Astragaloside IV prevents high glucose-induced podocyte apoptosis via downregulation of TRPC6

A systematic review of astragaloside IV effects on animal models of diabetes mellitus and its complications

Context

Diabetes mellitus (DM) is one of the fastest-growing diseases worldwide; however, its pathogenesis remains unclear. Complications seriously affect the quality of life of patients in the later stages of diabetes, ultimately leading to suffering. Natural small molecules are an important source of antidiabetic agents.

Objective

Astragaloside IV (AS-IV) is an active ingredient of Astragalus mongholicus (Fisch.) Bunge. We reviewed the efficacy and mechanism of action of AS-IV in animal and cellular models of diabetes and the mechanism of action of AS-IV on diabetic complications in animal and cellular models. We also summarized the safety of AS-IV and provided ideas and rationales for its future clinical application.

Methods

Articles on the intervention in DM and its complications using AS-IV, such as those published in SCIENCE, PubMed, Springer, ACS, SCOPUS, and CNKI from the establishment of the database to February 2022, were reviewed. The following points were systematically summarized: dose/concentration, route of administration, potential mechanisms, and efficacy of AS-IV in animal models of DM and its complications.

Results

AS-IV has shown therapeutic effects in animal models of DM, such as alleviating gestational diabetes, delaying diabetic nephropathy, preventing myocardial cell apoptosis, and inhibiting vascular endothelial dysfunction; however, the potential effects of AS-IV on DM should be investigated.

Conclusion

AS-IV is a potential drug for the treatment of diabetes and its complications, including diabetic vascular disease, cardiomyopathy, retinopathy, peripheral neuropathy, and nephropathy. In addition, preclinical toxicity studies indicate that it appears to be safe, but the safe human dose limit is yet to be determined, and formal assessments of adverse drug reactions among humans need to be further investigated. However, additional formulations or structural modifications are required to improve the pharmacokinetic parameters and facilitate the clinical use of AS-IV.

Pharmacological potential of Astragali Radix for the treatment of kidney diseases

BACKGROUND

With the increasing prevalence of hypertension, diabetes, and obesity, the incidence of kidney diseases is also increasing, resulting in a serious public burden. Conventional treatments for kidney diseases have unsatisfactory effects and are associated with adverse reactions. Traditional Chinese medicines have good curative effects and advantages over conventional treatments for preventing and treating kidney diseases. Astragali Radix is a Chinese herbal medicine widely used to treat kidney diseases.

PURPOSE

To review the potential applications and molecular mechanisms underlying the renal protective effects of Astragali Radix and its components and to provide direction and reference for new therapeutic strategies and future research and development of Astragali Radix.

STUDY DESIGN AND METHODS

PubMed, Google Scholar, and Web of Science were searched using keywords, including "Astragali Radix," "Astragalus," "Astragaloside IV" (AS-IV), "Astragali Radix polysaccharide" (APS), and "kidney diseases." Reports on the effects of Astragali Radix and its components on kidney diseases were identified and reviewed.

RESULTS

The main components of Astragali Radix with kidney-protective properties include AS-IV, APS, calycosin, formononetin, and hederagenin. Astragali Radix and its active components have potential pharmacological effects for the treatment of kidney diseases, including acute kidney injury, diabetic nephropathy, hypertensive renal damage, chronic glomerulonephritis, and kidney stones. The pharmacological effects of Astragali Radix are manifested through the inhibition of inflammation, oxidative stress, fibrosis, endoplasmic reticulum stress, apoptosis, and ferroptosis, as well as the regulation of autophagy.

CONCLUSION

Astragali Radix is a promising drug candidate for treating kidney diseases. However, current research is limited to animal and cell studies, underscoring the need for further verifications using high-quality clinical data.

Could Cyclosiversioside F Serve as a Dietary Supplement to Prevent Obesity and Relevant Disorders?

Obesity is the basis of numerous metabolic diseases and has become a major public health issue due to its rapidly increasing prevalence. Nevertheless, current obesity therapeutic strategies are not sufficiently effective, so there is an urgent need to develop novel anti-obesity agents. Naturally occurring saponins with outstanding bio-activities have been considered promising drug leads and templates for human diseases. Cyclosiversioside F (CSF) is a paramount multi-functional saponin separated from the roots of the food-medicinal herb Astragali Radix, which possesses a broad spectrum of bioactivities, including lowering blood lipid and glucose, alleviating insulin resistance, relieving adipocytes inflammation, and anti-apoptosis. Recently, the therapeutic potential of CSF in obesity and relevant disorders has been gradually explored and has become a hot research topic. This review highlights the role of CSF in treating obesity and obesity-induced complications, such as diabetes mellitus, diabetic nephropathy, cardiovascular and cerebrovascular diseases, and non-alcoholic fatty liver disease. Remarkably, the underlying molecular mechanisms associated with CSF in disease therapy have been partially elucidated, especially PI3K/Akt, NF-κB, MAPK, apoptotic pathway, TGF-β, NLRP3, Nrf-2, and AMPK, with the aim of promoting the development of CSF as a functional food and providing references for its clinical application in obesity-related disorders therapy.

