Protosappanin-A and oleanolic acid protect injured podocytes from apoptosis through inhibition of AKT-mTOR signaling

Oleanolic acid and its analogues: promising therapeutics for kidney disease

Kidney diseases pose a significant threat to human health due to their high prevalence and mortality rates. Worryingly, the clinical use of drugs for kidney diseases is associated with more side effects, so more effective and safer treatments are urgently needed. Oleanolic acid (OA) is a common pentacyclic triterpenoid that is widely available in nature and has been shown to have protective effects in kidney disease. However, comprehensive studies on its role in kidney diseases are still lacking. Therefore, this article first explores the botanical sources, pharmacokinetics, derivatives, and safety of OA, followed by a summary of the anti-inflammatory, immunomodulatory, anti-oxidative stress, autophagy-enhancing, and antifibrotic effects of OA and its analogues in renal diseases, and an analysis of the molecular mechanisms, aiming to provide further insights for the development of novel drugs for the treatment of kidney diseases.

Effects of a novel ANLN E841K mutation associated with SRNS on podocytes and its mechanism

BACKGROUND

Steroid-resistant nephrotic syndrome (SRNS) is characterized by unrelieved proteinuria after an initial 4-8 weeks of glucocorticoid therapy. Genes in podocytes play an important role in causing SRNS.

OBJECTIVE

This study aimed to report a pathogenic mutation in SRNS patients and investigate its effects on podocytes, as well as the pathogenic mechanism.

METHODS

We screened out a novel mutation by using whole-exon sequencing in the SRNS cohort and verified it via Sanger sequencing. Conservative analysis and bioinformatic analysis were used to predict the pathogenicity of the mutation. In vitro, stable podocyte cell lines were constructed to detect the effect of the mutation on the function of the podocyte. Moreover, an in vivo mouse model of podocyte ANLN gene knockout (ANLNpodKO) was used to confirm clinical manifestations. Transcriptome analysis was performed to identify differential gene expression and related signaling pathways.

RESULTS

ANLN E841K was screened from three unrelated families. ANLN E841K occurred in the functional domain and was predicted to be harmful. The pathological type of A-II-1 renal biopsy was minimal change disease, and the expression of ANLN was decreased. Cells in the mutation group showed disordered cytoskeleton, faster cell migration, decreased adhesion, increased endocytosis, slower proliferation, increased apoptosis, and weakened interaction with CD2 association protein. ANLNpodKO mice exhibited more obvious proteinuria, more severe mesangial proliferation, glomerular atrophy, foot process fusion, and increased tissue apoptosis levels than ANLNflox/flox mice after tail vein injection of adriamycin. Upregulated differentially expressed genes in cells of the mutation group were mainly enriched in the PI3K-AKT pathway.

CONCLUSION

The novel mutation known as ANLN E841K affected the function of the ANLN protein by activating the PI3K/AKT/mTOR/apoptosis pathway, thus resulting in structural and functional changes in podocytes. Our study indicated that ANLN played a vital role in maintaining the normal function of podocytes. Video Abstract.

Effects of Shenkang Pills on Early-Stage Diabetic Nephropathy in db/db Mice via Inhibiting AURKB/RacGAP1/RhoA Signaling Pathway

