Mitophagy Function Research Articles

Mitophagy drives maldifferentiation of tissue-resident memory T cells in patients with rheumatoid arthritis

Objective To investigate the function of mitophagy in instructing T-cell differentiation of patients with rheumatoid arthritis (RA). Method The mRNA and protein levels of optic atrophy protein-1 were detected in T cells from 94 RA patients and 37 age- and sex-matched healthy individuals by quantitative polymerase chain reaction and Western blotting. The impact of mitophagy on the differentiation of T cells was determined by flow cytometry. The therapeutic effect of targeting mitophagy was explored in humanized RA chimeras. Results Our study showed that T cells exerted high levels of mitophagy in RA patients. Since multiple T-cell subtypes play crucial roles in RA, we determined that mitophagy had a significant impact on the differentiation of tissue-resident memory T (Trm) cells, but not Th1 or Th17 cells. Importantly, we demonstrated that inhibiting mitophagy significantly reduced the number of Trm cells and downregulated inflammatory responses, as evidenced by diminished levels of T cell receptor β, interferon-γ, and interleukin-17A, in the humanized RA chimeras. Conclusions Mitophagy is elevated in RA T cells, leading to maldifferentiation of Trm cells in RA patients. Since these findings were obtained from clinical patients, mitophagy may be a potential therapeutic target for RA treatment.

FUNDC1-mediated mitophagy regulates photodamage independently of the PINK1/Parkin-dependent pathway

BackgroundUltraviolet B(UVB) triggers a pro-survival response through mitophagy, but the role of FUNDC1-mediated mitophagy in photodamaged skin remains unexplored. ObjectivesTo clarify the function of mitophagy in UVB-induced photodamaged skin. MethodsTo investigate the role of FUNDC1-mediated mitophagy in UVB-induced mitochondrial damage and cell apoptosis, FUNDC1 knockdown in C57BL/6 mice was performed using adeno-associated virus. Additionally, FUNDC1 overexpression and knockdown in HaCaT cells were conducted using lentivirus. A comprehensive analysis was conducted on a panel of human sun-exposed skin samples, alongside control samples, to assess the expression levels of FUNDC1. ResultsIn UVB-induced C57BL/6 mice, the dorsal skin showed photodamage including erythema, scaling, erosion, and scabs. The expression levels of PINK1, Parkin, and BNIP3 did not show significant changes, while FUNDC1 expression consistently declined along with LC3B. Cytochrome C, Bax, and cleaved-caspase3 were upregulated, while Bcl2 was downregulated. UVB-induced HaCaT cells showed mitochondrial damage, accompanied by FUNDC1 downregulation and BNIP3 upregulation, while PINK1 and Parkin showed no significant changes. FUNDC1 overexpression led to an increase in mtROS and a decrease in mitochondrial membrane potential and ATP levels, indicating complete mitochondrial clearance and exacerbated cell death. FUNDC1 knockdown protected against UVB-induced photodamage in mice and mitigated mitochondrial damage and apoptosis in HaCaT cells by activating compensatory PINK1/Parkin-dependent mitophagy, which was evidenced by upregulation of PINK1 and Bcl2 and downregulation of Bax. In human sun-exposed skin samples, there was a decrease in the number of FUNDC1+ cells compared with non-sun-exposed controls. ConclusionsFUNDC1-mediated mitophagy regulates skin photodamage and provides a novel mechanism for resisting photodamage, presenting a potential target for future therapeutic interventions.

GLS2 reduces the occurrence of epilepsy by affecting mitophagy function in mouse hippocampal neurons.