Pharmacological Effects of Astragaloside IV: A Review

Astragaloside IV (AS-IV) is one of the main active components extracted from the Chinese medicinal herb Astragali and serves as a marker for assessing the herb's quality. AS-IV is a tetracyclic triterpenoid saponin in the form of lanolin ester alcohol and exhibits various biological activities. This review article summarizes the chemical structure of AS-IV, its pharmacological effects, mechanism of action, applications, future prospects, potential weaknesses, and other unexplored biological activities, aiming at an overall analysis. Papers were retrieved from online electronic databases, such as PubMed, Web of Science, and CNKI, and data from studies conducted over the last 10 years on the pharmacological effects of AS-IV as well as its impact were collated. This review focuses on the pharmacological action of AS-IV, such as its anti-inflammatory effect, including suppressing inflammatory factors, increasing T and B lymphocyte proliferation, and inhibiting neutrophil adhesion-associated molecules; antioxidative stress, including scavenging reactive oxygen species, cellular scorching, and regulating mitochondrial gene mutations; neuroprotective effects, antifibrotic effects, and antitumor effects.

The beneficial effects of astragaloside IV on ameliorating diabetic kidney disease

Diabetic kidney disease (DKD) has become the major cause of chronic kidney disease or end-stage renal disease. There is still a need for innovative treatment strategies for preventing, arresting, treating, and reversing DKD, and a plethora of scientific evidence has revealed that Chinese herbal monomers can attenuate DKD in multiple ways. Astragaloside IV (AS-IV) is one of the active ingredients of Astragalus membranaceus and was selected as a chemical marker in the Chinese Pharmacopeia for quality control purposes. An increasing amount of studies indicate that AS-IV is a promising novel drug for the treatment of DKD. AS-IV has been shown to improve DKD by combating oxidative stress, attenuating endoplasmic reticulum stress, regulating calcium homeostasis, alleviating inflammation, improving vascular function, improving epithelial to mesenchymal transition and so on. This review briefly summarizes the pathogenesis of DKD, systematically reviews the mechanisms by which AS-IV improves DKD, and aims to facilitate related pharmacological research and development to promote the utilization of Chinese herbal monomers in DKD.

The Molecular Basis of the Anti-Inflammatory Property of Astragaloside IV for the Treatment of Diabetes and Its Complications

Astragali Radix is a significant traditional Chinese medication, and has a long history of clinical application in the treatment of diabetes mellitus (DM) and its complications. AS-IV is an active saponin isolated from it. Modern pharmacological study shows that AS-IV has anti-inflammatory, anti-oxidant and immunomodulatory activities. The popular inflammatory etiology of diabetes suggests that DM is a natural immune and low-grade inflammatory disease. Pharmacological intervention of the inflammatory response may provide promising and alternative approaches for the prevention and treatment of DM and its complications. Therefore, this article focuses on the potential of AS-IV in the treatment of DM from the perspective of an anti-inflammatory molecular basis. AS-IV plays a role by regulating a variety of anti-inflammatory pathways in multiple organs, tissues and target cells throughout the body. The blockade of the NF-κB inflammatory signaling pathway may be the central link of AS-IV's anti-inflammatory effect, resulting in a reduction in the tissue structure and function damage stimulated by inflammatory factors. In addition, AS-IV can delay the onset of DM and its complications by inhibiting inflammation-related oxidative stress, fibrosis and apoptosis signals. In conclusion, AS-IV has therapeutic prospects from the perspective of reducing the inflammation of DM and its complications. An in-depth study on the anti-inflammatory mechanism of AS-IV is of great significance for the effective use of Chinese herbal medicine and the promotion of its status and influence on the world.

Polydatin Ameliorates High Fructose-Induced Podocyte Oxidative Stress via Suppressing HIF-1α/NOX4 Pathway

Long-term high fructose intake drives oxidative stress, causing glomerular podocyte injury. Polydatin, isolated from Chinese herbal medicine Polygonum cuspidatum, is used as an antioxidant agent that protects kidney function. However, it remains unclear how polydatin prevents oxidative stress-driven podocyte damage. In this study, polydatin attenuated high fructose-induced high expression of HIF-1α, inhibited NOX4-mediated stromal cell-derived factor-1α/C-X-C chemokine receptor type 4 (SDF-1α/CXCR4) axis activation, reduced reactive oxygen species (ROS) production in rat glomeruli and cultured podocytes. As a result, polydatin up-regulated nephrin and podocin, down-regulated transient receptor potential cation channel 6 (TRPC6) in these animal and cell models. Moreover, the data from HIF-1α siRNA transfection showed that high fructose increased NOX4 expression and aggravated SDF-1α/CXCR4 axis activation in an HIF-1α-dependent manner, whereas polydatin down-regulated HIF-1α to inhibit NOX4 and suppressed SDF-1α/CXCR4 axis activation, ameliorating high fructose-induced podocyte oxidative stress and injury. These findings demonstrated that high fructose-driven HIF-1α/NOX4 pathway controlled podocyte oxidative stress damage. Intervention of this disturbance by polydatin could help the development of the therapeutic strategy to combat podocyte damage associated with high fructose diet.

Clinical evidence construction of East Asian herbal medicine for inflammatory pain in rheumatoid arthritis based on integrative data mining approach

BACKGROUND

Rheumatoid arthritis (RA) is a chronic inflammatory disease that leads to a significant social burden. East Asian herbal medicine (EAHM) has long been used to treat RA. Therefore, a systematic study of how EAHM treatments can be developed into new drugs using specific materials is needed.

METHODS

Eleven databases containing literature in English, Korean, Chinese, and Japanese were searched for randomized controlled trials comparing EAHM with conventional medicine (CM). A meta-analysis was performed on the variable data to assess their effects on inflammatory pain. Subsequently, we searched for core materials and combinations of core material-based data mining methods.

RESULTS

A total of 186 trials involving 19,716 patients with RA met the inclusion criteria. According to the meta-analysis, EAHM had a significantly superior effect on continuous pain intensity, tender joint count, and response rate. Patients treated with EAHM had a significantly reduced incidence of adverse events compared with those treated with CM. Based on additional analysis of the EAHM formula data included in this meta-analysis, 21 core materials and five core herbal combinations were identified.

