Project description:Mdivi-1, Mitochondrial DIVIsion inhibitor 1, has been widely employed in research under the assumption that it exclusively influences mitochondrial fusion, but effects other than mitochondrial dynamics have been underinvestigated. This paper provides transcriptome and DNA methylome-wide analysis for Mdivi-1 treated SH-SY5Y human neuroblastoma cells using RNA sequencing (RNA-seq) and methyl capture sequencing (MC-seq) methods. Gene ontology analysis of RNA sequences revealed that p53 transcriptional gene network and DNA replication initiation-related genes were significantly up and down-regulated, respectively, showing the correlation with the arrest cell cycle in the G1 phase. MC-seq, a powerful sequencing method for capturing DNA methylation status in CpG sites, revealed that although Mdivi-1 does not induce dramatic DNA methylation change, the subtle alterations were concentrated within the CpG island. Integrative analysis of both sequencing data disclosed that p53 transcriptional network was activated while Parkinson's disease pathway was halted. Next, we investigated several changes in mitochondria in response to Mdivi-1. Copy number and transcription of mitochondrial DNA were suppressed, while these results were not due to mitophagy. ROS and Ca2+ levels increased, and elevated ROS triggered mitochondrial retrograde signaling rather than inducing direct DNA damage. In this study, we could better understand the molecular network of Mdivi-1 by analyzing DNA methylation and mRNA transcription in the nucleus and further investigating various changes in mitochondria, providing inspiration for studying nuclear-mitochondrial communications.
Project description:Ectopic ATP synthase is a functional onco-protein increases cell proliferation when transported to plasma membrane of cancer cells. Our previous study performed large scale gene silencing screening indicated ER and mitochondrial transport pathways may lead to ectopic ATP synthase expression. Silencing dynamin-related protein 1 (Drp1), mitofusin-1 (Mfn1) and Parkin affected ectopic ATP synthases expression. However, the underlying trafficking mechanism is poorly understood. Here, we analyzed our membrane and mitochondrial proteome of lung cancer A549 cells and found that both nuclear-encoded ATP synthase subunits and mitochondrial-encoded components-ATP6 translocated to cell surface, indicating that ATP synthase subunits assembled in mitochondria. Furthermore, serum starvation enhanced ATP synthase translocation to plasma membrane, Mdivi-1, a chemical inhibitor of the mitochondrial fission protein Drp1, rescued the phenomena. Additionally, image quantification of mitochondria, showing that mitochondrial fission preference cells expressed more eATP synthase. Therefore, we proposed that eATP synthase trafficking may be related to mitochondrial dynamics. Additionally, ICC and flow cytometry revealed the expression of a critical transcription factor associated with high-risk neuroblastoma, MYCN, correlated with eATP synthase expression. To better understand whether MYCN mediated mitochondrial fission and affected ATP synthase trafficking, we first analyzed MYCN ChIP-sequencing data and found Drp1, Mfns and Parkin possessed the consensus DNA-binding motif of MYCN. Further high-resolution image analysis showed higher mitochondrial fission and eATP synthase expression in MYCN-amplified neuroblastoma. Last, silencing MYCN reduced the fission level by detecting DRP1. In summary, we suggest that trafficking of ectopic ATP synthase may via mitochondrial dynamics.
Project description:Here we aimed to investigate the function of mitochondrial fission genes in embryonic stem cells (ESCs). Homozygous knockout ESC lines, namely, Fis1-/- , Mff-/- , and Dnm1l-/- ESCs, were generated using the CRISPR-Cas9 system. After then, we analyzed whole genome expression profile for characterizing cellular responses by incomplete mitochondrial fission.
Project description:Fasting triggers diverse physiological adaptations including increases in circulating fatty acids and mitochondrial respiration to facilitate organismal survival. The mechanisms driving mitochondrial adaptations and respiratory sufficiency during fasting remain incompletely understood. Here we show that fasting or lipid availability stimulates mTORC2 activity. Activation of mTORC2 and phosphorylation of its downstream target NDRG1 at Ser336 sustains mitochondrial fission and respiratory sufficiency. Timelapse imaging shows that NDRG1, but not phosphorylation-deficient NDRG1Ser336Ala mutant, engages with mitochondria to facilitate fission in both control and Drp1-deficient cells, reflecting independency from Drp1. Using proteomics, an siRNA screen, and epistasis experiments, we show that mTORC2-phosphorylated NDRG1 cooperates with small GTPase Cdc42 and effectors and regulators of Cdc42 to orchestrate fission. Accordingly, RictorKO, NDRG1Ser336Ala mutants, and Cdc42-deficient cells each display mitochondrial phenotypes reminiscent of fission failure. During nutrient surplus, mTOR complexes perform anabolic functions; however, paradoxical reactivation of mTORC2 during fasting unexpectedly drives mitochondrial fission and respiration.
