Endoplasmic reticulum–mitochondria junction is required for iron homeostasis
Ontology highlight
ABSTRACT:
ORGANISM(S): Saccharomyces cerevisiae
PROVIDER: GSE99499 | GEO | 2017/06/20
SECONDARY ACCESSION(S): PRJNA388654
REPOSITORIES: GEO
Similar Datasets
Project description:The Saccharomyces cerevisiae transcription factor Aft1 is activated in iron-deficient cells to induce the expression of iron regulon genes, which coordinate the increase of iron uptake and remodel cellular metabolism to survive low iron conditions. In addition, Aft1 has been implicated in numerous cellular processes including cell cycle progression and chromosome stability; however it is unclear if all cellular effects of Aft1 are mediated through iron homeostasis. To further investigate the cellular processes impacted by Aft1 using genome-wide synthetic lethal and synthetic dosage lethal screens, we identified greater than 70 deletion mutants that are sensitive to perturbations in AFT1 levels. Our genetic network reveals that Aft1 impacts a diverse range of cellular processes, including the RIM101 pH pathway, cell wall stability, DNA damage, protein transport, chromosome stability and mitochondrial function. Surprisingly, only a subset of mutants identified are sensitive to iron fluctuations or display genetic interactions with mutants of iron regulon genes AFT2 or FET3. We demonstrate that Aft1 works in parallel with the RIM101 pH pathway and the role of Aft1 in cell wall structure and DNA damage repair is mediated by iron. In contrast, we show that the role of Aft1 in chromosome maintenance is independent of its iron regulatory role and that alterations in iron levels do not impact chromosome loss rates. Our study clearly demonstrates a novel iron-independent role for Aft1.
2010-05-01 | GSE20531 | GEO
Project description:The Saccharomyces cerevisiae transcription factor Aft1 is activated in iron-deficient cells to induce the expression of iron regulon genes, which coordinate the increase of iron uptake and remodel cellular metabolism to survive low iron conditions. In addition, Aft1 has been implicated in numerous cellular processes including cell cycle progression and chromosome stability; however it is unclear if all cellular effects of Aft1 are mediated through iron homeostasis. To further investigate the cellular processes impacted by Aft1 using genome-wide synthetic lethal and synthetic dosage lethal screens, we identified greater than 70 deletion mutants that are sensitive to perturbations in AFT1 levels. Our genetic network reveals that Aft1 impacts a diverse range of cellular processes, including the RIM101 pH pathway, cell wall stability, DNA damage, protein transport, chromosome stability and mitochondrial function. Surprisingly, only a subset of mutants identified are sensitive to iron fluctuations or display genetic interactions with mutants of iron regulon genes AFT2 or FET3. We demonstrate that Aft1 works in parallel with the RIM101 pH pathway and the role of Aft1 in cell wall structure and DNA damage repair is mediated by iron. In contrast, we show that the role of Aft1 in chromosome maintenance is independent of its iron regulatory role and that alterations in iron levels do not impact chromosome loss rates. Our study clearly demonstrates a novel iron-independent role for Aft1. For this experiment 4 samples (2 reference and 2 test samples), consisting of 3 biological reps were hybridized. Cy3 one-color labelling was used for each sample.
2010-05-01 | E-GEOD-20531 | biostudies-arrayexpress
Project description:Organelles such as endoplasmic reticulum (ER) and mitochondria interact with each other at specialized domains on the ER known as mitochondria-associated membranes (MAMs). Here, using three-dimensional high-resolution imaging techniques, we show that the Sel1LHrd1 protein complex, the most conserved branch of ER-associated protein degradation (ERAD), exerts a profound impact on ER-mitochondria contacts and mitochondrial dynamics, at least in part, by regulating the turnover and hence the abundance of the MAM protein sigma receptor 1 (SigmaR1). Sel1L or Hrd1 deficiency in brown adipocytes impairs dynamic interaction between ER and mitochondria, leading to the formation of pleomorphic “megamitochondria” and, in some cases with penetrating ER tubule(s), in response to acute cold challenge. Mice with ERAD deficiency are cold sensitive and exhibit mitochondrial dysfunction in brown adipocytes. Mechanistically, endogenous SigmaR1 is targeted for proteasomal degradation by Sel1L-Hrd1 ERAD, whose accumulation in ERAD-deficient cells leads to mitofusin 2 (Mfn2) oligomerization, thereby linking ERAD to mitochondrial dynamics. Our study identifies Sel1L-Hrd1 ERAD as a critical determinant of ER-mitochondria contacts, thereby regulating mitochondrial dynamics and thermogenesis.
