The m6A reader HNRNPC promotes glioma progression by enhancing the stability of IRAK1 mRNA through the MAPK pathway.

Glioma is the most common and aggressive type of primary malignant brain tumor. The N6-methyladenosine (m6A) modification widely exists in eukaryotic cells and plays an important role in the occurrence and development of human tumors. However, the function and mechanism of heterogeneous nuclear ribonucleoprotein C (HNRNPC), an RNA-binding protein and m6A reader in gliomas remains to be comprehensively and extensively explored. Herein, we found that HNRNPC mRNA and protein overexpression were associated with a poor prognosis for patients with gliomas, based on the data from TCGA, the CGGA, and the TMAs. Biologically, HNRNPC knockdown markedly repressed malignant phenotypes of glioma in vitro and in vivo, whereas ectopic HNRNPC expression had the opposite effect. Integrative RNA sequencing and MeRIP sequencing analyses identified interleukin-1 receptor-associated kinase 1 (IRAK1) as a downstream target of HNRNPC. The glioma public datasets and tissue microarrays (TMAs) data indicated that IRAK1 overexpression was associated with poor prognosis, and IRAK1 knockdown significantly repressed malignant biological behavior in vitro. Mechanistically, HNRNPC maintains the mRNA stability of IRAK1 in an m6A-dependent manner, resulting in activation of the mitogen-activated protein kinase (MAPK) signaling pathway, which was necessary for the malignant behavior of glioma. Our findings demonstrate the HNRNPC-IRAK1-MAPK axis as a crucial carcinogenic factor for glioma and the novel underlying mechanism of IRAK1 upregulation, which provides a rationale for therapeutically targeting epitranscriptomic modulators in glioma.

Association of blood urea nitrogen with all-cause and cardiovascular mortality in hyperlipidemia: NHANES 1999-2018.

OBJECTIVE: Although blood urea nitrogen (BUN) has a crucial impact on many diseases, its effect on outcomes in patients with hyperlipidemia remains unknown. The study aimed to investigate the relationships between BUN levels and all-cause and cardiovascular disease (CVD) mortality in individuals with hyperlipidemia. METHODS: This analysis comprised 28,122 subjects with hyperlipidemia from the National Health and Nutrition Examination Survey (NHANES) spanning 1999 to 2018. The risk of BUN on mortality was evaluated using weighted Cox regression models. Additionally, to illustrate the dose-response association, the restricted cubic spline (RCS) was used. RESULTS: During the observation period, 4276 participant deaths were recorded, of which 1206 were due to CVD. Compared to patients with hyperlipidemia in the third BUN quintile, the hazard ratios (HRs) for all-cause mortality were 1.26 (95% CIs: 1.09, 1.45) and 1.22 (95% CIs: 1.09, 1.37) for patients in the first and fifth quintiles of BUN, respectively. The HRs for CVD mortality among patients in the fifth quintile of BUN were 1.48 (95% CIs: 1.14, 1.93). BUN levels were found to have a U-shaped association with all-cause mortality and a linear association with CVD mortality using restricted triple spline analysis. CONCLUSIONS: This study revealed that both low and high BUN levels in patients with hyperlipidemia are associated with heightened all-cause mortality. Furthermore, elevated BUN levels are also associated with increased CVD mortality. The findings indicate that patients with hyperlipidemia may face an elevated risk of death if they have abnormal BUN levels.

The mechanisms of natural products for eye disorders by targeting mitochondrial dysfunction.

The human eye is susceptible to various disorders that affect its structure or function, including glaucoma, age-related macular degeneration (AMD) and diabetic retinopathy (DR). Mitochondrial dysfunction has been identified as a critical factor in the pathogenesis and progression of eye disorders, making it a potential therapeutic target in the clinic. Natural products have been used in traditional medicine for centuries and continue to play a significant role in modern drug development and clinical therapeutics. Recently, there has been a surge in research exploring the efficacy of natural products in treating eye disorders and their underlying physiological mechanisms. This review aims to discuss the involvement of mitochondrial dysfunction in eye disorders and summarize the recent advances in the application of natural products targeting mitochondria. In addition, we describe the future perspective and challenges in the development of mitochondria-targeting natural products.

Human amniotic mesenchymal stem cells-derived conditioned medium and exosomes alleviate oxidative stress-induced retinal degeneration by activating PI3K/Akt/FoxO3 pathway.

