Hsp90β is involved in the development of high salt-diet-induced nephropathy via interaction with various signalling proteins

Qian Yang Yu Yin granule improves hypertensive renal damage: A potential role for TRPC6-CaMKKβ-AMPK-mTOR-mediated autophagy

ETHNOPHARMACOLOGICAL RELEVANCE

Qian Yang Yu Yin granules (QYYYG) have a long history in the treatment of hypertensive renal damage (HRD) in China. Clinical studies have found that QYYYG stabilizes blood pressure and prevents early renal damage. However, the exact mechanism is not entirely clear.

AIM OF THE STUDY

To evaluate the therapeutic effect and further explore the therapeutic mechanism of QYYYG against HRD.

MATERIALS AND METHODS

The efficacy of QYYYG in treating HRD was assessed in spontaneous hypertension rats (SHR). Renal autophagy and the TRPC6-CaMKKβ-AMPK pathway in rats were evaluated. The regulatory role of QYYYG in angiotensin II (Ang II) induced abnormal autophagy in rat podocytes was determined by detecting autophagy-related proteins, intracellular Ca²⁺ content, and the TRPC6-CaMKKβ-AMPK-mTOR pathway expressions. Finally, we established a stable rat podocyte cell line overexpressing TRPC6 and used the cells to verify the regulatory effects of QYYYG.

RESULTS

QYYYG alleviated HRD and reversed the abnormal expression of autophagy-related genes in the SHR. In vitro, QYYYG protected against Ang II-induced podocyte damage. Furthermore, treatment of podocytes with QYYYG reversed Ang II-induced autophagy and inhibited Ang II-stimulated TRPC6 activation, Ca²⁺ influx and activation CaMKKβ-AMPK pathway. Overexpression of TRPC6 resulted in pronounced activation of CaMKKβ, AMPK, and autophagy induction in rat podocytes, which were significantly attenuated by QYYYG.

CONCLUSIONS

The present study suggested that QYYYG may exert its HRD protective effects in part by regulating the abnormal autophagy of podocytes through the TRPC6-CaMKKβ-AMPK-mTOR pathway.

Biomarkers of high salt intake

High salt intake is associated with hypertension, which is a leading modifiable risk factor for cardiovascular disease (CVD) and chronic kidney disease (CKD). International Guidelines recommend a large reduction in the consumption of sodium to reduce blood pressure, organ damage, and mortality. In its early stages, the symptoms of CKD are generally not apparent. CKD proceeds in a "silent" manner, necessitating the need for urinary biomarkers to detect kidney damage at an early stage. Since traditional renal biomarkers, such as serum creatinine, are not sufficiently sensitive, difficulties are associated with detecting kidney damage induced by a high salt intake, particularly in normotensive individuals. Several new biomarkers for renal tubular damage, such as neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), vanin-1, liver-type fatty acid-binding protein (L-FABP), and monocyte chemotactic protein-1 (MCP-1), have recently been identified. However, few studies have investigated early biomarkers for CKD progression associated with a high salt diet. This chapter provides insights into novel biomarkers for CKD in normo- and hypertensive individuals with a high salt intake. Recent studies using spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto rats (WKY) fed a high salt diet identified urinary vanin-1 and NGAL as early biomarkers for renal tubular damage in SHR and WKY, whereas urinary KIM-1 was a useful biomarker for salt-induced renal injury in SHR only. Clinical studies are needed to confirm these findings.

A Buthus martensii Karsch scorpion sting targets Nav1.7 in mice and mimics a phenotype of human chronic pain

GAIN

and loss-of-function mutations in Nav1.7 cause chronic pain and pain insensitivity, respectively. The preferential expression of Nav1.7 in peripheral nervous system and its role in human pain signaling make Nav1.7 a promising target for next-generation pain therapeutics. However, pharmacological agents have not fully recapitulated these pain phenotypes, and, due to the lack of subtype-selective molecular modulators, the role of Nav1.7 in the perception of pain remains poorly understood. Scorpion venom is an excellent source of bioactive peptides that modulate various ion channels, including voltage-gated sodium (Nav) channels . Here, we demonstrate that Buthus martensii Karsch scorpion venom (BV) elicits pain responses in mice through direct enhancement of Nav1.7 activity, and have identified that Makatoxin-3, an α-like toxin as a critical component for BV-mediated effects on Nav1.7. Blocking other Nav subtypes did not eliminate BV-evoked pain responses, supporting the pivotal role of Nav1.7 in BV-induced pain . Makatoxin-3 acts on the S3-S4 loop of voltage sensor domain IV (VSD4) of Nav1.7, which causes a hyperpolarizing shift in the steady-state fast inactivation and impairs inactivation kinetics. We also determined the key residues and structure-function relationships for the toxin-channel interactions, which are distinct from those of other well-studied α-toxins. This study not only reveals a new mechanism underlying BV-evoked pain, but also enriches our knowledge of key structural elements of scorpion toxins that are pivotal for toxin-Nav1.7 interaction, which facilitates the design of novel Nav1.7 selective modulators.

