scholarly journals The Proteasomal Deubiquitinating Enzyme PSMD14 Regulates Macroautophagy by Controlling Golgi-to-ER Retrograde Transport

Cells ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 777 ◽  
Author(s):  
Hianara A Bustamante ◽  
Karina Cereceda ◽  
Alexis E González ◽  
Guillermo E Valenzuela ◽  
Yorka Cheuquemilla ◽  
...  
Keyword(s):  
Golgi Apparatus ◽  
Membrane Trafficking ◽  
Retrograde Transport ◽  
Deubiquitinating Enzyme ◽  
Biological Processes ◽  
Intracellular Membrane ◽  
Pharmacological Inhibition ◽  
Protein Membrane ◽  
A Subunit

Ubiquitination regulates several biological processes, however the role of specific members of the ubiquitinome on intracellular membrane trafficking is not yet fully understood. Here, we search for ubiquitin-related genes implicated in protein membrane trafficking performing a High-Content siRNA Screening including 1187 genes of the human “ubiquitinome” using amyloid precursor protein (APP) as a reporter. We identified the deubiquitinating enzyme PSMD14, a subunit of the 19S regulatory particle of the proteasome, specific for K63-Ub chains in cells, as a novel regulator of Golgi-to-endoplasmic reticulum (ER) retrograde transport. Silencing or pharmacological inhibition of PSMD14 with Capzimin (CZM) caused a robust increase in APP levels at the Golgi apparatus and the swelling of this organelle. We showed that this phenotype is the result of rapid inhibition of Golgi-to-ER retrograde transport, a pathway implicated in the early steps of the autophagosomal formation. Indeed, we observed that inhibition of PSMD14 with CZM acts as a potent blocker of macroautophagy by a mechanism related to the retention of Atg9A and Rab1A at the Golgi apparatus. As pharmacological inhibition of the proteolytic core of the 20S proteasome did not recapitulate these effects, we concluded that PSMD14, and the K63-Ub chains, act as a crucial regulatory factor for macroautophagy by controlling Golgi-to-ER retrograde transport.

scholarly journals The proteasomal deubiquitinating enzyme PSMD14 regulates macroautophagy by controlling Golgi-to-ER retrograde transport

2020 ◽  
Author(s):  
HA Bustamante ◽  
K Cereceda ◽  
AE González ◽  
GE Valenzuela ◽  
Y Cheuquemilla ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
Membrane Trafficking ◽  
Retrograde Transport ◽  
Deubiquitinating Enzyme ◽  
20S Proteasome ◽  
Biological Processes ◽  
Pharmacological Inhibition ◽  
Protein Membrane ◽  
A Subunit

ABSTRACTUbiquitination regulates several biological processes. Here, we search for ubiquitin-related genes implicated in protein membrane trafficking performing a High-Content siRNA Screening including 1,187 genes of the human “ubiquitinome” using Amyloid Precursor Protein (APP) as a reporter. We identified the deubiquitinating enzyme PSMD14, a subunit of the 19S regulatory particle of the proteasome, specific for K63-Ub chains in cells, as a novel key regulator of Golgi-to-endoplasmic reticulum (ER) retrograde transport. Silencing or pharmacological inhibition of PSMD14 caused a robust and rapid inhibition of Golgi-to-ER retrograde transport which leads to a potent blockage of macroautophagy by a mechanism associated with the retention of Atg9A and Rab1A at the Golgi apparatus. Because pharmacological inhibition of the proteolytic core of the 20S proteasome did not recapitulate these effects, we concluded that PSMD14, and their K-63-Ub chains, act as a crucial regulator factor for macroautophagy by controlling Golgi-to-ER retrograde transport.

scholarly journals Spatiotemporal Control of Intracellular Membrane Trafficking by Rho GTPases

