Metabolomics,Unknown,Transcriptomics,Genomics,Proteomics

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Transcription profiling of mouse HtrA2 knockout mice with a movement disorder (possible Parkinsons model) reveals mitochondrial dysfunction by loss of HtrA2 results in the activation of a brain-specific transcriptional stress response

ABSTRACT: Cellular stress responses can be activated following functional defects in organelles such as mitochondria and the endoplasmic reticulum. Mitochondrial dysfunction caused by loss of the serine protease HtrA2 leads to a progressive movement disorder in mice and has been linked to parkinsonian neurodegeneration in humans. Here we demonstrate that loss of HtrA2 results in transcriptional up-regulation of nuclear genes characteristic of the integrated stress response, including the transcription factor CHOP, selectively in the brain. We also show that loss of HtrA2 results in the accumulation of unfolded proteins in the mitochondria, defective mitochondrial respiration and enhanced production of reactive oxygen species that contribute to the induction of CHOP expression and to neuronal cell death. CHOP expression is also significantly increased in Parkinson’s disease patients’ brain tissue. We therefore propose that this brain-specific transcriptional response to stress may be important in the advance of neurodegenerative diseases. This SuperSeries is composed of the following subset Series:; GSE13033: Differentially expressed genes in brain tissue from HtrA2 knockout mice; GSE13034: Differentially regulated genes in HtrA2 knockout MEFs upon rotenone treatment Experiment Overall Design: Refer to individual Series

ORGANISM(S): Mus musculus

SUBMITTER: Kristina Klupsch

PROVIDER: E-GEOD-13035 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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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.

Dataset Information

Transcription profiling of mouse HtrA2 knockout mice with a movement disorder (possible Parkinsons model) reveals mitochondrial dysfunction by loss of HtrA2 results in the activation of a brain-specific transcriptional stress response

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