REST contributes to AKI-to-CKD transition through inducing ferroptosis in renal tubular epithelial cells

Knockdown of nicotinamide N-methyltransferase ameliorates renal fibrosis caused by ischemia-reperfusion injury and remodels sphingosine metabolism

BACKGROUND

CKD currently affects 8.2% to 9.1% of the global population and the CKD mortality rate has increased during recent decades, making it necessary to identify new therapeutic targets. This study investigated the role of nicotinamide N-methyltransferase (NNMT) in renal fibrosis following ischemia-reperfusion injury (IRI), a key factor in chronic kidney disease (CKD) progression.

METHODS

We established a mouse model with a knockdown of NNMT to investigate the impact of this enzyme on renal fibrosis after unilateral IRI. We then utilized histology, immunohistochemistry, and metabolomic analyses to investigate fibrosis markers and sphingolipid metabolism in NNMT-deficient mice. We also utilized an Nnmt lentivirus interference vector or an Nnmt overexpression plasmid to transfect mouse kidney proximal tubule cells, stimulated these cells with TGF-β1, and then measured the pro-fibrotic response and the expression of the methylated and unmethylated forms of Sphk1.

RESULTS

The results demonstrated that reducing NNMT expression mitigated fibrosis, inflammation, and lipid deposition, potentially through the modulation of sphingolipid metabolism. Histology, immunohistochemistry, and metabolomic analyses provided evidence of decreased fibrosis and enhanced sphingolipid metabolism in NNMT-deficient mice. NNMT mediated the TGF-β1-induced pro-fibrotic response, knockdown of Nnmt decreased the level of unmethylated Sphk1 and increased the level of methylated Sphk1 in renal tubular epithelial cells.

CONCLUSIONS

Our findings suggest that NNMT functions in sphingolipid metabolism and has potential as a therapeutic target for CKD. Further research is needed to elucidate the mechanisms linking NNMT to sphingolipid metabolism and renal fibrosis.

TCF4 promotes apoptosis and Wnt/β-catenin signaling pathway in acute kidney injury via transcriptional regulation of COX7A2L

BACKGROUND

Acute kidney injury (AKI) is still a serious kidney illness with high morbidity and death rates, and it's crucial to comprehend the underlying molecular causes.

METHODS

Bioinformatics analysis was performed on GSE139061 and GSE30718 data sets, and COX7A2L was screened out. The role of COX7A2L in H/R-treated cells and its transcriptional regulation with TCF4 were assessed. In vitro experiments analyzed the regulation of COX7A2L and TCF4 on the proliferation, apoptosis, and Wnt/β-catenin signaling pathway of H/R-treated cells.

RESULTS

COX7A2L as a hub gene was downregulated in AKI samples. In H/R-treated cells, COX7A2L overexpression inhibited apoptosis and promoted cell proliferation, while COX7A2L knockdown promoted apoptosis and inhibited cell proliferation. Notably, TCF4 exhibited a significant positive correlation with COX7A2L. TCF4 overexpression-induced apoptosis was lessened and improved cell proliferation was countered by COX7A2L knockdown, according to rescue study findings. Besides, we discovered that TCF4 overexpression increased the expression of proteins linked to the Wnt/β-catenin signaling pathway (c-myc, β-catenin, and cyclin D1), while underexpression of COX7A2L counteracted this effect.

CONCLUSION

The study revealed the pivotal role of COX7A2L in AKI, which is regulated by TCF4 and modulates the Wnt/β-catenin signaling pathway, highlighting its potential as a therapeutic target.

MARCHF1 promotes breast cancer through accelerating REST ubiquitylation and following TFAM transcription

