Inhibition of p53/miR-34a/SIRT1 axis ameliorates podocyte injury in diabetic nephropathy

Kidney Aging and Chronic Kidney Disease

The process of aging inevitably leads to an increase in age-related comorbidities, including chronic kidney disease (CKD). In many aspects, CKD can be considered a state of accelerated and premature aging. Aging kidney and CKD have numerous common characteristic features, ranging from pathological presentation and clinical manifestation to underlying mechanisms. The shared mechanisms underlying the process of kidney aging and the development of CKD include the increase in cellular senescence, the decrease in autophagy, mitochondrial dysfunction, and the alterations of epigenetic regulation, suggesting the existence of potential therapeutic targets that are applicable to both conditions. In this review, we provide a comprehensive overview of the common characteristics between aging kidney and CKD, encompassing morphological changes, functional alterations, and recent advancements in understanding the underlying mechanisms. Moreover, we discuss potential therapeutic strategies for targeting senescent cells in both the aging process and CKD.

The regulatory role of miRNA and lncRNA on autophagy in diabetic nephropathy

Diabetic nephropathy (DN) is a serious complication of diabetes that causes glomerular sclerosis and end-stage renal disease, leading to ascending morbidity and mortality in diabetic patients. Excessive accumulation of aberrantly modified proteins or damaged organelles, such as advanced glycation end-products, dysfunctional mitochondria, and inflammasomes is associated with the pathogenesis of DN. As one of the main degradation pathways, autophagy recycles toxic substances to maintain cellular homeostasis and autophagy dysregulation plays a crucial role in DN progression. MicroRNA (miRNA) and long non-coding RNA (lncRNA) are non-coding RNA (ncRNA) molecules that regulate gene expression and have been implicated in both physiological and pathological conditions. Recent studies have revealed that autophagy-regulating miRNA and lncRNA have been involved in pathological processes of DN, including renal cell injury, mitochondrial dysfunction, inflammation, and renal fibrosis. This review summarizes the role of autophagy in DN and emphasizes the modulation of miRNA and lncRNA on autophagy during disease progression, for the development of promising interventions by targeting these ncRNAs in this disease.

Metformin inhibits high glucose-induced apoptosis of renal podocyte through regulating miR-34a/SIRT1 axis

BACKGROUND

Previous studies have reported SIRT1 was inversely modulated by miR-34a, However, mechanism of metformin (MFN)'s renal podocyte protection under high glucose (HG) conditions and the connection between miR-34a and SIRT1 expression in diabetic nephropathy (DN) remain unclear.

METHOD

We aimed to further elucidate the role of miR-34a in HG-treated podocytes in DN. A conditionally immortalized human podocyte cell line was cultivated in d-glucose (30 mM).

RESULTS

Microarray and RT-qPCR revealed that miR-34a was downregulated in HG-treated podocytes. Additionally, miR-34a levels increased in MFN-treated HG-induced podocytes. CCK-8 assay, colony formation assay, flow cytometry, and Western blot detection showed that HG treatment reduced cell viability and promoted via HG treatment, and MFN treatment reversed this phenotypic change. MiR-34a upregulation caused restored cell viability and suppressed cell apoptosis in HG-treated podocytes, and miR-34a downregulation led to damaged cell survival and induced apoptosis in MFN-administered and HG-treated podocytes. The dual luciferase reporter assay showed that SIRT1 3'-UTR was a direct miR-34a target. Further studies demonstrated an elevation in SIRT1 levels in HG-exposed podocytes, whereas MFN treatment decreased SIRT1 levels. In addition, miR-34a upregulation led to reduced SIRT1 expression, whereas miR-34a inhibition increased SIRT1 levels in cells. MFN-induced miR-34a suppresses podocyte apoptosis under HG conditions by acting on SIRT1.

CONCLUSION

This study proposes a promising approach to interpret the mechanisms of action of the MFN-miR-34a axis involved in DN.

The Role of Autophagy in Type 2 Diabetic Kidney Disease Management

Diabetic kidney disease (DKD), or diabetic nephropathy (DN), is one of the most prevalent complications of type 2 diabetes mellitus (T2DM) and causes severe burden on the general welfare of T2DM patients around the world. While several new agents have shown promise in treating this condition and potentially halting the progression of the disease, more work is needed to understand the complex regulatory network involved in the disorder. Recent studies have provided new insights into the connection between autophagy, a physiological metabolic process known to maintain cellular homeostasis, and the pathophysiological pathways of DKD. Typically, autophagic activity plays a role in DKD progression mainly by promoting an inflammatory response to tissue damage, while both overactivated and downregulated autophagy worsen disease outcomes in different stages of DKD. This correlation demonstrates the potential of autophagy as a novel therapeutic target for the disease, and also highlights new possibilities for utilizing already available DN-related medications. In this review, we summarize findings on the relationship between autophagy and DKD, and the impact of these results on clinical management strategies.