Age-related macular degeneration (AMD) is the leading cause of vision loss among the elderly, which is primarily attributed to oxidative stress-induced damage to the retinal pigment epithelium (RPE). Human amniotic mesenchymal stem cells (hAMSC) were considered to be one of the most promising stem cells for clinical application due to their low immunogenicity, tissue repair ability, pluripotent potential and potent paracrine effects. The conditional medium (hAMSC-CM) and exosomes (hAMSC-exo) derived from hAMSC, as mediators of intercellular communication, play an important role in the treatment of retinal diseases, but their effect and mechanism on oxidative stress-induced retinal degeneration are not explored. Here, we reported that hAMSC-CM alleviated H2O2-induced ARPE-19 cell death through inhibiting mitochondrial-mediated apoptosis pathway in vitro. The overproduction of reactive oxygen species (ROS), alteration in mitochondrial morphology, loss of mitochondrial membrane potential and elevation of Bax/Bcl2 ratio in ARPE-19 cells under oxidative stress were efficiently reversed by hAMSC-CM. Moreover, it was found that hAMSC-CM protected cells against oxidative injury via PI3K/Akt/FoxO3 signaling. Intriguingly, exosome inhibitor GW4869 alleviated the inhibitory effect of hAMSC-CM on H2O2-induced decrease in cell viability of ARPE-19 cells. We further demonstrated that hAMSC-exo exerted the similar protective effect on ARPE-19 cells against oxidative damage as hAMSC-CM. Additionally, both hAMSC-CM and hAMSC-exo ameliorated sodium iodate-induced deterioration of RPE and retinal damage in vivo. These results first indicate that hAMSC-CM and hAMSC-exo protect RPE cells from oxidative damage by regulating PI3K/Akt/FoxO3 pathway, suggesting hAMSC-CM and hAMSC-exo will be a promising cell-free therapy for the treatment of AMD in the future.

Targeted inhibition of branched-chain amino acid metabolism drives apoptosis of glioblastoma by facilitating ubiquitin degradation of Mfn2 and oxidative stress.

Glioblastoma is one of the most challenging malignancies with high aggressiveness and invasiveness and its development and progression of glioblastoma highly depends on branched-chain amino acid (BCAA) metabolism. The study aimed to investigate effects of inhibition of BCAA metabolism with cytosolic branched-chain amino acid transaminase (BCATc) Inhibitor 2 on glioblastoma, elucidate its underlying mechanisms, and explore therapeutic potential of targeting BCAA metabolism. The expression of BCATc was upregulated in glioblastoma and BCATc Inhibitor 2 precipitated apoptosis both in vivo and in vitro with the activation of Bax/Bcl2/Caspase-3/Caspase-9 axis. In addition, BCATc Inhibitor 2 promoted K63-linkage ubiquitination of mitofusin 2 (Mfn2), which subsequently caused lysosomal degradation of Mfn2, and then oxidative stress, mitochondrial fission and loss of mitochondrial membrane potential. Furthermore, BCATc Inhibitor 2 treatment resulted in metabolic reprogramming, and significant inhibition of expression of ATP5A, UQCRC2, SDHB and COX II, indicative of suppressed oxidative phosphorylation. Moreover, Mfn2 overexpression or scavenging mitochondria-originated reactive oxygen species (ROS) with mito-TEMPO ameliorated BCATc Inhibitor 2-induced oxidative stress, mitochondrial membrane potential disruption and mitochondrial fission, and abrogated the inhibitory effect of BCATc Inhibitor 2 on glioblastoma cells through PI3K/AKT/mTOR signaling. All of these findings indicate suppression of BCAA metabolism promotes glioblastoma cell apoptosis via disruption of Mfn2-mediated mitochondrial dynamics and inhibition of PI3K/AKT/mTOR pathway, and suggest that BCAA metabolism can be targeted for developing therapeutic agents to treat glioblastoma.

Natural Products in Liver Fibrosis Management: A Five-year Review.

