Project description:Coiled-helix coiled-helix domain containing protein 10 (CHCHD10) and its paralogue CHCHD2 belong to a family of twin CX9C motif proteins, most of which localize to the intermembrane space of mitochondria. Dominant mutations in CHCHD10 cause amyotrophic lateral sclerosis (ALS)/frontotemporal dementia, and mutations in CHCHD2 have been associated with Parkinson's disease, but the function of these proteins remains unknown. Here we show that the p.R15L CHCHD10 variant in ALS patient fibroblasts destabilizes the protein, leading to a defect in the assembly of Complex I, impaired cellular respiration, mitochondrial hyperfusion, an increase in the steady-state level of CHCHD2, and a severe proliferation defect on galactose, a substrate that forces cells to synthesize virtually all of their ATP aerobically. CHCHD10 and CHCHD2 appeared together in distinct foci by immunofluorescence analysis and could be quantitatively immunoprecipitated with antibodies against either protein. Blue native polyacrylamide gel electrophoresis analyses showed that both proteins migrated in a high molecular weight complex (220 kDa) in control cells, which was, however, absent in patient cells. CHCHD10 and CHCHD2 levels increased markedly in control cells in galactose medium, a response that was dampened in patient cells, and a new complex (40 kDa) appeared in both control and patient cells cultured in galactose. Re-entry of patient cells into the cell cycle, which occurred after prolonged culture in galactose, was associated with a marked increase in Complex I, and restoration of the oxygen consumption defect. Our results indicate that CHCHD10-CHCHD2 complexes are necessary for efficient mitochondrial respiration, and support a role for mitochondrial dysfunction in some patients with ALS.
Project description:CHCHD10 mutations are linked to amyotrophic lateral sclerosis, but their mode of action is unclear. In a 29-year-old patient with rapid disease progression, we discovered a novel mutation (Q108P) in a conserved residue within the coiled-coil-helix-coiled-coil-helix (CHCH) domain. The aggressive clinical phenotype prompted us to probe its pathogenicity. Unlike the wild-type protein, mitochondrial import of CHCHD10 Q108P was blocked nearly completely resulting in diffuse cytoplasmic localization and reduced stability. Other CHCHD10 variants reported in patients showed impaired mitochondrial import (C122R) or clustering within mitochondria (especially G66V and E127K) often associated with reduced expression. Truncation experiments suggest mitochondrial import of CHCHD10 is mediated by the CHCH domain rather than the proposed N-terminal mitochondrial targeting signal. Knockdown of Mia40, which introduces disulfide bonds into CHCH domain proteins, blocked mitochondrial import of CHCHD10. Overexpression of Mia40 rescued mitochondrial import of CHCHD10 Q108P by enhancing disulfide-bond formation. Since reduction in CHCHD10 inhibits respiration, mutations in its CHCH domain may cause aggressive disease by impairing mitochondrial import. Our data suggest Mia40 upregulation as a potential therapeutic salvage pathway.
Project description:Mutations in CHCHD10, coding for a mitochondrial intermembrane space protein, are a rare cause of autosomal dominant amyotrophic lateral sclerosis (ALS). Mutation-specific toxic gain of function or haploinsuffuciency models have been proposed to explain pathogenicity. To decipher the metabolic dysfunction associated with the haploinsufficient p.R15L variant we conducted a TMT labelling experiment. Fibroblasts with the CHCHD10 p.R15L variant (hereafter referred to as ‘patient’), were compared to the same cells expressing wild-type CHCHD10 cDNA (hereafter called ‘rescue’) under nutrient stress, in which galactose was substituted for glucose.
Project description:Salmonella causes a range of diseases in different hosts, including enterocolitis and systemic infection. Lysine acetylation regulates many eukaryotic cellular processes, but its function in prokaryotes is largely unknown. Reversible acetylation in Salmonella Typhimurium depends on acetyltransferase Pat and nicotinamide adenine dinucleotide (NAD+)-dependent deacetylase CobB. Here, we used cell and animal models to evaluate the virulence of pat and cobB deletion mutants in S. Typhimurium, and found that pat is essential for bacterial intestinal colonization, systemic infection and host inflammation response. Next, to understand the underlying mechanism, genome-wide transcriptome was analyzed. RNA-seq data showed the expression of Salmonella pathogenicity islands 1 (SPI-1) is partially dependent on pat. In addition, we found that HilD is a substrate of Pat, which is essential for maintaining HilD protein level. Taken together, these results suggested that protein acetylation system regulates SPI-1 expression by controlling HilD in a post-translational manner to mediate S. Typhimurium virulence. To use RNA-seq to analyze the transcriptome patterns of pat or cobB mutation in Salmonella Typhimurium 14028s.
