Berberine regulates mesangial cell proliferation and cell cycle to attenuate diabetic nephropathy through the PI3K/Akt/AS160/GLUT1 signalling pathway.

High glucose (HG) is one of the basic factors of diabetic nephropathy (DN), which leads to high morbidity and disability. During DN, the expression of glomerular glucose transporter 1 (GLUT1) increases, but the relationship between HG and GLUT1 is unclear. Glomerular mesangial cells (GMCs) have multiple roles in HG-induced DN. Here, we report prominent glomerular dysfunction, especially GMC abnormalities, in DN mice, which is closely related to GLUT1 alteration. In vivo studies have shown that BBR can alleviate pathological changes and abnormal renal function indicators of DN mice. In vitro, BBR (30, 60 and 90 µmol/L) not only increased the proportion of G1 phase cells but also reduced the proportion of S phase cells under HG conditions at different times. BBR (60 µmol/L) significantly reduced the expression of PI3K-p85, p-Akt, p-AS160, membrane-bound GLUT1 and cyclin D1, but had almost no effect on total protein. Furthermore, BBR significantly declined the glucose uptake and retarded cyclin D1-mediated GMC cell cycle arrest in the G1 phase. This study demonstrated that BBR can inhibit the development of DN, which may be due to BBR inhibiting the PI3K/Akt/AS160/GLUT1 signalling pathway to regulate HG-induced abnormal GMC proliferation and the cell cycle, supporting BBR as a potential therapeutic drug for DN.

Insulin-like growth factor binding protein 7 promotes acute kidney injury by alleviating poly ADP ribose polymerase 1 degradation.

The novel biomarker, insulin-like growth factor binding protein 7 (IGFBP7), is used clinically to predict different types of acute kidney injury (AKI) and has drawn significant attention as a urinary biomarker. However, as a secreted protein in the circulation of patients with AKI, it is unclear whether IGFBP7 acts as a key regulator in AKI progression, and if mechanisms underlying its upregulation still need to be determined. Here we found that IGFBP7 is highly expressed in the blood and urine of patients and mice with AKI, possibly via a c-Jun-dependent mechanism, and is positively correlated with kidney dysfunction. Global knockout of IGFBP7 ameliorated kidney dysfunction, inflammatory responses, and programmed cell death in murine models of cisplatin-, kidney ischemia/reperfusion-, and lipopolysaccharide-induced AKI. IGFBP7 mainly originated from kidney tubular epithelial cells. Conditional knockout of IGFBP7 from the kidney protected against AKI. By contrast, rescue of IGFBP7 expression in IGFBP7-knockout mice restored kidney damage and inflammation. IGFBP7 function was determined in vitro using recombinant IGFBP7 protein, IGFBP7 knockdown, or overexpression. Additionally, IGFBP7 was found to bind to poly [ADP-ribose] polymerase 1 (PARP1) and inhibit its degradation by antagonizing the E3 ubiquitin ligase ring finger protein 4 (RNF4). Thus, IGFBP7 in circulation acts as a biomarker and key mediator of AKI by inhibiting RNF4/PARP1-mediated tubular injury and inflammation. Hence, over-activation of the IGFBP7/PARP1 axis represents a promising target for AKI treatment.

Stratifin promotes renal dysfunction in ischemic and nephrotoxic AKI mouse models via enhancing RIPK3-mediated necroptosis.

Stratifin (SFN) is a member of the 14-3-3 family of highly conserved soluble acidic proteins, which regulates a variety of cellular activities such as cell cycle, cell growth and development, cell survival and death, and gene transcription. Acute kidney injury (AKI) is prevalent disorder characterized by inflammatory response, oxidative stress, and programmed cell death in renal tubular epithelial cells, but there is still a lack of effective therapeutic target for AKI. In this study, we investigated the role of SFN in AKI and the underlying mechanisms. We established ischemic and nephrotoxic AKI mouse models caused by ischemia-reperfusion (I/R) and cisplatin, respectively. We conducted proteomic and immunohistochemical analyses and found that SFN expression levels were significantly increased in AKI patients, cisplatin- or I/R-induced AKI mice. In cisplatin- or hypoxia/reoxygenation (H/R)-treated human proximal tubule epithelial cells (HK2), we showed that knockdown of SFN significantly reduced the expression of kidney injury marker Kim-1, attenuated programmed cell death and inflammatory response. Knockdown of SFN also significantly alleviated the decline of renal function and histological damage in cisplatin-caused AKI mice in vivo. We further revealed that SFN bound to RIPK3, a key signaling modulator in necroptosis, to induce necroptosis and the subsequent inflammation in cisplatin- or H/R-treated HK2 cells. Overexpression of SFN increased Kim-1 protein levels in cisplatin-treated MTEC cells, which was suppressed by RIPK3 knockout. Taken together, our results demonstrate that SFN that enhances cisplatin- or I/R-caused programmed cell death and inflammation via interacting with RIPK3 may serve as a promising therapeutic target for AKI treatment.

