scholarly journals Mfn2 Regulates High Glucose-Induced MAMs Dysfunction and Apoptosis in Podocytes via PERK Pathway

2021 ◽  
Vol 9 ◽  
Author(s):  
Yun Cao ◽  
Zhaowei Chen ◽  
Jijia Hu ◽  
Jun Feng ◽  
Zijing Zhu ◽  
...  
Keyword(s):  
Mitochondrial Dysfunction ◽  
High Glucose ◽  
Diabetic Rats ◽  
Mitochondrial Morphology ◽  
Podocyte Injury ◽  
Unfolded Protein ◽  
Mitochondrial Functions ◽  
Protein Response ◽  
Apoptotic Effects

The endoplasmic reticulum (ER) stress and mitochondrial dysfunction in high glucose (HG)-induced podocyte injury have been demonstrated to the progression of diabetic kidney disease (DKD). However, the pathological mechanisms remain equivocal. Mitofusin2 (Mfn2) was initially identified as a dynamin-like protein involved in fusing the outer mitochondrial membrane (OMM). More recently, Mfn2 has been reported to be located at the ER membranes that contact OMM. Mitochondria-associated ER membranes (MAMs) is the intercellular membrane subdomain, which connects the mitochondria and ER through a proteinaceous tether. Here, we observed the suppression of Mfn2 expression in the glomeruli and glomerular podocytes of patients with DKD. Streptozotocin (STZ)-induced diabetic rats exhibited abnormal mitochondrial morphology and MAMs reduction in podocytes, accompanied by decreased expression of Mfn2 and activation of all three unfolded protein response (UPR) pathways (IRE1, ATF6, and PERK). The HG-induced mitochondrial dysfunction, MAMs reduction, and increased apoptosis in vitro were accompanied by the downregulation of Mfn2 and activation of the PERK pathway. Mfn2 physically interacts with PERK, and HG promotes a decrease in Mfn2-PERK interaction. In addition, Mfn2-silenced podocytes showed mitochondrial dysfunction, MAMs reduction, activation of PERK pathway, and increased apoptosis. Conversely, all these effects of HG stimulation were alleviated significantly by Mfn2 overexpression. Furthermore, the inhibition of PERK phosphorylation protected mitochondrial functions but did not affect the expression of Mfn2 in HG-treated podocytes. Therefore, this study confirmed that Mfn2 regulates the morphology and functions of MAMs and mitochondria, and exerts anti-apoptotic effects on podocytes by inhibiting the PERK pathway. Hence, the Mfn2-PERK signaling pathway may be a new therapeutic target for preventing podocyte injury in DKD.

scholarly journals Dominant negative FADD dissipates the proapoptotic signalosome of the unfolded protein response in diabetic embryopathy

2015 ◽  
Vol 309 (10) ◽  
pp. E861-E873 ◽  
Author(s):  
Fang Wang ◽  
Hongbo Weng ◽  
Michael J. Quon ◽  
Jingwen Yu ◽  
Jian-Ying Wang ◽  
...  
Keyword(s):  
Er Stress ◽  
Unfolded Protein Response ◽  
High Glucose ◽  
Dominant Negative ◽  
Caspase 8 ◽  
Death Domain ◽  
Unfolded Protein ◽  
Protein Response

Endoplasmic reticulum (ER) stress and caspase 8-dependent apoptosis are two interlinked causal events in maternal diabetes-induced neural tube defects (NTDs). The inositol-requiring enzyme 1α (IRE1α) signalosome mediates the proapoptotic effect of ER stress. Diabetes increases tumor necrosis factor receptor type 1R-associated death domain (TRADD) expression. Here, we revealed two new unfolded protein response (UPR) regulators, TRADD and Fas-associated protein with death domain (FADD). TRADD interacted with both the IRE1α-TRAF2-ASK1 complex and FADD. In vivo overexpression of a FADD dominant negative (FADD-DN) mutant lacking the death effector domain disrupted diabetes-induced IRE1α signalosome and suppressed ER stress and caspase 8-dependent apoptosis, leading to NTD prevention. FADD-DN abrogated ER stress markers and blocked the JNK1/2-ASK1 pathway. Diabetes-induced mitochondrial translocation of proapoptotic Bcl-2 members mitochondrial dysfunction and caspase cleavage were also alleviated by FADD-DN. In vitro TRADD overexpression triggered UPR and ER stress before manifestation of caspase 3 and caspase 8 cleavage and apoptosis. FADD-DN overexpression repressed high glucose- or TRADD overexpression-induced IRE1α phosphorylation, its downstream proapoptotic kinase activation and endonuclease activities, and apoptosis. FADD-DN also attenuated tunicamycin-induced UPR and ER stress. These findings suggest that TRADD participates in the IRE1α signalosome and induces UPR and ER stress and that the association between TRADD and FADD is essential for diabetes- or high glucose-induced UPR and ER stress.

