MicroRNA-30/Cx43 axis contributes to podocyte injury by regulating ER stress in diabetic nephropathy

Editorial Office. Erratum: MicroRNA-30/Cx43 axis contributes to podocyte injury by regulating ER stress in diabetic nephropathy

[This corrects the article DOI: 10.21037/atm-20-6989.].

Inhibition of BMP4 alleviates diabetic retinal vascular dysfunction via the VEGF and smad1/5 signalling

Objective:The aim of our study was to determine the molecular mechanism of BMP4 (bone morphogenetic protein 4) in DR (diabetic retinopathy).Methods: Human retinal endothelial cell (HRECs) induced by high glucose to simulate one of the pathogenesis in the diabetic retinopathy (DR) model. RT-qPCR and western blot were used to detect the mRNA and protein levels of BMP4 in the STZ/HG group. Flow cytometry and TUNEL staining were performed to detect the apoptosis. Angiogenesis was evaluated by tube formation assay. Transwell assay and wound healing assay were used to detect cell migration ability. H&E staining was used to evaluate the pathological changes.Results: BMP4 was significantly upregulated in the STZ/HG group. Sh-BMP4 significantly inhibited the migration and angiogenesis of RVECs induced by HG. In addition, both in vivo and in vitro experiments confirmed that sh-BMP4 could significantly promote RVECs apoptosis in the HG/STZ group. Western blot results showed that sh-BMP4 could down-regulate the expressions of p-smad1, p-smad5 and VEGF.Conclusions: Inhibition of BMP4 could alleviate the damage of diabetic retinopathy by regulating the p-smad1/5/VEGF signaling axis, inhibiting angiogenesis and promoting apoptosis.

Long noncoding RNA protein-disulfide isomerase-associated 3 regulated high glucose-induced podocyte apoptosis in diabetic nephropathy through targeting miR-139-3p

BACKGROUND

Podocyte apoptosis plays a vital role in proteinuria pathogenesis in diabetic nephropathy (DN). The regulatory relationship between long noncoding RNAs (lncRNAs) and podocyte apoptosis has recently become another research hot spot in the DN field.

AIM

To investigate whether lncRNA protein-disulfide isomerase-associated 3 (Pdia3) could regulate podocyte apoptosis through miR-139-3p and revealed the underlying mechanism.

METHODS

Using normal glucose or high glucose (HG)-cultured podocytes, the cellular functions and exact mechanisms underlying the regulatory effects of lncRNA Pdia3 on podocyte apoptosis and endoplasmic reticulum stress (ERS) were explored. LncRNA Pdia3 and miR-139-3p expression were measured through quantitative real-time polymerase chain reaction. Relative cell viability was detected through the cell counting kit-8 colorimetric assay. The podocyte apoptosis rate in each group was measured through flow cytometry. The interaction between lncRNA Pdia3 and miR-139-3p was examined through the dual luciferase reporter assay. Finally, western blotting was performed to detect the effect of lncRNA Pdia3 on podocyte apoptosis and ERS via miR-139-3p.

RESULTS

The expression of lncRNA Pdia3 was significantly downregulated in HG-cultured podocytes. Next, lncRNA Pdia3 was involved in HG-induced podocyte apoptosis. Furthermore, the dual luciferase reporter assay confirmed the direct interaction between lncRNA Pdia3 and miR-139-3p. LncRNA Pdia3 overexpression attenuated podocyte apoptosis and ERS through miR-139-3p in HG-cultured podocytes.

CONCLUSION

Taken together, this study demonstrated that lncRNA Pdia3 overexpression could attenuate HG-induced podocyte apoptosis and ERS by acting as a competing endogenous RNA of miR-139-3p, which might provide a potential therapeutic target for DN.

Epigenetic regulation of mitochondrial-endoplasmic reticulum dynamics in kidney diseases

Kidney diseases are serious health problems affecting >800 million individuals worldwide. The high number of affected individuals and the severe consequences of kidney dysfunction demand an intensified effort toward more effective prevention and treatment. The pathophysiology of kidney diseases is complex and comprises diverse organelle dysfunctions including mitochondria and endoplasmic reticulum (ER). The recent findings prove interactions between the ER membrane and nearly all cell compartments and give new insights into molecular events involved in cellular mechanisms in health and disease. Interactions between the ER and mitochondrial membranes, known as the mitochondria-ER contacts regulate kidney physiology by interacting with each other via membrane contact sites (MCS). ER controls mitochondrial dynamics through ER stress sensor proteins or by direct communication via mitochondria-associated ER membrane to activate signaling pathways such as apoptosis, calcium transport, and autophagy. More importantly, these organelle dynamics are found to be regulated by several epigenetic mechanisms such as DNA methylation, histone modifications, and noncoding RNAs and can be a potential therapeutic target against kidney diseases. However, a thorough understanding of the role of epigenetic regulation of organelle dynamics and their functions is not well understood. Therefore, this review will unveil the role of epigenetic mechanisms in regulating organelle dynamics during various types of kidney diseases. Moreover, we will also shed light on different stress origins in organelles leading to kidney disease. Henceforth, by understanding this we can target epigenetic mechanisms to maintain/control organelle dynamics and serve them as a novel therapeutic approach against kidney diseases.

The pathological role of damaged organelles in renal tubular epithelial cells in the progression of acute kidney injury

Acute kidney injury (AKI) is a common clinical condition associated with high morbidity and mortality. The pathogenesis of AKI has not been fully elucidated, with a lack of effective treatment. Renal tubular epithelial cells (TECs) play an important role in AKI, and their damage and repair largely determine the progression and prognosis of AKI. In recent decades, it has been found that the mitochondria, endoplasmic reticulum (ER), lysosomes, and other organelles in TECs are damaged to varying degrees in AKI, and that they can influence each other through various signaling mechanisms that affect the recovery of TECs. However, the association between these multifaceted signaling platforms, particularly between mitochondria and lysosomes during AKI remains unclear. This review summarizes the specific pathophysiological mechanisms of the main TECs organelles in the context of AKI, particularly the potential interactions among them, in order to provide insights into possible novel treatment strategies.

