Adapter-mediated Substrate Selection for Endoplasmic Reticulum-associated Degradation

SLC26A9, a member of the solute carrier protein family, transports chloride ions across various epithelia. SLC26A9 also associates with other ion channels and transporters linked to human health, and in some cases these heterotypic interactions are essential to support the biogenesis of both proteins. Therefore, understanding how this complex membrane protein is initially folded might provide new therapeutic strategies to overcome deficits in the function of SLC26A9 partners, one of which is associated with Cystic Fibrosis. To this end, we developed a novel yeast expression system for SLC26A9. This facile system has been used extensively with other ion channels and transporters to screen for factors that oversee protein folding checkpoints. As commonly observed for other channels and transporters, we first noted that a substantial fraction of SLC26A9 is targeted for endoplasmic reticulum associated degradation (ERAD), which destroys folding-compromised proteins in the early secretory pathway. We next discovered that ERAD selection requires the Hsp70 chaperone, which can play a vital role in ERAD substrate selection. We then created SLC26A9 mutants and found that the transmembrane-rich domain of SLC26A9 was quite stable, whereas the soluble cytosolic STAS domain was responsible for Hsp70-dependent ERAD. To support data obtained in the yeast model, we were able to recapitulate Hsp70-facilitated ERAD of the STAS domain in human tissue culture cells. These results indicate that a critical barrier to nascent membrane protein folding can reside within a specific soluble domain, one that is monitored by components associated with the ERAD machinery.

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The protective and destructive roles played by molecular chaperones during ERAD (endoplasmic-reticulum-associated degradation)

Biochemical Journal ◽

10.1042/bj20061890 ◽

2007 ◽

Vol 404 (3) ◽

pp. 353-363 ◽

Cited By ~ 100

Author(s):

Jeffrey L. Brodsky

Keyword(s):

Endoplasmic Reticulum ◽

Molecular Chaperones ◽

Metabolic Disorders ◽

Substrate Selection ◽

Post Translational Modification ◽

Protein Maturation ◽

Endoplasmic Reticulum Associated Degradation ◽

Number Of Factors ◽

Protein Biogenesis ◽

Shock Proteins

Over one-third of all newly synthesized polypeptides in eukaryotes interact with or insert into the membrane or the lumenal space of the ER (endoplasmic reticulum), an event that is essential for the subsequent folding, post-translational modification, assembly and targeting of these proteins. Consequently, the ER houses a large number of factors that catalyse protein maturation, but, in the event that maturation is aborted or inefficient, the resulting aberrant proteins may be selected for ERAD (ER-associated degradation). Many of the factors that augment protein biogenesis in the ER and that mediate ERAD substrate selection are molecular chaperones, some of which are heat- and/or stress-inducible and are thus known as Hsps (heat-shock proteins). But, regardless of whether they are constitutively expressed or are inducible, it has been assumed that all molecular chaperones function identically. As presented in this review, this assumption may be false. Instead, a growing body of evidence suggests that a chaperone might be involved in either folding or degrading a given substrate that transits through the ER. A deeper appreciation of this fact is critical because (i) the destruction of some ERAD substrates results in specific diseases, and (ii) altered ERAD efficiency might predispose individuals to metabolic disorders. Moreover, a growing number of chaperone-modulating drugs are being developed to treat maladies that arise from the synthesis of a unique mutant protein; therefore it is critical to understand how altering the activity of a single chaperone will affect the quality control of other nascent proteins that enter the ER.

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2197-P: SEL1L-HRD1 Endoplasmic Reticulum-Associated Degradation Is Required for Maintaining Glucagon Production in Pancreatic Alpha Cells

Diabetes ◽

10.2337/db19-2197-p ◽

2019 ◽

Vol 68 (Supplement 1) ◽

pp. 2197-P ◽

Cited By ~ 1

Author(s):

RACHEL B. REINERT ◽

NEHA SHRESTHA ◽

YEWEI JI ◽

LING QI

Keyword(s):

Endoplasmic Reticulum ◽

Alpha Cells ◽

Pancreatic Alpha Cells ◽

Endoplasmic Reticulum Associated Degradation

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Faculty Opinions recommendation of Sec61p is part of the endoplasmic reticulum-associated degradation machinery.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1283970.751071 ◽

2009 ◽

Author(s):

Davis Ng

Keyword(s):

Endoplasmic Reticulum ◽

Endoplasmic Reticulum Associated Degradation

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Faculty Opinions recommendation of Sel1L is indispensable for mammalian endoplasmic reticulum-associated degradation, endoplasmic reticulum homeostasis, and survival.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.718248338.793496085 ◽

2014 ◽

Author(s):

Hidde Ploegh

Keyword(s):

Endoplasmic Reticulum ◽

Endoplasmic Reticulum Associated Degradation

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Faculty Opinions recommendation of The VCP/p97 and YOD1 Proteins Have Different Substrate-dependent Activities in Endoplasmic Reticulum-associated Degradation (ERAD).

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.725850722.793510540 ◽

2015 ◽

Author(s):

Karin Romisch

Keyword(s):

Endoplasmic Reticulum ◽

Endoplasmic Reticulum Associated Degradation

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Faculty Opinions recommendation of A technique for delineating the unfolding requirements for substrate entry into retrotranslocons during endoplasmic reticulum-associated degradation.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.736962058.793568094 ◽

2019 ◽

Author(s):

Karin Romisch

Keyword(s):

Endoplasmic Reticulum ◽

Endoplasmic Reticulum Associated Degradation

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Regulating the Regulators: Mechanisms of Substrate Selection of the O-GlcNAc Cycling Enzymes OGT and OGA

Glycobiology ◽

10.1093/glycob/cwab005 ◽

2021 ◽

Author(s):

Hannah M Stephen ◽

Trevor M Adams ◽

Lance Wells

Keyword(s):

Nutrient Sensing ◽

Substrate Selection ◽

Disease States ◽

Dynamic Modification ◽

Selection For ◽

Outstanding Question ◽

Glcnac Transferase ◽

Future Work ◽

Partner Proteins ◽

Selection Of

Abstract Thousands of nuclear and cytosolic proteins are modified with a single β-N-acetylglucosamine on serine and threonine residues in mammals, a modification termed O-GlcNAc. This modification is essential for normal development and plays important roles in virtually all intracellular processes. Additionally, O-GlcNAc is involved in many disease states, including cancer, diabetes, and X-linked intellectual disability. Given the myriad of functions of the O-GlcNAc modification, it is therefore somewhat surprising that O-GlcNAc cycling is mediated by only two enzymes: the O-GlcNAc transferase (OGT), which adds O-GlcNAc, and the O-GlcNAcase (OGA), which removes it. A significant outstanding question in the O-GlcNAc field is how do only two enzymes mediate such an abundant and dynamic modification. In this review, we explore the current understanding of mechanisms for substrate selection for the O-GlcNAc cycling enzymes. These mechanisms include direct substrate interaction with specific domains of OGT or OGA, selection of interactors via partner proteins, posttranslational modification of OGT or OGA, nutrient sensing, and localization alteration. Altogether, current research paints a picture of an exquisitely regulated and complex system by which OGT and OGA select substrates. We also make recommendations for future work, toward the goal of identifying interaction mechanisms for specific substrates that may be able to be exploited for various research and medical treatment goals.

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