Cells ◽  
2019 ◽  
Vol 8 (12) ◽  
pp. 1478 ◽  
Author(s):  
Monilola A. Olayioye ◽  
Bettina Noll ◽  
Angelika Hausser
Keyword(s):  
Membrane Trafficking ◽  
Rho Gtpases ◽  
Rho Gtpase ◽  
Regulatory Proteins ◽  
Biological Processes ◽  
Intracellular Membrane ◽  
Master Regulators ◽  
Cytoskeletal Remodeling ◽  
Wide Range ◽  
Spatiotemporal Control

As membrane-associated master regulators of cytoskeletal remodeling, Rho GTPases coordinate a wide range of biological processes such as cell adhesion, motility, and polarity. In the last years, Rho GTPases have also been recognized to control intracellular membrane sorting and trafficking steps directly; however, how Rho GTPase signaling is regulated at endomembranes is still poorly understood. In this review, we will specifically address the local Rho GTPase pools coordinating intracellular membrane trafficking with a focus on the endo- and exocytic pathways. We will further highlight the spatiotemporal molecular regulation of Rho signaling at endomembrane sites through Rho regulatory proteins, the GEFs and GAPs. Finally, we will discuss the contribution of dysregulated Rho signaling emanating from endomembranes to the development and progression of cancer.

scholarly journals Trs65p, a subunit of the Ypt1p GEF TRAPPII, interacts with the Arf1p exchange factor Gea2p to facilitate COPI-mediated vesicle traffic

2011 ◽  
Vol 22 (19) ◽  
pp. 3634-3644 ◽  
Author(s):  
Shuliang Chen ◽  
Huaqing Cai ◽  
Sei-Kyoung Park ◽  
Shekar Menon ◽  
Catherine L. Jackson ◽  
...  
Keyword(s):  
Membrane Trafficking ◽  
Rab Gtpase ◽  
Vesicle Traffic ◽  
Exchange Factor ◽  
Γ Subunit ◽  
C Terminus ◽  
A Subunit ◽  
Distinct Membrane

The TRAPP complexes are multimeric guanine exchange factors (GEFs) for the Rab GTPase Ypt1p. The three complexes (TRAPPI, TRAPPII, and TRAPPIII) share a core of common subunits required for GEF activity, as well as unique subunits (Trs130p, Trs120p, Trs85p, and Trs65p) that redirect the GEF from the endoplasmic reticulum–Golgi pathway to different cellular locations where TRAPP mediates distinct membrane trafficking events. Roles for three of the four unique TRAPP subunits have been described before; however, the role of the TRAPPII-specific subunit Trs65p has remained elusive. Here we demonstrate that Trs65p directly binds to the C-terminus of the Arf1p exchange factor Gea2p and provide in vivo evidence that this interaction is physiologically relevant. Gea2p and TRAPPII also bind to the yeast orthologue of the γ subunit of the COPI coat complex (Sec21p), a known Arf1p effector. These and previous findings reveal that TRAPPII is part of an Arf1p GEF-effector loop that appears to play a role in recruiting or stabilizing TRAPPII to membranes. In support of this proposal, we show that TRAPPII is more soluble in an arf1Δ mutant.

scholarly journals Rab GTPases: Central Coordinators of Membrane Trafficking in Cancer

2021 ◽  
Vol 9 ◽  
Author(s):  
Hongyuan Jin ◽  
Yuanxin Tang ◽  
Liang Yang ◽  
Xueqiang Peng ◽  
Bowen Li ◽  
...  
Keyword(s):  
Tumor Progression ◽  
Membrane Transport ◽  
Membrane Trafficking ◽  
Membrane Vesicle ◽  
Clinical Implications ◽  
Rab Gtpases ◽  
Intracellular Membrane ◽  
Cellular Functions ◽  
Vesicle Movement