MiR-34a targets SIRT1 to reduce p53 deacetylation and promote sevoflurane inhalation anesthesia-induced neuronal autophagy and apoptosis in neonatal mice

This study is to investigate the function of miR-34a and interactions between miR-34a, SIRT1, and p53 in sevoflurane-induced neuronal apoptosis and autophagy in neonatal mice. A mouse model was established by inhalation anesthesia with sevoflurane and injected with genetic reagents, followed by tests of learning and memory abilities and histological staining of the hippocampus. CCK-8 and AnnexinV/PI staining respectively measured the survival and apoptosis rates of primary hippocampal neurons cultured with sevoflurane. The expression levels of miR-34a, SIRT1, p53, Ac-p53, and autophagy- or apoptosis-related proteins were measured. Sevoflurane impaired the learning and memory abilities of mice, increased TUNEL-positive cells in their hippocampus, and hindered the survival of hippocampal neurons. Sevoflurane increased miR-34a, Bax, cleaved caspase-3, and the ratio of LC3-II/LC3-I and reduced SIRT1 and p62. MiR-34a overexpression promoted sevoflurane-induced neural damage, whereas SIRT1 inhibition or p53 upregulation counteracted the neuroprotection of miR-34a knockdown. SIRT1 was a target of miR-34a and promoted p53 deacetylation. MiR-34a promotes sevoflurane-stimulated neuronal apoptosis and autophagy in neonatal mice by inhibiting SIRT1 expression and subsequent p53 deacetylation.

Sirtuin family in autoimmune diseases

In recent years, epigenetic modifications have been widely researched. As humans age, environmental and genetic factors may drive inflammation and immune responses by influencing the epigenome, which can lead to abnormal autoimmune responses in the body. Currently, an increasing number of studies have emphasized the important role of epigenetic modification in the progression of autoimmune diseases. Sirtuins (SIRTs) are class III nicotinamide adenine dinucleotide (NAD)-dependent histone deacetylases and SIRT-mediated deacetylation is an important epigenetic alteration. The SIRT family comprises seven protein members (namely, SIRT1-7). While the catalytic core domain contains amino acid residues that have remained stable throughout the entire evolutionary process, the N- and C-terminal regions are structurally divergent and contribute to differences in subcellular localization, enzymatic activity and substrate specificity. SIRT1 and SIRT2 are localized in the nucleus and cytoplasm. SIRT3, SIRT4, and SIRT5 are mitochondrial, and SIRT6 and SIRT7 are predominantly found in the nucleus. SIRTs are key regulators of various physiological processes such as cellular differentiation, apoptosis, metabolism, ageing, immune response, oxidative stress, and mitochondrial function. We discuss the association between SIRTs and common autoimmune diseases to facilitate the development of more effective therapeutic strategies.

Interaction between SIRT1 and non-coding RNAs in different disorders

SIRT1 is a member of the sirtuin family functioning in the process of removal of acetyl groups from different proteins. This protein has several biological functions and is involved in the pathogenesis of metabolic diseases, malignancy, aging, neurodegenerative disorders and inflammation. Several long non-coding RNAs (lncRNAs), microRNAs (miRNAs) and circular RNAs (circRNAs) have been found to interact with SIRT1. These interactions have been assessed in the contexts of sepsis, cardiomyopathy, heart failure, non-alcoholic fatty liver disease, chronic hepatitis, cardiac fibrosis, myocardial ischemia/reperfusion injury, diabetes, ischemic stroke, immune-related disorders and cancers. Notably, SIRT1-interacting non-coding RNAs have been found to interact with each other. Several circRNA/miRNA and lncRNA/miRNA pairs that interact with SIRT1 have been identified. These axes are potential targets for design of novel therapies for different disorders. In the current review, we summarize the interactions between three classes of non-coding RNAs and SIRT1.

