A C. elegans model of human α1-antitrypsin deficiency links components of the RNAi pathway to misfolded protein turnover.
The accumulation of serpin oligomers and polymers within the endoplasmic reticulum (ER) causes cellular injury in patients with the classical form α1-antitrypsin deficiency (ATD). To better understand the cellular and molecular genetic aspects of this disorder, we generated transgenic C. elegans strains expressing either the wild-type (ATM) or Z mutant form (ATZ) of the human serpin fused to GFP. Animals secreted ATM, but retained polymerized ATZ within dilated ER cisternae. These latter animals also showed slow growth, smaller brood sizes and decreased longevity; phenotypes observed in ATD patients or transgenic mouse lines expressing ATZ. Similar to mammalian models, ATZ was disposed of by autophagy and ER-associated degradation pathways. Mutant strains defective in insulin signaling (daf-2) also showed a marked decrease in ATZ accumulation. Enhanced ATZ turnover was associated with the activity of two proteins central to systemic/exogenous (exo)-RNAi pathway: the dsRNA importer, SID-1 and the argonaute, RDE-1. Animals with enhanced exo-RNAi activity (rrf-3 mutant) phenocopied the insulin signaling mutants and also showed increased ATZ turnover. Taken together, these studies allude to the existence of a novel proteostasis pathway that mechanistically links misfolded protein turnover to components of the systemic RNAi machinery.
Departments of Pediatrics, Cell Biology, University of Pittsburgh School of Medicine, Children's Hospital of Pittsburgh of UPMC and Magee Womens Hospital Research Institute, 4401 Penn Avenue, Pittsburgh, PA 15224, USA.
Olivia S
OS
Long
Departments of Pediatrics, Cell Biology, University of Pittsburgh School of Medicine, Children's Hospital of Pittsburgh of UPMC and Magee Womens Hospital Research Institute, 4401 Penn Avenue, Pittsburgh, PA 15224, USA.
Joshua A
JA
Benson
Departments of Pediatrics, Cell Biology, University of Pittsburgh School of Medicine, Children's Hospital of Pittsburgh of UPMC and Magee Womens Hospital Research Institute, 4401 Penn Avenue, Pittsburgh, PA 15224, USA.
Joon Hyeok
JH
Kwak
Departments of Pediatrics, Cell Biology, University of Pittsburgh School of Medicine, Children's Hospital of Pittsburgh of UPMC and Magee Womens Hospital Research Institute, 4401 Penn Avenue, Pittsburgh, PA 15224, USA.
Cliff J
CJ
Luke
Departments of Pediatrics, Cell Biology, University of Pittsburgh School of Medicine, Children's Hospital of Pittsburgh of UPMC and Magee Womens Hospital Research Institute, 4401 Penn Avenue, Pittsburgh, PA 15224, USA.
Sager J
SJ
Gosai
Departments of Pediatrics, Cell Biology, University of Pittsburgh School of Medicine, Children's Hospital of Pittsburgh of UPMC and Magee Womens Hospital Research Institute, 4401 Penn Avenue, Pittsburgh, PA 15224, USA.
Linda P
LP
O'Reilly
Departments of Pediatrics, Cell Biology, University of Pittsburgh School of Medicine, Children's Hospital of Pittsburgh of UPMC and Magee Womens Hospital Research Institute, 4401 Penn Avenue, Pittsburgh, PA 15224, USA.
Yan
Y
Wang
Departments of Pediatrics, Cell Biology, University of Pittsburgh School of Medicine, Children's Hospital of Pittsburgh of UPMC and Magee Womens Hospital Research Institute, 4401 Penn Avenue, Pittsburgh, PA 15224, USA.
Jie
J
Li
Departments of Pediatrics, Cell Biology, University of Pittsburgh School of Medicine, Children's Hospital of Pittsburgh of UPMC and Magee Womens Hospital Research Institute, 4401 Penn Avenue, Pittsburgh, PA 15224, USA.
Anne C
AC
Vetica
Departments of Pediatrics, Cell Biology, University of Pittsburgh School of Medicine, Children's Hospital of Pittsburgh of UPMC and Magee Womens Hospital Research Institute, 4401 Penn Avenue, Pittsburgh, PA 15224, USA.
Mark T
MT
Miedel
Center for Biologic Imaging, University of Pittsburgh School of Medicine, 3500 Terrace Street, S233 BST, Pittsburgh, PA 15261, USA.
Donna B
DB
Stolz
Center for Biologic Imaging, University of Pittsburgh School of Medicine, 3500 Terrace Street, S233 BST, Pittsburgh, PA 15261, USA.
Simon C
SC
Watkins
Department of Human Genetics and Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, 1501 NW 10th Avenue, Miami, FL 33136, USA.
Stephan
S
Züchner
Departments of Pediatrics, Cell Biology, University of Pittsburgh School of Medicine, Children's Hospital of Pittsburgh of UPMC and Magee Womens Hospital Research Institute, 4401 Penn Avenue, Pittsburgh, PA 15224, USA.
David H
DH
Perlmutter
Departments of Pediatrics, Cell Biology, University of Pittsburgh School of Medicine, Children's Hospital of Pittsburgh of UPMC and Magee Womens Hospital Research Institute, 4401 Penn Avenue, Pittsburgh, PA 15224, USA.
Gary A
GA
Silverman
Departments of Pediatrics, Cell Biology, University of Pittsburgh School of Medicine, Children's Hospital of Pittsburgh of UPMC and Magee Womens Hospital Research Institute, 4401 Penn Avenue, Pittsburgh, PA 15224, USA, paksc@upmc.edu.
Stephen C
SC
Pak
D000818:Animals; D030801:Animals, Genetically Modified; D017173:Caenorhabditis elegans / Q000235:genetics* / Q000378:metabolism*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics; D002460:Cell Line; D004721:Endoplasmic Reticulum / Q000378:metabolism / Q000648:ultrastructure; D060746:Endoplasmic Reticulum-Associated Degradation; D015870:Gene Expression; D017930:Genes, Reporter; D006801:Humans; D007328:Insulin / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D009154:Mutation; D010641:Phenotype; D011401:Promoter Regions, Genetic; D059748:Proteolysis; D057165:Proteostasis Deficiencies / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015843:Serpins; D015398:Signal Transduction; D017923:Sodium-Hydrogen Exchangers / Q000235:genetics; D000515:alpha 1-Antitrypsin / Q000235:genetics* / Q000378:metabolism; D019896:alpha 1-Antitrypsin Deficiency / Q000235:genetics* / Q000378:metabolism
D029742:Caenorhabditis elegans Proteins; D007328:Insulin; C480043:NHX-2 protein, C elegans; D011993:Recombinant Fusion Proteins; D015843:Serpins; D017923:Sodium-Hydrogen Exchangers; D000515:alpha 1-Antitrypsin