Effects of electroacupuncture on mitophagy mediated by SIRT3/PINK1/Parkin pathway in Parkinson's disease mice. / ç”µé’ˆå¯¹å¸•é‡‘æ£®ç— å°é¼ SIRT3/PINK1/Parkin通路介导的线粒体自噬的影响.

OBJECTIVES: To observe the effects of electroacupuncture (EA) at "Fengfu"(GV16), "Taichong"(LR3), and "Zusanli"(ST36) on mitophagy mediated by silencing regulatory protein 3 (SIRT3)/ PTEN induced putative kinase 1 (PINK1)/PARK2 gene coding protein (Parkin) in the midbrain substantia nigra of Parkinson's disease (PD) mice, and to explore the potential mechanisms of EA in treating PD. METHODS: C57BL/6 mice were randomly divided into the control, model, EA, and sham EA groups, with 12 mice in each group. The PD mouse model was established by intraperitoneal injection of 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP). The EA group received EA stimulation at GV16, LR3 and ST36, while the sham EA group received shallow needling 1 mm away from the above acupoints without electrical stimulation. The motor ability of mice in each group was evaluated using an open field experiment. Immunohistochemistry was used to detect the expression of tyrosine hydroxylase (TH) and α-synuclein (α-syn) in the substantia nigra of mice. The ultrastructure of neurons in substantia nigra was observed by transmission electron microscope (TEM). Immunofluorescence was used to detect the expression of the autophagy marker autophagy-associated protein light chain 3 (LC3). The expression levels of TH, α-syn, SIRT3, PINK1, Parkin, P62, Beclin-1, LC3Ⅱ mRNA and protein were detected by PCR and Western blot. RESULTS: Compared with the control group, mice in the model group showed a decrease in the total exercise distance, time, movement speed and times of crossing central region (P<0.01)；the positive expressions of TH and LC3 were decreased (P<0.01), while the positive expression of α-syn increased (P<0.01), accompanied by mitochondrial swelling, mitochondrial cristae fragmentation and decrease, and decreased lysosome count；the expression levels of TH, SIRT3, PINK1, Parkin, Beclin-1, and LC3Ⅱ mRNA and protein in the midbrain substantia nigra were decreased (P<0.01), while the expression levels of α-syn and P62 mRNA and protein were increased (P<0.01, P<0.05). Compared with the model group, the mice in EA group showed a significant increase in the total exercise distance, time, movement speed and times of crossing central region (P<0.01, P<0.05)；the positive expressions of TH and LC3 were increased (P<0.01, P<0.05), while the positive expression of α-syn was decreased (P<0.01), accompanied by an increase in mitochondrial count, appearance of autophagic va-cuoles, and a decrease in swelling, the expression levels of TH, SIRT3, PINK1, Parkin, Beclin-1 and LC3Ⅱ mRNA and protein in the midbrain substantia nigra were increased (P<0.01, P<0.05), while the mRNA and protein expression levels of α-syn and P62 were decreased (P<0.01)；the sham EA group showed an increase in the total exercise distance and time(P<0.05), with an increase in the positive expression of TH (P<0.05) and a decrease in the positive expression of α-syn (P<0.05)；some mitochondria exhibited swelling, and no autophagic vacuoles were observed；the protein expression levels of TH, SIRT3, Parkin and LC3Ⅱ were increased (P<0.01, P<0.05), and the expression levels of P62 mRNA, α-syn mRNA and protein were decreased (P<0.01, P<0.05), and LC3Ⅱ mRNA expression was increased (P<0.05). In comparison to the sham EA group, the EA group showed an extension in the total exercise time (P<0.01), the positive expression and mRNA expression levels of α-syn were decreased (P<0.01, P<0.05), while the expression levels of TH, SIRT3, PINK1, Parkin mRNA and SIRT3 protein were increased (P<0.05). CONCLUSIONS: EA at GV16, LR3, and ST36 can exert neuroprotective function and improve the motor ability of PD mice by activating the SIRT3/PINK1/Parkin pathway to enhance the expression of TH and reduce α-syn aggregation in the substantia nigra of PD mice.

Regulation of mitophagy and mitochondrial function: Natural compounds as potential therapeutic strategies for Parkinson's disease.