Alcohol promotes renal fibrosis by activating Nox2/4-mediated DNA methylation of Smad7.

Alcohol consumption causes renal injury and compromises kidney function. The underlying mechanism of the alcoholic kidney disease remains largely unknown. In the present study, an alcoholic renal fibrosis animal model was first employed which mice received liquid diet containing alcohol for 4 to 12 weeks. The Masson's Trichrome staining analysis showed that kidney fibrosis increased at week 8 and 12 in the animal model that was further confirmed by albumin assay, Western blot, immunostaining and real-time PCR of fibrotic indexes (collagen I and α-SMA). In vitro analysis also confirmed that alcohol significantly induced fibrotic response (collagen I and α-SMA) in HK2 tubular epithelial cells. Importantly, both in vivo and in vitro studies showed alcohol treatments decreased Smad7 and activated Smad3. We further determined how the alcohol affected the balance of Smad7 (inhibitory Smad) and Smad3 (regulatory Smad). Genome-wide methylation sequencing showed an increased DNA methylation of many genes and bisulfite sequencing analysis showed an increased DNA methylation of Smad7 after alcohol ingestion. We also found DNA methylation of Smad7 was mediated by DNMT1 in ethyl alcohol (EtOH)-treated HK2 cells. Knockdown of Nox2 or Nox4 decreased DNMT1 and rebalanced Smad7/Smad3 axis, and thereby relieved EtOH-induced fibrotic response. The inhibition of reactive oxygen species by the intraperitoneal injection of apocynin attenuated renal fibrosis and restored renal function in the alcoholic mice. Collectively, we established novel in vivo and in vitro alcoholic kidney fibrosis models and found that alcohol induces renal fibrosis by activating oxidative stress-induced DNA methylation of Smad7. Suppression of Nox-mediated oxidative stress may be a potential therapy for long-term alcohol abuse-induced kidney fibrosis.

Percutaneous endoscopic lumbar discectomy and microsurgical laminotomy : A prospective, randomized controlled trial of patients with lumbar disc herniation and lateral recess stenosis.

BACKGROUND: Sufficient decompression of the nerve root canal is still regarded as the method of choice when operating on patients with lumbar disc herniation (LDH) with lumbar lateral recess stenosis; however, tissue-sparing procedures are becoming more popular. Endoscopic techniques offer advantages and the benefits of rehabilitation, which have become the standard in many surgical operations when operating on the spine. A significant issue has been the upgrading of instruments to provide enough bone resection under continuous visual control. MATERIAL AND METHODS: We examined patients who had LDH with lateral recess stenosis and compared the results of nerve root canal decompression using percutaneous endoscopic lumbar discectomy (PELD) with a microsurgical laminotomy (ML) technique. In this study 40 patients with full endoscopic decompression or microsurgery were followed up for 2 years. In addition to general and specific parameters, the following two parameters were also used for the investigation: the Visual Analog Scale (VAS) and the Oswestry Disability Index (ODI). RESULTS: Except for 1 patient in whom repair was done by fusion and 1 who was lost to follow-up, 38 patients remained in the study over the 2 years. The mean operating time in the PELD group was longer (p < 0.05), but intraoperative and postoperative blood loss was less than in the ML group (p < 0.05). The postoperative results were better than before surgery, and the VAS and ODI parameters indicated a clear improvement in leg pain and daily activities in both groups (p > 0.05). Of the patients three suffered increasing back pain (2 ML, 1 PELD). CONCLUSION: The results indicated that the PELD can provide an effective supplement and serve as an alternative for LDH with lateral recess stenosis compared with the ML technique when the indication criteria are fulfilled. The PELD also has the advantage of being a minimally invasive intervention.