2020-04-24 | GSE145895 | GEO
Project description:Emerging evidence implicates ER stress caused by unfolded mutant proteins in chondrocytes as the underlying pathology of chondrodysplasias. ER stress is triggered in hypertrophic chondrocytes (HCs) in a mouse model (13del) of metaphyseal chondrodysplasia type Schmid (MCDS) caused by misfolded mutant collagen X proteins, but the HCs do not undergo apoptosis, rather chondrocyte differentiation is altered causing skeletal abnormality. How 13del HCs can escape from apoptosis and survive ER stress is not understood. We compared using label-free quantitative mass spectrometry approach the proteomes of HCs isolated from 13del growth plates with normal HCs. In this paper we reveal significant changes in levels of proteins involved in in actin remodeling, glycolysis and ER-mitochondria communication in 13del HCs chondrocytes. Previous in vitro studies of chronic ER stress showed down-regulation of glycolysis and disrupted mitochondrial function leading to cell death. Our data showed that glucose uptake was maintained in ATDC5 chondrocytic cell lines expressing 13del collagen X. Furthermore expression of mitochondrial calcium channels was reduced while mitochondrial membrane polarity was maintained in in vivo 13del chondrocytes. Thus we propose that 13del HCs survive by a mechanism whereby changes in ER-mitochondria communication reduce import of calcium coupled with maintenance of mitochondrial membrane polarity.
2015-11-25 | PXD002125 | Pride
Project description:Functional crosstalk between organelles is critical for maintaining cellular homeostasis. Individually, dysfunction of both endoplasmic reticulum (ER) and mitochondria have been linked to cellular and organismal aging, but little is known about how mechanisms of inter-organelle communication might be targeted to extended longevity. The metazoan unfolded protein response (UPR) maintains ER health through a variety of mechanisms beyond its canonical role in proteostasis, including calcium storage and lipid metabolism. Here we provide evidence that in C. elegans, inhibition of the conserved UPR mediator, activating transcription factor (atf)-6 increases lifespan via modulation of calcium homeostasis and signaling to the mitochondria. Loss of atf-6 confers long life via downregulation of the ER calcium buffering protein, calreticulin. Function of the ER calcium release channel, the inositol triphosphate receptor (IP3R/itr-1), is required for atf-6 mutant longevity while a gain-of-function IP3R/itr-1 mutation is sufficient to extend lifespan. IP3R dysfunction leads to altered mitochondrial behavior and hyperfused morphology, which is sufficient to suppress long life in atf-6 mutants. Highlighting a novel and direct role for this inter-organelle coordination of calcium in longevity, the mitochondrial calcium import channel, mcu-1, is also required for atf-6 mutant longevity. Altogether this study reveals the importance of organellar coordination of calcium handling in determining the quality of aging, and highlights calcium homeostasis as a critical output for the UPR and atf-6 in particular.
2020-08-12 | GSE156037 | GEO
Project description:Iron overload in the brain, defined as excess stores of iron, is known to be related to neurological disorder. Among neurodegeneration with brain iron accumulation, we reported a specific point mutation, 977-1G>A in WDR45, showing iron accumulation in the brain, and autophagy defects in the fibroblasts. In this study, we investigated whether fibroblasts with mutated WDR45 accumulated iron, and other effects on cellular organelles. We first identified the main location of iron accumulation in the mutant fibroblasts and then investigated the effects of this accumulation on other organelles, including lipid droplets, mitochondria, and lysosomes. Ultrastructure analysis using transmission electron microscopy (TEM) and confocal microscopy showed structural changes in the organelles. Increased numbers of lipid droplets, fragmented mitochondria, and increased lysosomal vesicles with functional disorder due to WDR45 deficiency were observed. The majority of iron accumulation occurred in the lysosomal vesicles, according to correlative light and electron microscopy (CLEM). These changes were related to defects in autophagy and defective protein and organelle turnover. Gene expression profiling analysis also showed significant changes in lipid metabolism, mitochondrial function, and autophagy-related genes. Those data suggested that functional and structural changes caused impaired lipid metabolism, mitochondrial disorder, and unbalanced autophagy fluxes, due to iron overload.
2021-11-17 | GSE184520 | GEO
Project description:Deficiency of the ER protein seipin results in generalised lipodystrophy by incompletely understood mechanisms. Here, we report mitochondrial abnormalities in seipin deficient patient cells. A subset of seipin is enriched at ER-mitochondria contact sites (MAMs) in human and mouse cells and localizes in the vicinity of calcium regulators SERCA2, IP3R and VDAC. Seipin association with MAM calcium regulators is stimulated by fasting-like stimuli, while seipin association with lipid droplets is promoted by lipid loading. Acute seipin removal does not alter ER calcium stores but leads to defective mitochondrial calcium import accompanied by a widespread reduction in Krebs cycle metabolites and ATP levels. In mice, inducible seipin deletion leads to mitochondrial dysfunctions preceding the development of metabolic complications. Together, these data suggest that seipin controls mitochondrial energy metabolism by regulating mitochondrial calcium influx at MAMs. In seipin deficient adipose tissue, reduced ATP production compromises adipocyte properties, contributing to lipodystrophy pathogenesis.