Mitochondrial damage is associated with the development of Parkinson's disease (PD), indicating that mitochondrial-targeted treatments could hold promise as disease-modifying approaches for PD. Notably, natural compounds have demonstrated the ability to modulate mitochondrial-related processes. In this review article, we discussed the possible neuroprotective mechanisms of natural compounds against PD in modulating mitophagy and mitochondrial function. A comprehensive literature search on natural compounds related to the treatment of PD by regulating mitophagy and mitochondrial function was conducted from PubMed, Web of Science and Chinese National Knowledge Infrastructure databases from their inception until April 2023. We summarize recent advancements in mitophagy's molecular mechanisms, including upstream and downstream processes, and its relationship with PD-related genes or proteins. Importantly, we highlight how natural compounds can therapeutically regulate various mitochondrial processes through multiple targets and pathways to alleviate oxidative stress, neuroinflammation, Lewy's body aggregation and apoptosis, which are key contributors to PD pathogenesis. Unlike the single-target strategy of modern medicine, natural compounds provide neuroprotection against PD by modulating various mitochondrial-related processes, including ameliorating mitophagy by targeting the PINK1/parkin pathway, the NIX/BNIP3 pathway, and autophagosome formation (i.e., LC3 and p62). Given the prevalence of mitochondrial damage in various neurodegenerative diseases, exploring the exact mechanism of natural compounds on mitophagy and mitochondrial dysfunction could shed light on the development of highly effective disease-modifying or adjuvant therapies targeting PD and other neurodegenerative disorders.

Fangji Huangqi decoction ameliorates membranous nephropathy through the upregulation of BNIP3-mediated mitophagy.

ETHNOPHARMACOLOGICAL RELEVANCE: Fangji Huangqi Decoction (FJHQ), a traditional Chinese medicinal formula outlined in Zhang Zhongjing's "Jin Gui Yao Lue" during the Han Dynasty, is often used to treat conditions characterized by symptoms like edema and dysuria, including membranous nephropathy (MN). Despite its proven clinical effectiveness, the exact mechanisms through which FJHQ acts on MN remain elusive. AIM OF THE STUDY: This study aimed to investigate whether FJHQ enhances BNIP3-mediated mitophagy in podocytes by promoting BNIP3 expression and whether this improvement leads to the amelioration of MN. MATERIALS AND METHODS: In this study, by establishing passive Heymann nephritis (PHN) rats, an experimental rat model of MN induced by sheep anti-rat Fx1A serum, we evaluated the effects of FJHQ in vivo. In vitro experiments were carried out by treating primary podocytes with experimental rat serum. Furthermore, the potential mechanism by which FJHQ acts through BNIP3 was further examined by transfecting primary podocytes with the siRNA of BNIP3 or the corresponding control vector. RESULTS: After 4 weeks, significant kidney damage was observed in the rats in the model group, comparatively, FJHQ markedly decreased urine volume, 24-h urinary protein, blood urea nitrogen (BUN), creatinine (Scr), and increased serum total albumin (ALB). Histology showed that FJHQ caused significant improvements in glomerular hyperplasia, and IgG immune complex deposition in MN rats. JC-1 fluorescence labelling and flow cytometry analysis showed that FJHQ could significantly increase mitochondrial membrane potential in vivo. In the mitochondria of MN model rats, FJHQ was able to down-regulate the expression of P62 and up-regulate the expression of BNIP3, LC3B, and LC3 II/LC3 I, according to Western blot and immunofluorescence studies. Furthermore, FJHQ has been shown to significantly up-regulate mitochondrial membrane potential, down-regulate P62 expression in mitochondria, and up-regulate the expression of BNIP3, LC3B, and LC3 II/LC3 I in mitochondria at the cellular level. After the administration of the autophagy inhibitor chloroquine, the serum of rats treated with FJHQ further increased the expression of LC3 II/LC3 I in primary podocytes, showing higher autophagy flow. After the interference of BNIP3 in podocytes, the effect of FJHQ on mitochondrial membrane potential and autophagy-related proteins almost disappeared. CONCLUSION: FJHQ enhanced mitophagy in podocytes by promoting the expression of BNIP3, thereby contributing to the amelioration of MN. This work reveals the possible underlying mechanism by which FJHQ improves MN and provides a new avenue for MN treatment.

[Effect of acupotomy on mitophagy mediated by PINK1/Parkin pathway in cartilage of rabbits with knee osteoarthritis].