Renoprotective effect of berberine via regulating the PGE2 -EP1-Gαq-Ca(2+) signalling pathway in glomerular mesangial cells of diabetic rats.

G-protein coupled receptor-mediated pathogenesis is of great importance in the development of diabetic complications, but the detailed mechanisms have not yet been clarified. Therefore, we aimed to explore the roles of the prostaglandin E2 receptor 1 (EP1)-mediated signalling pathway and develop a corresponding treatment for diabetic nephropathy (DN). To create the DN model, rats fed a high-fat and high-glucose diet were injected with a single dose of streptozotocin (35 mg/kg, i.p.). Then, rats were either treated or not with berberine (100 mg/kg per day, i.g., 8 weeks). Cells were isolated from the renal cortex and cultured in high-sugar medium with 20% foetal bovine serum. Prostaglandin E2 (PGE2 ) levels were determined by ELISA, and cells were identified by fluorescence immunoassay. We measured the biochemical characteristics and observed morphological changes by periodic-acid-Schiff staining. The expression of the EP1 receptor and the roles of GRK2 and ß-arrestin2 were identified using western blotting and flow cytometry. Downstream proteins were detected by western blot, while molecular changes were assessed by ELISA and laser confocal scanning microscopy. Berberine not only improved the majority of biochemical and renal functional parameters but also improved the histopathological alterations. A significant increase in PGE2 level, EP1 membrane expression and Gαq expression, and concentration of Ca(2+) were observed, accompanied by increased GRK2 and ß-arrestin2 levels soon afterwards. Berberine decreased the abnormal concentration of Ca(2+) , the increased levels of PGE2 , the high expression of EP1 and Gαq and suppressed the proliferation of mesangial cells. The EP1 receptor, a critical therapeutic target of the signalling pathway, contributed to mesangial cell abnormalities, which are linked to renal injury in DN. The observed renoprotective effects of berberine via regulating the PGE2 -EP1-Gαq-Ca(2+) signalling pathway indicating that berberine could be a promising anti-DN medicine in the future.

G protein-coupled receptors: potential therapeutic targets for diabetic nephropathy.

Diabetic nephropathy, a lethal microvascular complication of diabetes mellitus, is characterized by progressive albuminuria, excessive deposition of extracellular matrix, thickened glomerular basement membrane, podocyte abnormalities, and podocyte loss. The G protein-coupled receptors (GPCRs) have attracted considerable attention in diabetic nephropathy, but the specific effects have not been elucidated yet. Likewise, abnormal signaling pathways are closely interrelated to the pathologic process of diabetic nephropathy, despite the fact that the mechanisms have not been explored clearly. Therefore, GPCRs and its mediated signaling pathways are essential for priority research, so that preventative strategies and potential targets might be developed for diabetic nephropathy. This article will give us comprehensive overview of predominant GPCR types, roles, and correlative signaling pathways in diabetic nephropathy.

Research progress in signalling pathway in diabetic nephropathy.

Diabetic nephropathy, a lethal diabetic complication, is a leading cause of end-stage renal disease, which is pathologically characterized by thickened tubular basal and glomerular membranes, accumulated extracellular matrix, and progressive mesangial hypertrophy. Growing evidence indicates that diabetic nephropathy is induced by multiple conditions, such as glucose metabolism disorder, oxidative stress, numerous inflammatory factors and cytokines, and haemodynamic changes that lead to the occurrence and development of diabetic nephropathy based on genetic susceptibility. A variety of abnormalities in the signalling pathway may interact to produce these pathologic processes. Research has aimed to highlight the signalling pathway mechanisms that lead to diabetic nephropathy so that preventative strategies and effective therapies might be developed. In this review, important pathways that appear to be involved in driving these processes are discussed.

RNA N6 -methyladenosine modifications and potential targeted therapeutic strategies in kidney disease.

Epigenetic modifications have received increasing attention and have been shown to be extensively involved in kidney development and disease progression. Among them, the most common RNA modification, N6 -methyladenosine (m6 A), has been shown to dynamically and reversibly exert its functions in multiple ways, including splicing, export, decay and translation initiation efficiency to regulate mRNA fate. Moreover, m6 A has also been reported to exert biological effects by destabilizing base pairing to modulate various functions of RNAs. Most importantly, an increasing number of kidney diseases, such as renal cell carcinoma, acute kidney injury and chronic kidney disease, have been found to be associated with aberrant m6 A patterns. In this review, we comprehensively review the critical roles of m6 A in kidney diseases and discuss the possibilities and relevance of m6 A-targeted epigenetic therapy, with an integrated comprehensive description of the detailed alterations in specific loci that contribute to cellular processes that are associated with kidney diseases.