scholarly journals PKC-α Triggers EGFR Ubiquitination, Endocytosis and ERK Activation in Podocytes Stimulated with High Glucose

2017 ◽  
Vol 42 (1) ◽  
pp. 281-294 ◽  
Author(s):  
Chun-Tao Lei ◽  
Yan-Hong Wei ◽  
Hui Tang ◽  
Qian Wen ◽  
Chen Ye ◽  
...  
Keyword(s):  
Lipid Raft ◽  
High Glucose ◽  
Growth Factor Receptor ◽  
In Vitro Study ◽  
Diabetic Rats ◽  
Kidney Cortex ◽  
Podocyte Injury ◽  
Erk Activation ◽  
Signaling Activation

Background: Protein Kinase C-α (PKC-α) and epidermal growth factor receptor (EGFR) are both involved in diabetic kidney disease; however, the connection between these two proteins during high glucose-induced podocyte injury remains uncertain. Methods: Diabetes was induced in SD rats by streptozotocin (STZ). Fourteen days later, the kidney cortex was removed and subjected to plasma membrane isolation and lipid raft fractionation. In vitro study human podocyte cell line was differentiated and subjected to various treatments. The levels of membranous protein and endocytosis were assessed by biotinylation and sodium 2-mercaptoethane sulfonate (MesNa) treatment. Gö6976 and PYR-41 were used as inhibitors of PKC-α and ubiquitin activating E1 enzyme, respectively. Results: In diabetic rats, the abundance of PKC-α in the membranous fraction and the lipid raft domain is elevated, whereas the EGFR level is reduced. Consistently, in vitro high glucose treated podocytes, membranous EGFR is downregulated with increased PKC-α. Furthermore, the ubiquitination and endocytosis of EGFR are enhanced accompanied by extracellular signal–regulated kinase (ERK) signaling activation and podocyte damage during hyperglycemia. However, these processes can be ameliorated by inhibition of either PKC-α or ubiquitin activating E1 enzyme. Conclusion: During hyperglycemia, PKC-α mediates podocytic EGFR ubiquitination, endocytosis from cell surface and the subsequent ERK activation, which contributes to podocyte injury.

scholarly journals Unfolded Protein Response Pathways Correlatively Modulate Endoplasmic Reticulum Stress Responses in Rat Retinal Müller Cells

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Shengyu Wu ◽  
Xiaolu Zhu ◽  
Biechuan Guo ◽  
Tian Zheng ◽  
Jiangbo Ren ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Transcription Factor ◽  
Endoplasmic Reticulum Stress ◽  
High Glucose ◽  
Müller Cells ◽  
Muller Cells ◽  
Unfolded Protein ◽  
Activating Transcription Factor ◽  
Protein Response

Background. Endoplasmic reticulum stress (ERS) in the retinal Müller cells is a key factor contributing to the retinal inflammation and vascular leakage in diabetic retinopathy (DR). This study was to investigate the underlying mechanisms through which the 3 main unfolded protein response (UPR) pathways regulate ERS and to examine the expression levels of vascular endothelial growth factor (VEGF) in Müller cells in vitro. Methods. Rat Müller cell lines were stimulated with high glucose to mimic a diabetic environment in vitro. PKR-like endoplasmic reticulum kinase (PERK), inositol-requiring enzyme 1 (IRE1) and activating transcription factor 6 (ATF6) were downregulated or upregulated with shRNA or overexpression plasmids. The transfected Müller cells were cultivated in high glucose medium for 48 hours. Expression of glucose-regulated protein 78 (GRP78), activating transcription factor 4 (ATF4), X-box binding protein 1 (XBP1), ATF6, and VEGF was examined with immunofluorescence and western blot. Results. Our data indicated that ERS was found in both high glucose and osmotic control groups. Overexpression or downregulation of UPR pathways effectively increased or reduced the production of GRP78, ATF4, XBP1, ATF6, and VEGF, respectively. These 3 signaling pathways had similar regulatory effects on VEGF. Conclusion. The 3 UPR-mediated inflammatory pathways were dependent on each other. Inhibition any of these signaling pathways in UPR might be a potential therapeutic target for DR.