OBJECTIVE: To observe the effect of acupotomy on mitophagy mediated by PINK1/Parkin pathway in cartilage of rabbits with knee osteoarthritis (KOA), so as to explore its mechanism in inhibiting cartilage damage. METHODS: Twenty-one New Zealand rabbits were randomly divided into normal, model, and acupotomy groups, with 7 rabbits in each group. The KOA rabbit model was established by using the Videman method. Rabbits in the acupotomy group received regular acupotomy treatment around the knee joint nodules or tendons once a week for 3 consecutive weeks. HE staining and transmission electron microscopy were used to observe the morphological and ultrastructural changes in knee joint cartilage of rabbits. Flow cytometry was used to measure the mitochondrial membrane potential (Δψm) and reactive oxygen species (ROS) average fluorescence intensity in chondrocytes. Immunofluorescence was performed to detect the fluorescence intensity of LC3B, PINK1 and Parkin in cartilage tissue. Western blot was conducted to measure the protein expression levels of p62, LC3Ⅱ/Ⅰ, PINK1, and Parkin in cartilage tissue. RESULTS: Compared to the normal group, the model group showed fissures and tissue fibrosis on the surface of rabbit knee joint cartilages, loose distribution of chondrocytes, decreased autophagosomes, and abnormal mitochondrial morphology. The fluorescence intensity of LC3B, PINK1 and Parkin, the expression levels of LC3Ⅱ/Ⅰ, PINK1 and Parkin proteins in cartilage tissue were significantly decreased (P<0.01), while the percentage of chondrocytes with low Δψm, the average fluorescence intensity of ROS, and the expression of p62 protein in cartilage tissue were significantly increased (P<0.01). Compared to the model group, the acupotomy group showed no obvious defects on the surface of rabbit knee joint cartilage, relatively dense distribution of chondrocytes, increased autophagosomes, and relatively normal mitochondrial morphology. The fluorescence intensity of LC3B, PINK1 and Parkin, the expression of LC3Ⅱ/Ⅰ, PINK1 and Parkin proteins in cartilage tissue were significantly increased (P<0.01, P<0.05), while the percentage of chondrocytes with low Δψm, the average fluorescence intensity of ROS, and the expression of p62 protein in cartilage tissue were significantly decreased (P<0.01). CONCLUSION: Acupotomy may promote mitophagy by regulating the PINK1/Parkin pathway, thereby improving cartilage damage in rabbits with KOA.

Role of Mitophagy in Myocardial Ischemia/Reperfusion Injury and Chinese Medicine Treatment.

Mitophagy is one of the important targets for the prevention and treatment of myocardial ischemia/reperfusion injury (MIRI). Moderate mitophagy can remove damaged mitochondria, inhibit excessive reactive oxygen species accumulation, and protect mitochondria from damage. However, excessive enhancement of mitophagy greatly reduces adenosine triphosphate production and energy supply for cell survival, and aggravates cell death. How dysfunctional mitochondria are selectively recognized and engulfed is related to the interaction of adaptors on the mitochondrial membrane, which mainly include phosphatase and tensin homolog deleted on chromosome ten (PTEN)-induced kinase 1/Parkin, hypoxia-inducible factor-1 α/Bcl-2 and adenovirus e1b19k Da interacting protein 3, FUN-14 domain containing protein 1 receptor-mediated mitophagy pathway and so on. In this review, the authors briefly summarize the main pathways currently studied on mitophagy and the relationship between mitophagy and MIRI, and incorporate and analyze research data on prevention and treatment of MIRI with Chinese medicine, thereby provide relevant theoretical basis and treatment ideas for clinical prevention of MIRI.

GlyNAC (Glycine and N-Acetylcysteine) Supplementation in Mice Increases Length of Life by Correcting Glutathione Deficiency, Oxidative Stress, Mitochondrial Dysfunction, Abnormalities in Mitophagy and Nutrient Sensing, and Genomic Damage.

Determinants of length of life are not well understood, and therefore increasing lifespan is a challenge. Cardinal theories of aging suggest that oxidative stress (OxS) and mitochondrial dysfunction contribute to the aging process, but it is unclear if they could also impact lifespan. Glutathione (GSH), the most abundant intracellular antioxidant, protects cells from OxS and is necessary for maintaining mitochondrial health, but GSH levels decline with aging. Based on published human studies where we found that supplementing glycine and N-acetylcysteine (GlyNAC) improved/corrected GSH deficiency, OxS and mitochondrial dysfunction, we hypothesized that GlyNAC supplementation could increase longevity. We tested our hypothesis by evaluating the effect of supplementing GlyNAC vs. placebo in C57BL/6J mice on (a) length of life; and (b) age-associated GSH deficiency, OxS, mitochondrial dysfunction, abnormal mitophagy and nutrient-sensing, and genomic-damage in the heart, liver and kidneys. Results showed that mice receiving GlyNAC supplementation (1) lived 24% longer than control mice; (2) improved/corrected impaired GSH synthesis, GSH deficiency, OxS, mitochondrial dysfunction, abnormal mitophagy and nutrient-sensing, and genomic-damage. These studies provide proof-of-concept that GlyNAC supplementation can increase lifespan and improve multiple age-associated defects. GlyNAC could be a novel and simple nutritional supplement to improve lifespan and healthspan, and warrants additional investigation.

CDK9 inhibition blocks the initiation of PINK1-PRKN-mediated mitophagy by regulating the SIRT1-FOXO3-BNIP3 axis and enhances the therapeutic effects involving mitochondrial dysfunction in hepatocellular carcinoma.

