Insight into endoplasmic reticulum-mitochondria contacts in human amyotrophic lateral sclerosis.
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ABSTRACT:
SUBMITTER: Hartopp N
PROVIDER: S-EPMC10883496 | biostudies-literature | 2024 Jul
REPOSITORIES: biostudies-literature
Publications
Insight into endoplasmic reticulum-mitochondria contacts in human amyotrophic lateral sclerosis.
Hartopp Naomi N Markovinovic Andrea A Miller Christopher Cj CC Gomez-Suaga Patricia P
Neural regeneration research 20231108 7
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Project description:Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease without effective treatment. The progressive motoneuron death in ALS is associated with alterations in lipid metabolism. As its regulation occurs in mitochondria-associated endoplasmic reticulum (ER) membranes (MAMs), modulation of mitochondria-ER contacts (MERCs) is emerging as a crucial factor in MAM formation and lipid metabolism control. Using the MERLIN biosensor in a high-throughput screening within the EU-OPENSCREEN ERIC, we discovered small molecules that increase MERCs in HCT116 cells, enhancing their ability to uptake cholesterol. We demonstrated that cholesterol trafficking is decreased in an ALS patient-derived cell model, and this trafficking is restored after treatment with the discovered MERC modulator 24. Electron microscopy revealed that treatment with compound 24 increases MERCs, promotes lipid droplet formation, and restores mitochondrial cristae. Overall, the brain-permeable MERC modulator, compound 24, may serve as a valuable pharmacological tool for studying MAM function and holds potential for in vivo studies in ALS and other MAM dysfunction diseases.
| S-EPMC11770630 | biostudies-literature
Project description:The endoplasmic reticulum (ER) is a major organelle involved in protein quality control and cellular homeostasis. ER stress results from structural and functional dysfunction of the organelle, along with the accumulation of misfolded proteins and changes in calcium homeostasis, it leads to ER stress response pathway such as unfolded protein response (UPR). Neurons are particularly sensitive to the accumulation of misfolded proteins. Thus, the ER stress is involved in neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, prion disease and motor neuron disease (MND). Recently, the complex involvement of ER stress pathways has been demonstrated in experimental models of amyotrophic lateral sclerosis (ALS)/MND using pharmacological and genetic manipulation of the unfolded protein response (UPR), an adaptive response to ER stress. Here, we aim to provide recent evidence demonstrating that the ER stress pathway is an essential pathological mechanism of ALS. In addition, we also provide therapeutic strategies that can help treat diseases by targeting the ER stress pathway.
| S-EPMC9974850 | biostudies-literature
Project description:Amyotrophic lateral sclerosis is a progressive neurodegenerative disease that affects motor neurons in the spinal cord, brainstem and motor cortex, leading to paralysis and eventually to death within 3-5 years of symptom onset. To date, no cure or effective therapy is available. The role of chronic endoplasmic reticulum stress in the pathophysiology of amyotrophic lateral sclerosis, as well as a potential drug target, has received increasing attention. Here, we investigated the mode of action and therapeutic effect of the endoplasmic reticulum-resident protein cerebral dopamine neurotrophic factor in three preclinical models of amyotrophic lateral sclerosis, exhibiting different disease development and aetiology: (i) the conditional choline acetyltransferase-tTA/TRE-hTDP43-M337V rat model previously described; (ii) the widely used SOD1-G93A mouse model; and (iii) a novel slow-progressive TDP43-M337V mouse model. To specifically analyse the endoplasmic reticulum stress response in motor neurons, we used three main methods: (i) primary cultures of motor neurons derived from embryonic Day 13 embryos; (ii) immunohistochemical analyses of spinal cord sections with choline acetyltransferase as spinal motor neuron marker; and (iii) quantitative polymerase chain reaction analyses of lumbar motor neurons isolated via laser microdissection. We show that intracerebroventricular administration of cerebral dopamine neurotrophic factor significantly halts the progression of the disease and improves motor behaviour in TDP43-M337V and SOD1-G93A rodent models of amyotrophic lateral sclerosis. Cerebral dopamine neurotrophic factor rescues motor neurons in vitro and in vivo from endoplasmic reticulum stress-associated cell death and its beneficial effect is independent of genetic disease aetiology. Notably, cerebral dopamine neurotrophic factor regulates the unfolded protein response initiated by transducers IRE1α, PERK and ATF6, thereby enhancing motor neuron survival. Thus, cerebral dopamine neurotrophic factor holds great promise for the design of new rational treatments for amyotrophic lateral sclerosis.