Project description:Well-balanced mitochondrial fission and fusion processes are essential for nervous system development. Loss of function of the main mitochondrial fission mediator, dynamin-related protein 1 (Drp1), is lethal early during embryonic development or around birth, but the role of mitochondrial fission in adult neurons remains unclear. Here we show that inducible Drp1 ablation in neurons of the adult mouse forebrain results in progressive, neuronal subtype-specific alterations of mitochondrial morphology in the hippocampus that are marginally responsive to antioxidant treatment. Furthermore, DRP1 loss affects synaptic transmission and memory function. Although these changes culminate in hippocampal atrophy, they are not sufficient to cause neuronal cell death within 10 weeks of genetic Drp1 ablation. Collectively, our in vivo observations clarify the role of mitochondrial fission in neurons, demonstrating that Drp1 ablation in adult forebrain neurons compromises critical neuronal functions without causing overt neurodegeneration.
Project description:Succinate dehydrogenase, which is known as mitochondrial complex II, has proven to be a fascinating machinery, attracting renewed and increased interest in its involvement in human diseases. Herein, we find that succinate dehydrogenase assembly factor 4 (SDHAF4) is downregulated in cardiac muscle in response to pathological stresses and in diseased hearts from human patients. Cardiac loss of Sdhaf4 suppresses complex II assembly and results in subunit degradation and complex II deficiency in fetal mice. These defects are exacerbated in young adults with globally impaired metabolic capacity and activation of dynamin-related protein 1, which induces excess mitochondrial fission and mitophagy, thereby causing progressive dilated cardiomyopathy and lethal heart failure in animals. Targeting mitochondria via supplementation with fumarate or inhibiting mitochondrial fission improves mitochondrial dynamics, partially restores cardiac function and prolongs the lifespan of mutant mice. Moreover, the addition of fumarate is found to dramatically improve cardiac function in myocardial infarction mice. These findings reveal a vital role for complex II assembly in the development of dilated cardiomyopathy and provide additional insights into therapeutic interventions for heart diseases.
Project description:Mitotic fission is increased in hyperproliferative, apoptosis-resistant diseases, such as pulmonary arterial hypertension (PAH). PAH’s fissogenic phenotype includes activation of the fission mediator, dynamin related protein 1 (Drp1), which must complex with its adaptor proteins to cause fission. Drp1-induced fission has been therapeutically targeted in experimental PAH. Here we examine the role of two recently discovered, poorly understood, Drp1 adapter proteins, mitochondrial dynamics protein of 49 and 51 kDa (MiD49 and MiD51) in normal vascular cells and explore the role of their dysregulation in the pathogenesis of PAH. MiDs are increased in PAH PASMC. This accelerates Drp1-mediated mitotic fission, which increases cell proliferation and decreases apoptosis. Silencing MiDs (but not Fis1 or MFF) promotes mitochondrial fusion and G1-phase cell cycle arrest through an ERK1/2 and CDK4-dependent mechanism. Augmenting MiDs in normal cells causes fission and recapitulates the PAH phenotype. MiD upregulation results from decreased microRNA-34a-3p (miR-34a-3p) expression. Circulatory miR34a-3p expression is decreased in PAH patients as well as in preclinical models of PAH. Silencing MiDs or augmenting miR-34a-3p regresses experimental PAH. We used microarrays to identify differences in miR expression in pulmonary artery smooth muscle cells (PASMC) taken from either pulmonary arterial hypertension patients or healthy controls
Project description:Excessive mitochondrial fission plays a key role in podocyte injury in diabetic kidney disease (DKD), and long noncoding RNAs (lncRNAs) are important in the development and progression of DKD. However, lncRNA regulation of mitochondrial fission in podocytes is poorly understood. Here, we want to identify how lncRNA changes in human podocytes cultured with high glucose.
Project description:Atherosclerosis (AS) is one of the most common diseases in middle-age and elderly population. Lipid metabolism disorder induced foaming of vascular smooth muscle cell (VSMC) is an important pathological process of AS. Mitochondria plays an important role in lipids metabolism. While it is not known whether regulating mitochondrial function can protect ox-LDL induced VSMC foaming via metabolic reprogramming. With ox-LDL induced mouse model of VSMC injury, the injury effect of ox-LDL and the protective effect of mdivi-1, the mitochondrial fission inhibitor on mitochondrial morphology and function of VSMC, and the formation of lipid droplet were observed. With metabonomics and proteomics techniques, the main lipid metabolites and regulation proteins were identified. The results showed that Ox-LDL induced a significant mitochondrial fission and fragmentation of VSMC, and mitochondrial function disorder along with lipid deposition and foaming. Mdivi-1 significantly antagonized the damage effect of ox-LDL on mitochondrial morphology and function of VSMC, and blocked the lipid deposition. Metabonomics analysis found 848 different metabolites between ox-LDL and mdivi-1 treatment group, in which the lipid metabolites were the main, and heptadecanoic acid, palmitoleic acid and myristic acid were the critical metabolites changed most. Proteomics results showed that there were 125 differential expressed proteins between ox-LDL and mdivi-1 treatment, acetyl -CoA carboxylase1 and fatty acid synthase were the main differential expressed proteins. This study suggest that Mitochondrial fission plays an important role in VSMC lipid deposition and foaming. Inhibition of mitochondrial fission may effectively fight against ox-LDL induced lipid deposition and foaming of VSMC via improving mitochondrial function and metabolic reprogramming. This finding provides a new insight for prevention and treatment of AS.