Mitophagy is a type of selective macroautophagy/autophagy that degrades dysfunctional or excessive mitochondria. Regulation of this process is critical for maintaining cellular homeostasis and has been closely implicated in acquired drug resistance. However, the regulatory mechanisms and influences of mitophagy in cancer are still unclear. Here, we reported that inhibition of CDK9 blocked PINK1-PRKN-mediated mitophagy in HCC (hepatocellular carcinoma) by interrupting mitophagy initiation. We demonstrated that CDK9 inhibitors promoted dephosphorylation of SIRT1 and promoted FOXO3 protein degradation, which was regulated by its acetylation, leading to the transcriptional repression of FOXO3-driven BNIP3 and impairing the BNIP3-mediated stability of the PINK1 protein. Lysosomal degradation inhibitors could not rescue mitophagy flux blocked by CDK9 inhibitors. Thus, CDK9 inhibitors inactivated the SIRT1-FOXO3-BNIP3 axis and PINK1-PRKN pathway to subsequently block mitophagy initiation. Moreover, CDK9 inhibitors facilitated mitochondrial dysfunction. The dual effects of CDK9 inhibitors resulted in the destruction of mitochondrial homeostasis and cell death in HCC. Importantly, a novel CDK9 inhibitor, oroxylin A (OA), from Scutellaria baicalensis was investigated, and it showed strong therapeutic potential against HCC and a striking capacity to overcome drug resistance by downregulating PINK1-PRKN-mediated mitophagy. Additionally, because of the moderate and controlled inhibition of CDK9, OA not led to extreme repression of general transcription and appeared to overcome the inconsistent anti-HCC efficacy and high normal tissue toxicity that was associated with existing CDK9 inhibitors. All of the findings reveal that mitophagy disruption is a promising strategy for HCC treatment and OA is a potential candidate for the development of mitophagy inhibitors.Abbreviations: BNIP3: BCL2 interacting protein 3; CCCP: carbonyl cyanide p-trichloromethoxy-phenylhydrazone; CDK9: cyclin dependent kinase 9; CHX: cycloheximide; CQ, chloroquine; DFP: deferiprone; DOX: doxorubicin; EBSS: Earle's balanced salt solution; E64d: aloxistatin; FOXO3: forkhead box O3; HCC: hepatocellular carcinoma; HepG2/ADR: adriamycin-resistant HepG2 cells; MMP: mitochondrial membrane potential; mito-Keima: mitochondria-targeted and pH-sensitive fluorescent protein; MitoSOX: mitochondrial reactive oxygen species; OA: oroxylin A; PB: phosphate buffer; PDX: patient-derived tumor xenograft; PINK1: PTEN induced kinase 1; POLR2A: RNA polymerase II subunit A; p-POLR2A-S2: Ser2 phosphorylation of RNA polymerase II subunit A; PRKN: parkin RBR E3 ubiquitin protein ligase; SIRT1: sirtuin 1.

[Rosmarinic acid bolsters antibacterial immunity activity of macrophages by up-regulating PINK1/Parkin-mediated mitophagy].

This study aims to explore the molecular mechanism through which rosmarinic acid up-regulates mitophagy and enhances antibacterial immunity activity of macrophages. To be specific, RAW264.7 macrophages were treated with rosmarinic acid and then infected with Staphylococcus aureus. The total mRNA and proteins of the cells were then extracted. The mRNA and protein levels of phosphatase and tensin homolog(PTEN)-induced putative kinase 1(PINK1) were detected by q-PCR and Western blot, respectively. Cell mitochondria isolation kit was employed to isolate mitochondria in macrophages. Recruitment of E3 ubiquitin ligase Parkin to mitochondria and the phosphorylation of Parkin were detected by Western blot. Co-immunoprecipitation and laser confocal microscopy were employed to observe the co-localization of PINK1 and Parkin. Mitochondrial division inhibitor 1(Mdivi-1), small interfering RNA(siRNA)-directed gene knockdown, and plate-colony counting were used to detect the levels of inflammatory cytokines and the intracellular antibacterial ability, in an attempt to confirm that rosmarinic acid promotes antibacterial immunity activity of macrophages through strengthening PINK1/Parkin-mediated mitophagy. The results showed that rosmarinic acid up-regulated the mRNA and protein expression of PINK1, promoted the recruitment of Parkin from cytoplasm to mitochondria and the phosphorylation, and enhanced the interaction between PINK1 and Parkin and their co-localization in macrophages. Blocking mitophagy or knocking PINK1 significantly abrogated the promotion of macrophage antibacterial immune response by rosmarinic acid. In summary, rosmarinic acid enhances antibacterial immunity activity of macrophages through up-regulating PINK1/Parkin-mediated mitophagy.

Nujiangexanthone A Inhibits Cervical Cancer Cell Proliferation by Promoting Mitophagy.