Tumor progression involves invasion, migration, metabolism, autophagy, exosome secretion, and drug resistance. Cargos transported by membrane vesicle trafficking underlie all of these processes. Rab GTPases, which, through coordinated and dynamic intracellular membrane trafficking alongside cytoskeletal pathways, determine the maintenance of homeostasis and a series of cellular functions. The mechanism of vesicle movement regulated by Rab GTPases plays essential roles in cancers. Therefore, targeting Rab GTPases to adjust membrane trafficking has the potential to become a novel way to adjust cancer treatment. In this review, we describe the characteristics of Rab GTPases; in particular, we discuss the role of their activation in the regulation of membrane transport and provide examples of Rab GTPases regulating membrane transport in tumor progression. Finally, we discuss the clinical implications and the potential as a cancer therapeutic target of Rab GTPases.

scholarly journals The transmembrane protein p23 contributes to the organization of the Golgi apparatus

2000 ◽  
Vol 113 (6) ◽  
pp. 1043-1057 ◽  
Author(s):  
M. Rojo ◽  
G. Emery ◽  
V. Marjomaki ◽  
A.W. McDowall ◽  
R.G. Parton ◽  
...  
Keyword(s):  
Golgi Apparatus ◽  
Secretory Pathway ◽  
Transmembrane Protein ◽  
Ectopic Expression ◽  
Retrograde Transport ◽  
Early Secretory Pathway ◽  
Golgi Membranes ◽  
Constant Diameter ◽  
Golgi Network

In previous studies we have shown that p23, a member of the p24-family of small transmembrane proteins, is highly abundant in membranes of the cis-Golgi network (CGN), and is involved in sorting/trafficking in the early secretory pathway. In the present study, we have further investigated the role of p23 after ectopic expression. We found that ectopically expressed p23 folded and oligomerized properly, even after overexpression. However, in contrast to endogenous p23, exogenous p23 molecules did not localize to the CGN, but induced a significant expansion of characteristic smooth ER membranes, where they accumulated in high amounts. This ER-derived, p23-rich subdomain displayed a highly regular morphology, consisting of tubules and/or cisternae of constant diameter, which were reminiscent of the CGN membranes containing p23 in control cells. The expression of exogenous p23 also led to the specific relocalization of endogenous p23, but not of other proteins, to these specialized ER-derived membranes. Relocalization of p23 modified the ultrastructure of the CGN and Golgi membranes, but did not affect anterograde and retrograde transport reactions to any significant extent. We conclude (i) that p23 has a morphogenic activity that contributes to the morphology of CGN-membranes; and (ii) that the presence of p23 in the CGN is necessary for the proper organization of the Golgi apparatus.

scholarly journals Receptor for Retrograde Transport in the Apicomplexan Parasite Toxoplasma gondii

2005 ◽  
Vol 4 (2) ◽  
pp. 432-442 ◽  
Author(s):  
Stacy L. Pfluger ◽  
Holly V. Goodson ◽  
Jennifer M. Moran ◽  
Christine J. Ruggiero ◽  
Xin Ye ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Membrane Trafficking ◽  
Cell Biology ◽  
Retrograde Transport ◽  
Stable Expression ◽  
Host Cells ◽  
Functional Assay ◽  
Obligate Intracellular ◽  
Intracellular Parasites ◽  
A Subunit

ABSTRACT Toxoplasma gondii and its apicomplexan relatives (such as Plasmodium falciparum, which causes malaria) are obligate intracellular parasites that rely on sequential protein release from specialized secretory organelles for invasion and multiplication within host cells. Because of the importance of these unusual membrane trafficking pathways for drug development and comparative cell biology, characterizing them is essential. In particular, it is unclear what role retrieval mechanisms play in parasite membrane trafficking or where they operate. Previously, we showed that T. gondii’s beta-COP (TgΒCOP; a subunit of coatomer protein complex I, COPI) and retrieval reporters localize exclusively to the zone between the parasite endoplasmic reticulum (ER) and Golgi apparatus. This suggested the existence of an HDEL receptor in T. gondii. We have now identified, cloned, and sequenced this receptor, TgERD2. TgERD2 localizes in a Golgi or ER pattern suggestive of the HDEL retrieval reporter (K. M. Hager, B. Striepen, L. G. Tilney, and D. S. Roos, J. Cell Sci. 112 :2631-2638, 1999). A functional assay reveals that TgERD2 is able to complement the Saccharomyces cerevisiae ERD2 null mutant. Retrieval studies reveal that stable expression of a fluorescent exogenous retrieval ligand results in a dispersal of βCOP signal throughout the cytoplasm and, surprisingly, results in βCOP staining of the vacuolar space of the parasite. In contrast, stable expression of TgERD2GFP does not appear to disturb βCOP staining. In addition to TgERD2, Toxoplasma contains two more divergent ERD2 relatives. Phylogenetic analysis reveals that these proteins belong to a previously unrecognized ERD2 subfamily common to plants and alveolate organisms and as such could represent mediators of parasite-specific retrieval functions. No evidence of class 2 ERD2 proteins was found in metazoan organisms or fungi.