CONCLUSION

EAHM remedies for RA have the adequate potential for use as candidate materials for treating inflammatory pain in RA. The candidate core herbs evaluated in this study act on multiple pathways and are expected to provide pain relief, sustained inflammation suppression, immune regulation, and prevention of joint destruction. It seems worthwhile to conduct follow-up research on drug development using the core materials derived from this review.

Roles of transient receptor potential channel 6 in glucose-induced cardiomyocyte injury

BACKGROUND

Diabetic cardiomyopathy (DCM) is a serious complication of end-stage diabetes that presents symptoms such as cardiac hypertrophy and heart failure. The transient receptor potential channel 6 (TRPC6) protein is a very important selective calcium channel that is closely related to the development of various cardiomyopathies.

AIM

To explore whether TRPC6 affects cardiomyocyte apoptosis and proliferation inhibition in DCM.

METHODS

We compared cardiac function and myocardial pathological changes in wild-type mice and mice injected with streptozotocin (STZ), in addition to comparing the expression of TRPC6 and P-calmodulin-dependent protein kinase II (P-CaMKII) in them. At the same time, we treated H9C2 cardiomyocytes with high glucose and then evaluated the effects of addition of SAR, a TRPC6 inhibitor, and KN-93, a CaMKII inhibitor, to such H9C2 cells in a high-glucose environment.

RESULTS

We found that STZ-treated mice had DCM, decreased cardiac function, necrotic cardiomyocytes, and limited proliferation. Western blot and immunofluorescence were used to detect the expression levels of various appropriate proteins in the myocardial tissue of mice and H9C2 cells. Compared to those in the control group, the expression levels of the apoptosis-related proteins cleaved caspase 3 and Bax were significantly higher in the experimental group, while the expression of the proliferation-related proteins proliferating cell nuclear antigen (PCNA) and CyclinD1 was significantly lower. In vivo and in vitro, the expression of TRPC6 and P-CaMKII increased in a high-glucose environment. However, addition of inhibitors to H9C2 cells in a high-glucose environment resulted in alleviation of both apoptosis and proliferation inhibition.

CONCLUSION

The inhibition of apoptosis and proliferation of cardiomyocytes in a high-glucose environment may be closely related to activation of the TRPC6/P-CaMKII pathway.

Recent Advances in Traditional Chinese Medicine for Treatment of Podocyte Injury

Podocyte is also called glomerular epithelial cell, which has been considered as the final gatekeeper of glomerular filtration barrier (GFB). As a major contributor to proteinuria, podocyte injury underlies a variety of glomerular diseases and becomes the challenge to patients and their families in general. At present, the therapeutic methods of podocyte injury mainly include angiotensin-converting enzyme inhibitors or angiotensin receptor blockers, steroid and immunosuppressive medications. Nevertheless, the higher cost and side effects seriously disturb patients with podocyte injury. Promisingly, traditional Chinese medicine (TCM) has received an increasing amount of attention from different countries in the treatment of podocyte injury by invigorating spleen and kidney, clearing heat and eliminating dampness, as well enriching qi and activating blood. Therefore, we searched articles published in peer-reviewed English-language journals through Google Scholar, PubMed, Web of Science, and Science Direct. The protective effects of active ingredients, herbs, compound prescriptions, acupuncture and moxibustion for treatment of podocyte injury were further summarized and analyzed. Meanwhile, we discussed feasible directions for future development, and analyzed existing deficiencies and shortcomings of TCM in the treatment of podocyte injury. In conclusion, this paper shows that TCM treatments can serve as promising auxiliary therapeutic methods for the treatment of podocyte injury.

Yishen capsule promotes podocyte autophagy through regulating SIRT1/NF-κB signaling pathway to improve diabetic nephropathy

Diabetic nephropathy (DN) is a common complication of diabetes. Yishen capsule, composed of Chinese herbs, improves the clinical outcome in DN patients. However, its therapeutic potential and underlying mechanisms require further elucidation. Hence, our study aimed to investigate the underlying mechanisms and therapeutic potential of Yishen capsule in DN. Streptozotocin-induced DN rats were treated with Yishen capsules (1.25 g/kg/day) for 8 weeks. Then, blood glucose and urine protein levels were measured. Hematoxylin and eosin staining and western blot assays were used to examine the histologic changes and gene expression, respectively, in kidney samples. Mouse podocytes were treated with rat serum containing Yishen capsule and transmission electron microscopy was used to examine autophagosome formation. Cell counting kit-8 assay was performed to examine cell proliferation. Western blot and reverse transcription-quantitative polymerase chain reaction (RT-qPCR) analyses were conducted to detect changes in gene expression. The localization of SIRT1 was examined in the podocytes using immunocytofluorescence assay. We found that Yishen capsule relieved pathological changes, decreased urine protein, increased SIRT1, LC3-II, and Beclin-1 expression, and reduced acetylated NF-κB p65 expression in vivo. In addition, rat serum containing Yishen capsule showed improved podocyte proliferation, promoted the mRNA and protein levels of LC3-II and Beclin-1, and induced nuclear translocation of SIRT1. Furthermore, it increased SIRT1 expression and decreased mRNA level of NF-κB in the serum. SIRT1 inhibitor increased the mRNA level of NF-κB. Our data suggests that Yishen capsule improves DN by promoting podocyte autophagy via the SIRT1/NF-κB pathway.