Altered mitophagy has been observed in various neurological disorders, such as epilepsy. The role of mitophagy in causing neuronal damage during epileptic episodes is significant, and recent research has indicated that GLS2 plays a crucial role in regulating autophagy. However, exactly how GLS2 affects epilepsy is still unclear. To investigate the expression and distribution characteristics of GLS2 in epilepsy, and then observed the changes in behavior and electrophysiology caused by overexpression of GLS2 in epileptic mice, and determined whether GLS2 regulated seizure-like changes in the mouse model through the protective mechanism of mitophagy. The expression of GLS2 in a kainic acid (KA)-induced epileptic mouse model and aglutamate-inducedneuronal excitatory damage in HT22 cells model was downregulation. In brief, overexpression of GLS2 can alleviate epileptic activity. Subsequently, we demonstrated that GLS2 interacts with mitophagy-related proteins in a KA-induced epilepsy mouse model. Mechanistically, overexpression of GLS2 inhibited mitophagy in epileptic mice, downregulating the expression of LC3 and reducing ROS production. This study proves the GLS2 expression pattern is abnormal in epileptic mice. The function of mitophagy in hippocampal neurons is affected by GLS2, and overexpression of GLS2 can reduce the occurrence of seizure-like events (SLEs) by altering mitophagy function. Thus, GLS2 might control seizures, and our findings provide a fresh avenue for antiepileptic treatment and offer novel insights into treating and preventing epilepsy.

Inhibition of mitophagy via the EIF2S1-ATF4-PRKN pathway contributes to viral encephalitis

IntroductionMitophagy, a selective form of autophagy responsible for maintaining mitochondrial homeostasis, regulates the antiviral immune response and acts as viral replication platforms to facilitate infection with various viruses. However, its precise role in herpes simplex virus 1 (HSV-1) infection and herpes simplex encephalitis (HSE) remains largely unknown. ObjectivesWe aimed to investigate the regulation of mitophagy by HSV-1 neurotropic infection and its role in viral encephalitis, and to identify small compounds that regulate mitophagy to affect HSV-1 infection. MethodsThe antiviral effects of compounds were investigated by Western blot, RT-PCR and plaque assay. The changes of Parkin (PRKN)-mediated mitophagy and Nuclear Factor kappa B (NFKB)-mediated neuroinflammation were examined by TEM, RT-qPCR, Western blot and ELISA. The therapeutic effect of taurine or PRKN-overexpression was confirmed in the HSE mouse model by evaluating survival rate, eye damage, neurodegenerative symptoms, immunohistochemistry analysis and histopathology. ResultsHSV-1 infection caused the accumulation of damaged mitochondria in neuronal cells and in the brain tissue of HSE mice. Early HSV-1 infection led to mitophagy activation, followed by inhibition in the later viral infection. The HSV-1 proteins ICP34.5 or US11 deregulated the EIF2S1-ATF4 axis to suppress PRKN/Parkin mRNA expression, thereby impeding PRKN-dependent mitophagy. Consequently, inhibition of mitophagy by specific inhibitor midiv-1 promoted HSV-1 infection, whereas mitophagy activation by PRKN overexpression or agonists (CCCP and rotenone) attenuated HSV-1 infection and reduced the NF-κB-mediated neuroinflammation. Moreover, PRKN-overexpressing mice showed enhanced resistance to HSV-1 infection and ameliorated HSE pathogenesis. Furthermore, taurine, a differentially regulated gut microbial metabolite upon HSV-1 infection, acted as a mitophagy activator that transcriptionally promotes PRKN expression to stimulate mitophagy and to limit HSV-1 infection both in vitro and in vivo. ConclusionThese results reveal the protective function of mitophagy in HSE pathogenesis and highlight mitophagy activation as a potential antiviral therapeutic strategy for HSV-1-related diseases.

Multi omics analysis of mitophagy subtypes and integration of machine learning for predicting immunotherapy responses in head and neck squamous cell carcinoma.