Carnosine alleviates podocyte injury in diabetic nephropathy by targeting caspase-1-mediated pyroptosis

Diabetic nephropathy (DN) is a main complication of diabetes and often develops into end-stage nephropathy. Histologically, DN progresses as the gradual loss of podocytes with the loss of glomerular podocytes being the earliest sign of DN. Pyroptosis is a new type of programmed cell death and has been mechanistically correlated with podocyte injury in DN. The current study aimed to evaluate the protective effects of carnosine on glomerular podocytes in DN, both in vivo and in vitro. Using high glucose-treated cultured MPC5 cells and a streptozotocin (STZ)-induced diabetic mouse model, we evaluated the effects of carnosine on alleviating podocyte injury in DN. We found that carnosine significantly reversed albuminuria and histopathological lesions and alleviated renal inflammatory and pyroptosis responses in STZ-induced diabetic mice for 12 weeks. The results also showed that carnosine strongly inhibited podocyte inflammation and podocyte pyroptosis in vitro. Cellular Thermal Shift Assay (CETSA) and molecular docking results revealed that mechnaistically caspase-1 was the target of carnosine. We then found that silencing caspase-1 eliminated the protective effect of carnosine. Interestingly, we also found that caspase-1 and gasdermin D expression were increased in renal biopsy tissue of patients with DN. Our study is the first to demonstrate the novel role of carnosine in alleviating podocyte injury by inhibiting pyroptosis via the targeting of caspase-1. Carnosine may have potential as a therapeutic agent in treating DN by targeting caspase-1.

The bioinformatics and experimental analysis of AlkB family for prognosis and immune cell infiltration in hepatocellular carcinoma

BACKGROUND

Serving as N6-methyladenosine demethylases, the AlkB family is involved in the tumorigenesis of hepatocellular carcinoma (HCC). However, the molecular profiles and clinical values of the AlkB family in HCC are not well known.

METHODS

Several bioinformatics tools and in vitro experiments were used to identify the immune-related profiles and prognostic values of AlkB family in HCC.

RESULTS

In this study expression levels of ALKBH1/2/3/4/7 were all remarkably increased in HCC tissues when compared with normal tissues. Quantitative PCR (qPCR) and immunohistochemistry were used to validate the expression of AlkB family members in HCC tissues and normal liver tissues. In addition, high expression levels of ALKBH4 were negatively correlated with overall survival (OS) and disease-free survival (DFS) in patients with HCC. Increased ALKBH4 was also associated with pathological stage in HCC patients. The molecular profiles of AlkB family in HCC were mainly associated with peptidyl-serine modification, peptidyl-tyrosine modification, regulation of metal ion transport, etc. Furthermore, tumor-infiltrating immune cell analysis indicated that ALKBH1/2/3/4/5/6/7/8 and FTO were related to the infiltration of different immune cell, such as CD8+ T cells, macrophages, neutrophils, dendritic cells and CD4+ T cells. We also discovered that the methylation levels of ALKBH1/2/4/5/6/8 and FTO were remarkably reduced in HCC tissues.

CONCLUSIONS

Collectively, our findings may deepen the understanding of specific molecular profiles of the AlkB family in HCC pathology. In particular, ALKBH4 could serve as a promising prognostic candidate for treating HCC, and these results might potentiate the development of more reliable therapeutic strategies for patients with HCC.

Urinary Extracellular Vesicles and Their miRNA Cargo in Patients with Fabry Nephropathy

Current biomarkers of Fabry nephropathy lack sensitivity in detecting early kidney damage and do not predict progression of nephropathy. Urinary extracellular vesicles (uEVs) and their molecular cargo could reflect early changes in renal impairment as they are secreted by the cells lining the urinary tract. We aimed to conduct a proof-of-concept study to investigate whether analysis of uEV characteristics and expression of uEV-derived microRNAs (miRNAs) could be applicable in studies to predict the development and progression of nephropathy in Fabry disease. A total of 20 Fabry patients were divided into two groups, depending on the presence of nephropathy. Chronological urine samples collected during 10-year follow-up were used for uEVs isolation with size exclusion chromatography. Nanoparticle tracking analysis was used to determine concentration and size of uEVs. We evaluated the expression of five uEV-derived miRNAs by qPCR (miR-23a-3p, miR-29a-3p, miR-30b-5p, miR-34a-5p, miR-200a-3p). There was no difference in the concentration and size of uEVs between patients with and without nephropathy at last follow-up or longitudinally. However, we found increased expression of miR-29a-3p and miR-200a-3p in uEVs isolated from chronological samples of patients with Fabry nephropathy. This may indicate an attempt by the organism to prevent the progression of renal damage leading to end-stage renal disease as previously reported in type 1 diabetes. In addition, we found an increased expression of miR-30b-5p in the 10-year period in uEVs of patients without renal dysfunction. miR-30b-5 was reported to have a protective role in podocyte injury and may possibly be important in Fabry nephropathy. These findings indicate that uEVs and their molecular cargo could be a promising target of studies focusing on elucidation of Fabry nephropathy. Nevertheless, total concentration and size of uEVs were neither indicative of the presence nor progression of Fabry nephropathy, while the role of the analyzed miRNAs in Fabry nephropathy progression was merely indicated and needs further in-depth studies.