Astragaloside IV inhibits palmitic acid-induced apoptosis through regulation of calcium homeostasis in mice podocytes

Loss of podocytes is a hallmark of diabetic nephropathy, and a growing body of evidence indicates that podocytes are susceptible to palmitic acid (PA). We have previously shown that AS-IV inhibited PA-induced podocyte apoptosis by activating sarcoendoplasmic reticulum Ca²⁺ ATPase (SERCA), which indicate calcium regulation may involve in the process. Immunofluorescence staining, Western blot and flow cytometry were used to measure the protective efficacy of AS-IV to ameliorate PA-induced ER stress and podocyte apoptosis. Meanwhile, AS-IV inhibited cytochrome c release, decreased mitochondrial membrane potential, accompany with the depletion of endoplasmic reticulum Ca²⁺ and elevation of cytosolic and mitochondrial Ca²⁺. Sequestration of cytosolic calcium with BAPTA-AM limited the response of podocyte apoptosis, while during the process the effect of AS-IV was also restrained. In contrast, elevation of cytosolic calcium with calcium ionophore ionomycin was depressed by AS-IV addition. Furthermore, inhibiting TRPC6 expression with SKF96365 or TRPC6 siRNA counteracted the beneficial effect of AS-IV. Our study provides further evidence to conclude the inhibitory effect of AS-IV to podocyte apoptosis is Ca²⁺-dependent. And the efficacy correlates with inhibiting TRPC6-mediated Ca²⁺ influx, and then cellular Ca²⁺ disturbance was coordinated.

Astragaloside IV protects against podocyte apoptosis by inhibiting oxidative stress via activating PPARγ-Klotho-FoxO1 axis in diabetic nephropathy

AIMS

Podocyte apoptosis plays an important role in the pathogenesis of diabetic nephropathy (DN). Astragaloside IV (AS-IV) has been shown to protect against podocyte apoptosis. Here we aim to investigate the mechanism responsible for the protective effects of AS-IV.

MAIN METHODS

Diabetic db/db mice and high glucose (HG)-cultured podocytes were treated with AS-IV. Renal function and histopathological changes were measured to evaluate the therapeutic effects of AS-IV against DN. Adenovirus-mediated Klotho overexpression, Klotho siRNA, and PPARγ inhibitor were applied in vitro to investigate the potential mechanism. The expression levels of mRNA and proteins were analyzed by qRT-PCR, western blot or immunofluorescence. Intracellular ROS and mitochondrial superoxide were detected by DHE and MitoSOx Red, respectively. Cell apoptosis was evaluated by TUNEL staining and flow cytometry.

KEY FINDINGS

AS-IV improved renal function and ameliorated podocyte injury in db/db mice accompanied with enhanced Klotho expression in glomerular podocytes. In vitro, AS-IV inhibited HG-induced podocyte apoptosis and restored HG-inhibited Klotho expression, whereas Klotho knockdown abrogated the anti-apoptosis action of AS-IV. Further study showed that adenovirus-mediated Klotho overexpression enhanced Forkhead transcription factor O1 (FoxO1)-dependent antioxidant activity and attenuated HG-evoked oxidative stress and apoptosis. AS-IV prevented HG-induced FoxO1 inhibition and oxidative stress, whereas Klotho knockdown reversed these effects. Cotreatment with PPARγ inhibitor T0070907 abolished AS-IV-induced Klotho expression and anti-apoptosis action.

SIGNIFICANCE

These data suggested that AS-IV attenuated podocyte apoptosis presumably by inhibiting oxidative stress via activating PPARγ-Klotho-FoxO1 signaling pathway, thereby ameliorating DN. This study provided new insights into the molecular mechanisms of AS-IV against DN.

Qizhijiangtang capsule for the treatment of diabetic kidney disease: A protocol for systematic review and meta-analysis

BACKGROUNDS

Diabetic kidney disease (DKD) is 1 of the common microvascular complications of diabetes, and the therapeutic effect of modern medicine on DKD is limited. At present, patented Chinese medicine Qizhijiangtang (QZJT) capsule has been widely used in the treatment of DKD. We aim to systematically assess the efficacy and safety of QZJT capsule for the treatment of diabetic kidney disease (DKD).

METHODS

Randomized controlled trials of QZJT capsule for DKD treatment will be searched until July 1, 2020, in 7 electronic databases: PubMed, Embase, Cochrane Library, CNKI, Wanfang, VIP, and Chinese Biomedical Literature. Furthermore, additional relevant publications will be manually searched according to reference lists from the resulting publications. The Cochrane risk test from the Cochrane Handbook will be used as a bias tool to evaluate the methodological quality. The clinical efficacy will be the primary outcome, which is based on the changes in symptoms and levels of proteinuria. Review Manager 5.3 will be used to analyze the results.

RESULTS AND CONCLUSIONS

Our meta-analysis will provide evidence to the clinical application of QZJT capsule in the treatment of DKD from the 4 aspects including the clinical efficacy, changes in proteinuria, the renal function and level of blood glucose. Meanwhile, the results can also reflect the role of traditional Chinese medicine in the treatment of DKD.

PROSPERO REGISTRATION NUMBER

CRD42020153949.

TRPC6 channel and its implications in breast cancer: an overview

TRPC6 channel is widely expressed in most human tissues and participates in a number of physiological processes. TRPC6 belongs to the DAG-activated subfamily of channels, but has also been postulated as a mediator in the store-operated calcium entry pathway. The recent characterization of TRPC6 crystal structure has granted a wonderful tool to finally dissect and understand TRPC6 physiological and biophysical properties. Growing evidences have demonstrated that the pattern of expression of TRPC6 proteins is upregulated in several pathophysiological conditions, including breast cancer. However, the real role of TRPC6 in breast cancer persists still unknown. Here we present the current state of the art concerning the function and significance of TRPC6 in this disease. Future investigations should be focus in the creation and identification of compounds that specifically target the channel to ameliorate TRPC6-related diseases.