Targeted modulation of gut microbiota by traditional Chinese medicine and natural products for liver disease therapy.

The gut microbiota not only constitutes intestinal microenvironment homeostasis and human health but also exerts indispensable roles in the occurrence and progression of multiple liver diseases, including alcohol-related liver disease, nonalcoholic fatty liver disease, autoimmune liver disease and liver cancer. Given the therapeutic status of these diseases, their prevention and early therapy are crucial, and the detailed mechanism of gut microbiota in liver disease urgently needs to be explored. Meanwhile, multiple studies have shown that various traditional Chinese medicines, such as Si Miao Formula, Jiangzhi Granules, Liushen Capsules, Chaihu-Shugan Power, Cassiae Semen and Gynostemma, as well as some natural products, including Costunolide, Coprinus comatus polysaccharide, Antarctic krill oil, Oridonin and Berberine, can repair liver injury, improve fatty liver, regulate liver immunity, and even inhibit liver cancer through multiple targets, links, and pathways. Intriguingly, the aforementioned effects demonstrated by these traditional Chinese medicines and natural products have been shown to be closely related to the gut microbiota, directly driving the strategy of traditional Chinese medicines and natural products to regulate the gut microbiota as one of the breakthroughs in the treatment of liver diseases. Based on this, this review comprehensively summarizes and discusses the characteristics, functions and potential mechanisms of these medicines targeting gut microbiota during liver disease treatment. Research on the potential effects on gut microbiota and the regulatory mechanisms of traditional Chinese medicine and natural products provides novel insights and significant references for developing liver disease treatment strategies. In parallel, such explorations will enhance the comprehension of traditional Chinese medicine and natural products modulating gut microbiota during disease treatment, thus facilitating their clinical investigation and application.

Genetic and pharmacological inhibition of METTL3 alleviates renal fibrosis by reducing EVL m6A modification through an IGF2BP2-dependent mechanism.

BACKGROUND: N6 -methyladenosine (m6A) is of great importance in renal physiology and disease progression, but its function and mechanism in renal fibrosis remain to be comprehensively and extensively explored. Hence, this study will explore the function and potential mechanism of critical regulator-mediated m6A modification during renal fibrosis and thereby explore promising anti-renal fibrosis agents. METHODS: Renal tissues from humans and mice as well as HK-2 cells were used as research subjects. The profiles of m6A modification and regulators in renal fibrosis were analysed at the protein and RNA levels using Western blotting, quantitative real-time polymerase chain reaction and other methods. Methylation RNA immunoprecipitation sequencing and RNA sequencing coupled with methyltransferase-like 3 (METTL3) conditional knockout were used to explore the function of METTL3 and potential targets. Gene silencing and overexpression combined with RNA immunoprecipitation were performed to investigate the underlying mechanism by which METTL3 regulates the Ena/VASP-like (EVL) m6A modification that promotes renal fibrosis. Molecular docking and virtual screening with in vitro and in vivo experiments were applied to screen promising traditional Chinese medicine (TCM) monomers and explore their mechanism of regulating the METTL3/EVL m6A axis and anti-renal fibrosis. RESULTS: METTL3 and m6A modifications were hyperactivated in both the tubular region of fibrotic kidneys and HK-2 cells. Upregulated METTL3 enhanced the m6A modification of EVL mRNA to improve its stability and expression in an insulin-like growth factor 2 mRNA-binding protein 2 (IGF2BP2)-dependent manner. Highly expressed EVL binding to Smad7 abrogated the Smad7-induced suppression of transforming growth factor-ß (TGF-ß1)/Smad3 signal transduction, which conversely facilitated renal fibrosis progression. Molecular docking and virtual screening based on the structure of METTL3 identified a TCM monomer named isoforsythiaside, which inhibited METTL3 activity together with the METTL3/EVL m6A axis to exert anti-renal fibrosis effects. CONCLUSIONS: Collectively, the overactivated METTL3/EVL m6A axis is a potential target for renal fibrosis therapy, and the pharmacological inhibition of METTL3 activity by isoforsythiaside suggests that it is a promising anti-renal fibrosis agent.