Breast cancer has become the leading cause of death in women. Membrane associated ring-CH-type finger 1 (MARCHF1) is associated with the development of various types of cancer, but the exact role of MARCHF1 in breast cancer remains unclear. In our study, the higher MARCHF1 expression was observed in tumor samples of patients with breast cancer and then the role of MARCHF1 in breast cancer was further evaluated. Overexpression of MARCHF1 contributed to proliferation of cancer cells and inhibition of oxidative stress. Knockdown of MARCHF1 reduced breast cancer cell proliferation, increased mitochondrial dysfunction induced by oxidative stress, eventually aggravating cell death. In vivo, MARCHF1 promoted the tumor growth and oppositely, MARCHF1 silencing suppressed the tumor development. Moreover, MARCHF1 interacted with repressor Element-1 silencing transcription factor (REST) and facilitated its ubiquitylation and degradation. Subsequently, REST negatively regulated the transcription of mitochondrial transcription factor A (TFAM). The subcutaneous tumor formation assay in nude mice also supported these conclusions. In details, knockdown of MARCHF1 upregulated the protein expression of REST and downregulated the mRNA level of TFAM. On the contrary, MARCHF1 overexpression exhibited opposite effects. Thus, MARCHF1 is conducive to the progression of breast cancer via promoting the ubiquitylation and degradation of RSET and then the transcription of TFAM. Downregulating MARCHF1 could provide a novel direction for treating breast cancer.

Iron homeostasis and ferroptosis in human diseases: mechanisms and therapeutic prospects

Iron, an essential mineral in the body, is involved in numerous physiological processes, making the maintenance of iron homeostasis crucial for overall health. Both iron overload and deficiency can cause various disorders and human diseases. Ferroptosis, a form of cell death dependent on iron, is characterized by the extensive peroxidation of lipids. Unlike other kinds of classical unprogrammed cell death, ferroptosis is primarily linked to disruptions in iron metabolism, lipid peroxidation, and antioxidant system imbalance. Ferroptosis is regulated through transcription, translation, and post-translational modifications, which affect cellular sensitivity to ferroptosis. Over the past decade or so, numerous diseases have been linked to ferroptosis as part of their etiology, including cancers, metabolic disorders, autoimmune diseases, central nervous system diseases, cardiovascular diseases, and musculoskeletal diseases. Ferroptosis-related proteins have become attractive targets for many major human diseases that are currently incurable, and some ferroptosis regulators have shown therapeutic effects in clinical trials although further validation of their clinical potential is needed. Therefore, in-depth analysis of ferroptosis and its potential molecular mechanisms in human diseases may offer additional strategies for clinical prevention and treatment. In this review, we discuss the physiological significance of iron homeostasis in the body, the potential contribution of ferroptosis to the etiology and development of human diseases, along with the evidence supporting targeting ferroptosis as a therapeutic approach. Importantly, we evaluate recent potential therapeutic targets and promising interventions, providing guidance for future targeted treatment therapies against human diseases.

Effect of Sodium Thiosulfate Pre-Treatment on Renal Ischemia-Reperfusion Injury in Kidney Transplantation

We recently reported in a rat model of kidney transplantation that the addition of sodium thiosulfate (STS) to organ preservation solution improved renal graft quality and prolonged recipient survival. The present study investigates whether STS pre-treatment would produce a similar effect. In vitro, rat kidney epithelial cells were treated with 150 μM STS before and/or during exposure to hypoxia followed by reoxygenation. In vivo, donor rats were treated with PBS or 2.4 mg/kg STS 30 min before donor kidneys were procured and stored in UW or UW+150 μM STS solution at 4 °C for 24 h. Renal grafts were then transplanted into bilaterally nephrectomised recipient rats which were then sacrificed on post-operative day 3. STS pre-treatment significantly reduced cell death compared to untreated and other treated cells in vitro (p < 0.05), which corresponded with our in vivo result (p < 0.05). However, no significant differences were observed in other parameters of tissue injury. Our results suggest that STS pre-treatment may improve renal graft function after transplantation.

Renal tubular epithelial cells response to injury in acute kidney injury

Acute kidney injury (AKI) is a clinical syndrome characterized by a rapid and significant decrease in renal function that can arise from various etiologies, and is associated with high morbidity and mortality. The renal tubular epithelial cells (TECs) represent the central cell type affected by AKI, and their notable regenerative capacity is critical for the recovery of renal function in afflicted patients. The adaptive repair process initiated by surviving TECs following mild AKI facilitates full renal recovery. Conversely, when injury is severe or persistent, it allows the TECs to undergo pathological responses, abnormal adaptive repair and phenotypic transformation, which will lead to the development of renal fibrosis. Given the implications of TECs fate after injury in renal outcomes, a deeper understanding of these mechanisms is necessary to identify promising therapeutic targets and biomarkers of the repair process in the human kidney.