Mitophagy serves as a critical mechanism for tumor cell death, significantly impacting the progression of tumors and their treatment approaches. There are significant challenges in treating patients with head and neck squamous cell carcinoma, underscoring the importance of identifying new targets for therapy. The function of mitophagy in head and neck squamous carcinoma remains uncertain, thus investigating its impact on patient outcomes and immunotherapeutic responses is especially crucial. We initially analyzed the differential expression, prognostic value, intergene correlations, copy number variations, and mutation frequencies of mitophagy-related genes at the pan-cancer level. Through unsupervised clustering, we divided head and neck squamous carcinoma into three subtypes with distinct prognoses, identified the signaling pathway features of each subtype using ssGSEA, and characterized subtype B as having features of an immune desert using various immune infiltration calculation methods. Using multi-omics data, we identified the genomic variation characteristics, mutated gene pathway features, and drug sensitivity features of the mitophagy subtypes. Utilizing a combination of 10 machine learning algorithms, we have developed a prognostic scoring model called Mitophagy Subgroup Risk Score (MSRS), which is used to predict patient survival and the response to immune checkpoint blockade therapy. Simultaneously, we applied MSRS to single-cell analysis to explore intercellular communication. Through laboratory experiments, we validated the biological function of SLC26A9, one of the genes in the risk model. In summary, we have explored the significant role of mitophagy in head and neck tumors through multi-omics data, providing new directions for clinical treatment.

FUDNC1-dependent mitophagy ameliorate motor neuron death in an amyotrophic lateral sclerosis mouse model

Amyotrophic lateral sclerosis (ALS) is one of the most common neurodegenerative diseases, yet effective treatment is lacking. Moreover, the underlying pathomechanisms of ALS remain unclear, with impaired mitophagy function being increasingly recognized as a contributing factor. FUN14 domain-containing protein 1 (FUNDC1) is an autophagy receptor localized to the outer mitochondrial membrane and a mitochondrial membrane protein that mediates mitophagy and therefore considered as important factor in neurodegenerative diseases. However, its specific role in ALS is not yet clear. Therefore, this study aimed to investigate the regulatory role of FUNDC1 in ALS and determine its regulatory mechanisms. ALS transgenic mice were obtained and maintained under standard conditions. Cell lines were generated by stable transfection with hSOD1G93A or control vectors. Mice received intrathecal injections of AAV9 vectors expressing FUNDC1 or EGFP. Motor function was assessed through behavioral tests, and histological and immunostaining analyses were performed. Colocalization analysis was conducted in transfected cells, and protein expression was evaluated via western blotting. We first observed that FUNDC1 was significantly downregulated in the spinal cord tissues of SOD1G93A mice. FUNDC1 overexpression considerably improved locomotor activity and prolonged survival time in SOD1G93A mice. Mechanistically, reduced expression of FUNDC1 resulted in decreased mitophagy, as indicated by decreased recruitment through LC3 in SOD1G93A mice and cellular models. Consequently, this led to increased mitochondrial accumulation and cell apoptosis, exacerbating the ALS phenotype. Furthermore, we identified transcription factor FOXD3 as an essential upstream factor of FUNDC1, resulting in reduced transcription of FUNDC1 in ALS lesions. This study suggests a novel strategy of targeting FUNDC1-mediated mitophagy for developing therapeutic interventions to mitigate disease progression and improve outcomes for ALS patients.

Chinese botanical drugs targeting mitophagy to alleviate diabetic kidney disease, a comprehensive review.

Diabetic kidney disease (DKD) is one of the chronic microvascular complications caused by diabetes, which is characterized by persistent albuminuria and/or progressive decline of estimated glomerular filtration rate (eGFR), and has been the major cause of dialysis around the world. At present, although the treatments for DKD including lifestyle modification, glycemic control and even using of Sodium-glucose cotransporter 2 (SGLT2) inhibitors can relieve kidney damage caused to a certain extent, there is still a lack of effective treatment schemes that can prevent DKD progressing to ESRD. It is urgent to find new complementary and effective therapeutic agents. Growing animal researches have shown that mitophagy makes a great difference to the pathogenesis of DKD, therefore, exploration of new drugs that target the restoration of mitophagy maybe a potential perspective treatment for DKD. The use of Chinese botanical drugs (CBD) has been identified to be an effective treatment option for DKD. There is growing concern on the molecular mechanism of CBD for treatment of DKD by regulating mitophagy. In this review, we highlight the current findings regarding the function of mitophagy in the pathological damages and progression of DKD and summarize the contributions of CBD that ameliorate renal injuries in DKD by interfering with mitophagy, which will help us further explain the mechanism of CBD in treatment for DKD and explore potential therapeutic strategies for DKD.