scholarly journals Effect of Tongxinluo on Nephrin Expression via Inhibition of Notch1/Snail Pathway in Diabetic Rats

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Fangqiang Cui ◽  
Dawei Zou ◽  
Yanbin Gao ◽  
Na Zhang ◽  
Jinyang Wang ◽  
...  
Keyword(s):  
Diabetic Nephropathy ◽  
Molecular Mechanism ◽  
High Glucose ◽  
Diabetic Rats ◽  
In Vitro Studies ◽  
Podocyte Injury ◽  
Snail Expression ◽  
Renal Structure

Podocyte injury is an important mechanism of diabetic nephropathy (DN). Accumulating evidence suggests that nephrin expression is decreased in podocyte in DN. Moreover, it has been demonstrated that tongxinluo (TXL) can ameliorate renal structure disruption and dysfunction in DN. However, the effect of TXL on podocyte injury in DN and its molecular mechanism is unclear. In order to explore the effect of TXL on podocyte injury and its molecular mechanism in DN, our in vivo and in vitro studies were performed. Our results showed that TXL increased nephrin expression in diabetic rats and in high glucose cultured podocyte. Meanwhile, TXL decreased ICN1 (the intracellular domain of notch), HES1, and snail expression in podocyte in vivo and in vitro. More importantly, we found that TXL protected podocyte from injury in DN. The results demonstrated that TXL inhibited the activation of notch1/snail pathway and increased nephrin expression, which may be a mechanism of protecting effect on podocyte injury in DN.

scholarly journals The Role of Mitochondrial Dysfunction and ER Stress in TDP-43 and C9ORF72 ALS

2021 ◽  
Vol 15 ◽  
Author(s):  
Ruxandra Dafinca ◽  
Paola Barbagallo ◽  
Kevin Talbot
Keyword(s):  
Er Stress ◽  
Mitochondrial Dysfunction ◽  
Unfolded Protein Response ◽  
Nucleocytoplasmic Transport ◽  
Cellular Processes ◽  
Unfolded Protein ◽  
The Unfolded Protein Response ◽  
Protein Response

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease of the motor system with complex determinants, including genetic and non-genetic factors. Despite this heterogeneity, a key pathological signature is the mislocalization and aggregation of specific proteins in the cytoplasm, suggesting that convergent pathogenic mechanisms focusing on disturbances in proteostasis are important in ALS. In addition, many cellular processes have been identified as potentially contributing to disease initiation and progression, such as defects in axonal transport, autophagy, nucleocytoplasmic transport, ER stress, calcium metabolism, the unfolded protein response and mitochondrial function. Here we review the evidence from in vitro and in vivo models of C9ORF72 and TDP-43-related ALS supporting a central role in pathogenesis for endoplasmic reticulum stress, which activates an unfolded protein response (UPR), and mitochondrial dysfunction. Disruption in the finely tuned signaling between the ER and mitochondria through calcium ions may be a crucial trigger of mitochondrial deficits and initiate an apoptotic signaling cascade, thus acting as a point of convergence for multiple upstream disturbances of cellular homeostasis and constituting a potentially important therapeutic target.