The role of ferroptosis in acute kidney injury: mechanisms and potential therapeutic targets

Acute kidney injury (AKI) is one of the most common and severe clinical renal syndromes with high morbidity and mortality. Ferroptosis is a form of programmed cell death (PCD), is characterized by iron overload, reactive oxygen species accumulation, and lipid peroxidation. As ferroptosis has been increasingly studied in recent years, it is closely associated with the pathophysiological process of AKI and provides a target for the treatment of AKI. This review offers a comprehensive overview of the regulatory mechanisms of ferroptosis, summarizes its role in various AKI models, and explores its interaction with other forms of cell death, it also presents research on ferroptosis in AKI progression to other diseases. Additionally, the review highlights methods for detecting and assessing AKI through the lens of ferroptosis and describes potential inhibitors of ferroptosis for AKI treatment. Finally, the review presents a perspective on the future of clinical AKI treatment, aiming to stimulate further research on ferroptosis in AKI.

Advance in Iron Metabolism, Oxidative Stress and Cellular Dysfunction in Experimental and Human Kidney Diseases

Kidney diseases pose a significant global health issue, frequently resulting in the gradual decline of renal function and eventually leading to end-stage renal failure. Abnormal iron metabolism and oxidative stress-mediated cellular dysfunction facilitates the advancement of kidney diseases. Iron homeostasis is strictly regulated in the body, and disturbance in this regulatory system results in abnormal iron accumulation or deficiency, both of which are associated with the pathogenesis of kidney diseases. Iron overload promotes the production of reactive oxygen species (ROS) through the Fenton reaction, resulting in oxidative damage to cellular molecules and impaired cellular function. Increased oxidative stress can also influence iron metabolism through upregulation of iron regulatory proteins and altering the expression and activity of key iron transport and storage proteins. This creates a harmful cycle in which abnormal iron metabolism and oxidative stress perpetuate each other, ultimately contributing to the advancement of kidney diseases. The crosstalk of iron metabolism and oxidative stress involves multiple signaling pathways, such as hypoxia-inducible factor (HIF) and nuclear factor erythroid 2-related factor 2 (Nrf2) pathways. This review delves into the functions and mechanisms of iron metabolism and oxidative stress, along with the intricate relationship between these two factors in the context of kidney diseases. Understanding the underlying mechanisms should help to identify potential therapeutic targets and develop novel and effective therapeutic strategies to combat the burden of kidney diseases.

Regulation of regulated cell death by extracellular vesicles in acute kidney injury and chronic kidney disease

The imbalance between proliferation and death of kidney resident cells is a crucial factor in the development of acute or chronic renal dysfunction. Acute kidney injury (AKI) is often associated with the rapid loss of tubular epithelial cells (TECs). Sustained injury leads to the loss of glomerular endothelial cells (GECs) and podocytes, which is a key mechanism in the pathogenesis of glomerular diseases. This irreversible damage resulting from progressive cell loss eventually leads to deterioration of renal function characterized by glomerular compensatory hypertrophy, tubular degeneration, and renal fibrosis. Regulated cell death (RCD), which involves a cascade of gene expression events with tight structures, plays a certain role in regulating kidney health by determining the fate of kidney resident cells. Under pathological conditions, cells in the nephron have been demonstrated to constitutively release extracellular vesicles (EVs) which act as messengers that specifically interact with recipient cells to regulate their cell death process. For therapeutic intervention, exogenous EVs have exhibited great potential for the prevention and treatment of kidney disease by modulating RCD, with enhanced effects through engineering modification. Based on the functional role of EVs, this review comprehensively explores the regulation of RCD by EVs in AKI and chronic kidney disease (CKD), with emphasis on pathogenesis and therapeutic intervention.

Comprehensive molecular and cellular characterization of endoplasmic reticulum stress-related key genes in renal ischemia/reperfusion injury

Background

Renal ischemia-reperfusion injury (RIRI) is an inevitable complication in the process of kidney transplantation and lacks specific therapy. The study aims to determine the underlying mechanisms of RIRI to uncover a promising target for efficient renoprotection.