Project description:We sought to compare changes in gene expression levels and pathway-level dysregulation between FUS-ALS, sporadic ALS, and healthy control patient derived fibroblasts. Gene expression profiling analysis were performed on bulk RNA-seq data obtained from 12 FUS, 11 sporadic, and 13 healthy control cell lines.
Project description:Salmonella causes a range of diseases in different hosts, including enterocolitis and systemic infection. Lysine acetylation regulates many eukaryotic cellular processes, but its function in prokaryotes is largely unknown. Reversible acetylation in Salmonella Typhimurium depends on acetyltransferase Pat and nicotinamide adenine dinucleotide (NAD+)-dependent deacetylase CobB. Here, we used cell and animal models to evaluate the virulence of pat and cobB deletion mutants in S. Typhimurium, and found that pat is essential for bacterial intestinal colonization, systemic infection and host inflammation response. Next, to understand the underlying mechanism, genome-wide transcriptome was analyzed. RNA-seq data showed the expression of Salmonella pathogenicity islands 1 (SPI-1) is partially dependent on pat. In addition, we found that HilD is a substrate of Pat, which is essential for maintaining HilD protein level. Taken together, these results suggested that protein acetylation system regulates SPI-1 expression by controlling HilD in a post-translational manner to mediate S. Typhimurium virulence.
Project description:Mutations in coiled-coil-helix-coiled-coil-helix domain containing 10 (CHCHD10), a mitochondrial protein of unknown function, cause a disease spectrum with clinical features of motor neuron disease, dementia, myopathy and cardiomyopathy. To investigate the pathogenic mechanisms of CHCHD10, we generated mutant knock-in mice harboring the mouse-equivalent of a disease-associated human S59L mutation, S55L in the endogenous mouse gene. CHCHD10S55L mice develop progressive motor deficits, myopathy, cardiomyopathy and accelerated mortality. Critically, CHCHD10 accumulates in aggregates with its paralog CHCHD2 specifically in affected tissues of CHCHD10S55L mice, leading to aberrant organelle morphology and function. Aggregates induce a potent mitochondrial integrated stress response (mtISR) through mTORC1 activation, with elevation of stress-induced transcription factors, secretion of myokines, upregulated serine and one-carbon metabolism, and downregulation of respiratory chain enzymes. Conversely, CHCHD10 ablation does not induce disease pathology or activate the mtISR, indicating that CHCHD10S55L-dependent disease pathology is not caused by loss-of-function. Overall, CHCHD10S55L mice recapitulate crucial aspects of human disease and reveal a novel toxic gain-of-function mechanism through maladaptive mtISR and metabolic dysregulation.
Project description:The purpose of this project is to identify the substrates that are specific for B'delta regulatory subunit. For this purpose, we have generated two doxycycline-inducible stable cell lines (OE and RE) that express B'delta. In the OE cell lines, B'delta is overexpressed without downregulation of the endogenous regulatory subunits. On the other hand, in the RE cell lines, B'delta is overexpressed concurrently with a downregulation of the endogenous regulatory subunits. To stimulate protein phosphorylation, we used isoproterenol, a beta-adrenergic agonist that is known to induce the PKA-mediated phosphorylation and activation of the B'd.
Project description:Mutations in coiled-coil-helix-coiled-coil-helix domain containing 10 (CHCHD10) have been identified in patients suffering from various degenerative diseases including mitochondrial myopathy, spinal muscular atrophy Jokela type, frontotemporal dementia, and/or amyotrophic lateral sclerosis (ALS). The pathogenic mechanism underlying CHCHD10-linked divergent disorders remains largely unknown. Here we show that transgenic mice overexpressing an ALS-linked CHCHD10 p.R15L mutation leads to an abbreviated lifespan compared with CHCHD10-WT transgenic mice. The occurrence and severity of the phenotype correlates to transgene copy number. Central nervous system (CNS), skeletal muscle, and cardiac pathology is apparent in CHCHD10-R15L transgenic mice. Despite the pathology, CHCHD10-R15L transgenic mice perform comparably to control mice in motor behavioral tasks until very close to death. Although paralysis is not observed, these models provide insight into the pleiotropic nature of CHCHD10 and suggest a contribution of CNS, skeletal muscle, and cardiac pathology to CHCHD10 p.R15L-ALS pathogenesis.