Liver fibrosis, characterized by the overproduction of extracellular matrix proteins within liver tissue, poses a rising global health concern. However, no approved antifibrotic drugs are currently available, highlighting the critical need for understanding the molecular mechanisms of liver fibrosis. This knowledge could not only aid in developing therapies but also enable early intervention, enhance disease prediction, and improve our understanding of the interaction between various underlying conditions and the liver. Notably, natural products used in traditional medicine systems worldwide and demonstrating diverse biochemical and pharmacological activities are increasingly recognized for their potential in treating liver fibrosis. This review aims to comprehensively understand liver fibrosis, emphasizing the molecular mechanisms and advancements in exploring natural products' antifibrotic potential over the past five years. It also acknowledges the challenges in their development and seeks to underscore their potency in enhancing patient prognosis and reducing the global burden of liver disease.

p32/OPA1 axis-mediated mitochondrial dynamics contributes to cisplatin resistance in non-small cell lung cancer.

Cisplatin resistance is a major obstacle in the treatment of non-small cell lung cancer (NSCLC). p32 and OPA1 are the key regulators of mitochondrial morphology and function. This study aims to investigate the role of the p32/OPA1 axis in cisplatin resistance in NSCLC and its underlying mechanism. The levels of p32 protein and mitochondrial fusion protein OPA1 are higher in cisplatin-resistant A549/DDP cells than in cisplatin-sensitive A549 cells, which facilitates mitochondrial fusion in A549/DDP cells. In addition, the expression of p32 and OPA1 protein is also upregulated in A549 cells during the development of cisplatin resistance. Moreover, p32 knockdown effectively downregulates the expression of OPA1, stimulates mitochondrial fission, decreases ATP generation and sensitizes A549/DDP cells to cisplatin-induced apoptosis. Furthermore, metformin significantly downregulates the expressions of p32 and OPA1 and induces mitochondrial fission and a decrease in ATP level in A549/DDP cells. The co-administration of metformin and cisplatin shows a significantly greater decrease in A549/DDP cell viability than cisplatin treatment alone. Moreover, D-erythro-Sphingosine, a potent p32 kinase activator, counteracts the metformin-induced downregulation of OPA1 and mitochondrial fission in A549/DDP cells. Taken together, these findings indicate that p32/OPA1 axis-mediated mitochondrial dynamics contributes to the acquired cisplatin resistance in NSCLC and that metformin resensitizes NSCLC to cisplatin, suggesting that targeting p32 and mitochondrial dynamics is an effective strategy for the prevention of cisplatin resistance.

A novel polymer enabled by polymerized small molecule strategy for tumor photothermal and photodynamic therapy.

Photothermal therapy (PTT) and photodynamic therapy (PDT) are effective method for tumor treatment. However, the limited variety and quantity of photothermal agents (PTAs) and photosensitizer (PSs) are still major challenges. Moreover, the cell apoptosis mechanism induced by PDT and PTT is still elusive. A fused-ring small molecule acceptor-donor acceptor' donor-acceptor (A-DA'D-A) type of Y5 (Scheme 1) has a narrow band-gap and strong light absorption. Herein, we used Y5 to polymerize with thiophene unit to obtain polymer PYT based on polymerized small molecule strategy, and PYT nanoparticles (PYT NPs) was prepared via one-step nanoprecipitation strategy with DSPE-PEG2000. PYT NPs had excellent biocompatibility, good photostability, high photothermal conversion efficiency (67%) and reactive oxygen species (ROS) production capacity under 808 nm laser irradiation (PYT NPs + NIR). In vitro and in vivo experiments revealed that PYT NPs + NIR had the ability to completely ablate tumor cells. It was demonstrated that cell apoptosis induced by PYT NPs + NIR was closely related to mitochondrial damage. This study provides valuable guidance for constructing high-performance organic PTAs and PSs for tumor treatment. Scheme 1 PYT enabled by polymerized small molecule strategy for tumor photothermal and photodynamic therapy.

Digital twin-driven dynamic monitoring system of the upper limb force.

Digital twin represents the core technology to realize the dynamic monitoring of complex industrial systems. However, the human body, as the most complex system in the physical world, digital twin is rarely applied in it. In this study, we successfully demonstrated a digital twin in the human biomedical application by proposing a dynamic monitoring system of the upper limb force. In this system, the real upper limb drives the motion of the virtual one in real-time and dynamically updates the force. Meanwhile, the virtual upper limb feeds back the monitoring-results of the force to the controller of the real upper limb via immersive virtual reality interaction. Experimental results of the typical motions of the upper limb revealed that the proposed system functioned interactively in real-time in a non-invasive manner, while ensuring the accurate solving of the muscle force. In conclusion, our digital twin-driven system is of great importance for rehabilitation medicine, biomechanical scientific research and physical training, promoting the application of the digital twin in the human biomedical field.