Mitophagy in plants: Emerging regulators of mitochondrial targeting for selective autophagy.

The degradation and turnover of mitochondria is fundamental to Eukaryotes and is a key homeostatic mechanism for maintaining functional mitochondrial populations. Autophagy is an important pathway by which mitochondria are degraded, involving their sequestration into membrane-bound autophagosomes and targeting to lytic endosomal compartments (the lysosome in animals, the vacuole in plants and yeast). Selective targeting of mitochondria for autophagy, also known as mitophagy, distinguishes mitochondria from other cell components for degradation and is necessary for the regulation of mitochondria-specific cell processes. In mammals and yeast, mitophagy has been well characterised and is regulated by numerous pathways with diverse and important functions in the regulation of cell homeostasis, metabolism and responses to specific stresses. In contrast, we are only just beginning to understand the importance and functions of mitophagy in plants, chiefly as the proteins that target mitochondria for autophagy in plants are only recently emerging. Here, we discuss the current progress of our understanding of mitophagy in plants, the importance of mitophagy for plant life and the regulatory autophagy proteins involved in mitochondrial degradation. In particular, we will discuss the recent emergence of mitophagy receptor proteins that selectively target mitochondria for autophagy, and discuss the missing links in our knowledge of mitophagy-regulatory proteins in plants compared to animals and yeast.

Age-Related Changes in Proportions of Urolithins A, B, and 0

Nowadays, aging is the actual theme above the world. Scientists are working on to prevent aging. In this article, we discuss how Urolithin effects on human body and aging process. Urolithin A (UA) is a natural compound produced by gut bacteria from ingested ellagitannins (ETs) and ellagic acid (EA), complex polyphenols abundant in foods such as pomegranate, berries, and nuts. Mitochondria play a crucial role in cellular function and are particularly important in aging and decrepit cells by the function of mitophagy. During this process pathological mitochondria are killed, that controls the quality of mitochondrias and proteins. Mitochondrial dysfunction can trigger cellular responses associated with inflammation and cellular senescence. Urolithins (microbial metabolites) found in various tissues after ellagitannin consumption, has been demonstrated to possess antioxidant and anti-inflammatory effects.

PINK1 Immunoexpression Predicts Survival in Patients Undergoing Hepatic Resection for Colorectal Liver Metastases.

PTEN-induced kinase-1 (PINK1) is the initiator of the canonical mitophagy pathway. Our aim was to study the immunoexpression of PINK1 in surgical specimens from ninety patients with metastatic colorectal adenocarcinoma (CRC) to the liver (CRLM). Tissue arrays were produced, and immunohistochemical studies were analyzed by the H-Score method. The mean immunoexpression of PINK1 in normal tissues was between 40 to 100 points. In tumoral tissues, positive PINK1 immunoexpression was observed in all samples, and no differences were noted between CRCs. In CRLMs, a significant under-expression was noted for PINK1 from the rectum (71.3 ± 30.8; p < 0.042) compared to other sites. Altered PINK1 immunoexpression in CRCs, either higher than 100 points or lower than 40 points, was associated with worse overall survival (OS) (p < 0.012) due to a shorter post-metastatic survival (PMS) (p < 0.023), and it was found to be a significant independent predictor of prognosis in a multivariate model for OS and PMS (HR = 1.972, 95% CI 0.971-4.005; p = 0.022. HR = 2.023, 95% CI 1.003-4.091; p = 0.037, respectively). In conclusion, altered PINK1 immunoexpression determined in CRCs with resected CRLM predicts a worse prognosis, possibly due to the abnormal function of mitophagy.

Role of mitophagy in the neurodegenerative diseases and its pharmacological advances: A review

Neurodegenerative diseases are a class of incurable and debilitating diseases characterized by progressive degeneration and death of cells in the central nervous system. They have multiple underlying mechanisms; however, they all share common degenerative features, such as mitochondrial dysfunction. According to recent studies, neurodegenerative diseases are associated with the accumulation of dysfunctional mitochondria. Selective autophagy of mitochondria, called mitophagy, can specifically degrade excess or dysfunctional mitochondria within cells. In this review, we highlight recent findings on the role of mitophagy in neurodegenerative disorders. Multiple studies were collected, including those related to the importance of mitochondria, the mechanism of mitophagy in protecting mitochondrial health, and canonical and non-canonical pathways in mitophagy. This review elucidated the important function of mitophagy in neurodegenerative diseases, discussed the research progress of mitophagy in neurodegenerative diseases, and summarized the role of mitophagy-related proteins in neurological diseases. In addition, we also highlight pharmacological advances in neurodegeneration.