Nujiangexanthone A (NJXA), a bioactive component isolated from the leaves of Garcinia nujiangensis, has been reported to exhibit anti-inflammatory, antioxidant, and antitumor effects. Our previous work has shown that NJXA induced G0/1 arrest and apoptosis, thus suppressing cervical cancer cell growth. The present study provides new evidence that NJXA can induce cell death in HeLa cells by promoting mitophagy. We first identified that NJXA triggered GFP-LC3 and YFP-Parkin puncta accumulation, which are biomarkers of mitophagy. Moreover, NJXA degraded the mitochondrial membrane proteins Tom20 and Tim23 and mitochondrial fusion proteins MFN1 and MFN2, downregulated Parkin, and stabilized PINK1. Additionally, we revealed that NJXA induced lysosome degradation and colocalization of mitochondria and autophagosomes, which was attenuated by knocking down ATG7, the key regulator of mitophagy. Furthermore, since mitophagy is induced under starvation conditions, we detected the cytotoxic effect of NJXA in nutrient-deprived HeLa cells and observed better cytotoxicity. Taken together, our work contributes to the further clarification of the mechanism by which NJXA inhibits cervical cancer cell proliferation and provides evidence that NJXA has the potential to develop anticancer drugs.

Transcription- and phosphorylation-dependent control of a functional interplay between XBP1s and PINK1 governs mitophagy and potentially impacts Parkinson disease pathophysiology.

Parkinson disease (PD)-affected brains show consistent endoplasmic reticulum (ER) stress and mitophagic dysfunctions. The mechanisms underlying these perturbations and how they are directly linked remain a matter of questions. XBP1 is a transcription factor activated upon ER stress after unconventional splicing by the nuclease ERN1/IREα thereby yielding XBP1s, whereas PINK1 is a kinase considered as the sensor of mitochondrial physiology and a master gatekeeper of mitophagy process. We showed that XBP1s transactivates PINK1 in human cells, primary cultured neurons and mice brain, and triggered a pro-mitophagic phenotype that was fully dependent of endogenous PINK1. We also unraveled a PINK1-dependent phosphorylation of XBP1s that conditioned its nuclear localization and thereby, governed its transcriptional activity. PINK1-induced XBP1s phosphorylation occurred at residues reminiscent of, and correlated to, those phosphorylated in substantia nigra of sporadic PD-affected brains. Overall, our study delineated a functional loop between XBP1s and PINK1 governing mitophagy that was disrupted in PD condition.Abbreviations: 6OHDA: 6-hydroxydopamine; baf: bafilomycin A1; BECN1: beclin 1; CALCOCO2/NDP52: calcium binding and coiled-coil domain 2; CASP3: caspase 3; CCCP: carbonyl cyanide chlorophenylhydrazone; COX8A: cytochrome c oxidase subunit 8A; DDIT3/CHOP: DNA damage inducible transcript 3; EGFP: enhanced green fluorescent protein; ER: endoplasmic reticulum; ERN1/IRE1α: endoplasmic reticulum to nucleus signaling 1; FACS: fluorescence-activated cell sorting; HSPD1/HSP60: heat shock protein family D (Hsp60) member 1; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MFN2: mitofusin 2; OPTN: optineurin; PD: Parkinson disease; PINK1: PTEN-induced kinase 1; PCR: polymerase chain reaction:; PRKN: parkin RBR E3 ubiquitin protein ligase; XBP1s [p-S61A]: XBP1s phosphorylated at serine 61; XBP1s [p-T48A]: XBP1s phosphorylated at threonine 48; shRNA: short hairpin RNA, SQSTM1/p62: sequestosome 1; TIMM23: translocase of inner mitochondrial membrane 23; TM: tunicamycin; TMRM: tetramethyl rhodamine methylester; TOMM20: translocase of outer mitochondrial membrane 20; Toy: toyocamycin; TP: thapsigargin; UB: ubiquitin; UB (S65): ubiquitin phosphorylated at serine 65; UPR: unfolded protein response, XBP1: X-box binding protein 1; XBP1s: spliced X-box binding protein 1.

NAD+ supplementation prevents STING-induced senescence in ataxia telangiectasia by improving mitophagy.

Senescence phenotypes and mitochondrial dysfunction are implicated in aging and in premature aging diseases, including ataxia telangiectasia (A-T). Loss of mitochondrial function can drive age-related decline in the brain, but little is known about whether improving mitochondrial homeostasis alleviates senescence phenotypes. We demonstrate here that mitochondrial dysfunction and cellular senescence with a senescence-associated secretory phenotype (SASP) occur in A-T patient fibroblasts, and in ATM-deficient cells and mice. Senescence is mediated by stimulator of interferon genes (STING) and involves ectopic cytoplasmic DNA. We further show that boosting intracellular NAD+ levels with nicotinamide riboside (NR) prevents senescence and SASP by promoting mitophagy in a PINK1-dependent manner. NR treatment also prevents neurodegeneration, suppresses senescence and neuroinflammation, and improves motor function in Atm-/- mice. Our findings suggest a central role for mitochondrial dysfunction-induced senescence in A-T pathogenesis, and that enhancing mitophagy as a potential therapeutic intervention.