Metformin protects against retinal ischemia/reperfusion injury through AMPK-mediated mitochondrial fusion.

Retinal ischemia/reperfusion (I/R) injury is a common pathological process responsible for cellular damage in glaucoma, diabetic retinopathy and hypertensive retinopathy. Metformin is a biguanide drug that exerts strong effects on multiple diseases. This study aims to evaluate the protective effect of metformin against retinal I/R injury and its underlying mechanism. I/R induced reduction in retina thickness and cell number in ganglion cell layer, and metformin alleviated I/R-induced retinal injury. Both retinal I/R and simulated ischemia/reperfusion (SIR) in R28 cells down-regulated expression of mitochondrial fusion protein Mfn2 and OPA1, which led to mitochondrial fission. Metformin also alleviated damage in R28 cells, and reversed the alteration in Mfn2 and OPA1, mitochondrial fission and mitochondrial membrane potential (MMP) disruption-induced by I/R or SIR as well. Intriguingly, inhibition of AMPK by compound C or siRNA prevented metformin-mediated up-regulation of Mfn2 and OPA1. Compound C and knockdown of Mfn2 or OPA1 dramatically alleviated the protective effect of metformin against intracellular ROS generation, MMP disruption, mitochondrial fission and loss of RGCs in ganglion cell layer induced by SIR or I/R. Moreover, scavenging mitochondrial ROS (mito-ROS) by mito-TEMPO exerted the similar protection against I/R-induced retinal injury or SIR-induced damage in R28 cells as metformin. Our data show for the first time that metformin protects against retinal I/R injury through AMPK-mediated mitochondrial fusion and the decreased mito-ROS generation. These findings might also repurpose metformin as a therapeutic agent for retinal I/R injury.

Lactate protects against oxidative stress-induced retinal degeneration by activating autophagy.

Age-related macular degeneration is a common cause of blindless among the aged, which can mainly be attributed to oxidative stress and dysregulated autophagy in retinal pigment epithelium cells. Lactate was reported to act as a signaling molecule and exerted beneficial effect against oxidative stress. This study aims to investigate the protective effect of lactate against oxidative stress-induced retinal degeneration. Here, H2O2-induced oxidative stress cell model and sodium iodate-induced mice retinal degeneration model were established. It was found that H2O2 inhibited cell viability in ARPE-19 cells and sodium iodate induced deterioration of retinal pigment epithelium as well as apoptosis in retina. Pretreatment with lactate alleviated oxidative stress-induced cell death and retinal degeneration. Molecularly, lactate activated autophagy by up-regulating the ratio of LC3II/I, increased formation of LC3 puncta and autophagic vacuole. Further, lactate prevented H2O2-induced mitochondrial fission and maintained mitochondrial function by alleviating H2O2-induced mitochondrial membrane potential disruption and intracellular ROS generation. In contrast, application of 3-methyladenine, an inhibitor of autophagy, effectively weakened the protective effect of lactate against oxidative stress in vivo and in vitro. Taken together, all data in this study indicate that lactate protects against oxidative stress-induced retinal degeneration and preserves mitochondrial function by activating autophagy.

Baicalein sensitizes triple negative breast cancer MDA-MB-231 cells to doxorubicin via autophagy-mediated down-regulation of CDK1.

Triple negative breast cancer (TNBC) is a kind of refractory cancer with poor response to conventional chemotherapy. Recently, the combination of baicalein and doxorubicin was reported to exert a synergistic antitumor effect on breast cancer. However, the underlying mechanism how baicalein sensitizes breast cancer cells to doxorubicin remains to be elucidated. Here, it was found that 20 µM baicalein increased the autophagy markers including the ratio of LC3B II/I, GFP-LC3 punctate aggregates and down-regulation of p62 expression, and up-regulated mitophagy marker PINK1 and Parkin in TNBC MDA-MB-231 cells as well. In contrast, doxorubicin decreased the levels of autophagy markers, and significantly up-regulated CDK1 in MDA-MB-231 cells. Pretreatment with baicalein markedly inhibited the doxorubicin-induced decrease in autophagy markers and up-regulation of CDK1, which was reversed by the autophagy inhibitor 3-Methyladenine. Moreover, baicalein alleviated the doxorubicin-induced expression and phosphorylation (at Ser616) of mitochondrial fission protein Drp1. Intriguingly, the autophagy inhibitor 3-Methyladenine also significantly weakened the effect of baicalein on doxorubicin-induced viability decrease and apoptosis in MDA-MB-231 cells. Taken together, our data indicate that baicalein improves the chemosensitivity of TNBC cells to doxorubicin through promoting the autophagy-mediated down-regulation of CDK1, also suggest a novel strategy for prevention of TNBC in the future.