Evaluating mitophagy in embryonic stem cells by using fluorescence-based imaging.

Embryonic stem cells (ESCs), which are characterized by the capacity for self-renewal and pluripotency, hold great promise for regenerative medicine. Increasing evidence points to the essential role of mitophagy in pluripotency regulation. Our recent work showed that PINK1/OPTN take part in guarding ESC mitochondrial homeostasis and pluripotency. Evaluating mitophagy in ESCs is important for exploring the relationships between mitochondrial homeostasis and pluripotency. ESCs are smaller in size than adult somatic cells and the mitophagosomes in ESCs are difficult to observe. Many methods have been employed—for example, detecting colocalization of LC3-II and mitochondria—to evaluate mitophagy in ESCs. However, it is important to define an objective way to detect mitophagy in ESCs. Here, we evaluated two commonly used fluorescence-based imaging methods to detect mitophagy in ESCs. By using autophagy- or mitophagy-defective ESC lines, we showed that the mito-Keima (mt-Keima) system is a suitable and effective way for detecting and quantifying mitophagy in ESCs. Our study provides evidence that mt-Keima is an effective tool to study mitophagy function in ESCs.

FUNDC1 Mediated Mitophagy in Epileptic Hippocampal Neuronal Injury Induced by Magnesium-Free Fluid.

Mitophagy plays a key role in epileptic neuronal injury, and recent studies have shown that FUNDC1 plays an important role in regulating mitophagy. However, the specificeffect of FUNDC1 on neuronal damage in epilepsy is unknown. In this study, we investigated the role of FUNDC1 in mitophagy and neuronal apoptosis using a hippocampal neuronal culture model of acquired epilepsy (AE) in vitro. We found that mitophagy levels were significantly increased in this model, as indicated by elevated LC3A/B ratios. FUNDC1 overexpression using lentiviral vectors enhanced mitophagy, whereas FUNDC1 down-regulation using lentiviral vectors impaired this process. Overexpression of FUNDC1 significantly decreased AE-induced superoxide anion, enhanced cell viability, reduced oxidative stress, and reduced neuronal apoptosis in epileptic hippocampus, while FUNDC1 down-regulation caused the opposite effect. In conclusion, we demonstrated that FUNDC1 is an important modulator of AE-induced neuronal apoptosis by controlling mitophagy function.

Mitophagy initiates retrograde mitochondrial-nuclear signaling to guide retinal pigment cell heterogeneity