Diabetic nephropathy (DN) is the leading cause of end-stage renal disease, so there is an urgent need to suppress its development at early stage. Shenkang pills (SKP) are a hospital prescription selected and optimized from effective traditional Chinese medicinal formulas for clinical treatment of DN. In the present study, liquid chromatography-quadrupole-time of flight-mass spectrometry (LC-Q-TOF-MS) and total contents qualification were applied to generate a quality control standard of SKP. For verifying the therapeutic effects of SKP, db/db mice were administered intragastrically with SKP at a human-equivalent dose (1.82 g/kg) for 4 weeks. Moreover, the underlying mechanism of SKP were analyzed by the renal RNA sequencing and network pharmacology. LC-Q-TOF-MS identified 46 compounds in SKP. The total polysaccharide and organic acid content in SKP were 4.60 and 0.11 mg/ml, respectively, while the total flavonoid, saponin, and protein content were 0.25, 0.31, and 0.42 mg/ml, respectively. Treatment of SKP significantly reduced fasting blood glucose, improved renal function, and ameliorated glomerulosclerosis and focal foot processes effacement in db/db mice. In addition, SKP protected podocytes from injury by increasing nephrin and podocin expression. Furthermore, transcriptome analyses revealed that 430 and 288 genes were up and down-regulated in mice treated with SKP, relative to untreated controls. Gene ontology enrichment analysis revealed that the differentially expressed genes mainly involved in modulation of cell division and chromosome segregation. Weighted gene co-expression network analysis and network pharmacology analysis indicated that aurora kinase B (AURKB), Rac GTPase activating protein 1 (RacGAP1) and SHC binding, and spindle associated 1 (shcbp1) might be the core targets of SKP. This protein and Ras homolog family member A (RhoA) were found overexpression in db/db mice, but significantly decreased with SKP treatment. We conclude that SKP can effectively treat early-stage DN and improve renal podocyte dysfunction. The mechanism may involve down-regulation of the AURKB/RacGAP1/RhoA pathway.

Protective Effects of Caesalpinia sappan Linn. and Its Bioactive Compounds on Cardiovascular Organs

Cardiovascular diseases are the leading cause of death worldwide. The long-term aim of cardiovascular disease therapy is to reduce the mortality rate and decelerate the progression of cardiovascular organ damage. Current therapies focus on recovering heart function and reducing risk factors such as hyperglycemia and dyslipidemia. However, oxidative stress and inflammation are important causes of further damage to cardiovascular organs. Caesalpinia sappan Linn. (Fabaceae), a flowering tree native to tropical Asia, has antioxidant and anti-inflammatory properties. It is used as a natural dye to color food and beverages and as a traditional treatment for diarrhea, diabetes, and blood stasis. The phytochemical compounds in C. sappan, mainly the homoisoflavonoids brazilin, sappanone A, protosappanin, and hematoxylin, can potentially be used to protect cardiovascular organs. This review aims to provide updates on recent developments in research on C. sappan in relation to treatment of cardiovascular diseases. Many studies have reported protective effects of the plant’s bioactive compounds that reduce cardiac damage and enhance vasorelaxation. For example, brazilin and sappanone A have an impact on molecular and cellular changes in cardiovascular disease pathogenesis, mainly by modulating oxidative, inflammatory, and apoptotic signaling pathways. Therefore, bioactive compounds of C. sappan have the potential to be developed as therapeutic agents to combat cardiovascular diseases like myocardial infarction and vascular disease. This review could help further the understanding of the possible modulatory role of the compounds in cardiovascular diseases, thereby facilitating future studies.

Protosappanin A Maintains Neuronal Mitochondrial Homeostasis through Promoting Autophagic Degradation of Bax

Cerebral ischemia is accompanied by mitochondrial integrity destruction. Thus, reversion of mitochondrial damage holds great potential for cerebral ischemia therapy. As a crucial Bcl-2 family member, pro-apoptotic Bax protein is a main effector of mitochondrial permeabilization and plays an important role in mitochondrial homeostasis. However, there is still a lack of an effective cerebral protective strategy through selectively targeting Bax. In this study, we reported that natural small-molecule protosappanin A (PTA) showed a significant mitochondrial protective effect on oxygen-glucose deprivation/reperfusion (OGD/R)-induced PC12 cells injury through increasing ATP production and maintaining mitochondrial DNA (mtDNA) content. The mechanism study revealed that PTA selectively induced pro-apoptotic protein Bax degradation, without affecting other Bcl-2 family members such as Bcl-2, Bcl-xl, Bad, Puma, Bid, Bim, and Bik. In addition, we found that PTA promoted the association of autophagosomal marker LC3B to Bax for its degradation via an autophagy-dependent manner but not the ubiquitin-proteasome pathway. Collectively, our findings offered a new pharmacological strategy for maintaining mitochondrial function by inducing autophagic degradation of Bax and also provided a novel drug candidate against ischemic neuronal injury.