Scutellarin ameliorates high glucose-induced vascular endothelial cells injury by activating PINK1/Parkin-mediated mitophagy.

ETHNOPHARMACOLOGICAL RELEVANCE: Scutellarin (Scu) is one of the main active ingredients of Erigeron breviscapus (Vant.) Hand.-Mazz which has been used to treat cardiovascular disease including vascular dysfunction caused by diabetes. Scu also has a protective effect on vascular endothelial cells against hyperglycemia. However, molecular mechanisms underlying this effect are not clear. AIM OF THE STUDY: This aim of this study was to investigate the effect of Scu on human umbilical vein endothelial cells (HUVECs) injury induced by high glucose (HG), especially the regulation of PTEN-induced kinase 1 (PINK1)/Parkin-mediated mitophagy. MATERIALS AND METHODS: HUVECs were exposed to HG to induce vascular endothelial cells injury in vitro. Cell viability was assessed by MTT assay. The extent of cell apoptosis was measured by Hoechst staining and flow cytometry. Mitophagy was assayed by fluorescent immunostaining, transmission electron microscope and immunoblot. Besides, virtual docking was conducted to validate the interaction of PINK1 protein and Scu. RESULTS: We found that Scu significantly increased cell viability in HG-treated HUVECs. Scu reduces the expression of Bcl-2, Bax and cytochrome C (Cyt.c) to inhibit apoptosis through a mitochondria-dependent pathway. Meanwhile, Scu improved the overload of reactive oxygen species (ROS), superoxide dismutase (SOD) activity and SOD2 protein expression, and reversed the collapse of mitochondrial membrane potential. Besides, Scu increased autophagic flux, improved the expression of microtubule-associated protein 1 light chain 3 Ⅱ (LC3 II), Beclin 1 and autophagy-related gene 5 (Atg 5) and decreased the expression of Sequestosome1/P62 in HG-treated HUVECs. Furthermore, Scu improved the expressions of PINK1, Parkin, and Mitofusin2, which revealed the enhancement of mitophagy. Moreover, the beneficial effects of Scu on HG-induced low expression of Parkin, overproduction of ROS, and over expressions of P62, Cyt.c and Cleaved caspase-3 were weakened by PINK1 gene knockdown. Molecular docking suggested good interaction of Scu and PINK1 protein. CONCLUSION: These results suggest that Scu may protect vascular endothelial cells against hyperglycemia-induced injury by up-regulating mitophagy via PINK1/Parkin signal pathway.

Induction of Autophagy by Vasicinone Protects Neural Cells from Mitochondrial Dysfunction and Attenuates Paraquat-Mediated Parkinson's Disease Associated α-Synuclein Levels.

Mitochondrial dysfunction and disturbed mitochondrial dynamics were found to be common phenomena in the pathogenesis of Parkinson's disease (PD). Vasicinone is a quinazoline alkaloid from Adhatoda vasica. Here, we investigated the autophagy/mitophagy-enhancing effect of vasicinone and explored its neuroprotective mechanism in paraquat-mimic PD modal in SH-SY5Y cells. Vasicinone rescued the paraquat-induced loss of cell viability and mitochondrial membrane potential. Subsequently, the accumulation of mitochondrial reactive oxygen species (ROS) was balanced by an increase in the expression of antioxidant enzymes. Furthermore, vasicinone restored paraquat-impaired autophagy and mitophagy regulators DJ-1, PINK-1 and Parkin in SH-SY5Y cells. The vasicinone mediated autophagy pathways were abrogated by treatment with the autophagy inhibitor 3-MA, which lead to increases α-synuclein accumulation and decreased the expression of p-ULK and ATG proteins and the autophagy marker LC3-II compared to that observed without 3-MA treatment. These results demonstrated that vasicinone exerted neuroprotective effects by upregulating autophagy and PINK-1/Parkin mediated mitophagy in SH-SY5Y cells.

Parkin-mediated mitophagy and autophagy flux disruption in cellular models of MERRF syndrome.