ABSTRACT Age-related macular degeneration (AMD), the leading cause of blindness among the elderly, is without treatment for early disease. Degenerative retinal pigment epithelial (RPE) cell heterogeneity is a well-recognized but understudied pathogenic factor. Due to the daily phagocytosis of photoreceptor outer segments, unique photo-oxidative stress, and high metabolism for maintaining vision, the RPE has robust macroautophagy/autophagy, and mitochondrial and antioxidant networks. However, the autophagy subtype, mitophagy, in the RPE and AMD is understudied. Here, we found decreased PINK1 (PTEN induced kinase 1) in perifoveal RPE of early AMD eyes. PINK1-deficient RPE have impaired mitophagy and mitochondrial function that triggers death-resistant epithelial-mesenchymal transition (EMT). This reprogramming is mediated by novel retrograde mitochondrial-nuclear signaling (RMNS) through superoxide, NFE2L2 (NFE2 like bZIP transcription factor 2), TXNRD1 (thioredoxin reductase 1), and phosphoinositide 3-kinase (PI3K)-AKT (AKT serine/threonine kinase) that induced canonical transcription factors ZEB1 (zinc finger E-box binding homeobox 1) and SNAI1 (Snail family transcriptional repressor 1) and an EMT transcriptome. NFE2L2 deficiency disrupted RMNS that paradoxically normalized morphology but decreased function and viability. Thus, RPE heterogeneity is defined by the interaction of two cytoprotective pathways that is triggered by mitophagy function. By neutralizing the consequences of impaired mitophagy, an antioxidant dendrimer tropic for the RPE and mitochondria, EMT (a recognized AMD alteration) was abrogated to offer potential therapy for early AMD, a stage without treatment. Abbreviations: ACTB: actin beta; AKT: AKT serine/threonine kinase; AMD: age-related macular degeneration; CCCP: cyanide m-chlorophenyl hydrazone; CDH1: cadherin 1; DAVID: Database for Annotation, Visualization and Integrated Discovery; DHE: dihydroethidium; D-NAC: N-acetyl-l-cysteine conjugated to a poly(amido amine) dendrimer; ECAR: extracellular acidification rate; EMT: epithelial-mesenchymal transition; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; GSEA: Gene Set Enrichment Analysis; HSPD1: heat shock protein family D (Hsp60) member 1; IVT: intravitreal; KD: knockdown; LMNA, lamin A/C; MAP1LC3B: microtubule associated protein 1 light chain 3 beta; MMP: mitochondrial membrane potential; NAC: N-acetyl-l-cysteine; NQO1: NAD(P)H quinone dehydrogenase 1; NFE2L2: NFE2 like bZIP transcription factor 2; O2 −: superoxide anion; OCR: oxygen consumption rate; PI3K: phosphoinositide 3-kinase; PINK1: PTEN induced kinase 1; RMNS: retrograde mitochondrial-nuclear signaling; ROS: reactive oxygen species; RPE: retinal pigment epithelium; SNAI1: snail family transcriptional repressor 1; TJP1: tight junction protein 1; TPP-D-NAC: triphenyl phosphinium and N-acetyl-l-cysteine conjugated to a poly(amido amine) dendrimer; TIMM23: translocase of inner mitochondrial membrane 23; TOMM20: translocase of outer mitochondrial membrane 20; Trig: trigonelline; TXNRD1: thioredoxin reductase 1; VIM: vimentin; WT: wild-type; ZEB1: zinc finger E-box binding homeobox 1

Systematic Functional Analysis of PINK1 and PRKN Coding Variants.

Loss of either PINK1 or PRKN causes an early onset Parkinson’s disease (PD) phenotype. Functionally, PINK1 and PRKN work together to mediate stress-activated mitochondrial quality control. Upon mitochondrial damage, PINK1, a ubiquitin kinase and PRKN, a ubiquitin ligase, decorate damaged organelles with phosphorylated ubiquitin for sequestration and degradation in lysosomes, a process known as mitophagy. While several genetic mutations are established to result in loss of mitophagy function, many others have not been extensively characterized and are of unknown significance. Here, we analyzed a set of twenty variants, ten in each gene, focusing on understudied variants mostly from the Parkinson’s progressive marker initiative, with sensitive assays to define potential functional deficits. Our results nominate specific rare genetic PINK1 and PRKN variants that cause loss of enzymatic function in line with a potential causative role for PD. Additionally, we identify several variants with intermediate phenotypes and follow up on two of them by gene editing midbrain-derived neuronal precursor cells. Thereof derived isogenic neurons show a stability defect of the rare PINK1 D525N mutation, while the common PINK1 Q115L substitution results in reduced kinase activity. Our strategy to analyze variants with sensitive functional readouts will help aid diagnostics and disease treatment in line with current genomic and therapeutic advances.

Mitophagy: An Emergence of New Player in Alzheimer's Disease.

