scholarly journals Degradation of integral membrane proteins modified with the photosensitive degron module requires the cytosolic endoplasmic reticulum–associated degradation pathway

2019 ◽  
Vol 30 (20) ◽  
pp. 2558-2570 ◽  
Author(s):  
Johannes Scheffer ◽  
Sophia Hasenjäger ◽  
Christof Taxis
Keyword(s):  
Endoplasmic Reticulum ◽  
Membrane Proteins ◽  
Protein Quality ◽  
Degradation Pathway ◽  
Integral Membrane Proteins ◽  
Secretory Proteins ◽  
Ubiquitin Protein Ligase ◽  
Aaa Atpase ◽  
Endoplasmic Reticulum Associated Degradation ◽  
Ubiquitin Conjugating Enzymes

Protein quality mechanisms are fundamental for proteostasis of eukaryotic cells. Endoplasmic reticulum–associated degradation (ERAD) is a well-studied pathway that ensures quality control of secretory and endoplasmic reticulum (ER)–resident proteins. Different branches of ERAD are involved in degradation of malfolded secretory proteins, depending on the localization of the misfolded part, the ER lumen (ERAD-L), the ER membrane (ERAD-M), and the cytosol (ERAD-C). Here we report that modification of several ER transmembrane proteins with the photosensitive degron (psd) module resulted in light-dependent degradation of the membrane proteins via the ERAD-C pathway. We found dependency on the ubiquitylation machinery including the ubiquitin-activating enzyme Uba1, the ubiquitin-­conjugating enzymes Ubc6 and Ubc7, and the ubiquitin–protein ligase Doa10. Moreover, we found involvement of the Cdc48 AAA-ATPase complex members Ufd1 and Npl4, as well as the proteasome, in degradation of Sec62-myc-psd. Thus, our work shows that ERAD-C substrates can be systematically generated via synthetic degron constructs, which facilitates future investigations of the ERAD-C pathway.

scholarly journals AAA ATPase p97/Valosin-containing Protein Interacts with gp78, a Ubiquitin Ligase for Endoplasmic Reticulum-associated Degradation

2004 ◽  
Vol 279 (44) ◽  
pp. 45676-45684 ◽  
Author(s):  
Xiaoyan Zhong ◽  
Yuxian Shen ◽  
Petek Ballar ◽  
Andria Apostolou ◽  
Reuven Agami ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Ubiquitin Ligase ◽  
Protein Quality ◽  
Proteasomal Degradation ◽  
Degradation Pathway ◽  
Aaa Atpase ◽  
Endoplasmic Reticulum Associated Degradation ◽  
Ubiquitin Ligase E3 ◽  
Quality Control Mechanism ◽  
Interacting Domain

Endoplasmic reticulum-associated degradation (ERAD) is a protein quality control mechanism that eliminates unwanted proteins from the endoplasmic reticulum (ER) through a ubiquitin-dependent proteasomal degradation pathway. gp78 is a previously described ER membrane-anchored ubiquitin ligase (E3) involved in ubiquitination of ER proteins. AAA ATPase (ATPase associated with various cellular activities) p97/valosin-containing protein (VCP) subsequently dislodges the ubiquitinated proteins from the ER and chaperones them to the cytosol, where they undergo proteasomal degradation. We now report that gp78 physically interacts with p97/VCP and enhances p97/VCP-polyubiquitin association. The enhanced association correlates with decreases in ER stress-induced accumulation of polyubiquitinated proteins. This effect is abolished when the p97/VCP-interacting domain of gp78 is removed. Further, using ERAD substrate CD3δ, gp78 consistently enhances p97/VCP-CD3δ binding and facilitates CD3δ degradation. Moreover, inhibition of endogenous gp78 expression by RNA interference markedly increases the levels of total polyubiquitinated proteins, including CD3δ, and abrogates VCP-CD3δ interactions. The gp78 mutant with deletion of its p97/VCP-interacting domain fails to increase CD3δ degradation and leads to accumulation of polyubiquitinated CD3δ, suggesting a failure in delivering ubiquitinated CD3δ for degradation. These data suggest that gp78-p97/VCP interaction may represent one way of coupling ubiquitination with retrotranslocation and degradation of ERAD substrates.