Tetrandrine Suppresses Transient Receptor Potential Cation Channel Protein 6 Overexpression- Induced Podocyte Damage via Blockage of RhoA/ROCK1 Signaling

Objective

Podocyte damage is common in many renal diseases characterized by proteinuria. Transient receptor potential cation channel protein 6 (TRPC6) plays an important role in renal function through its regulation of intracellular Ca²⁺ influx and RhoA/ROCK pathways. Chinese herb Stephania tetrandra, with the main active component being tetrandrine, has been used for the treatment of various kidney diseases for several years and has shown a positive effect. This study aimed at investigating the effect and mechanism of tetrandrine in podocyte damage induced by high expression of TRPC6.

Methods

Immortalized, differentiated murine podocytes, MPC5 were treated with valsartan (0–800 μM) and tetrandrine (0–40 μM) for 48 h. The maximum safe concentrations of valsartan and tetrandrine were selected using a cell viability assay. MPC5 podocytes stably expressing TRPC6 were constructed using a lentivirus packaging system, followed by treatment with valsartan, tetrandrine, and Y-27632 for 48 h and U73122 (10 μM) for 10 min. The RhoA/ROCK pathway and podocyte-specific proteins (nephrin and synaptopodin) levels were quantified. Podocyte apoptosis and intracellular Ca²⁺ concentration were measured.

Results

Maximum safe concentrations of 100 μM valsartan and 10 μM tetrandrine showed no observable toxicity in podocytes. MPC5 podocytes stably expressing TRPC6 had higher intracellular Ca²⁺ influx, apoptotic percentages, and expression of RhoA/ROCK proteins, but lower expression of nephrin and synaptopodin proteins. U73122 treatment for 10 min did not inhibit TRPC6, but suppressed RhoA/ROCK protein. Y-27632 decreased ROCK1 expression, but did not influence the expression of TRPC6 protein. Both 100 μM valsartan and 10 μM tetrandrine for 48 h significantly inhibited intracellular Ca²⁺ influx, apoptosis, and RhoA/ROCK pathway, and increased nephrin and synaptopodin proteins in podocytes stably expressing TRPC6.

Conclusion

Elevated TRPC6 expression can lead to podocyte injury by inducing intracellular Ca²⁺ influx and apoptosis of podocytes, and this effect may be mediated by activation of the RhoA/ROCK1 pathway. Tetrandrine can alleviate podocyte injury induced by TRPC6 expression through inhibition of the RhoA/ROCK pathway, suggesting a protective role in podocyte damage.

MicroRNA26a inhibits cisplatin-induced renal tubular epithelial cells apoptosis through suppressing the expression of transient receptor potential channel 6 mediated dynamin-related protein 1

Acute kidney injury (AKI) is a common adverse reaction of the anticancer drug. Among these chemotherapeutic agents, cisplatin, an effective chemotherapeutic drug, is extensively applied to the treatment of solid tumours, yet various adverse reactions, especially AKI, often limit their use. However, the pathogenesis of AKI caused by cisplatin remains poorly clarified. Therefore, we tested whether microRNAs, which have been certified as key regulators of disease are involved in this process. AKI mouse and HK2 cells were treated with cisplatin. Annexin V/PI staining and cleaved caspase-3 were used to assess apoptosis. Western blot analyses and qRT-PCR were used to evaluate the protein and mRNA level of TRPC6 and DRP1. miR-26a was remarkably decreased in cisplatin-induced AKI and in cisplatin co-cultured HK2 cells. Furthermore, we used a miR-26a mimics in vitro and found that apoptosis was alleviated than that in the control cells. We further verified that miR-26a protected against cisplatin-induced cell apoptosis by acting on transient receptor potential channel 6 (TRPC6) which can regulate the expression of dynamin-related protein 1 (DRP1), thus inhibited the mitochondrial apoptosis pathway. Therefore, the study unveiled that miR-26a/TRPC6/DRP1 is a novel protective pathway in cisplatin-induced AKI and may be targeted for the prevention and treatment of drug-related renal injury. SIGNIFICANCE OF THE STUDY: Our study found that miR-26a was significantly downregulated during cisplatin-induced AKI and during cisplatin co-cultured HK2 cells. Further, in vitro we used miR-26a mimic to intervene cells and found that apoptosis alleviated compared with control group. We further verified that miR-26a protected cisplatin-induced apoptosis by target transient receptor potential channel 6 (TRPC6) which can regulate the expression of dynamic-related protein 1 (DRP1) and inhibit the mitochondrial apoptosis pathway. Thus, miR-26a/TRPC6/DRP1 is a new protective pathway in cisplatin-induced AKI and may be targeted for the prevention and treatment of drug-related acute kidney injury.