Mitochondria provide neurons not only energy as ATP to keep them growing, proliferating and developing, but they also control apoptosis. Due to their high bioenergetic demand, neurons which are highly specific terminally differentiated cells, essentially depend on mitochondria. Defective mitochondrial function is thus related to numerous age-linked neurodegenerative ailments like Alzheimer’s disease (AD), in which the build-up of impaired and malfunctioning mitochondria has been identified as a primary sign, paying to disease development. Mitophagy, selective autophagy, is a key mitochondrial quality control system that helps neurons to stay healthy and functional by removing undesired and damaged mitochondria. Dysfunctional mitochondria and dysregulated mitophagy have been closely associated with the onset of ADs. Various proteins associated with mitophagy were found to be altered in AD. Therapeutic strategies focusing on the restoration of mitophagy capabilities could be utilized to strike the development of AD pathogenesis. We summarize the mechanism and role of mitophagy in the onset and advancement of AD, in the quality control mechanism of mitochondria, the consequences of dysfunctional mitophagy in AD, and potential therapeutic approaches involving mitophagy modulation in AD. To develop new therapeutic methods, a better knowledge of the function of mitophagy in the pathophysiology of AD is required.

PINK1/Parkin-Mediated Mitophagy Plays a Protective Role in Albumin Overload-Induced Renal Tubular Cell Injury

Proteinuria is an important symptom of chronic kidney disease irrespective of its initial pathogenesis. Mitochondrial dysfunction is an early pathophysiological event in proteinuria-induced tubular damage. Mitophagy, the selective degradation of damaged mitochondria targeted by autophagy, contributes to mitochondrial homeostasis and is primarily regulated by the PTEN-induced kinase 1 (PINK1)/Parkin pathway. In this study, we evaluated the function of mitophagy in proteinuria-induced tubular injury and mechanism. HK-2 cells were transfected with Parkin siRNA or Parkin overexpression plasmids for 48 h followed by treatment with albumin (8 mg/mL) for 8 h. JC-1 staining, ATP detection, and reactive oxygen species (ROS) detection were used to determine mitochondrial function. Immunoblot, LC3/mitochondria co-localization analyses, and Mito-Keima were employed to detect mitophagy. Immunoblot analysis and TUNEL were used to detect apoptosis. Albumin overload induced mitochondrial dysfunction and mitophagy activation in HK-2 cells. Parkin knockdown inhibited albumin overload induced-mitophagy. Parkin overexpression further upregulated albumin overload induced-mitophagy. Parkin deficiency aggravated albumin overload-induced mitochondrial dysfunction and the overproduction of ROS, resulting in increased cell injury. Contrarily, Parkin overexpression helped maintain mitochondrial function and attenuate ROS generation, contributing to cell protection. Our results suggest that by clearing damaged mitochondria and maintaining mitochondrial function, PINK1/Parkin-mediated mitophagy contributed to tubular cell survival during albumin overload. PINK1/Parkin-mediated mitophagy may be a potential therapeutic target for proteinuria in tubular epithelial cells.

Ligustilide ameliorates hippocampal neuronal injury after cerebral ischemia reperfusion through activating PINK1/Parkin-dependent mitophagy

BackgroundMitophagy plays a critical role in cerebral ischemia/reperfusion by timely removal of dysfunctional mitochondria. In mammals, PINK1/Parkin is the most classic pathway mediating mitophagy. And the activation of PINK1/Parkin mediated mitophagy exerts neuroprotective effects during cerebral ischemia reperfusion injury (CIRI). Ligustilide (LIG) is a natural compound extracted from ligusticum chuanxiong hort and angelica sinensis (Oliv.) diels that exerts neuroprotective activity after cerebral ischemia reperfusion injury (CIRI). However, it still remains unclear whether LIG could attenuates cerebral ischemia reperfusion injury (CIRI) through regulating mitophagy mediated by PINK1/Parkin. PurposeTo explore the underlying mechanism of LIG on PINK1/Parkin mediated mitophagy in the hippocampus induced by ischemia reperfusion. MethodsThis research used the middle cerebral artery occlusion and reperfusion (MCAO/R) animal model and oxygen-glucose deprivation and reperfusion (OGD/R) as in vitro model. Neurological behavior score, 2, 3, 5-triphenyl tetrazolium chloride (TTC) staining and Hematoxylin and Eosin (HE) Staining were used to detect the neuroprotection of LIG in MCAO/R rats. Also, the levels of ROS, mitochondrial membrane potential (MMP) and activities of Na+-K+-ATPase were detected to reflect mitochondrial function. Moreover, transmission electron microscope (TEM) and fluorescence microscope were used to observe mitophagy and the western blot was performed to explore the changes in protein expression in PINK1/Parkin mediated mitophagy. Finally, exact mechanism between neuroprotection of LIG and mitophagy mediated by PINK1/Parkin was explored by cell transfection. ResultsThe results show that LIG improved mitochondrial functions by mitophagy enhancement in vivo and vitro to alleviate CIRI. Whereas, mitophagy enhanced by LIG under CIRI is abolished by PINK1 deficiency and midivi-1, a mitochondrial division inhibitor which has been reported to have the function of mitophagy, which could further aggravate the ischemia-induced brain damage, mitochondrial dysfunction and neuronal injury. ConclusionLIG could ameliorate the neuronal injury against ischemia stroke by promoting mitophagy via PINK1/Parkin. Targeting PINK1/Parkin mediated mitophagy with LIG treatment might be a promising therapeutic strategy for ischemia stroke.

