complex ◽  
Steady State Level ◽  
Cog Complex ◽  
Target Membrane ◽  
Steady State Levels ◽  
Retrograde Traffic ◽  
Golgi Network

The conserved oligomeric Golgi (COG) complex has been implicated in the regulation of endosome to trans-Golgi network (TGN) retrograde trafficking in both yeast and mammals. However, the exact mechanisms by which it regulates this transport route remain largely unknown. In this paper, we show that COG interacts directly with the target membrane SNARE (t-SNARE) Syntaxin 6 via the Cog6 subunit. In Cog6-depleted cells, the steady-state level of Syntaxin 6 was markedly reduced, and concomitantly, endosome-to-TGN retrograde traffic was significantly attenuated. Cog6 knockdown also affected the steady-state levels and/or subcellular distributions of Syntaxin 16, Vti1a, and VAMP4 and impaired the assembly of the Syntaxin 6–Syntaxin16–Vti1a–VAMP4 SNARE complex. Remarkably, overexpression of VAMP4, but not of Syntaxin 6, bypassed the requirement for COG and restored endosome-to-TGN trafficking in Cog6-depleted cells. These results suggest that COG directly interacts with specific t-SNAREs and positively regulates SNARE complex assembly, thereby affecting their associated trafficking steps.

scholarly journals The Arf GAP SMAP2 is necessary for organized vesicle budding from the trans-Golgi network and subsequent acrosome formation in spermiogenesis

2013 ◽  
Vol 24 (17) ◽  
pp. 2633-2644 ◽  
Author(s):  
Tomo Funaki ◽  
Shunsuke Kon ◽  
Kenji Tanabe ◽  
Waka Natsume ◽  
Sayaka Sato ◽  
...  
Keyword(s):  
Membrane Vesicles ◽  
Round Spermatid ◽  
Snare Complex ◽  
Coated Vesicle ◽  
Vesicle Budding ◽  
Trans Golgi Network ◽  
Protein Receptor ◽  
Acrosome Formation ◽  
Golgi Network ◽  
Coated Membrane

The trans-Golgi network (TGN) functions as a hub organelle in the exocytosis of clathrin-coated membrane vesicles, and SMAP2 is an Arf GTPase-activating protein that binds to both clathrin and the clathrin assembly protein (CALM). In the present study, SMAP2 is detected on the TGN in the pachytene spermatocyte to the round spermatid stages of spermatogenesis. Gene targeting reveals that SMAP2-deficient male mice are healthy and survive to adulthood but are infertile and exhibit globozoospermia. In SMAP2-deficient spermatids, the diameter of proacrosomal vesicles budding from TGN increases, TGN structures are distorted, acrosome formation is severely impaired, and reorganization of the nucleus does not proceed properly. CALM functions to regulate vesicle sizes, and this study shows that CALM is not recruited to the TGN in the absence of SMAP2. Furthermore, syntaxin2, a component of the soluble N-ethylmaleimide–sensitive factor attachment protein receptor (SNARE) complex, is not properly concentrated at the site of acrosome formation. Thus this study reveals a link between SMAP2 and CALM/syntaxin2 in clathrin-coated vesicle formation from the TGN and subsequent acrosome formation. SMAP2-deficient mice provide a model for globozoospermia in humans.

scholarly journals The Tlg SNARE complex is required for TGN homotypic fusion

2001 ◽  
Vol 155 (6) ◽  
pp. 969-978 ◽  
Author(s):  
Jason H. Brickner ◽  
Jennifer M. Blanchette ◽  
György Sipos ◽  
Robert S. Fuller
Keyword(s):  
Membrane Fusion ◽  
Fusion Reaction ◽  
Snare Complex ◽  
Snare Proteins ◽  
Attachment Protein ◽  
Trans Golgi Network ◽  
Rab Protein ◽  
Protein Receptor ◽  
Golgi Network ◽  
Antibody Inhibition

Using a new assay for membrane fusion between late Golgi/endosomal compartments, we have reconstituted a rapid, robust homotypic fusion reaction between membranes containing Kex2p and Ste13p, two enzymes resident in the yeast trans-Golgi network (TGN). Fusion was temperature, ATP, and cytosol dependent. It was inhibited by dilution, Ca+2 chelation, N-ethylmaleimide, and detergent. Coimmunoisolation confirmed that the reaction resulted in cointegration of the two enzymes into the same bilayer. Antibody inhibition experiments coupled with antigen competition indicated a requirement for soluble NSF attachment protein receptor (SNARE) proteins Tlg1p, Tlg2p, and Vti1p in this reaction. Membrane fusion also required the rab protein Vps21p. Vps21p was sufficient if present on either the Kex2p or Ste13p membranes alone, indicative of an inherent symmetry in the reaction. These results identify roles for a Tlg SNARE complex composed of Tlg1p, Tlg2p, Vti1p, and the rab Vps21p in this previously uncharacterized homotypic TGN fusion reaction.

scholarly journals Prohibitin: A Novel Molecular Player in KDEL Receptor Signalling

2015 ◽  
Vol 2015 ◽  
pp. 1-13 ◽  
Author(s):  
Monica Giannotta ◽  
Giorgia Fragassi ◽  
Antonio Tamburro ◽  
Capone Vanessa ◽  
Alberto Luini ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Complex ◽  
Membrane Trafficking ◽  
Transmembrane Domain ◽  
Cell Cycle Control ◽  
Retrograde Transport ◽  
Multifunctional Protein ◽  
G Protein Coupled ◽  
Kdel Receptor ◽  
Prohibitin 1

The KDEL receptor (KDELR) is a seven-transmembrane-domain protein involved in retrograde transport of protein chaperones from the Golgi complex to the endoplasmic reticulum. Our recent findings have shown that the Golgi-localised KDELR acts as a functional G-protein-coupled receptor by binding to and activating Gs and Gq. These G proteins induce activation of PKA and Src and regulate retrograde and anterograde Golgi trafficking. Here we used an integrated coimmunoprecipitation and mass spectrometry approach to identify prohibitin-1 (PHB) as a KDELR interactor. PHB is a multifunctional protein that is involved in signal transduction, cell-cycle control, and stabilisation of mitochondrial proteins. We provide evidence that depletion of PHB induces intense membrane-trafficking activity at the ER–Golgi interface, as revealed by formation of GM130-positive Golgi tubules, and recruitment of p115,β-COP, and GBF1 to the Golgi complex. There is also massive recruitment of SEC31 to endoplasmic-reticulum exit sites. Furthermore, absence of PHB decreases the levels of the Golgi-localised KDELR, thus preventing KDELR-dependent activation of Golgi-Src and inhibiting Golgi-to-plasma-membrane transport of VSVG. We propose a model whereby in analogy to previous findings (e.g., the RAS-RAF signalling pathway), PHB can act as a signalling scaffold protein to assist in KDELR-dependent Src activation.

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