Method

Four bulk RNA-seq datasets including 495 renal samples of pre- and post-reperfusion were collected from the GEO database. The machine learning algorithms were utilized to ascertain pivotal endoplasmic reticulum stress genes. Then, we incorporated correlation analysis and determined the interaction pathways of these key genes. Considering the heterogeneous nature of bulk-RNA analysis, the single-cell RNA-seq analysis was performed to investigate the mechanisms of key genes at the single-cell level. Besides, 4-PBA was applied to inhibit endoplasmic reticulum stress and hence validate the pathological role of these key genes in RIRI. Finally, three clinical datasets with transcriptomic profiles were used to assess the prognostic role of these key genes in renal allograft outcomes after RIRI.

Results

In the bulk-RNA analysis, endoplasmic reticulum stress was identified as the top enriched pathway and three endoplasmic reticulum stress-related genes (PPP1R15A, JUN, and ATF3) were ranked as top performers in both LASSO and Boruta analyses. The three genes were found to significantly interact with kidney injury-related pathways, including apoptosis, inflammatory response, oxidative stress, and pyroptosis. For oxidative stress, these genes were more strongly related to oxidative markers compared with antioxidant markers. In single-cell transcriptome, the three genes were primarily upregulated in endothelium, distal convoluted tubule cells, and collecting duct principal cells among 12 cell types of renal tissues in RIRI. Furthermore, distal convoluted tubule cells and collecting duct principal cells exhibited pro-inflammatory status and the highest pyroptosis levels, suggesting their potential as main effectors of three key genes for mediating RIRI-associated injuries. Importantly, inhibition of these key genes using 4-phenyl butyric acid alleviated functional and histological damage in a mouse RIRI model. Finally, the three genes demonstrated highly prognostic value in predicting graft survival outcomes.

Conclusion

The study identified three key endoplasmic reticulum stress-related genes and demonstrated their prognostic value for graft survival, providing references for individualized clinical prevention and treatment of postoperative complications after renal transplantation.

Role of ferroptosis in chronic kidney disease

Chronic kidney disease (CKD) has historically been a significant global health concern, profoundly impacting both life and well-being. In the process of CKD, with the gradual loss of renal function, the incidence of various life-threatening complications, such as cardiovascular diseases, cerebrovascular accident, infection and stroke, is also increasing rapidly. Unfortunately, existing treatments exhibit limited ability to halt the progression of kidney injury in CKD, emphasizing the urgent need to delve into the precise molecular mechanisms governing the occurrence and development of CKD while identifying novel therapeutic targets. Renal fibrosis, a typical pathological feature of CKD, plays a pivotal role in disrupting normal renal structures and the loss of renal function. Ferroptosis is a recently discovered iron-dependent form of cell death characterized by lipid peroxide accumulation. Ferroptosis has emerged as a potential key player in various diseases and the initiation of organ fibrosis. Substantial evidence suggests that ferroptosis may significantly contribute to the intricate interplay between CKD and its progression. This review comprehensively outlines the intricate relationship between CKD and ferroptosis in terms of iron metabolism and lipid peroxidation, and discusses the current landscape of pharmacological research on ferroptosis, shedding light on promising avenues for intervention. It further illustrates recent breakthroughs in ferroptosis-related regulatory mechanisms implicated in the progression of CKD, thereby providing new insights for CKD treatment. Video Abstract.

The mechanisms crosstalk and therapeutic opportunities between ferroptosis and ovary diseases

Ferroptosis, a form of regulated cell death, was first defined in 2012. Ferroptosis mainly involves iron-driven lipid peroxidation damage of cells. This process is regulated by iron homeostasis, redox balance, lipid metabolism, glutathione metabolism, and various disease signaling pathways. Iron is one of the key mineral elements that regulate the physiological function of women and the development of ovarian tumors. Occurrence of Ferroptosis has some hidden dangers and advantages in ovary diseases. Some scholars have shown that ferroptosis of ovarian granulosa cells (GC) promotes the development of ovarian dysfunction and polycystic ovary syndrome (PCOS). Interestingly, drug-resistant ovarian cancer cells are very sensitive to ferroptosis, suggesting that pharmacological positive and negative regulation of ferroptosis has great potential in the treatment of benign ovarian diseases and ovarian cancer. This article aimed to assess how ferroptosis occurs and the factors controlling ferroptosis. Moreover, we summarize how ferroptosis can be used to predict, diagnose and target treatment ovary disease. Meanwhile, we also evaluated the different phenomena of Ferroptosis in ovarian diseases. It aims to provide new directions for the research and prevention of female reproductive diseases.