Hyperbaric oxygen therapy attenuates D-galactose-induced-age-related cardiac dysfunction through mitigating cardiac mitochondrial dysfunction in pre-diabetic rats

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
C Bo-Htay ◽  
T Shwe ◽  
S Palee ◽  
T Pattarasakulchai ◽  
K Shinlapawittayatorn ◽  
...  
Keyword(s):  
Mitochondrial Dysfunction ◽  
High Fat Diet ◽  
Diabetic Rats ◽  
Normal Diet ◽  
Lv Function ◽  
High Fat ◽  
Insulin Resistant ◽  
Lv Dysfunction ◽  
Age Related ◽  
Mitochondrial Functions

Abstract Background D-galactose (D-gal) induced ageing has been shown to exacerbate left ventricular (LV) dysfunction via worsening of apoptosis and mitochondrial dysfunction in the heart of obese rats. Hyperbaric oxygen therapy (HBOT) has been demonstrated to exert anti-inflammatory and anti-apoptotic effects in multiple neurological disorders. However, the cardioprotective effect of HBOT on inflammation, apoptosis, LV and mitochondrial functions in D-gal induced ageing rats in the presence of obese-insulin resistant condition has never been investigated. Purpose We sought to determine the effect of HBOT on inflammation, apoptosis, mitochondrial functions and LV function in pre-diabetic rats with D-gal induced ageing. We hypothesized that HBOT attenuates D-gal induced cardiac mitochondrial dysfunctions and reduces inflammation and apoptosis, leading to improved LV function in pre-diabetic rats. Methods Forty-eight male Wistar rats were fed with either normal diet or high-fat diet for 12 weeks. Then, rats were treated with either vehicle groups (0.9% NSS, subcutaneous injection (SC)) or D-gal groups (150 mg/kg/day, SC) for 8 weeks. At week 21, rats in each group were equally divided into 6 sub-groups: normal diet fed rats treated with vehicle (NDV) sham, normal diet fed rats treated with D-gal (NDDg) sham, high fat diet fed rats treated with D-gal (HFDg) sham, high fat diet fed rats treated with vehicle (HFV) + HBOT, NDDg + HBOT and HFDg + HBOT. Sham treated rats were given normal concentration of O2 (flow rate of 80 L/min, 1 ATA for 60 minutes), whereas HBOT treated rats were subjected to 100% O2 (flow rate of 250 L/min, 2 ATA for 60 minutes), given once daily for 2 weeks. Results Under obese-insulin resistant condition, D-gal-induced ageing aggravated LV dysfunction (Fig 1A) and impaired cardiac mitochondrial function, increased cardiac inflammatory and apoptotic markers (Fig 1B). HBOT markedly reduced cardiac TNF-α level and TUNEL positive apoptotic cells, and improved cardiac mitochondrial function as indicated by decreased mitochondrial ROS production, mitochondrial depolarization and mitochondrial swelling, resulting in the restoration of the normal LV function in HFV and NDDg rats, compared to sham NDDg rats. In addition, in HFDg treated rats, HBOT attenuated cardiac TNF-α level, TUNEL positive apoptotic cells and cardiac mitochondrial dysfunction, compared to sham HFDg rats, leading to improved cardiac function as indicated by increased %LV ejection fraction (LVEF) (Figure 1). Conclusion HBOT efficiently alleviates D-gal-induced-age-related LV dysfunction through mitigating inflammation, apoptosis and mitochondrial dysfunction in pre-diabetic rats. Figure 1 Funding Acknowledgement Type of funding source: Public grant(s) – National budget only. Main funding source(s): 1. The National Science and Technology Development Agency Thailand, 2. Thailand Research Fund Grants

scholarly journals The Effects of Bergamot Polyphenolic Fraction, Cynara cardunculus, and Olea europea L. Extract on Doxorubicin-Induced Cardiotoxicity

Nutrients ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 2158
Author(s):  
Jessica Maiuolo ◽  
Irene Bava ◽  
Cristina Carresi ◽  
Micaela Gliozzi ◽  
Vincenzo Musolino ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Apoptotic Cell ◽  
Natural Compounds ◽  
Cynara Cardunculus ◽  
Unfolded Protein ◽  
Wide Range ◽  
Vitro Model ◽  
The Unfolded Protein Response ◽  
Protein Response