scholarly journals HRDGene Dependence of Endoplasmic Reticulum-associated Degradation

2000 ◽  
Vol 11 (5) ◽  
pp. 1697-1708 ◽  
Author(s):  
Sharon Wilhovsky ◽  
Richard Gardner ◽  
Randolph Hampton
Keyword(s):  
Endoplasmic Reticulum ◽  
Membrane Proteins ◽  
Protein Degradation ◽  
Degradation Pathway ◽  
Encoded Proteins ◽  
Absolute Dependence ◽  
Coa Reductase ◽  
Ubiquitin Conjugating Enzymes ◽  
Er Membrane

Work from several laboratories has indicated that many different proteins are subject to endoplasmic reticulum (ER) degradation by a common ER-associated machinery. This machinery includes ER membrane proteins Hrd1p/Der3p and Hrd3p and the ER-associated ubiquitin-conjugating enzymes Ubc7p and Ubc6p. The wide variety of substrates for this degradation pathway has led to the reasonable hypothesis that the HRD (Hmg CoA reductase degradation) gene-encoded proteins are generally involved in ER protein degradation in eukaryotes. We have tested this model by directly comparing the HRD dependency of the ER-associated degradation for various ER membrane proteins. Our data indicated that the role of HRD genes in protein degradation, even in this highly defined subset of proteins, can vary from absolute dependence to complete independence. Thus, ER-associated degradation can occur by mechanisms that do not involve Hrd1p or Hrd3p, despite their apparently broad envelope of substrates. These data favor models in which the HRD gene-encoded proteins function as specificity factors, such as ubiquitin ligases, rather than as factors involved in common aspects of ER degradation.

scholarly journals p97 Is in a Complex with Cholera Toxin and Influences the Transport of Cholera Toxin and Related Toxins to the Cytoplasm

2005 ◽  
Vol 280 (16) ◽  
pp. 15865-15871 ◽  
Author(s):  
Ramzey J. AbuJarour ◽  
Seema Dalal ◽  
Phyllis I. Hanson ◽  
Rockford K. Draper
Keyword(s):  
Endoplasmic Reticulum ◽  
Cholera Toxin ◽  
Vero Cells ◽  
Degradation Pathway ◽  
Endoplasmic Reticulum Membrane ◽  
Toxin A ◽  
Aaa Atpase ◽  
Endoplasmic Reticulum Associated Degradation ◽  
Protein Toxins ◽  
A Chain

Certain protein toxins, including cholera toxin, ricin, andPseudomonas aeruginosaexotoxin A, are transported to the lumen of the endoplasmic reticulum where they retro-translocate across the endoplasmic reticulum membrane to enter the cytoplasm. The mechanism of retrotranslocation is poorly understood but may involve the endoplasmic reticulum-associated degradation pathway. The AAA ATPase p97 (also called valosin-containing protein) participates in the retro-translocation of cellular endoplasmic reticulum-associated degradation substrates and is therefore a candidate to participate in the retrotranslocation of protein toxins. To investigate whether p97 functions in toxin delivery to the cytoplasm, we measured the sensitivity to toxins of cells expressing either wild-type p97 or a dominant ATPase-defective p97 mutant under control of a tetracycline-inducible promoter. The rate at which cholera toxin and related toxins entered the cytoplasm was reduced in cells expressing the ATPase-defective p97, suggesting that the toxins might interact with p97. To detect interaction, the cholera toxin A chain was immunoprecipitated from cholera toxin-treated Vero cells, and co-immunoprecipitation of p97 was assessed by immunoblotting. The immunoprecipitates contained both cholera toxin A chain and p97, evidence that the two proteins are in a complex. Altogether, these results provide functional and structural evidence that p97 participates in the transport of cholera toxin to the cytoplasm.

scholarly journals Genes that control the fidelity of endoplasmic reticulum to Golgi transport identified as suppressors of vesicle budding mutations.