Rosmarinic acid mitigates chlorpyrifos-induced oxidative stress, inflammation, and kidney injury in rats by modulating SIRT1 and Nrf2/HO-1 signaling

Chlorpyrifos (CPF) is a widely used broad-spectrum pesticide with multi-organ toxic effects. Oxidative stress was found to play a role in the deleterious effects of CPF, including nephrotoxicity. This study investigated the protective effect of the antioxidant polyphenol rosmarinic acid (RA) against CPF-induced kidney injury, with an emphasis on oxidative injury, inflammation, SIRT1, and Nrf2/HO-1 signaling. Rats received 10 mg/kg CPF and 25, 50, and 100 mg/kg RA orally for 28 days, and the samples were collected for analysis. CPF increased serum urea and creatinine and kidney Kim-1 and caused several histopathological alterations. ROS, MDA, NO, NF-κB p65, TNF-α, and IL-1β were elevated in the kidney of CPF-intoxicated rats. RA ameliorated kidney function markers, prevented tissue injury, suppressed ROS, MDA, and NO, and downregulated NF-κB p65, TNF-α, and IL-1β in CPF-intoxicated rats in a dose-dependent manner. RA decreased Bax, caspase-3, oxidative DNA damage, and Keap1, boosted antioxidant enzymes and Bcl-2, and upregulated Nrf2, HO-1, and SIRT1 in CPF-administered rats. Molecular docking simulation revealed the binding affinity of RA toward NF-κB, Keap1, HO-1, and SIRT1. In conclusion, RA prevented CPF nephrotoxicity by attenuating oxidative stress, inflammation, and apoptosis and upregulating SIRT1 and Nrf2/HO-1 signaling.

Integrated Network Pharmacology and Cellular Assay to Explore the Mechanisms of Selenized Tripterine Phytosomes (Se@Tri-PTs) Alleviating Podocyte Injury in Diabetic Nephropathy

AIM

This work aimed to elucidate the mechanisms of Se@Tri-PTs in alleviating podocyte injury via network pharmacology and in vitro cellular assay.

BACKGROUND

Selenized tripterine phytosomes (Se@Tri-PTs) have been confirmed to undertake synergistic and sensitized effects on inflammation, which may be curatively promising for diabetic nephropathy (DN). However, the mechanisms of Se@Tri-PTs in alleviating podocyte injury, a major contributor to DN, still remain unclear.

OBJECTIVE

The objective of the study was to find out the underlying mechanisms of Se@Tri-PTs in alleviating podocyte injury in diabetic nephropathy.

METHODS

The key components and targets of Tripterygium wilfordii (TW) significant for DN as well as the signaling pathways involved have been identified. A high glucose-induced podocyte injury model was established and verified by western blot. The protective concentration of Se@Tri-PTs was screened by CCK-8 assay. Podocytes cultured with high glucose were treated with Se@Tri-PTs under protective levels. The expression of key protective proteins, nephrin and desmin, in podocytes, was assayed by western blot. Further, autophagy- related proteins and factors, like NLRP3, Beclin-1, LC3II/LC3, P62, and SIRT1, were analyzed, which was followed by apoptosis detection.

RESULTS

Network pharmacology revealed that several monomeric components of TW, especially Tri, act on DN through multiple targets and pathways, including the NLRP3-mediated inflammatory pathway. Se@Tri-PTs improved the viability of podocytes and alleviated their injury induced by high glucose at 5 μg/L or above. High-glucose induction promoted the expression of NLRP3 in podocytes, while a low concentration of Se@Tri-PTs suppressed the expression. A long-term exposure of high glucose significantly inhibited the autophagic activity of podocytes, as manifested by decreased Beclin-1 level, lower ratio of LC3 II/LC3 I, and up- regulation of P62. This abnormality was efficiently reversed by Se@Tri-PTs. Importantly, the expression of SIRT1 was up-regulated and podocyte apoptosis was reduced.

CONCLUSION

Se@Tri-PTs can alleviate podocyte injury associated with DN by modulating NLRP3 expression through the pathway of SIRT1-mediated autophagy.

The molecular activity of cannabidiol in the regulation of Nrf2 system interacting with NF-κB pathway under oxidative stress

Cannabidiol (CBD), the major non-psychoactive phytocannabinoid of Cannabis sativa L., is one of the most studied compounds in pharmacotherapeutic approaches to treat oxidative stress-related diseases such as cardiovascular, metabolic, neurodegenerative, and neoplastic diseases. The literature data to date indicate the possibility of both antioxidant and pro-oxidative effects of CBD. Thus, the mechanism of action of this natural compound in the regulation of nuclear factor 2 associated with erythroid 2 (Nrf2), which plays the role of the main cytoprotective regulator of redox balance and inflammation under oxidative stress conditions, seems to be particularly important. Moreover, Nrf2 is strongly correlated with the cellular neoplastic profile and malignancy, which in turn is critical in determining the cellular response induced by CBD under pathophysiological conditions. This paper summarizes the CBD-mediated pathways of regulation of the Nrf2 system by altering the expression and modification of both proteins directly involved in Nrf2 transcriptional activity and proteins involved in the relationship between Nrf2 and the nuclear factor kappa B (NF-κB) which is another redox-sensitive transcription factor.