Mitochondrial diseases are considered rare genetic disorders characterized by defects in oxidative phosphorylation (OXPHOS). They can be provoked by mutations in nuclear DNA (nDNA) or mitochondrial DNA (mtDNA). MERRF (Myoclonic Epilepsy with Ragged-Red Fibers) syndrome is one of the most frequent mitochondrial diseases, principally caused by the m.8344A>G mutation in mtDNA, which affects the translation of all mtDNA-encoded proteins and therefore impairs mitochondrial function. In the present work, we evaluated autophagy and mitophagy flux in transmitochondrial cybrids and fibroblasts derived from a MERRF patient, reporting that Parkin-mediated mitophagy is increased in MERRF cell cultures. Our results suggest that supplementation with coenzyme Q10 (CoQ), a component of the electron transport chain (ETC) and lipid antioxidant, prevents Parkin translocation to the mitochondria. In addition, CoQ acts as an enhancer of autophagy and mitophagy flux, which partially improves cell pathophysiology. The significance of Parkin-mediated mitophagy in cell survival was evaluated by silencing the expression of Parkin in MERRF cybrids. Our results show that mitophagy acts as a cell survival mechanism in mutant cells. To confirm these results in one of the main affected cell types in MERRF syndrome, mutant induced neurons (iNs) were generated by direct reprogramming of patients-derived skin fibroblasts. The treatment of MERRF iNs with Guttaquinon CoQ10 (GuttaQ), a water-soluble derivative of CoQ, revealed a significant improvement in cell bioenergetics. These results indicate that iNs, along with fibroblasts and cybrids, can be utilized as reliable cellular models to shed light on disease pathomechanisms as well as for drug screening.

Progress in the genetic analysis of Parkinson's disease.

The pace of genetic discovery in complex disease has accelerated exponentially over the last decade. Our fund of knowledge of the foundational genetics in disease has never been as great. There is a clear path forward to the resolution of the genetic architecture toward a point at which we will saturate the biological understanding of disease through genetics. This understanding continues to provide fundamental insights into disease biology and, with the advent of new data and methodologies, the path from gene to function is becoming clearer and cleaner. In this opinion piece, we discuss progress in the genetics of Parkinson disease. We explore what genetics has revealed thus far in the context of disease biology. We highlight mitophagy/autophagy, dopamine metabolism and the adaptive immune system. We try and link these findings together to give a holistic view of pathogenesis with the underlying theme that disease pathogenesis relates to a failure of damage response pathways. In the 1990s, Parkinson's disease was regarded a non-genetic disorder. Since that time, however, a huge number of Mendelian loci and risk loci have been identified by positional cloning and by genome-wide association studies. In this review, it is not our intent to list each gene and locus and review their identification [Hernandez, D.G., Reed, X. and Singleton, A.B. (2016) Genetics in Parkinson disease: Mendelian versus non-Mendelian inheritance. J. Neurochem., 139 Suppl 1, 59-74] but rather to outline the pathogenetic mechanisms that these analyses are revealing and then, given the large number of loci already identified, to lay out what we hope future analyses may help us understand, both in terms of disease mechanisms and for risk prediction for the syndrome.

Akebia saponin D alleviates hepatic steatosis through BNip3 induced mitophagy.

Akebia Saponin D (ASD) is the most abundant constituent of the rhizome of Dipsacus asper Wall. The prior studies have shown that ASD alleviates hepatic steatosis targeted at the modulation of autophagy and exerts hepatoprotective effects through mitochondria. However, it is still unclear which signal transduction pathway that ASD increase autophagy and protect the mitochondria. The purpose of this paper was to explore the mechanisms through which ASD alleviates hepatic steatosis. ASD significantly reduced lipid accumulation in BRL cells. Furthermore, ASD significantly increased the mitophagy acting as increase the colocalization between mitochondria and punctate EGFP-LC3. ASD treatment increased the expression of BNip3, phospho-AMPK, prevented oleic acid (OA) induced LC3-II and phospho-mTOR expression. These effects were similar to the effects cotreatment with rapamycin. ASD treatment could not attenuate the expression of BNip3 blocked by chloroquine (CQ) or siRNA-mediated knockdown of BNip3. These results suggest that Akebia saponin D alleviates hepatic steatosis targeted at BNip3 mediated mitophagy. Activation of BNip3 via ASD may offer a new strategy for treating NAFLD.

Acute mental stress induces mitochondrial bioenergetic crisis and hyper-fission along with aberrant mitophagy in the gut mucosa in rodent model of stress-related mucosal disease.