1996 ◽  
Vol 7 (7) ◽  
pp. 1043-1058 ◽  
Author(s):  
M J Elrod-Erickson ◽  
C A Kaiser
Keyword(s):  
Endoplasmic Reticulum ◽  
Membrane Proteins ◽  
Integral Membrane Proteins ◽  
Secretory Proteins ◽  
Vesicle Formation ◽  
Gene Products ◽  
Vesicle Budding ◽  
Golgi Transport ◽  
Transport Vesicles ◽  
Copii Vesicle

Although convergent evidence suggests that proteins destined for export from the endoplasmic reticulum (ER) are separated from resident ER proteins and are concentrated into transport vesicles, the proteins that regulate this process have remained largely unknown. In a screen for suppressors of mutations in the essential COPII gene SEC13, we identified three genes (BST1, BST2/EMP24, and BST3) that negatively regulate COPII vesicle formation, preventing the production of vesicles with defective or missing subunits. Mutations in these genes slow the secretion of some secretory proteins and cause the resident ER proteins Kar2p and Pdi1p to leak more rapidly from the ER, indicating that these genes are also required for proper discrimination between resident ER proteins and Golgi-bound cargo molecules. The BST1 and BST2/EMP24 genes code for integral membrane proteins that reside predominantly in the ER. Our data suggest that the BST gene products represent a novel class of ER proteins that link the regulation of vesicle coat assembly to cargo sorting.

Making membrane proteins at the mammalian endoplasmic reticulum

2003 ◽  
Vol 31 (6) ◽  
pp. 1248-1252 ◽  
Author(s):  
F.J.L. Lecomte ◽  
N. Ismail ◽  
S. High
Keyword(s):  
Endoplasmic Reticulum ◽  
Protein Synthesis ◽  
Membrane Proteins ◽  
Lipid Bilayer ◽  
Integral Membrane Proteins ◽  
Current Understanding ◽  
Secretory Proteins ◽  
Protein Biogenesis ◽  
Membrane Spanning ◽  
Membrane Spanning Domains

Whereas protein biogenesis at the endoplasmic reticulum is well understood in the case of secretory proteins and simple membrane proteins, much less is known about the synthesis of multi-spanning integral membrane proteins. While it is clear that the multiple membrane-spanning domains of these proteins must be inserted into the lipid bilayer during biosynthesis, the mechanism by which their integration is achieved and their subsequent folding/assembly are poorly defined. In this review, we summarize our current understanding of protein synthesis at the endoplasmic reticulum and highlight specific features that are relevant to the biogenesis of multi-spanning membrane proteins.

scholarly journals Proteostasis In The Endoplasmic Reticulum: Road to Cure

Cancers ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 1793 ◽  
Author(s):  
Nam ◽  
Jeon
Keyword(s):  
Endoplasmic Reticulum ◽  
Er Stress ◽  
Unfolded Protein Response ◽  
Protein Quality ◽  
Tumor Development ◽  
Therapeutic Interventions ◽  
Secretory Proteins ◽  
Unfolded Protein ◽  
Stress Signals ◽  
Protein Response

The endoplasmic reticulum (ER) is an interconnected organelle that is responsible for the biosynthesis, folding, maturation, stabilization, and trafficking of transmembrane and secretory proteins. Therefore, cells evolve protein quality-control equipment of the ER to ensure protein homeostasis, also termed proteostasis. However, disruption in the folding capacity of the ER caused by a large variety of pathophysiological insults leads to the accumulation of unfolded or misfolded proteins in this organelle, known as ER stress. Upon ER stress, unfolded protein response (UPR) of the ER is activated, integrates ER stress signals, and transduces the integrated signals to relive ER stress, thereby leading to the re-establishment of proteostasis. Intriguingly, severe and persistent ER stress and the subsequently sustained unfolded protein response (UPR) are closely associated with tumor development, angiogenesis, aggressiveness, immunosuppression, and therapeutic response of cancer. Additionally, the UPR interconnects various processes in and around the tumor microenvironment. Therefore, it has begun to be delineated that pharmacologically and genetically manipulating strategies directed to target the UPR of the ER might exhibit positive clinical outcome in cancer. In the present review, we summarize recent advances in our understanding of the UPR of the ER and the UPR of the ER–mitochondria interconnection. We also highlight new insights into how the UPR of the ER in response to pathophysiological perturbations is implicated in the pathogenesis of cancer. We provide the concept to target the UPR of the ER, eventually discussing the potential of therapeutic interventions for targeting the UPR of the ER for cancer treatment.

Sign in / Sign up

Export Citation Format

Share Document