BCATc inhibitor 2 ameliorated mitochondrial dysfunction and apoptosis in oleic acid-induced non-alcoholic fatty liver disease model.

Nonalcoholic fatty liver disease (NAFLD) is a prevalent hepatic disease in the world. Disorders of branched chain amino acid (BCAA) metabolism is involved in various diseases. In this study, we aim to explore the role of BCAA metabolism in the development of NAFLD and the protective effect of BCATc Inhibitor 2, an inhibitor of cytosolic branched chain amino acid transaminase, against NAFLD as well as its underlying mechanism. It was found that oleic acid induced lipid accumulation and apoptosis in HepG2 and LO2 cells. Supplementation of BCAAs further aggravated oleic acid-induced lipid accumulation and apoptosis. In contrast, treatment of BCATc Inhibitor 2 ameliorated oleic acid-induced lipid accumulation and apoptosis. Molecularly, supplementation of BCAAs or treatment of BCATc Inhibitor 2 up-regulated or down-regulated the expression of SREBP1 and lipogenesis-related genes without affecting lipolysis-related genes. BCATc Inhibitor 2 maintained mitochondrial function by ameliorating oleic acid-induced mitochondrial ROS generation and mitochondrial membrane potential disruption. In addition, BCATc Inhibitor 2 treatment alleviated oleic acid-induced activation of JNK and AKT signaling pathway and Bcl2/Bax/Caspase axis. In conclusion, our results indicate BCAA metabolism is involved in NAFLD and BCATc Inhibitor 2 protects against oleic acid-induced lipid accumulation and apoptosis. These findings suggest that BCATc Inhibitor 2 is a promising candidate drug for the treatment of NAFLD.

Metformin-induced AMPK activation promotes cisplatin resistance through PINK1/Parkin dependent mitophagy in gastric cancer.

Gastric cancer (GC) is one of the most common tumors worldwide, and cisplatin is a standard chemotherapeutic reagent for GC treatment. However, chemoresistance is an inherent challenge which limits its application and effectiveness in clinic. This study aims to investigate the mechanism of metformin-induced cisplatin resistance in GC. Intriguingly, the upregulation of mitophagy markers, mitochondrial fission, autophagy and mitophagosome were observed in SGC-7901/DDP cells compared to those in the SGC-7901 cells. Treatment with metformin significantly increased mitochondrial fission and mitophagy in both AGS and SGC-7901 cells, resulting in decreased ATP production, which unexpectedly protected GC cells against the cytotoxicity of cisplatin. In contrast, application of Chloroquine and 3-methyladenine, two inhibitors of autophagy, significantly alleviated the protective effect of metformin on SGC-7901 and AGS cells against cytotoxicity of cisplatin. Moreover, metformin also stimulated the phosphorylation of AMPK (Thr172) and increased the expression of mitophagy markers including Parkin and PINK1 in the AMPK signaling-dependent manner. Consistently, the cell viability and cell apoptosis assay showed that metformin-induced cisplatin resistance was prevented by knockdown of AMPKα1. Taken together, all data in this study indicate that metformin induced AMPK activation and PINK1/Parkin dependent mitophagy, which may contribute to the progression of cisplatin resistance in GC.

Curcumin protects retinal neuronal cells against oxidative stress-induced damage by regulating mitochondrial dynamics.

