TRPC5 deletion in the central amygdala antagonizes high-fat diet-induced obesity by increasing sympathetic innervation.

Transient receptor potential channel 5 (TRPC5) is predominantly distributed in the brain, especially in the central amygdala (CeA), which is closely associated with pain and addiction. Although mounting evidence indicates that the CeA is related to energy homeostasis, the possible regulatory effect of TRPC5 in the CeA on metabolism remains unclear. Here, we reported that the expression of TRPC5 in the CeA of mice was increased under a high-fat diet (HFD). Specifically, the deleted TRPC5 protein in the CeA of mice using adeno-associated virus resisted HFD-induced weight gain, accompanied by increased food intake. Furthermore, the energy expenditure of CeA-specific TRPC5 deletion mice (TRPC5 KO) was elevated due to augmented white adipose tissue (WAT) browning and brown adipose tissue (BAT) activity. Mechanistically, deficiency of TRPC5 in the CeA boosted nonshivering thermogenesis under cold stimulation by stimulating sympathetic nerves, as the ß3-adrenoceptor (Adrb3) antagonist SR59230A blocked the effect of TRPC5 KO on this process. In summary, TRPC5 deletion in the CeA alleviated the metabolic deterioration of mice fed a HFD, and these phenotypic improvements were correlated with the increased sympathetic distribution and activity of adipose tissue.

Dietary cinnamaldehyde activation of TRPA1 antagonizes high-salt induced hypertension through restoring renal tubular mitochondrial dysfunction.

BACKGROUND: Renal proximal tubule plays a pivotal role in regulating sodium reabsorption and thus blood pressure. Transient receptor potential ankyrin 1 (TRPA1) has been reported to protect against renal injury by modulating mitochondrial function. We hypothesize that the activation of TRPA1 by its agonist cinnamaldehyde may mitigates high salt intake induced hypertension by inhibiting urinary sodium reabsorption through restoration of renal tubular epithelial mitochondrial function. METHODS: Trpa1-deficient (Trpa1-/-) mice and wild-type (WT) mice were fed standard laboratory chow [normal diet (ND) group, 0.4% salt], standard laboratory chow with 8% salt [high-salt diet (HS) group] or standard laboratory chow with 8% salt plus 0.015% cinnamaldehyde [high-salt plus cinnamaldehyde diet (HSC) group] for six months. Urinary sodium excretion, ROS production, mitochondrial function and the expression of NHE3 and Na+/K+-ATPase of renal proximal tubules were determined. RESULTS: Chronic dietary cinnamaldehyde supplementation reduced tail systolic blood pressure and 24-hour ambulatory arterial pressure in HS-fed WT mice. Compared with the mice fed HS, cinnamaldehyde supplementation significantly increased urinary sodium excretion, inhibited excess ROS production and alleviated mitochondrial dysfunction of renal proximal tubules in WT mice. However, these effects of cinnamaldehyde were absent in Trpa1-/- mice. Furthermore, chronic dietary cinnamaldehyde supplementation blunted HS-induced upregulation of NHE3 and Na+/K+-ATPase in WT mice but not Trpa1-/- mice. CONCLUSION: The present study demonstrated that chronic activation of Trpa1 attenuates HS-induced hypertension by inhibiting urinary sodium reabsorption through restoring renal tubular epithelial mitochondrial function. Renal TRPA1 may be a potential target for the management of excessive dietary salt intake-associated hypertension.

A high-salt diet promotes hypertrophic scarring through TRPC3-mediated mitochondrial Ca2+ homeostasis dysfunction.

Diet High in salt content have been associated with cardiovascular disease and chronic inflammation. We recently demonstrated that transient receptor potential canonical 3 (TRPC3) channels regulate myofibroblast transdifferentiation in hypertrophic scars. Here, we examined how high salt activation of TRPC3 participates in hypertrophic scarring during wound healing. In vitro, we confirmed that high salt increased the TRPC3 protein expression and the marker of myofibroblast alpha smooth muscle actin (α-SMA) in wild-type mice (WT) primary cultured dermal fibroblasts but not Trpc3-/- mice. Activation of TRPC3 by high salt elevated cytosolic Ca2+ influx and mitochondrial Ca2+ uptake in dermal fibroblasts in a TRPC3-dependent manner. High salt activation of TRPC3 enhanced mitochondrial respiratory dysfunction and excessive ROS production by inhibiting pyruvate dehydrogenase action, that activated ROS-triggered Ca2+ influx and the Rho kinase/MLC pathway in WT mice but not Trpc3-/- mice. In vivo, a persistent high-salt diet promoted myofibroblast transdifferentiation and collagen deposition in a TRPC3-dependent manner. Therefore, this study demonstrates that high salt enhances myofibroblast transdifferentiation and promotes hypertrophic scar formation through enhanced mitochondrial Ca2+ homeostasis, which activates the ROS-mediated pMLC/pMYPT1 pathway. TRPC3 deficiency antagonizes high salt diet-induced hypertrophic scarring. TRPC3 may be a novel target for hypertrophic scarring during wound healing.