Sirtuins as novel pharmacological targets in podocyte injury and related glomerular diseases

Podocyte injury is a major cause of proteinuria in kidney diseases, and persistent loss of podocytes leads to rapid irreversible progression of kidney disease. Sirtuins, a class of nicotinamide adenine dinucleotide-dependent deacetylases, can promote DNA repair, modify transcription factors, and regulate the cell cycle. Additionally, sirtuins play a critical role in renoprotection, particularly against podocyte injury. They also have pleiotropic protective effects on podocyte injury-related glomerular diseases, such as improving the immune inflammatory status and oxidative stress levels, maintaining mitochondrial homeostasis, enhancing autophagy, and regulating lipid metabolism. Sirtuins deficiency causes podocyte injury in different glomerular diseases. Studies using podocyte sirtuin-specific knockout and transgenic models corroborate this conclusion. Of note, sirtuin activators have protective effects in different podocyte injury-related glomerular diseases, including diabetic kidney disease, focal segmental glomerulosclerosis, membranous nephropathy, IgA nephropathy, and lupus nephritis. These findings suggest that sirtuins are promising therapeutic targets for preventing podocyte injury. This review provides an overview of recent advances in the role of sirtuins in kidney diseases, especially their role in podocyte injury, and summarizes the possible rationale for sirtuins as targets for pharmacological intervention in podocyte injury-related glomerular diseases.

Natural Products Against Renal Fibrosis via Modulation of SUMOylation

Renal fibrosis is the common and final pathological process of kidney diseases. As a dynamic and reversible post-translational modification, SUMOylation and deSUMOylation of transcriptional factors and key mediators significantly affect the development of renal fibrosis. Recent advances suggest that SUMOylation functions as the promising intervening target against renal fibrosis, and natural products prevent renal fibrosis via modulating SUMOylation. Here, we introduce the mechanism of SUMOylation in renal fibrosis and therapeutic effects of natural products. This process starts by summarizing the key mediators and enzymes during SUMOylation and deSUMOylation and its regulation role in transcriptional factors and key mediators in renal fibrosis, then linking the mechanism findings of SUMOylation and natural products to develop novel therapeutic candidates for treating renal fibrosis, and concludes by commenting on promising therapeutic targets and candidate natural products in renal fibrosis via modulating SUMOylation, which highlights modulating SUMOylation as a promising strategy for natural products against renal fibrosis.

Targeting the microRNA-34a as a Novel Therapeutic Strategy for Cardiovascular Diseases

Cardiovascular diseases (CVDs) are still the main cause of morbidity and mortality worldwide and include a group of disorders varying from vasculature, myocardium, arrhythmias and cardiac development. MicroRNAs (miRs) are endogenous non-coding RNAs with 18–23 nucleotides that regulate gene expression. The miR-34 family, including miR-34a/b/c, plays a vital role in the regulation of myocardial physiology and pathophysiological processes. Recently, miR-34a has been implicated in cardiovascular fibrosis, dysfunction and related cardiovascular disorders as an essential regulator. Interestingly, there is a pivotal link among miR-34a, cardiovascular fibrosis, and Smad4/TGF-β1 signaling. Notably, both loss-of-function and gain-of-function approaches identified the critical roles of miR-34a in cardiovascular apoptosis, autophagy, inflammation, senescence and remodeling by modulating multifunctional signaling pathways. In this article, we focus on the current understanding of miR-34a in biogenesis, its biological effects and its implications for cardiac pathologies including myocardial infarction, heart failure, ischaemia reperfusion injury, cardiomyopathy, atherosclerosis, hypertension and atrial fibrillation. Thus, further understanding of the effects of miR-34a on cardiovascular diseases will aid the development of effective interventions. Targeting for miR-34a has emerged as a potential therapeutic target for cardiovascular dysfunction and related diseases.

Podocyte Bioenergetics in the Development of Diabetic Nephropathy: The Role of Mitochondria

Diabetic nephropathy (DN) is the leading cause of kidney failure, with an increasing incidence worldwide. Mitochondrial dysfunction is known to occur in DN and has been implicated in the underlying pathogenesis of disease. These complex organelles have an array of important cellular functions and involvement in signaling pathways, and understanding the intricacies of these responses in health, as well as how they are damaged in disease, is likely to highlight novel therapeutic avenues. A key cell type damaged early in DN is the podocyte, and increasing studies have focused on investigating the role of mitochondria in podocyte injury. This review will summarize what is known about podocyte mitochondrial dynamics in DN, with a particular focus on bioenergetic pathways, highlighting key studies in this field and potential opportunities to target, enhance or protect podocyte mitochondrial function in the treatment of DN.