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Chinchankar MN, Taylor WB, Ko SH, Apple EC, Rodriguez KA, Chen L, Fisher AL. A novel endoplasmic reticulum adaptation is critical for the long-lived Caenorhabditis elegans rpn-10 proteasomal mutant. BIOCHIMICA ET BIOPHYSICA ACTA. GENE REGULATORY MECHANISMS 2023; 1866:194957. [PMID: 37355092 PMCID: PMC10528105 DOI: 10.1016/j.bbagrm.2023.194957] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 04/24/2023] [Accepted: 06/14/2023] [Indexed: 06/26/2023]
Abstract
The loss of proteostasis due to reduced efficiency of protein degradation pathways plays a key role in multiple age-related diseases and is a hallmark of the aging process. Paradoxically, we have previously reported that the Caenorhabditis elegans rpn-10(ok1865) mutant, which lacks the RPN-10/RPN10/PSMD4 subunit of the 19S regulatory particle of the 26S proteasome, exhibits enhanced cytosolic proteostasis, elevated stress resistance and extended lifespan, despite possessing reduced proteasome function. However, the response of this mutant against threats to endoplasmic reticulum (ER) homeostasis and proteostasis was unknown. Here, we find that the rpn-10 mutant is highly ER stress resistant compared to the wildtype. Under unstressed conditions, the ER unfolded protein response (UPR) is activated in the rpn-10 mutant as signified by increased xbp-1 splicing. This primed response appears to alter ER homeostasis through the upregulated expression of genes involved in ER protein quality control (ERQC), including those in the ER-associated protein degradation (ERAD) pathway. Pertinently, we find that ERQC is critical for the rpn-10 mutant longevity. These changes also alter ER proteostasis, as studied using the C. elegans alpha-1 antitrypsin (AAT) deficiency model, which comprises an intestinal ER-localised transgenic reporter of an aggregation-prone form of AAT called ATZ. The rpn-10 mutant shows a significant reduction in the accumulation of the ATZ reporter, thus indicating that its ER proteostasis is augmented. Via a genetic screen for suppressors of decreased ATZ aggregation in the rpn-10 mutant, we then identified ecps-2/H04D03.3, a novel ortholog of the proteasome-associated adaptor and scaffold protein ECM29/ECPAS. We further show that ecps-2 is required for improved ER proteostasis as well as lifespan extension of the rpn-10 mutant. Thus, we propose that ECPS-2-proteasome functional interactions, alongside additional putative molecular processes, contribute to a novel ERQC adaptation which underlies the superior proteostasis and longevity of the rpn-10 mutant.
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Affiliation(s)
- Meghna N Chinchankar
- Barshop Institute for Longevity and Aging Studies, UT Health San Antonio (UTHSCSA), SA, TX, United States of America; Department of Cell Systems and Anatomy, UTHSCSA, SA, TX, United States of America
| | - William B Taylor
- Division of Geriatrics, Gerontology, and Palliative Medicine, Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE, United States of America
| | - Su-Hyuk Ko
- Barshop Institute for Longevity and Aging Studies, UT Health San Antonio (UTHSCSA), SA, TX, United States of America; Department of Cell Systems and Anatomy, UTHSCSA, SA, TX, United States of America
| | - Ellen C Apple
- Barshop Institute for Longevity and Aging Studies, UT Health San Antonio (UTHSCSA), SA, TX, United States of America; Department of Cell Systems and Anatomy, UTHSCSA, SA, TX, United States of America
| | - Karl A Rodriguez
- Department of Cell Systems and Anatomy, UTHSCSA, SA, TX, United States of America
| | - Lizhen Chen
- Barshop Institute for Longevity and Aging Studies, UT Health San Antonio (UTHSCSA), SA, TX, United States of America; Department of Cell Systems and Anatomy, UTHSCSA, SA, TX, United States of America
| | - Alfred L Fisher
- Division of Geriatrics, Gerontology, and Palliative Medicine, Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE, United States of America.
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Gorbea C, Pratt G, Ustrell V, Bell R, Sahasrabudhe S, Hughes RE, Rechsteiner M. A protein interaction network for Ecm29 links the 26 S proteasome to molecular motors and endosomal components. J Biol Chem 2010; 285:31616-33. [PMID: 20682791 DOI: 10.1074/jbc.m110.154120] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Ecm29 is a 200-kDa HEAT repeat protein that binds the 26 S proteasome. Genome-wide two-hybrid screens and mass spectrometry have identified molecular motors, endosomal components, and ubiquitin-proteasome factors as Ecm29-interacting proteins. The C-terminal half of human Ecm29 binds myosins and kinesins; its N-terminal region binds the endocytic proteins, Vps11, Rab11-FIP4, and rabaptin. Whereas full-length FLAG-Ecm29, its C-terminal half, and a small central fragment of Ecm29 remain bound to glycerol-gradient-separated 26 S proteasomes, the N-terminal half of Ecm29 does not. Confocal microscopy showed that Ecm-26 S proteasomes are present on flotillin-positive endosomes, but they are virtually absent from caveolin- and clathrin-decorated endosomes. Expression of the small central fragment of Ecm29 markedly reduces proteasome association with flotillin-positive endosomes. Identification of regions within Ecm29 capable of binding molecular motors, endosomal proteins, and the 26 S proteasome supports the hypothesis that Ecm29 serves as an adaptor for coupling 26 S proteasomes to specific cellular compartments.
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Affiliation(s)
- Carlos Gorbea
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, Utah 84112, USA
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