CHCHD2 harboring Parkinson’s disease-linked T61I mutation precipitates inside mitochondria and induces precipitation of wild-type CHCHD2

Abstract

The T61I mutation in coiled-coil-helix-coiled-coil-helix domain containing 2 (CHCHD2), a protein residing in the mitochondrial intermembrane space (IMS), causes an autosomal dominant form of Parkinson’s disease (PD), but the underlying pathogenic mechanisms are not well understood. Here, we compared the subcellular localization and solubility of wild-type (WT) and T61I mutant CHCHD2 in human cells. We found that mitochondrial targeting of both WT and T61I CHCHD2 depended on the four cysteine residues in the C-terminal coiled-coil-helix-coiled-coil-helix (CHCH) domain but not on the N-terminal predicted mitochondrial targeting sequence. The T61I mutation did not interfere with mitochondrial targeting of the mutant protein but induced its precipitation in the IMS. Moreover, T61I CHCHD2 induced increased mitochondrial production of reactive oxygen species and apoptosis, which was prevented by treatment with anti-oxidants. Retention of T61I CHCHD2 in the cytosol through mutation of the cysteine residues in the CHCH domain prevented its precipitation as well as its apoptosis-inducing effect. Importantly, T61I CHCHD2 potently impaired the solubility of WT CHCHD2. In conclusion, our data show that the T61I mutation renders mutant CHCHD2 insoluble inside mitochondria, suggesting loss of function of the mutant protein. In addition, T61I CHCHD2 exerts a dominant-negative effect on the solubility of WT CHCHD2, explaining the dominant inheritance of this form of PD.

Mitochondrial Dysfunction and Mitophagy in Parkinson’s Disease: From Mechanism to Therapy

“…Further analysis of this pathway has identified that CHCHD2 accumulates in damaged mitochondria and regulates CHCHD10 oligomerisation [60]. CHCHD2 has been shown to play a significant role in the maintenance of mitochondrial cristae [59] as well as stabilising OPA1 to promote mitochondrial fusion [61]. Mutations in CHCHD2 have been demonstrated to induce precipitation of both mutant and wild type (WT) protein in the intermembrane space (IMS) [61] as well as cytochrome C destabilization, impaired respiration, and mitochondrial ROS generation [62].…”

Lipopolysaccharide induces placental mitochondrial dysfunction by reducing MNRR1 levels via a TLR4-independent pathway

“…Depleted MNRR1 protein levels have been found in an in vivo model for juvenile Niemann Pick type C disease [82] and in vitro model for MELAS (Mitochondrial Encephalomyopathy Lactic Acidosis and Stroke-like episodes) syndrome [32]. Mutations in MNRR1 have been associated with a number of neurodegenerative diseases such as Parkinson's [83][84][85], Alzheimer's [86,87], and Charcot-Marie-Tooth disease type 1A [28]. Of note, MELAS, caused by a mtDNA mutation in the mitochondrial tRNA Leu(UUR) gene (m.3243A > G), has been associated with spontaneous preterm birth [88,89] and increased incidence of preeclampsia and gestational diabetes mellitus [88].…”

PARK Genes Link Mitochondrial Dysfunction and Alpha-Synuclein Pathology in Sporadic Parkinson’s Disease

“…α-Synuclein aggregation was accelerated by CHCHD2 T61I in human cells and in Drosophila. Human cells from T61I patients show accumulated CHCHD2 in the mitochondrial intermembrane space (IMS), resulting in increased ROS and apoptosis ( Cornelissen et al, 2020 ).…”