Corrigendum: MicroRNAs as Regulators of Immune and Inflammatory Responses: Potential Therapeutic Targets in Diabetic Nephropathy.

[This corrects the article DOI: 10.3389/fcell.2020.618536.].

Advances in Pathogenesis, Progression, Potential Targets and Targeted Therapeutic Strategies in SARS-CoV-2-Induced COVID-19.

As the new year of 2020 approaches, an acute respiratory disease quietly caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), also known as coronavirus disease 2019 (COVID-19) was reported in Wuhan, China. Subsequently, COVID-19 broke out on a global scale and formed a global public health emergency. To date, the destruction that has lasted for more than two years has not stopped and has caused the virus to continuously evolve new mutant strains. SARS-CoV-2 infection has been shown to cause multiple complications and lead to severe disability and death, which has dealt a heavy blow to global development, not only in the medical field but also in social security, economic development, global cooperation and communication. To date, studies on the epidemiology, pathogenic mechanism and pathological characteristics of SARS-CoV-2-induced COVID-19, as well as target confirmation, drug screening, and clinical intervention have achieved remarkable effects. With the continuous efforts of the WHO, governments of various countries, and scientific research and medical personnel, the public's awareness of COVID-19 is gradually deepening, a variety of prevention methods and detection methods have been implemented, and multiple vaccines and drugs have been developed and urgently marketed. However, these do not appear to have completely stopped the pandemic and ravages of this virus. Meanwhile, research on SARS-CoV-2-induced COVID-19 has also seen some twists and controversies, such as potential drugs and the role of vaccines. In view of the fact that research on SARS-CoV-2 and COVID-19 has been extensive and in depth, this review will systematically update the current understanding of the epidemiology, transmission mechanism, pathological features, potential targets, promising drugs and ongoing clinical trials, which will provide important references and new directions for SARS-CoV-2 and COVID-19 research.

Targeting TMEM88 as an Attractive Therapeutic Strategy in Malignant Tumors.

According to authoritative surveys, the overall morbidity and mortality of malignant tumors show an upward trend, and it is predicted that this trend will not be well contained in the upcoming new period. Since the influencing factors, pathogenesis, and progression characteristics of malignant tumors have not been fully elucidated, the existing treatment strategies, mainly including surgical resection, ablation therapy and chemotherapy, cannot achieve satisfactory results. Therefore, exploring potential therapeutic targets and clarifying their functions and mechanisms in continuous research and practice will provide new ideas and possibilities for the treatment of malignant tumors. Recently, a double-transmembrane protein named transmembrane protein 88 (TMEM88) was reported to regulate changes in downstream effectors by mediating different signaling pathways and was confirmed to be widely involved in cell proliferation, differentiation, apoptosis and tumor progression. At present, abnormal changes in TMEM88 have been found in breast cancer, ovarian cancer, lung cancer, thyroid cancer and other malignant tumors, which has also attracted the attention of tumor research and attempted to clarify its function and mechanism. However, due to the lack of systematic generalization, comprehensive and detailed research results have not been comprehensively summarized. In view of this, this article will describe in detail the changes in TMEM88 in the occurrence and development of malignant tumors, comprehensively summarize the corresponding molecular mechanisms, and explore the potential of targeting TMEM88 in the treatment of malignant tumors to provide valuable candidate targets and promising intervention strategies for the diagnosis and cure of malignant tumors.

Effect of CX3CL1/CX3CR1 gene polymorphisms on the clinical efficacy of carboplatin therapy in Han patients with ovarian cancer.

Gene polymorphisms have a close relationship with the clinical effects of carboplatin for ovarian cancer. Here, we investigated the relationship between CX3CL1 and CX3CR1 genotypes and the clinical efficacy of carboplatin in ovarian cancer, thereby clarifying the unidentified genetic factors that influence the efficacy of carboplatin in ovarian cancer. Based on the above purposes, we used Sequenom Mass ARRAY technology to detect CX3CL1 and CX3CR1 gene polymorphisms in 127 patients with carboplatin-treated ovarian cancer. We performed various statistical analyses to evaluate the effects of CX3CL1 and CX3CR1 genetic variants, demographic data, and clinical characteristics on the effect of carboplatin therapy. The results show that the CX3CL1 genotypes rs223815 (G>C) and rs682082 (G>A) will significantly affect the clinical efficacy of carboplatin for ovarian cancer (p < 0.05), while the other six genotypes and all CX3CR1 genotypes have no significant effect (p > 0.05). In addition, only one population factor, age, had a significant effect on the clinical efficacy of carboplatin-treated ovarian cancer (p < 0.05). Based on the above research results, we concluded that the clinical efficacy of carboplatin in ovarian cancer patients was significantly correlated with age and CX3CL1 polymorphism factors; however, more in-depth effects and mechanisms need to be explored by large-scale, multicenter studies.