Psychological stress, depression and anxiety lead to multiple organ dysfunctions wherein stress-related mucosal disease (SRMD) is common to people experiencing stress and also occur as a side effect in patients admitted to intensive care units; however the underlying molecular aetiology is still obscure. We report that in rat-SRMD model, cold restraint-stress severely damaged gut mitochondrial functions to generate superoxide anion (O2•-), depleted ATP and shifted mitochondrial fission-fusion dynamics towards enhanced fission to induce mucosal injury. Activation of mitophagy to clear damaged and fragmented mitochondria was evident from mitochondrial translocation of Parkin and PINK1 along with enhanced mitochondrial proteome ubiquitination, depletion of mitochondrial DNA copy number and TOM 20. However, excess and sustained accumulation of O2•--generating defective mitochondria overpowered the mitophagic machinery, ultimately triggering Bax-dependent apoptosis and NF-κB-intervened pro-inflammatory mucosal injury. We further observed that stress-induced enhanced serum corticosterone stimulated mitochondrial recruitment of glucocorticoid receptor (GR), which contributed to gut mitochondrial dysfunctions as documented from reduced ETC complex 1 activity, mitochondrial O2•- accumulation, depolarization and hyper-fission. GR-antagonism by RU486 or specific scavenging of mitochondrial O2•- by a mitochondrially targeted antioxidant mitoTEMPO ameliorated stress-induced mucosal damage. Gut mitopathology and mucosal injury were also averted when the perception of mental stress was blocked by pre-treatment with a sedative or antipsychotic. Altogether, we suggest the role of mitochondrial GR-O2•--fission cohort in brain-mitochondria cross-talk during acute mental stress and advocate the utilization of this pathway as a potential target to prevent mitochondrial unrest and gastropathy bypassing central nervous system.

Elimination of dysfunctional mitochondria through mitophagy suppresses benzo[a]pyrene-induced apoptosis.

Mitophagy, a special type of autophagy, plays an important role in the mitochondria quality control and cellular homeostasis. In this study, we examined the molecular mechanism of mitophagy induction with benzo[a]pyrene (B[a]P), a ubiquitous polycyclic aromatic hydrocarbon, which acts as a prosurvival response against apoptotic cell death. Our study showed that B[a]P displayed higher cytotoxicity in autophagy-deficient HaCaT cells as compared to control. Further, we showed that B[a]P triggered the Beclin-1-dependent autophagy through the mammalian target of rapamycin (mTOR)/AMP-activated protein kinase (AMPK) pathway. Moreover, our study indicated that the B[a]P-induced autophagy was initiated through the activation of cytochrome P450 1B1 (CYP1B1) and the aryl hydrocarbon receptor (AhR) in HaCaT cells. Intriguingly, the B[a]P-induced Beclin-1-mediated mitophagy was suppressed in CYP1B1 and AhR knockdown HaCaT cells, indicating a crucial role of B[a]P activation in the mitophagy induction to regulate cell death. B[a]P was shown to increase the mitochondrial dysfunction and decrease the mitochondrial membrane potential, resulting in depletion of ATP level along with the inhibition of the oxygen consumption rate in HaCaT cells. Importantly, the supplementation of methyl pyruvate compensated for the B[a]P-induced drop in the ATP level and mitigated the reactive oxygen species burden and autophagy. Mechanistically, B[a]P inhibited the manganese superoxide dismutase (MnSOD) activity and we found that the activated mitochondrial CYP1B1 interacted with MnSOD, inflicting mitophagy to protect from B[a]P-induced apoptosis. In summary, our study reveals mitophagy induction as a cellular protection mechanism against B[a]P-triggered toxicity and carcinogenesis.

Involvement of PINK1/Parkin-mediated mitophagy in AGE-induced cardiomyocyte aging.

CONTEXT AND OBJECTIVES: Advanced glycation end products (AGEs) can induce senescence in cardiomyocytes. However, its underlying molecular mechanisms remain unknown. METHODS: Neonatal rat cardiomyocytes were incubated with AGEs, and cellular senescence was evaluated by senescence-associated beta-galactosidase (SA-ß-gal) activity and aging-associated p16 expression. In addition, mitophagic activity was evaluated by measuring the expression of the PINK1, Parkin, LC3 and p62 proteins. The mitophagy inhibitor cyclosporine A (CsA) or PINK1 siRNAs was then administered to cardiomyocytes to study the role of mitophagy in AGE-induced aging. RESULTS: A significantly increased number of SA-ß-gal positive cells and increased p16 protein levels were observed in cardiomyocytes treated with AGEs. Moreover, AGEs significantly increased the protein levels of PINK1 and Parkin as well as the LC3-II/LC3-I ratio, which occurred in a dose-dependent manner. However, the expression of p62 decreased significantly in the AGE group compared to the control. Surprisingly, both CsA and the knockdown of PINK1 by small-interfering RNA (siRNA) significantly decreased the LC3-II/LC3-I ratio and the PINK1 and Parkin protein levels in AGE-treated cardiomyocytes. Moreover, CsA treatment or knockdown of PINK1 expression attenuated the increased number of SA-ß-gal positive cells and the upregulated p16 level in cardiomyocytes induced by AGEs. CONCLUSIONS: PINK1/Parkin-mediated mitophagy is involved in the process of cardiomyocyte senescence induced by AGEs, and a reduction in mitophagic activity might be a promising approach to block the senescent state in cardiomyocytes.