V. Confluence of membrane trafficking and motility in epithelial cell models

2002 ◽  
Vol 283 (5) ◽  
pp. G1015-G1019 ◽  
Author(s):  
James E. Casanova
Keyword(s):  
Wound Healing ◽  
Membrane Trafficking ◽  
Driving Force ◽  
Future Research ◽  
Biological Processes ◽  
Cell Models ◽  
Intracellular Membrane ◽  
Direction Of Movement ◽  
Junctional Complexes ◽  
Review Current

Migration of epithelial cells occurs in a variety of important biological processes including tissue morphogenesis, wound healing, and the metastasis of epithelial tumors. In some instances, the cells remain attached to each other and migrate together as a sheet, maintaining epithelial integrity. In others (e.g., metastasis), junctional complexes are disrupted and cells migrate individually. In both cases, motility involves the extension of membranous protrusions (filopodia and lamellipodia) in the direction of movement and the transient assembly and disassembly of integrin-mediated adhesions with the extracellular matrix. The driving force for these events is provided by regulated changes in the organization of the actin cytoskeleton, which are thought to be coordinated with alterations in intracellular membrane traffic. In this themes article, I review current hypotheses about how these processes are integrated and attempt to identify fruitful areas for future research.

scholarly journals Role of Xklp3, a Subunit of the Xenopus Kinesin II Heterotrimeric Complex, in Membrane Transport between the Endoplasmic Reticulum and the Golgi Apparatus

1998 ◽  
Vol 143 (6) ◽  
pp. 1559-1573 ◽  
Author(s):  
Nathalie Le Bot ◽  
Claude Antony ◽  
Jamie White ◽  
Eric Karsenti ◽  
Isabelle Vernos
Keyword(s):  
Golgi Apparatus ◽  
Dominant Negative ◽  
Normal Delivery ◽  
Final Destination ◽  
Golgi Region ◽  
Dominant Negative Form ◽  
A Subunit ◽  
And Function ◽  
State Size

The function of the Golgi apparatus is to modify proteins and lipids synthesized in the ER and sort them to their final destination. The steady-state size and function of the Golgi apparatus is maintained through the recycling of some components back to the ER. Several lines of evidence indicate that the spatial segregation between the ER and the Golgi apparatus as well as trafficking between these two compartments require both microtubules and motors. We have cloned and characterized a new Xenopus kinesin like protein, Xklp3, a subunit of the heterotrimeric Kinesin II. By immunofluorescence it is found in the Golgi region. A more detailed analysis by EM shows that it is associated with a subset of membranes that contain the KDEL receptor and are localized between the ER and Golgi apparatus. An association of Xklp3 with the recycling compartment is further supported by a biochemical analysis and the behavior of Xklp3 in BFA-treated cells. The function of Xklp3 was analyzed by transfecting cells with a dominant-negative form lacking the motor domain. In these cells, the normal delivery of newly synthesized proteins to the Golgi apparatus is blocked. Taken together, these results indicate that Xklp3 is involved in the transport of tubular-vesicular elements between the ER and the Golgi apparatus.

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