Astragaloside IV derived from Astragalus membranaceus: A research review on the pharmacological effects

Decoctions prepared from the roots of Astragali Radix are known as "Huangqi" and are widely used in traditional Chinese medicine for treatment of viral and bacterial infections, inflammation, as well as cancer. Astragaloside IV (AS-IV), one of the major compounds from the aqueous extract of Astragalus membranaceus, is a cycloartane-type triterpene glycoside chemical. To date, many studies in cellular and animal models have demonstrated that AS-IV possesses potent protective effects in cardiovascular, lung, kidney and brain. Based on studies over the past several decades, this review systematically summarizes the pharmacological effects, pharmacokinetics and the toxicity of AS-IV. We analyze in detail the pharmacological effects of AS-IV on neuroprotection, liver protection, anti-cancer and anti-diabetes, attributable to its antioxidant, anti-inflammatory, anti-apoptotic properties, and the roles in enhancement of immunity, attenuation of the migration and invasion of cancer cells and improvement of chemosensitivity of chemotherapy drugs. In addition, the latest developments in the combination of AS-IV and other active ingredients of traditional Chinese medicine or chemical drugs are detailed. These pharmacological effects are associated with multiple signaling pathways, including the Raf-MEK-ERK pathway, EGFR-Nrf2 signaling pathway, Akt/PDE3B signaling pathway, AMPK signaling pathway, NF-κB signaling pathway, Nrf2 antioxidant signaling pathways, PI3K/Akt/mTOR signaling pathway, PKC-α-ERK1/2-NF-κB pathway, IL-11/STAT3 signaling pathway, Akt/GSK-3β/β-catenin pathway, JNK/c-Jun/AP-1 signaling pathway, PI3K/Akt/NF-κB pathway, miRNA-34a/LDHA pathway, Nox4/Smad2 pathway, JNK pathway and NF-kB/PPARγ pathway. This review will provide an overall understanding of the pharmacological functions of astragaloside IV on neuroprotection, liver protection, anti-cancer and anti-diabetes. In light of this, AS-IV will be a potent alternative therapeutic agent for treatment of the above mentioned diseases.

TRPC6 inactivation does not protect against diabetic kidney disease in streptozotocin (STZ)-treated Sprague-Dawley rats

Canonical transient receptor potential-6 (TRPC6) channels have been implicated in the progression of several forms of kidney disease (1). While there is strong evidence that glomerular TRPC6 channels are dysregulated in diabetic nephropathy (DN), there is no consensus as to whether deletion or inactivation of TRPC6 is protective in animal models of DN. A previous study in Dahl salt-sensitive rats suggests that TRPC6 knockout has a modest protective effect in streptozotocin (STZ)-induced DN (2). In the present study, we examined whether inactivation of TRPC6 channels by CRISPR/Cas9 editing (Trpc6 del/del rats) affects progression of STZ-induced DN in Sprague-Dawley rats. Wild-type littermates (Trpc6 wt/wt rats) were used as controls. We observed that a single injection of STZ resulted in severe hyperglycemia that was sustained over a 10-week period, accompanied by a marked reduction in circulating C-peptide, dyslipidemia, and failure to gain weight compared to vehicle-treated animals. Those effects were equally severe in Trpc6 wt/wt and Trpc6 del/del rats. STZ treatment resulted in increased urine albumin excretion at 4, 8, and 10 weeks after injection, and this effect was equally severe in Trpc6 wt/wt and Trpc6 del/del rats. TRPC6 inactivation had no effect on blood urea nitrogen (BUN), plasma creatinine concentration, urine nephrin excretion, or kidney weight:body weight ratio measured 10 weeks after STZ injection. STZ treatment evoked modest and equivalent mesangial expansion in Trpc6 wt/wt and Trpc6 del/del rats. In summary, we observed no protective effect of TRPC6 inactivation on STZ-induced DN in rats on the Sprague-Dawley background.

Effect of astragaloside IV and the role of nuclear receptor RXRα in human peritoneal mesothelial cells in high glucose‑based peritoneal dialysis fluids

Peritoneal fibrosis is a serious complication that can occur during peritoneal dialysis (PD), which is primarily caused by damage to peritoneal mesothelial cells (PMCs). The onset of peritoneal fibrosis is delayed or inhibited by promoting PMC survival and inhibiting PMC epithelial-to-mesenchymal transition (EMT). In the present study, the effect of astragaloside IV and the role of the nuclear receptor retinoid X receptor-α (RXRα) in PMCs in high glucose-based PD fluids was investigated. Human PMC HMrSV5 cells were transfected with RXRα short hairpin RNA (shRNA), or an empty vector, and then treated with PD fluids and astragaloside IV. Cell viability, apoptosis and EMT were examined using the Cell Counting Kit-8 assay and flow cytometry, and by determining the levels of caspase-3, E-cadherin and α-smooth muscle actin (α-SMA) via western blot analysis. Cell viability and apoptosis were increased, as were the levels of E-cadherin in HMrSV5 cells following treatment with PD fluid. The protein levels of α-SMA and caspase-3 were increased by treatment with PD fluid. Exposure to astragaloside IV inhibited these changes; however, astragaloside IV did not change cell viability, apoptosis, E-cadherin or α-SMA levels in HMrSV5 cells under normal conditions. Transfection of HMrSV5 cells with RXRα shRNA resulted in decreased viability and E-cadherin expression, and increased apoptosis and α-SMA levels, in HMrSV5 cells treated with PD fluids and co-treated with astragaloside IV or vehicle. These results suggested that astragaloside IV increased cell viability, and inhibited apoptosis and EMT in PMCs in PD fluids, but did not affect these properties of PMCs under normal condition. Thus, the present study suggested that RXRα is involved in maintaining viability, inhibiting apoptosis and reducing EMT of PMCs in PD fluid.

Protective effect of silencing Stat1 on high glucose-induced podocytes injury via Forkhead transcription factor O1-regulated the oxidative stress response

Background

Podocyte plays an important role in maintaining the integrity and function of the glomerular filtration barrier. Various studies reported that forkhead transcription factor (Fox) O1 played a key role in anti-oxidative signaling. This study aimed to investigate the role of Stat1 in high glucose (HG) -induced podocyte injury.