Highly pathogenic coronaviruses and the kidney.

Since the end of 2019, the outbreak of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has triggered a pneumonia epidemic, posing a significant public health challenge in 236 countries, territories, and regions worldwide. Clinically, in addition to the symptoms of pulmonary infection, many patients with SARS-CoV-2 infections, especially those with a critical illness, eventually develop multiple organ failure in which damage to the kidney function is common, ultimately leading to severe consequences such as increased mortality and morbidity. To date, three coronaviruses have set off major global public health security incidents: Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV), Middle East Respiratory Syndrome Coronavirus (MERS-CoV), and SARS-CoV-2. Among the diseases caused by the coronaviruses, the coronavirus disease 2019 (COVID-19) has been the most impactful and harmful. Similar to with SARS-CoV-2 infections, previous studies have shown that kidney injury is also common and prominent in patients with the two other highly pathogenic coronaviruses. Therefore, in this review, we aimed to comprehensively summarize the epidemiological and clinical characteristics of these three pandemic-level infections, provide a deep analysis of the potential mechanism of COVID-19 in various types of kidney diseases, and explore the causes of secondary kidney diseases of SARS-CoV-2, so as to provide a reference for further research and the clinical prevention of kidney damage caused by coronaviruses.

Targeted inhibition of TGF-ß type I receptor by AZ12601011 protects against kidney fibrosis.

Renal fibrosis, a common feature of chronic kidney disease, causes the progressive loss of renal function, in which TGF-ß1 plays a critical role. In this study, we found that expression levels of TGF-ß1 and its receptor 1 (TGF-ßR1) were both significantly increased in obstructive fibrosis kidneys. AZ12601011 is a small molecular inhibitor of TGF-ßR1; however, its therapeutic potential for renal fibrosis remains unclear. During the experiments, AZ12601011 was applied to various models of renal fibrosis followed by unilateral ureteral obstruction (UUO) and ischemia/reperfusion (I/R) in vivo, in addition to renal tubular epithelial cells (TECs) challenged by hypoxia/reoxygenation (H/R) and TGF-ß1in vitro. Our results revealed that AZ12601011 ameliorated renal injuries and fibrosis shown by PAS, HE, and Masson staining, which was consistent with the decrease in Col-1 and α-SMA expression in the kidneys from UUO and I/R mice. Similarly, in vitro data showed that AZ12601011 inhibited the induction of Col-1 and α-SMA in both TECs treated with TGF-ß1 and H/R. In addition, the results of cellular thermal shift assay (CETSA), molecular docking, and western bolt indicated that AZ12601011 could directly bind to TGF-ßR1 and block activation of the downstream Smad3. Taken together, our findings suggest that AZ12601011 can attenuate renal fibrosis by blocking the TGF-ß/Smad3 signaling pathway and it might serve as a promising clinical candidate in the fight against fibrotic kidney diseases.

RIPK3 inhibitor-AZD5423 alleviates acute kidney injury by inhibiting necroptosis and inflammation.

Acute kidney injury (AKI) is a clinical syndrome that is defined as a sudden decline in renal function and characterized by inflammation and programmed cell death of renal tubular epithelial cells. Necroptosis is a form of regulated cell death that requires activation of receptor interacting protein kinase 3 (RIPK3) and its phosphorylation of the substrate MLKL. RIPK3 plays an important role in acute kidney injury, and hence developing its inhibitors is considered as one of the promising strategies aimed at prevention and treatment of AKI. Recently, we discovered AZD5423 as a novel potent RIPK3 inhibitor using a computer-aided hybrid virtual screening strategy according to three-dimensional structure of RIPK3. Our findings revealed that AZD5423 strongly inhibits activation of RIPK3, and MLKL phosphorylation upon cisplatin-, hypoxia/reoxygenation (H/R)- and TNF-α stimuli as compared with GSK872, which is a previously identified RIPK3 inhibitor. Importantly, AZD5423 exerts effective protection against cisplatin- and ischemia/reperfusion (I/R)-induced AKI mouse model. The results of cellular thermal shift assay and experiments in RIPK3 knockout cells indicated that AZD5423 could directly target RIPK3 to inhibit RIPK3 kinase activity. Mechanistically, the docking of AZD5423 and RIPK3 suggested that the kinase domain of RIPK3 for Lys50, Arg313, Lys29, Arg37 might form hydrogen bonds with AZD5423. Site-directed mutagenesis further revealed that AZD5423 reduces injury response via interacting with the key RIPK3 amino acid residues of Lys50 and Arg313. In conclusion, our study has demonstrated that AZD5423 may serve as a potent inhibitor of RIPK3 kinase and a promising clinical candidate for AKI treatment.