Doxorubicin is an anthracycline that is commonly used as a chemotherapy drug due to its cytotoxic effects. The clinical use of doxorubicin is limited due to its known cardiotoxic effects. Treatment with anthracyclines causes heart failure in 15–17% of patients, resulting in mitochondrial dysfunction, the accumulation of reactive oxygen species, intracellular calcium dysregulation, the deterioration of the cardiomyocyte structure, and apoptotic cell death. Polyphenols have a wide range of beneficial properties, and particular importance is given to Bergamot Polyphenolic Fraction; Oleuropein, one of the main polyphenolic compounds of olive oil; and Cynara cardunculus extract. These natural compounds have particular beneficial characteristics, owing to their high polyphenol contents. Among these, their antioxidant and antoproliferative properties are the most important. The aim of this paper was to investigate the effects of these three plant derivatives using an in vitro model of cardiotoxicity induced by the treatment of rat embryonic cardiomyoblasts (H9c2) with doxorubicin. The biological mechanisms involved and the crosstalk existing between the mitochondria and the endoplasmic reticulum were examined. Bergamot Polyphenolic Fraction, Oleuropein, and Cynara cardunculus extract were able to decrease the damage induced by exposure to doxorubicin. In particular, these natural compounds were found to reduce cell mortality and oxidative damage, increase the lipid content, and decrease the concentration of calcium ions that escaped from the endoplasmic reticulum. In addition, the direct involvement of this cellular organelle was demonstrated by silencing the ATF6 arm of the Unfolded Protein Response, which was activated after treatment with doxorubicin.

scholarly journals High glucose induces Drp1-mediated mitochondrial fission via the Orai1 calcium channel to participate in diabetic cardiomyocyte hypertrophy

2021 ◽  
Vol 12 (2) ◽  
Author(s):  
Qing-Rui Wu ◽  
Dan-Lin Zheng ◽  
Pei-Ming Liu ◽  
Hui Yang ◽  
Lu-An Li ◽  
...  
Keyword(s):  
Calcium Channel ◽  
Mitochondrial Dysfunction ◽  
High Glucose ◽  
Mitochondrial Dynamics ◽  
Mitochondrial Fission ◽  
Calcium Handling ◽  
Cardiomyocyte Hypertrophy ◽  
Mitochondrial Morphology ◽  
Calmodulin Binding ◽  
Downstream Target

AbstractMitochondrial dysfunction and impaired Ca2+ handling are involved in the development of diabetic cardiomyopathy (DCM). Dynamic relative protein 1 (Drp1) regulates mitochondrial fission by changing its level of phosphorylation, and the Orai1 (Ca2+ release-activated calcium channel protein 1) calcium channel is important for the increase in Ca2+ entry into cardiomyocytes. We aimed to explore the mechanism of Drp1 and Orai1 in cardiomyocyte hypertrophy caused by high glucose (HG). We found that Zucker diabetic fat rats induced by administration of a high-fat diet develop cardiac hypertrophy and impaired cardiac function, accompanied by the activation of mitochondrial dynamics and calcium handling pathway-related proteins. Moreover, HG induces cardiomyocyte hypertrophy, accompanied by abnormal mitochondrial morphology and function, and increased Orai1-mediated Ca2+ influx. Mechanistically, the Drp1 inhibitor mitochondrial division inhibitor 1 (Mdivi-1) prevents cardiomyocyte hypertrophy induced by HG by reducing phosphorylation of Drp1 at serine 616 (S616) and increasing phosphorylation at S637. Inhibition of Orai1 with single guide RNA (sgOrai1) or an inhibitor (BTP2) not only suppressed Drp1 activity and calmodulin-binding catalytic subunit A (CnA) and phosphorylated-extracellular signal-regulated kinase (p-ERK1/2) expression but also alleviated mitochondrial dysfunction and cardiomyocyte hypertrophy caused by HG. In addition, the CnA inhibitor cyclosporin A and p-ERK1/2 inhibitor U0126 improved HG-induced cardiomyocyte hypertrophy by promoting and inhibiting phosphorylation of Drp1 at S637 and S616, respectively. In summary, we identified Drp1 as a downstream target of Orai1-mediated Ca2+ entry, via activation by p-ERK1/2-mediated phosphorylation at S616 or CnA-mediated dephosphorylation at S637 in DCM. Thus, the Orai1–Drp1 axis is a novel target for treating DCM.