Long noncoding RNA Kcnq1ot1 promotes sC5b-9-induced podocyte pyroptosis by inhibiting miR-486a-3p and upregulating NLRP3

Podocytes are epithelial cells adhering glomerular capillaries, which regulate the integrity of glomerular filtration barrier. Irreversible podocyte injury induces glomerular inflammation and causes chronic renal diseases. Kcnq1ot1, a long noncoding RNA, participates in the pathogenesis of diabetic retinopathy and cardiomyopathy. However, its function in podocyte injury is elusive. Pyroptosis of murine podocyte MPC5 was triggered by sublytic complement C5b-9 (sC5b-9) for subsequent in vitro functional and mechanistic investigation. Gain/loss-of-function analysis was conducted to examine the functional role of Kcnq1ot1 in podocyte pyroptosis. Meanwhile, the molecular mechanism of Kcnq1ot1's effect on podocyte injury was explored by identifying downstream molecules and their intermediate interactions. Kcnq1ot1 was upregulated in sC5b-9-induced podocytes, and silencing Kcnq1ot1 could inhibit sC5b-9's effect on podocyte pyroptosis. We also identified the interaction between Kcnq1ot1 and miR-486a-3p, through which Kcnq1ot1 mediated miR-486a-3p inhibition by sC5b-9. Furthermore, miR-486a-3p reduced the transcriptional activity of NLRP3, while the overexpression of NLRP3 enhanced sC5b-9's effect on podocyte pyroptosis through activating NLRP3 inflammasome. sC5b-9 induces pyroptosis in podocytes through modulating the Kcnq1ot1/miR-486a-3p/NLRP3 regulatory axis, and these uncovered key molecules might facilitate podocyte-targeted treatment for renal inflammatory diseases.

Oleanolic acid mitigates interleukin-1β-induced chondrocyte dysfunction by regulating miR-148-3p-modulated FGF2 expression

BACKGROUND

microRNA (miR)-mediated post-transcriptional repression has been reported in the process of chondrocyte dysfunction. The present study aimed to investigate the molecular mechanisms underlying in oleanolic acid (OLA)-prevented interleukin (IL)-1β-induced chondrocyte dysfunction via the miR-148-3p/fibroblast growth factor-2 (FGF-2) signaling pathway.

METHODS

Candidate miRs were filtrated using miR microarray assays in chondrocytes with or without IL-1β stimulation. Gene expression of candidate miRs and protein expression of FGF2 were analyzed using a quantitative reverse transcriptase-polymerase chain reaction and western blotting, respectively. Cell growth was evaluated using cell counting kit-8 assays. Cell apoptosis was detected using Annexin V-fluorescein isothiocyanate double staining.

RESULTS

Treatment with OLA counteracted IL-1β-evoked chondrocyte growth inhibition, apoptosis, caspase3 production, and release of malondialdehyde (MDA) and 8-hydroxy-2'-deoxyguanosine. Additionally, FGF2 protein expression levels elevated by IL-1β were down-regulated by OLA and transfection with miR-148-3p mimics. IL-1β-induced down-regulation of miR-148-3p in chondrocytes was evaluated by OLA administration. Bioinformatics algorithms and experimental measurements indicated that FGF2 might be a direct target of miR-148-3p. miR-148-3p mimics exhibited equal authenticity of OLA to protect against IL-1β-induced chondrocyte dysfunction.

CONCLUSIONS

Our present findings highlight a protective effect of OLA on IL-1β-induced chondrocyte dysfunction, and a novel signal cascade comprising the miR-148-3p/FGF2 signaling pathway might be a potential therapeutic target of OLA with respect to preventing the progression of osteoarthritis.