Methods

Under normal glucose, hypertonic and HG stimulated podocyte conditions, cell counting kit-8 (CCK-8) assay, flow cytometry and western blot and quantitative real-time polymerase chain reaction (qRT-PCR) were respectively carried out to determine cell viability, apoptosis, reactive oxygen species (ROS) production and related genes expressions. We then respectively used silent Stat1, simultaneous silencing Stat1 and FoxO1 and over-expression of FoxO1, to observe whether they/it could reverse the damage of podocytes induced by HG.

Results

High glucose attenuated cell survival and promoted cell apoptosis in MPC-5 cells at the same time, and it was also observed to promote the protein expression of Stat1 and the FoxO1 expression inhibition. Silencing Stat1 could reverse HG-induced podocytes injury. Specifically, siStat1 increased cell viability, inhibited cell apoptosis and attenuated ROS level in a high-glucose environment. Cleaved caspase-3 and pro-apoptosis protein Bax was significantly down-regulated, and anti-apoptosis protein Bcl-2 was up-regulated by siStat1. The antioxidant genes Catalase, MnSOD, NQO1 and HO1 were up-regulated by siStat1. We found that silencing FoxO1 reversed the protective effect of siStat1 on the HG-induced podocytes injury.

Conclusions

Silencing Stat1 could reverse the effects of high glucose-triggered low cell viability, cell apoptosis and ROS release and the functions of Stat1 might be involved in FoxO1 mediated-oxidative stress in nucleus.

Chemical constituents of Kopsia officinalis and their antagonizing high glucose-evoked podocyte injury activity

Four new indole alkaloids (1-4) and twenty known compounds (5-24) were isolated from the leaves and stems, and fruits of Kopsia officinalis. Their structures were confirmed by means of spectroscopic methods. All these isolates were evaluated for their antagonizing high glucose-evoked podocyte injury activity for the first time, and compounds 5-8 showed potent activity with EC₅₀ values of 3.0-12.0 μM.

TRPC channels: Regulation, dysregulation and contributions to chronic kidney disease

Mutations in the gene encoding canonical transient receptor potential-6 (TRPC6) channels result in severe nephrotic syndromes that typically lead to end-stage renal disease. Many but not all of these mutations result in a gain in the function of the resulting channel protein. Since those observations were first made, substantial work has supported the hypothesis that TRPC6 channels can also contribute to progression of acquired (non-genetic) glomerular diseases, including primary and secondary FSGS, glomerulosclerosis during autoimmune glomerulonephritis, and possibly in type-1 diabetes. Their regulation has been extensively studied, especially in podocytes, but also in mesangial cells and other cell types present in the kidney. More recent evidence has implicated TRPC6 in renal fibrosis and tubulointerstitial disease caused by urinary obstruction. Consequently TRPC6 is being extensively investigated as a target for drug discovery. Other TRPC family members are present in kidney. TRPC6 can form a functional heteromultimer with TRPC3, and it has been suggested that TRPC5 may also play a role in glomerular disease progression, although the evidence on this is contradictory. Here we review literature on the expression and regulation of TRPC6, TRPC3 and TRPC5 in various cell types of the vertebrate kidney, the evidence that these channels are dysregulated in disease models, and research showing that knock-out or pharmacological inhibition of these channels can reduce the severity of kidney disease. We also summarize several areas that remain controversial, and some of the large gaps of knowledge concerning the fundamental role of these proteins in regulation of renal function.

Protective or deleterious role of Wnt/beta-catenin signaling in diabetic nephropathy: An unresolved issue

In recent years, the Wnt/β-catenin signaling has gained tremendous attention due to its ability to modulate a number of diseases including diabetic nephropathy. Studies have shown that there is decrease in the secretion of Wnt proteins including Wnt4, 5a and Wnt 6 during high glucose concentration or diabetic conditions, which leads to decreased translocation of β-catenin to nucleus. The down-regulation of Wnt/β-catenin signaling leads to detrimental effects on kidney including increased apoptosis of mesangial cells and increased deposition of fibrous tissue in mesangium. The pharmacological modulators such as spironolactone, NO donor and antioxidant are shown to produce beneficial effects in diabetic nephropathy by up regulating the expression of Wnt proteins and activation of diabetes-induced suppressed Wnt/β-catenin signaling. On the other hand, it is documented that diabetes leads to overactivation of Wnt1/β-catenin signaling, which promotes podocyte injury, induce epithelial-mesenchymal transition of podocytes along with renal injury and fibrosis. Accordingly, different interventions aimed to suppress overactivated Wnt/β-catenin signaling are reported to improve the condition and symptoms associated with diabetic nephropathy. The present review discusses the dual role of Wnt/beta-catenin signaling in the pathogenesis of diabetic nephropathy.

(-)‑Oleocanthal inhibits proliferation and migration by modulating Ca2+ entry through TRPC6 in breast cancer cells

Triple negative breast cancer is an aggressive type of cancer that does not respond to hormonal therapy and current therapeutic strategies are accompanied by side effects due to cytotoxic actions on normal tissues. Therefore, there is a need for the identification of anti-cancer compounds with negligible effects on non-tumoral cells. Here we show that (-)‑oleocanthal (OLCT), a phenolic compound isolated from olive oil, selectively impairs MDA-MB-231 cell proliferation and viability without affecting the ability of non-tumoral MCF10A cells to proliferate or their viability. Similarly, OLCT selectively impairs the ability of MDA-MB-231 cells to migrate while the ability of MCF10A to migrate was unaffected. The effect of OLCT was not exclusive for triple negative breast cancer cells as we found that OLCT also attenuate cell viability and proliferation of MCF7 cells. Our results indicate that OLCT is unable to induce Ca²⁺ mobilization in non-tumoral cells. By contrast, OLCT induces Ca²⁺ entry in MCF7 and MDA-MB-231 cells, which is impaired by TRPC6 expression silencing. We have found that MDA-MB-231 and MCF7 cells overexpress the channel TRPC6 as compared to non-tumoral MCF10A and treatment with OLCT for 24-72 h downregulates TRPC6 expression in MDA-MB-231 cells. These findings indicate that OLCT impairs the ability of breast cancer cells to proliferate and migrate via downregulation of TRPC6 channel expression while having no effect on the biology of non-tumoral breast cells.