scholarly journals Increased long noncoding RNA maternally expressed gene 3 contributes to podocyte injury induced by high glucose through regulation of mitochondrial fission

2020 ◽  
Vol 11 (9) ◽  
Author(s):  
Qiongxia Deng ◽  
Ruowei Wen ◽  
Sirui Liu ◽  
Xiaoqiu Chen ◽  
Shicong Song ◽  
...  
Keyword(s):  
High Glucose ◽  
Noncoding Rna ◽  
Diabetic Kidney Disease ◽  
Mitochondrial Fission ◽  
Diabetic Mice ◽  
Podocyte Injury ◽  
Mitochondrial Translocation ◽  
Maternally Expressed Gene 3

Abstract Excessive mitochondrial fission plays a key role in podocyte injury in diabetic kidney disease (DKD), and long noncoding RNAs (lncRNAs) are important in the development and progression of DKD. However, lncRNA regulation of mitochondrial fission in podocytes is poorly understood. Here, we studied lncRNA maternally expressed gene 3 (Meg3) in mitochondrial fission in vivo and in vitro using human podocytes and Meg3 podocyte-specific knockdown mice. Expression of lncRNA Meg3 in STZ-induced diabetic mice was higher, and correlated with the number of podocytes. Excessive mitochondrial fission of podocytes and renal histopathological and physiological parameters were improved in podocyte-specific Meg3 knockdown diabetic mice. Elongated mitochondria with attenuated podocyte damage, as well as mitochondrial translocation of dynamin-related protein 1 (Drp1), were decreased in Meg3 knockout podocytes. By contrast, increased fragmented mitochondria, podocyte injury, and Drp1 expression and phosphorylation were observed in lncRNA Meg3-overexpressing podocytes. Treatment with Mdivi1 significantly blunted more fragmented mitochondria and reduced podocyte injury in lncRNA Meg3-overexpressing podocytes. Finally, fragmented mitochondria and Drp1 mitochondrial translocation induced by high glucose were reduced following treatment with Mdivi1. Our data show that expression of Meg3 in podocytes in both human cells and diabetic mice was higher, which regulates mitochondrial fission and contributes to podocyte injury through increased Drp1 and its translocation to mitochondria.

scholarly journals HiPSC-Derived Hepatocyte-like Cells Can Be Used as a Model for Transcriptomics-Based Study of Chemical Toxicity

Toxics ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 1
Author(s):  
Sreya Ghosh ◽  
Jonathan De Smedt ◽  
Tine Tricot ◽  
Susana Proença ◽  
Manoj Kumar ◽  
...  
Keyword(s):  
Response To Treatment ◽  
Chemical Toxicity ◽  
Hepatocellular Injury ◽  
Unfolded Protein ◽  
Toxicity Studies ◽  
Toxicity Risk ◽  
Transcriptomics Data ◽  
Induced Pluripotent ◽  
Protein Response

Traditional toxicity risk assessment approaches have until recently focussed mainly on histochemical readouts for cell death. Modern toxicology methods attempt to deduce a mechanistic understanding of pathways involved in the development of toxicity, by using transcriptomics and other big data-driven methods such as high-content screening. Here, we used a recently described optimised method to differentiate human induced pluripotent stem cells (hiPSCs) to hepatocyte-like cells (HLCs), to assess their potential to classify hepatotoxic and non-hepatotoxic chemicals and their use in mechanistic toxicity studies. The iPSC-HLCs could accurately classify chemicals causing acute hepatocellular injury, and the transcriptomics data on treated HLCs obtained by TempO-Seq technology linked the cytotoxicity to cellular stress pathways, including oxidative stress and unfolded protein response (UPR). Induction of these stress pathways in response to amiodarone, diclofenac, and ibuprofen, was demonstrated to be concentration and time dependent. The transcriptomics data on diclofenac-treated HLCs were found to be more sensitive in detecting differentially expressed genes in response to treatment, as compared to existing datasets of other diclofenac-treated in vitro hepatocyte models. Hence iPSC-HLCs generated by transcription factor overexpression and in metabolically optimised medium appear suitable for chemical toxicity detection as well as mechanistic toxicity studies.

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