| S-EPMC10473573 | biostudies-literature
Project description:Astrocytes have emerged for playing important roles in brain tissue repair; however, the underlying mechanisms remain poorly understood. We show that acute injury and blood-brain barrier disruption trigger the formation of a prominent mitochondrial-enriched compartment in astrocytic endfeet, which enables vascular remodeling. Integrated imaging approaches revealed that this mitochondrial clustering is part of an adaptive response regulated by fusion dynamics. Astrocyte-specific conditional deletion of Mitofusin 2 (Mfn2) suppressed perivascular mitochondrial clustering and disrupted mitochondria-endoplasmic reticulum (ER) contact sites. Functionally, two-photon imaging experiments showed that these structural changes were mirrored by impaired mitochondrial Ca2+ uptake leading to abnormal cytosolic transients within endfeet in vivo. At the tissue level, a compromised vascular complexity in the lesioned area was restored by boosting mitochondrial-ER perivascular tethering in MFN2-deficient astrocytes. These data unmask a crucial role for mitochondrial dynamics in coordinating astrocytic local domains and have important implications for repairing the injured brain.
| S-EPMC7139200 | biostudies-literature
Project description:SEPN1-related myopathy (SEPN1-RM) is a muscle disorder due to mutations of the SEPN1 gene, which is characterized by muscle weakness and fatigue leading to scoliosis and life-threatening respiratory failure. Core lesions, focal areas of mitochondria depletion in skeletal muscle fibers, are the most common histopathological lesion. SEPN1-RM underlying mechanisms and the precise role of SEPN1 in muscle remained incompletely understood, hindering the development of biomarkers and therapies for this untreatable disease. To investigate the pathophysiological pathways in SEPN1-RM, we performed metabolic studies, calcium and ATP measurements, super-resolution and electron microscopy on in vivo and in vitro models of SEPN1 deficiency as well as muscle biopsies from SEPN1-RM patients. Mouse models of SEPN1 deficiency showed marked alterations in mitochondrial physiology and energy metabolism, suggesting that SEPN1 controls mitochondrial bioenergetics. Moreover, we found that SEPN1 was enriched at the mitochondria-associated membranes (MAM), and was needed for calcium transients between ER and mitochondria, as well as for the integrity of ER-mitochondria contacts. Consistently, loss of SEPN1 in patients was associated with alterations in body composition which correlated with the severity of muscle weakness, and with impaired ER-mitochondria contacts and low ATP levels. Our results indicate a role of SEPN1 as a novel MAM protein involved in mitochondrial bioenergetics. They also identify a systemic bioenergetic component in SEPN1-RM and establish mitochondria as a novel therapeutic target. This role of SEPN1 contributes to explain the fatigue and core lesions in skeletal muscle as well as the body composition abnormalities identified as part of the SEPN1-RM phenotype. Finally, these results point out to an unrecognized interplay between mitochondrial bioenergetics and ER homeostasis in skeletal muscle. They could therefore pave the way to the identification of biomarkers and therapeutic drugs for SEPN1-RM and for other disorders in which muscle ER-mitochondria cross-talk are impaired.
| S-EPMC7853070 | biostudies-literature
Project description:Abnormal modifications to mutant superoxide dismutase 1 (SOD1) are linked to familial amyotrophic lateral sclerosis (fALS). Misfolding of wild-type SOD1 (SOD1WT) is also observed in postmortem tissue of a subset of sporadic ALS (sALS) cases, but cellular and molecular mechanisms generating abnormal SOD1WT species are unknown. We analyzed aberrant human SOD1WT species over the lifetime of transgenic mice and found the accumulation of disulfide-cross-linked high-molecular-weight SOD1WT aggregates during aging. Subcellular fractionation of spinal cord tissue and protein overexpression in NSC-34 motoneuron-like cells revealed that endoplasmic reticulum (ER) localization favors oxidation and disulfide-dependent aggregation of SOD1WT We established a pharmacological paradigm of chronic ER stress in vivo, which recapitulated SOD1WTaggregation in young transgenic mice. These species were soluble in nondenaturing detergents and did not react with a SOD1 conformation-specific antibody. Interestingly, SOD1WT aggregation under ER stress correlated with astrocyte activation in the spinal cord of transgenic mice. Finally, the disulfide-cross-linked SOD1WT species were also found augmented in spinal cord tissue of sALS patients, correlating with the presence of ER stress markers. Overall, this study suggests that ER stress increases the susceptibility of SOD1WT to aggregate during aging, operating as a possible risk factor for developing ALS.