Oxidative stress plays a crucial role in the damage of retinal neuronal cells. Curcumin, the phytocompound, has anti-inflammatory and antioxidative properties. It was shown that curcumin exerted a beneficial effect on retinal neuronal cell survival. However, the role of mitochondrial dynamics in curcumin-mediated protective effect on retinal neuronal cells remains to be elucidated. Here, H2O2 was used to mimic the oxidative stress in retinal neuronal R28 cells. Drp1 and Mfn2 are key regulators of mitochondrial fission and fusion. 100 µM of H2O2 significantly increased the cleavage of caspase-3 and Drp1 expression, but downregulated the expression of Mfn2. Pretreatment with 5 µM curcumin effectively alleviated H2O2-induced alterations in the expression of Drp1 and Mfn2 and mitochondrial fission in R28 cells. In addition, curcumin and Drp1 knockdown prevented H2O2-induced intracellular ROS increment and mitochondrial membrane potential disruption. On the contrary, knockdown of Mfn2 diminished curcumin-mediated protection against ROS increment and mitochondrial membrane potential disruption after H2O2. Moreover, curcumin protected R28 cells against H2O2-induced PINK1 expression, mitophagy, caspase-3 cleavage and apoptosis. Knockdown of Mfn2 significantly alleviated the protective effect of curcumin on R28 cells after H2O2. Taken together, our data indicate that curcumin protects against oxidative stress-induced injury in retinal neuronal cells by promoting mitochondrial fusion.

Chrysophanol-8-O-glucoside protects mice against acute liver injury by inhibiting autophagy in hepatic stellate cells and inflammatory response in liver-resident macrophages.

Acute liver failure (ALF) is an unfavorable condition characterized by the rapid loss of liver function and high mortality. Chrysophanol-8-O-glucoside (CPOG) is an anthraquinone derivative isolated from rhubarb. This study aims to evaluate the protective effect of CPOG on lipopolysaccharide (LPS)/D-GalN-induced ALF and its underlying mechanisms. LPS/D-GalN-induced mice ALF model and LPS treatment model in RAW 264.7 and LX2 cells were established. It was found that CPOG ameliorated LPS/D-GalN-induced liver injury and improved mortality as indicated by Hematoxylin-eosin (H&E) staining. Molecularly, qPCR and ELISA results showed that CPOG alleviated LPS/D-GalN-induced release of alanine aminotransferase and aspartate transaminase and the secretion of TNF-α and IL-1ß in vivo. LPS/D-GalN-induced intracellular ROS production was also attenuated by CPOG in liver tissue. Further, CPOG attenuated ROS generation and inhibited the expression of p-IκB and p-p65 as well as the expression of TNF-α and IL-1ß stimulated by LPS in RAW 264.7 cells. In addition, CPOG alleviated LPS-induced up-regulation of LC3B, p62, ATG5 and Beclin1 by attenuating ROS production and inhibiting MAPK signaling in LX2 cells. Taken together, our data indicated that the CPOG protected against LPS/D-GalN-induced ALF by inhibiting oxidative stress, inflammation response and autophagy. These findings suggest that CPOG could be potential drug for the treatment of ALF in clinic.

Drp1-dependent mitochondrial fission mediates corneal injury induced by alkali burn.

Corneal alkali burn, one of the most serious ophthalmic emergencies, is difficult to be cured by conservative treatments. It is well known that oxidative stress, inflammation and neovascularization are the main causes of corneal damage after alkali burn, but its underlying mechanism remains to be elucidated. Here, we reported that the expression and phosphorylation (Ser616) of mitochondrial fission protein Drp1 were up-regulated at day 3 after alkali burn, while mitochondrial fusion protein Mfn2 was down-regulated. The phosphorylation of ERK1/2 in corneas was increased at day 1, 3, 7 and peaked at day 3 after alkali burn. In human corneal epithelial cells (HCE-2), NaOH treatment induced mitochondrial fission, intracellular ROS production and mitochondrial membrane potential disruption, which was prevented by Drp1 inhibitor Mdivi-1. In corneas, Mdivi-1 or knockdown of Drp1 by Lenti-Drp1 shRNA attenuated alkali burn-induced ROS production and phosphorylation of IκBα and p65. In immunofluorescence staining, it was detected that Mdivi-1 also prevented NaOH-induced nuclear translocation of p65 in HCE-2 cells. Moreover, the expression of NADPH oxidase NOX2 and NOX4 in corneas peaked at day 7 after alkali burn. Mdivi-1, Lenti-Drp1 shRNA or the mitochondria-targeted antioxidant mito-TEMPO efficiently alleviated activation of NF-κB, expression of NOX2/4 and inflammatory cytokines including IL-6, IL-1ß and TNF-α in corneas after alkali burn. In pharmacological experiments, both Mdivi-1 and NADPH oxidases inhibitor Apocynin protected the corneas against alkali burn-induced neovascularization. Intriguingly, the combined administration of Mdivi-1 and Apocynin had a synergistic inhibitory effect on corneal neovascularization after alkali burn. Taken together, these results indicate that Drp1-dependent mitochondrial fission is involved in alkali burn-induced corneal injury through regulating oxidative stress, inflammatory responses and corneal neovascularization. This might provide a novel therapeutic target for corneal injury after alkali burn in the future.