DsbA-L mediated renal tubulointerstitial fibrosis in UUO mice

Recent studies have reported that upregulation of disulfide-bond A oxidoreductase-like protein (DsbA-L) prevented lipid-induced renal injury in diabetic nephropathy (DN). However, the role and regulation of proximal tubular DsbA-L for renal tubulointerstitial fibrosis (TIF) remains unclear. In current study, we found that a proximal tubules-specific DsbA-L knockout mouse (PT-DsbA-L-KO) attenuated UUO-induced TIF, renal cell apoptosis and inflammation. Mechanistically, the DsbA-L interacted with Hsp90 in mitochondria of BUMPT cells which activated the signaling of Smad3 and p53 to produce connective tissue growth factor (CTGF) and then resulted in accumulation of ECM of BUMPT cells and mouse kidney fibroblasts. In addition, the progression of TIF caused by UUO, ischemic/reperfusion (I/R), aristolochic acid, and repeated acute low-dose cisplatin was also alleviated in PT-DsbA-L-KO mice via the activation of Hsp90 /Smad3 and p53/CTGF axis. Finally, the above molecular changes were verified in the kidney biopsies from patients with obstructive nephropathy (Ob). Together, these results suggest that DsbA-L in proximal tubular cells promotes TIF via activation of the Hsp90 /Smad3 and p53/CTGF axis.

DsbA-L upregulation prevents lipid-induced renal injury in diabetic nephropathy. Here, the authors show that DsbA-L knockout attenuates tubulointerstitial fibrosis in mice, and show that this occurs via activation of Smad3 and p53, which result in modulation of CTGF, a regulator of kidney fibrosis.

Tyrosine nitrations impaired intracellular trafficking of FSHR to the cell surface and FSH-induced Akt-FoxO3a signaling in human granulosa cells

Many infertile women suffered from poor ovarian response, and increased reactive oxygen species with age might mediate the poor ovarian response to FSH. In this study, we collected follicular fluids and isolated granulosa cells from female patients. Increased levels of peroxynitrite, tyrosine nitrations of FSH receptor (FSHR) and apoptosis were obviously detectable with decreased FSHR protein expressions in granulosa cells of the poor ovarian responders. In KGN (a human ovarian granulosa cell line) cells, exogenous peroxynitrite could sequester FSHR in the cytoplasm, and these dislocated FSHR might suffer from proteasome-mediated degradations. Here, we identified four peroxynitrite-mediated nitrated tyrosine residues of FSHR. Site-directed mutagenesis of FSHR revealed that Y626 was pivotal for intracellular trafficking of FSHR to the cell surface. Akt-induced inactivation of FoxO3a was required for the repression of FSH on granulosa cell apoptosis. However, peroxynitrite impaired FSH-induced Akt-FoxO3a signaling, while FSHR-Y626A mutant took similar effects. In addition, FoxO3a knockdown indeed impaired FSH-mediated cell survival, while FoxO3a-S253A mutant reversed that significantly.

Quantitative Proteomic Analysis Reveals That Arctigenin Alleviates Concanavalin A-Induced Hepatitis Through Suppressing Immune System and Regulating Autophagy

Concanavalin A-induced autoimmune hepatitis is a well-established experimental model for immune-mediated liver injury. It has been widely used in the therapeutic studies of immune hepatitis. The in-depth analysis of dysregulated proteins from comparative proteomic results indicated that the activation of immune system resulted in the deregulation of autophagy. Follow-up studies validated that some immune related proteins, including Stat1, Pkr, Atg7, and Adrm1, were indeed upregulated. The accumulations of LC3B-II and p62 were confirmed by immunohistochemistry and Western blot analyses. Arctigenin pretreatment significantly alleviated the liver injury, as evidenced by biochemical and histopathological investigations, whose protective effects were comparable with Prednisone acetate and Cyclosporin A. Arctigenin pretreatment decreased the levels of IL-6 and IFN-γ, but increased the ones of IL-10. Next, the quantitative proteomic analysis demonstrated that ARC pretreatment suppressed the activation of immune system through the inhibition of IFN-γ signaling, when it downregulated the protein expressions of Stat1, P-Stat1, Pkr, P-Pkr, Bnip3, Beclin1, Atg7, LC3B, Adrm1, and p62. Meanwhile, Arctigenin pretreatment also reduced the gene expressions of Stat1, Pkr, and Atg7. These results suggested that Arctigenin alleviated autophagy as well as apoptosis through inhibiting IFN-γ/IL-6/Stat1 pathway and IL-6/Bnip3 pathway. In summary, the comparative proteomic analysis revealed that the activation of immune system led to Concanavalin A-induced hepatitis. Both autophagy and apoptosis had important clinical implications for the treatment of immune hepatitis. Arctigenin might exert great therapeutic potential in immune-mediated liver injury.

Modulations of Keap1-Nrf2 signaling axis by TIIA ameliorated the oxidative stress-induced myocardial apoptosis

Mounting evidence has strongly implicated oxidative stress in the development of cardiac dysfunction, and myocardial apoptosis contributes to the pathogenesis of heart failure. Quantitative cardiac proteomics data revealed that pressure load by TAC resulted in a significant decline in mitochondrial metabolic activity, where TIIA (Tanshinone IIA sulfonate) treatment reversed it in vivo, which might be mediated by Nrf2. In NRVMs, TIIA treatment ameliorated H₂O₂-induced caspase-3/9 activations through the suppression of p38 and mTOR signaling pathways, where caspase-mediated cleavage of YY1 and PARP resulted in the defects in mitochondrial biogenesis and DNA repair, and this event finally led to cardiomyocyte apoptosis. Mass spectrometry analysis showed that TIIA hydrophobically interacted with Keap1 (the cytoplasmic repressor of Nrf2) and induced its degradation in vitro. Site-directed mutagenesis of Keap1 identified V122/V123/I125 to be the critical residues for the TIIA-induced de-dimerization and degradation of Keap1. Besides, TIIA treatment also epigenetically up-regulated Nrf2 gene transcription, where it hypomethylated the first 5 CpGs of Nrf2 promoter. Furthermore, cardiac-specific Nrf2 knockout mice exhibited the significantly dampened anti-apoptotic effects of TIIA.