| S-EPMC6094144 | biostudies-literature
Project description:While unbiased proteomics of human cerebrospinal fluid (CSF) has been used successfully to identify biomarkers of amyotrophic lateral sclerosis (ALS), high-abundance proteins mask the presence of lower abundance proteins that may have diagnostic and prognostic value. However, developments in mass spectrometry (MS) proteomic data acquisition methods offer improved protein depth. In this study, MS with library-free data-independent acquisition (DIA) was used to compare the CSF proteome of people with ALS (n = 40), healthy (n = 15) and disease (n = 8) controls. Quantified protein groups were subsequently correlated with clinical variables. Univariate analysis identified 7 proteins, all significantly upregulated in ALS versus healthy controls, and 9 with altered abundance in ALS versus disease controls (FDR < 0.1). Elevated chitotriosidase-1 (CHIT1) was common to both comparisons and was proportional to ALS disability progression rate (Pearson r = 0.41, FDR-adjusted p = 0.035) but not overall survival. Ubiquitin carboxyl-terminal hydrolase isozyme L1 (UCHL1; upregulated in ALS versus healthy controls) was proportional to disability progression rate (Pearson r = 0.53, FDR-adjusted p = 0.003) and survival (Kaplan Meier log-rank p = 0.013) but not independently in multivariate proportional hazards models. Weighted correlation network analysis was used to identify functionally relevant modules of proteins. One module, enriched for inflammatory functions, was associated with age at symptom onset (Pearson r = 0.58, FDR-adjusted p = 0.005) and survival (Hazard Ratio = 1.78, FDR = 0.065), and a second module, enriched for endoplasmic reticulum proteins, was negatively correlated with disability progression rate (r = -0.42, FDR-adjusted p = 0.109). DIA acquisition methodology therefore strengthened the biomarker candidacy of CHIT1 and UCHL1 in ALS, while additionally highlighted inflammatory and endoplasmic reticulum proteins as novel sources of prognostic biomarkers.
| S-EPMC10952667 | biostudies-literature
Project description:Mutations in Cu/Zn superoxide dismutase (SOD1) are one of the genetic causes of Amyotrophic Lateral Sclerosis (ALS). Although the primary symptom of ALS is muscle weakness, the link between SOD1 mutations, cellular dysfunction and muscle atrophy and weakness is not well understood. The purpose of this study was to characterize cellular markers of ER stress in skeletal muscle across the lifespan of G93A*SOD1 (ALS-Tg) mice. Muscles were obtained from ALS-Tg and age-matched wild type (WT) mice at 70d (pre-symptomatic), 90d and 120-140d (symptomatic) and analyzed for ER stress markers. In white gastrocnemius (WG) muscle, ER stress sensors PERK and IRE1α were upregulated ~2-fold at 70d and remained (PERK) or increased further (IRE1α) at 120-140d. Phospho-eIF2α, a downstream target of PERK and an inhibitor of protein translation, was increased by 70d and increased further to 12.9-fold at 120-140d. IRE1α upregulation leads to increased splicing of X-box binding protein 1 (XBP-1) to the XBP-1s isoform. XBP-1s transcript was increased at 90d and 120-140d indicating activation of IRE1α signaling. The ER chaperone/heat shock protein Grp78/BiP was upregulated 2-fold at 70d and 90d and increased to 6.1-fold by 120-140d. The ER-stress-specific apoptotic signaling protein CHOP was upregulated 2-fold at 70d and 90d and increased to 13.3-fold at 120-140d indicating progressive activation of an apoptotic signal in muscle. There was a greater increase in Grp78/BiP and CHOP in WG vs. the more oxidative red gastrocnemius (RG) ALS-Tg at 120-140d indicating greater ER stress and apoptosis in fast glycolytic muscle. These data show that the ER stress response is activated in skeletal muscle of ALS-Tg mice by an early pre-symptomatic age and increases with disease progression. These data suggest a mechanism by which myocellular ER stress leads to reduced protein translation and contributes to muscle atrophy and weakness in ALS.
| S-EPMC4435075 | biostudies-literature
Project description:This SuperSeries is composed of the following subset Series: GSE39642: NanoString nCounter immune-related gene expression in blood sorted CD14+CD16- monocytes from sALS, fALS and HC subjects GSE39643: NanoString miRNA profiling of peripheral blood sorted CD14+CD16- monocytes from amyotrophic lateral sclerosis, multiple sclerosis and healthy control subjects Refer to individual Series
2012-07-25 | E-GEOD-39644 | biostudies-arrayexpress
Project description:Amyotrophic lateral sclerosis is the most common form of motor neuron disease. Mutations in TARDBP, the gene encoding the RNA-binding protein TDP-43, are responsible for about 5% of familial ALS. Here we report the clinical and biological features of an ALS patients with pA382T mutation in TPD-43 protein. Disease began with right hand muscles weakness, and equally involved upper and lower motor neuron with a classic phenotype, without cognitive impairment. While a family history of neurological diseases was reported, there was no evidence of familial frontotemporal dementia. Cultured fibroblasts from the patient were characterized by profound alterations of cell proteome, which impacts particularly the mitochondrial metabolic pathways and the endoplasmic reticulum. TDP-43 levels were similar to control, healthy fibroblasts, but a higher fraction localized in mitochondria. Mitochondrial network appeared fragmented, and the organelles smaller and more spheric. In agreement with impaired proteome and morphology of mitochondria, basal cell respiration was reduced. Mitochondrial DNA levels appeared normal. However, a higher amount of mitochondrial DNA was present in the cytosol, suggesting a pronounced mitochondrial DNA misplacement which can promote a pro-inflammatory response mediating by cGAS/STING. Thus, this case report further expands the clinical and pathological phenotype of A382T mutation.
| S-EPMC9570187 | biostudies-literature