Blockage of Drp1 phosphorylation at Ser579 protects neurons against Aß1­42­induced degeneration.

Alzheimer's disease (AD), one of the most common types of chronic neurodegenerative diseases, is pathologically characterized by the formation of amyloid ß (Aß) peptide­containing plaques and neurofibrillary tangles. Among Aß peptides, Aß1­42 induces neuronal toxicity and neurodegeneration. In our previous studies, Cdk5 was found to regulate Aß1­42­induced mitochondrial fission via the phosphorylation of dynamin­related protein 1 (Drp1) at Ser579. However, whether blockage of Drp1 phosphorylation at Ser579 protects neurons against Aß1­42­induced degeneration remains to be elucidated. Thus, the aim the present study was to examine the effect of mutant Drp1­S579A on neurodegeneration and its underlying mechanism. First, the phosphorylation­defect (phospho­defect) mutant, Lenti­Drp1­S579A was constructed. Phospho­defect Drp1­S579A expression was detected in primary cultures of mouse cortical neurons infected with Lenti­Drp1­S579A using western blotting and it was found to successfully attenuate the phosphorylation of endogenous Drp1 at Ser579. In primary neuronal cultures, the neuronal processes were evaluated under microscopy. Treatment with 10 µM Aß1­42 significantly decreased dendritic density and length, spine outgrowth and synapse number. As expected, infection of neurons with Lenti­Drp1­S579A efficiently alleviated the inhibitory effect of Aß1­42 on neurite outgrowth and synapse density. In addition, infection with Lenti­Drp1­S579A abolished the cleavage of caspase­3 and apoptosis in neurons exposed to Aß1­42. Thus, the current data demonstrated that blockage of Drp1 phosphorylation at Ser579 may be an effective strategy to protect neurons against Aß1­42­induced degeneration and apoptosis. These findings underline the therapeutic potential of targeting Drp1 in the treatment of AD.

Mitochondrial Dynamics Mediated by DRP1 and MFN2 Contributes to Cisplatin Chemoresistance in Human Ovarian Cancer SKOV3 cells.

Cisplatin (DDP) is the first-line chemotherapeutic agent for ovarian cancer. However, the development of DDP resistance seriously influences the chemotherapeutic effect and prognosis of ovarian cancer. It was reported that DDP can directly impinge on the mitochondria and activate the intrinsic apoptotic pathway. Herein, the role of mitochondrial dynamics in DDP chemoresistance in human ovarian cancer SKOV3 cells was investigated. In DDP-resistant SKOV3/DDP cells, mitochondrial fission protein DRP1 was down-regulated, while mitochondrial fusion protein MFN2 was up-regulated. In accordance with the expression of DRP1 and MFN2, the average mitochondrial length was significantly increased in SKOV3/DDP cells. In DDP-sensitive parental SKOV3 cells, downregulation of DRP1 and upregulation of mitochondrial fusion proteins including MFN1,2 and OPA1 occurred at day 2~6 under cisplatin stress. Knockdown of DRP1 or overexpression of MFN2 promoted the resistance of SKOV3 cells to cisplatin. Intriguingly, weaker migration capability and lower ATP level were detected in SKOV3/DDP cells. Respective knockdown of DRP1 in parental SKOV3 cells or MFN2 in SKOV3/DDP cells using siRNA efficiently reversed mitochondrial dynamics, migration capability and ATP level. Moreover, MFN2 siRNA significantly aggravated the DDP-induced ROS production, mitochondrial membrane potential disruption, expression of pro-apoptotic protein BAX and Cleaved Caspase-3/9 in SKOV3/DDP cells. In contrast, DRP1 siRNA alleviated DDP-induced ROS production, mitochondrial membrane potential disruption, expression of pro-apoptotic protein BAX and Cleaved Caspase-3/9 in SKOV3 cells. Thus, these results indicate that mitochondrial dynamics mediated by DRP1 and MFN2 contributes to the development of DDP resistance in ovarian cancer cells, and will also provide a new strategy to prevent chemoresistance in ovarian cancer by targeting mitochondrial dynamics.