Inhibition of METTL3 attenuates renal injury and inflammation by alleviating TAB3 m6A modifications via IGF2BP2-dependent mechanisms.

The role of N6-methyladenosine (m6A) modifications in renal diseases is largely unknown. Here, we characterized the role of N6-adenosine-methyltransferase-like 3 (METTL3), whose expression is elevated in renal tubules in different acute kidney injury (AKI) models as well as in human biopsies and cultured tubular epithelial cells (TECs). METTL3 silencing alleviated renal inflammation and programmed cell death in TECs in response to stimulation by tumor necrosis factor-α (TNF-α), cisplatin, and lipopolysaccharide (LPS), whereas METTL3 overexpression had the opposite effects. Conditional knockout of METTL3 from mouse kidneys attenuated cisplatin- and ischemic/reperfusion (I/R)-induced renal dysfunction, injury, and inflammation. Moreover, TAB3 [TGF-ß-activated kinase 1 (MAP3K7) binding protein 3] was identified as a target of METTL3 by m6A methylated RNA immunoprecipitation sequencing and RNA sequencing. The stability of TAB3 was increased through binding of IGF2BP2 (insulin-like growth factor 2 binding protein 2) to its m6A-modified stop codon regions. The proinflammatory effects of TAB3 were then explored both in vitro and in vivo. Adeno-associated virus 9 (AAV9)-mediated METTL3 silencing attenuated renal injury and inflammation in cisplatin- and LPS-induced AKI mouse models. We further identified Cpd-564 as a METTL3 inhibitor that had better protective effects against cisplatin- and ischemia/reperfusion-induced renal injury and inflammation than S-adenosyl-l-homocysteine, a previously identified METTL3 inhibitor. Collectively, METTL3 promoted m6A modifications of TAB3 and enhanced its stability via IGF2BP2-dependent mechanisms. Both genetic and pharmacological inhibition of METTL3 attenuated renal injury and inflammation, suggesting that the METTL3/TAB3 axis is a potential target for treatment of AKI.

Cpd-0225 attenuates renal fibrosis via inhibiting ALK5.

Chronic kidney disease (CKD) is an increasing public health concern, characterized by a reduced glomerular filtration rate and increased urinary albumin excretion. Renal fibrosis is an important pathological condition in patients with CKD. In this study, we evaluated the anti-fibrotic effect of Cpd-0225, a novel transforming growth factor-ß (TGF-ß) type I receptor (also known as ALK5) inhibitor, in vitro and in vivo, by comparing its effect with that of SB431542, a classic ALK5 inhibitor, which has not entered the clinical trial stage owing to multiple side effects. Our data showed that Cpd-0225 attenuated fibrotic response in TGF-ß1-stimulated human kidney tubular epithelial cells and repeated hypoxia/reoxygenation-treated mouse tubular epithelial cells. We further confirmed that Cpd-0225 improved renal tubular injury and ameliorated collagen deposition in unilateral ureteral obstruction-, ischemia/reperfusion-, and aristolochic acid-induced mouse models of renal fibrosis. In addition, molecular docking and site-directed mutagenesis showed that Cpd-0225 exerted a higher reno-protective effect than SB431542, by physically binding to the key amino acid residues, Lys232 and Lys335 of ALK5, thereby suppressing the phosphorylation of Smad3 and ERK1/2. Taken together, these findings suggest that Cpd-0225 administration attenuates renal fibrosis via ALK5-dependent mechanisms and displays a more effective therapeutic effect than SB431542. Thus, Cpd-0225 may serve as a potential therapeutic agent for the treatment of CKD.