2022-01-18 | PXD029637 | Pride
Project description:SEPN1 is a type II protein of the endoplasmic reticulum (ER) whose loss of function gives rise to a collection of debilitating autosomal recessive myopathies gathered under the umbrella term of SEPN1-related myopathy (RM). At the moment, SEPN1-RM lacks an effective pharmacological treatment; thus, the medical management of the disease is only supportive. The potentially fatal diaphragmatic weakness leading to respiratory insufficiency in patients still ambulant is the main reason for medical concerns. Thus, studies on SEPN1-RM pathogenesis are necessary to implement a targeted pharmacological therapy aimed at relieving the general muscle weakness and the more worrisome diaphragmatic dysfunction. Here, we show a physical and functional interaction between SEPN1 and the ER stress mediator ERO1 alpha (henceforth, ERO1). Both SEPN1 and ERO1 are involved in the redox regulation of proteins into the ER, although in an opposite way SEPN1 imposes a less oxidant ER poise while ERO1 a more oxidant one, conceivable with a reductase function of SEPN1 and an oxidase one of ERO1. Furthermore, both are mainly localized in a region of the ER in close contact with mitochondria termed mitochondria-associated membranes (MAMs) and their loss impacts oppositely on the short-range MAMs, thereby impinging ER-mitochondria Ca2+ dynamics, OXPHOS, and bioenergetics. We find that ERO1 depletion restores the impaired short-range MAMs due to SEPN1 loss together with mitochondrial ATP. ERO1 knockout in a mouse background of SEPN1 loss blunts ER stress and the consequent Unfolded Protein Response (UPR) while it rescues the diaphragmatic weakness by improving ER/mitochondria contacts, calcium dynamics, and OXPHOS. Importantly, treatments of SEPN1 knock out mice with the chemical chaperone tauroursodeoxycholic acid (TUDCA) mimic the results of ERO1 loss improving calcium dynamics, OXPHOS, ER/mitochondria contacts, thereby rescuing diaphragmatic weakness as well. In addition, TUDCA-treated SEPN1-RM patients-derived myoblasts show a dynamic dose-dependent increase in ATP levels under ER stress conditions suggesting improved mitochondrial function. Thus, our findings point to the ERO1 axis in the pathogenesis of SEPN1-RM thereby impinging on MAMs and mitochondria bioenergetics and recall for the efficacy of a pharmacology therapy with ad hoc ER stress/ERO1 inhibitors for SEPN1-RM.
2024-02-14 | E-MTAB-12460 | biostudies-arrayexpress
Project description:Mitochondria and the endoplasmic reticulum (ER) physically interact by close structural juxtaposition, via the mitochondrial-associated ER membrane. Recently, great advances have been made in the understanding of inter-organelle communication between the ER and mitochondria. To clarify the role of mitochondrial dynamics in this communication, we generated mice lacking the mitochondrial fission protein dynamin-related protein 1 (Drp1) in the liver (Drp1LiKO). While intake of a high-fat diet (HFD) resulted in histological changes characterized by hepatic steatosis, inflammation, apoptosis, necrosis and fibrosis, reminiscent of nonalcoholic steatohepatitis, Drp1LiKO mice showed decreased fat mass and were protected from HFD-induced obesity. Analysis of liver gene expression profiles demonstrated marked elevation of ER stress markers. In addition, we observed increased expression of fibroblast growth factor 21 (Fgf21) through induction of activating transcription factor 4 and X-box binding protein 1, master regulators of the integrated stress response.
2015-06-01 | GSE64222 | GEO
Project description:Niemann Pick Type C1 (NPC1) is an endolysosomal transmembrane protein involved in the export of cholesterol and sphingolipids to other cellular compartments such as the endoplasmic reticulum and plasma membrane. NPC1 loss of function is the major cause of NPC disease, a rare lysosomal storage disorder characterized by an abnormal accumulation of lipids in the late endosomal/lysosomal network, mitochondrial dysfunction, and impaired autophagy. NPC phenotypes are conserved in yeast lacking Ncr1, orthologue of human NPC1, leading to premature ageing. Herein, we performed a phosphoproteomic analysis to investigate the effect of Ncr1 loss on cellular functions mediated by the yeast lysosome-like vacuoles. Our results revealed changes in vacuolar membrane proteins that are associated mostly with vesicle biology (fusion, transport, organization), autophagy and ion homeostasis, including iron, manganese, and calcium. Consistently, the Cytoplasm to vacuole targeting (Cvt) pathway was increased in ncr1∆ cells and autophagy was compromised despite TORC1 inhibition. Moreover, ncr1∆ cells exhibited iron overload mediated by the low‑iron sensing transcription factor Aft1. Iron deprivation restored the autophagic flux of ncr1∆ cells and increased its chronological lifespan and oxidative stress resistance. These results implicate iron overload on autophagy impairment, oxidative stress sensitivity and cell death in the yeast model of NPC1.
2023-03-31 | PXD039881 | Pride