TREM2 ameliorates anesthesia and surgery-induced cognitive impairment by regulating mitophagy and NLRP3 inflammasome in aged C57/BL6 mice

Postoperative cognitive dysfunction (POCD) is a major postoperative complication. Triggering receptor expressed on myeloid cells 2 (TREM2) exerts a neuroprotective function against neuro-inflammatory responses. The present study investigated the role of TREM2 in anesthesia and surgery-induced cognitive impairment and the potential related mechanism. Our results revealed that TREM2 was downregulated, coupled with activation of the NLRP3 inflammasome and subsequent IL-1β expression on postoperative day 3. A corresponding decline in PSD-95 and BDNF was found at the same time point. The key regulator of mitophagy PINK1 and Parkin protein levels were significantly decreased following surgery and anesthesia. TREM2 overexpression partially reversed postoperative cognitive impairment and enhanced PSD-95 and BDNF expression. TREM2 overexpression also improved mitophagy function and inhibited activation of the NLRP3 inflammasome and associated production of IL-1β. Our findings demonstrate that TREM2 rescues anesthesia and surgery-induced spatial learning and memory impairment and neuro-inflammation in aged C57/BL6 mice, which may be at least partially mediated through the activation of mitophagy and subsequent inhibition of the NLRP3 inflammasome.

Poly (ADP-ribose) polymerase 1-mediated defective mitophagy contributes to painful diabetic neuropathy in the db/db model.

Studies have shown that poly (ADP-ribose) polymerase 1 (PARP1) is involved in the pathological process of diabetes. Mitophagy is widely acknowledged to be a key regulatory process in maintaining reactive oxygen species homeostasis via lysosome degradation of damaged mitochondria. However, the regulatory role of PARP1 in mitophagy-related mitochondrial oxidative injury and progression of painful diabetic neuropathy (PDN) is unclear. In this study, we studied the in vitro and in vivo mechanisms of PARP1-mediated mitophagy blockade in a leptin gene-mutation (db/db) mouse model of PDN. Db/db mice models of PDN were established by assessing the sciatic nerve conduction velocity (SNCV), mechanical withdrawal threshold (MWT), and thermal withdrawal latency (TWL). The results showed that PARP1 activity and mitochondrial injury of dorsal root ganglion (DRG) neurons were increased, and mitophagy was impaired in PDN mice. PARP1 was found to mediate the impairment of mitophagy in DRG neurons isolated from PDN mice. PARP1 inhibitors (PJ34 or AG14361) attenuated diabetes-induced peripheral nerve hyperalgesia, restored DRG neuron mitophagy function and decreased mitochondrial oxidative injury. Mitophagy impairment induced by lysosome deacidificant (DC661) aggravated diabetes-induced DRG neuron mitochondrial oxidative stress and injury. Taken together, our data revealed that PARP1-induced defective mitophagy of DRG neurons is a key mechanism in diabetes-induced peripheral neuropathic injury. Inhibition of PARP1 and restoration of mitophagy function are potential therapeutic targets for PDN.