[NFAT2 mediates high glucose-induced apoptosis in glomerular podocytes in vitro]

OBJECTIVE

To determine whether hyperglycemia activates NFAT2 in cultured podocytes to cause podocyte apoptosis and explore the role of NFAT2 in high glucose-induced podocyte apoptosis.

METHODS

Immortalized mouse podocytes were cultured in the presence of normal (5.3 mmol/L) or high glucose (10, 20, 30, and 40 mmol/L) or pretreated with 11R-vivit (100 nmol/L) or cyclosporine A (500 nmol/L) before exposure to 20 mmol/L glucose for different durations (0.5-48 h). The activation of NFAT2 in the podocytes was detected using Western blotting and immunofluorescence assay. The role of NFAT2 in hyperglycemia-induced podocyte apoptosis was explored by observing the inhibition of NFAT2 activation by 11R-vivit using flow cytometry. Intracellular Ca²⁺ was monitored in high glucose-treated podocytes using Fluo-3/AM. The mRNA and protein expressions of the apoptosis gene Bax were detected using real time-qPCR and Western blotting.

RESULTS

Exposure to high glucose in the medium time- and dose-dependently activated NFAT2 in cultured podocytes. Pretreatment with cyclosporine A or 11R- VIVIT completely blocked nuclear accumulation of NFAT2. Treatment with 11R- vivit also inhibited high glucoseinduced apoptosis in cultured podocytes. Exposure to high glucose obviously increased [Ca^{2 +}]I in the podocytes to cause activation of calcineurin and the subsequent increment of nuclear accumulation of NFAT2 and Bax expression.

CONCLUSIONS

High glucose-induced apoptosis in podocytes is mediated by calcineurin/NFAT2/Bax signaling pathway, which may serve as a potential target for therapeutic intervention.

Astragaloside IV/lncRNA-TUG1/TRAF5 signaling pathway participates in podocyte apoptosis of diabetic nephropathy rats

Objective

This study aims to figure out the mechanism of astragaloside IV (AS-IV) in the protection of podocyte apoptosis in diabetic nephropathy (DN) rats.

Materials and methods

Streptozotocin (STZ) was used to induce diabetes in rats, and the diabetic rats were treated with 5 mg/kg/d of AS-IV for 12 weeks. Albuminuria level, relative TUG1 and TRAF5 levels, and TRAF5 and cleaved-caspase-3 protein levels were examined by ELISA, quantitative reverse transcription (qRT)-PCR, and Western blot analyses, respectively. The interaction between TUG1 and TRAF5 was confirmed by RNA pull-down and RNA precipitation. TUNEL assay was used to detect podocyte apoptosis.

Results

Compared with control rats, DN rats had higher albuminuria and TRAF5 levels and lower TUG1 level. AS-IV treatment attenuated albuminuria and TRAF5 levels and improved TUG1 level in DN rats. TUG1 was downregulated and TRAF5 was upregulated in high-glucose-treated MPC5 cells, and AS-IV ameliorated the TUG1 level. In addition, TUG1 interacted with TRAF5, and TUG1 overexpression promoted degradation of TRAF5 protein. Besides, AS-IV modulated TRAF5 expression through regulating TUG1. AS-IV decreased podocyte apoptosis via the TUG1/TRAF5 pathway. Finally, in vivo experiment proved that si-TUG1 abrogated the protective effect of AS-IV on DN.

Conclusion

AS-IV attenuated podocyte apoptosis and protected diabetic rats from DN via the lncRNA-TUG1/TRAF5 pathway.

[Research advances in the association between transient receptor potential cation channel 6 and kidney disease]

Transient receptor potential cation channel 6 (TRPC6) is a member of the transient receptor superfamily encoded by the TRPC6 gene and is widely expressed in tissues and organs of the human body, especially in the glomerular podocytes. TRPC6 interacts with various slit diaphragm (SD) proteins including podocin, nephrin, ACTN4, and CD2AP to maintain the normal structure and function of glomerular podocytes. Foot process fusion caused by podocyte damage due to various factors is the most important morphological change in kidney disease. This article reviews the biological function of TRPC6 and its effect on kidney disease.

Research Progress on Mechanism of Podocyte Depletion in Diabetic Nephropathy

Diabetic nephropathy (DN) together with glomerular hyperfiltration has been implicated in the development of diabetic microangiopathy in the initial stage of diabetic diseases. Increased amounts of urinary protein in DN may be associated with functional and morphological alterations of podocyte, mainly including podocyte hypertrophy, epithelial-mesenchymal transdifferentiation (EMT), podocyte detachment, and podocyte apoptosis. Accumulating studies have revealed that disruption in multiple renal signaling pathways had been critical in the progression of these pathological damages, such as adenosine monophosphate-activated kinase signaling pathways (AMPK), wnt/β-catenin signaling pathways, endoplasmic reticulum stress-related signaling pathways, mammalian target of rapamycin (mTOR)/autophagy pathway, and Rho GTPases. In this review, we highlight new molecular insights underlying podocyte injury in the progression of DN, which offer new therapeutic targets to develop important renoprotective treatments for DN over the next decade.