Sodium-Glucose Cotransporter 2 Inhibitor Canagliflozin Antagonizes Salt-Sensitive Hypertension Through Modifying Transient Receptor Potential Channels 3 Mediated Vascular Calcium Handling.

Background Salt-sensitive hypertension is highly prevalent and associated with cardiorenal damage. Large clinical trials have demonstrated that SGLT2 (sodium-glucose cotransporter 2) inhibitors exert hypotensive effect and cardiorenal protective benefits in patients with hypertension with and without diabetes. However, the underlying mechanism remains elusive. Methods and Results Dahl salt-sensitive rats and salt-insensitive controls were fed with 8% high-salt diet and some of them were treated with canagliflozin. The blood pressure, urinary sodium excretion, and vascular function were detected. Transient receptor potential channel 3 (TRPC3) knockout mice were used to explain the mechanism. Canagliflozin treatment significantly reduced high-salt-induced hypertension and this effect was not totally dependent on urinary sodium excretion in salt-sensitive hypertensive rats. Assay of vascular function and proteomics showed that canagliflozin significantly inhibited vascular cytoplasmic calcium increase and vasoconstriction in response to high-salt diet. High salt intake increased vascular expression of TRPC3 in salt-sensitive rats, which could be alleviated by canagliflozin treatment. Overexpression of TRPC3 mimicked salt-induced vascular cytosolic calcium increase in vitro and knockout of TRPC3 erased the antihypertensive effect of canagliflozin. Mechanistically, high-salt-induced activation of NCX1 (sodium-calcium exchanger 1) reverse mode increased cytoplasmic calcium level and vasoconstriction, which required TRPC3, and this process could be blocked by canagliflozin. Conclusions We define a previously unrecognized role of TRPC3/NCX1 mediated vascular calcium dysfunction in the development of high-salt-induced hypertension, which can be improved by canagliflozin treatment. This pathway is potentially a novel therapeutic target to antagonize salt-sensitive hypertension.

Plasma Secretagogin is Increased in Individuals with Glucose Dysregulation.

OBJECTIVE: Secretagogin, a Ca2+ binding protein, is one of the most abundant proteins in pancreatic ß-cells and is critical for maintaining the structural integrity and signaling competence of ß-cells. This study seeks to assess the concentrations of plasma secretagogin in participants with prediabetes (pre-DM) and newly diagnosed type 2 diabetes (T2DM) and to explore its relationship to parameters of glucose and lipid metabolism, first-phase insulin secretion, insulin resistance and pancreatic ß-cell function. MATERIALS AND METHODS: A total of 126 eligible subjects were divided into three groups: a normal glucose tolerance (NGT, n=45), a pre-DM (n=30), and a T2DM (n=51) group. An intravenous glucose tolerance test (IVGTT) was performed, and clinical and biochemical parameters were measured for all subjects. RESULTS: Plasma secretagogin levels were significantly higher in both pre-DM and T2DM patients compared with NGT subjects and were highest in the T2DM group. Correlation analysis showed that plasma secretagogin levels were positively correlated with fasting plasma glucose, postchallenge plasma glucose (2hPG), HbA1c and body mass index (BMI) but were not correlated with waist-hip ratio, blood pressure, lipid profiles, fasting serum insulin, homeostasis model assessment for insulin resistance, homeostasis model assessment for ß-cell function and first-phase insulin secretion indicators. Multiple logistic regression analysis revealed that 2hPG and BMI were independent predictors for elevation of plasma secretagogin concentrations. CONCLUSIONS: Increased circulating secretagogin might be a molecular predictor for early diagnosis of diabetes. Further studies are needed to confirm this finding and explore the role of secretagogin in obesity.

Reducing NADPH Synthesis Counteracts Diabetic Nephropathy through Restoration of AMPK Activity in Type 1 Diabetic Rats.

Diabetic nephropathy (DN) is a major complication of diabetes mellitus and a primary cause of end-stage renal failure. Clinical studies indicate that metabolic surgery improves DN; however, the mechanism remains unclear. Here, we report that Roux-en-Y Gastric Bypass (RYGB) surgery significantly blocked and reversed DN without affecting the insulin signaling pathway. This protective role of RYGB surgery is almost blocked by either inhibition or knockout of 5'AMP-activated protein kinase (AMPK) in podocytes. Furthermore, mRNA microarray data reveal that RYGB surgery obviously reduced the gene expression involved in nicotinamide adenine dinucleotide phosphate (NAPDH) synthesis. The expression of a key NADPH synthase, hexose-6-phosphate dehydrogenase (H6PD), was inhibited by the low plasma corticosterone level after surgery. In addition, blocking NAPDH synthesis by knocking down H6PD mimicked the beneficial role of RYGB surgery through activation of AMPK in podocytes. Therefore, this study demonstrates that reducing NADPH production is critical for renal AMPK activation in response to RYGB surgery.

Activation of the bitter taste sensor TRPM5 prevents high salt-induced cardiovascular dysfunction.

High salt intake is a known risk factor of cardiovascular diseases. Our recent study demonstrated that long-term high salt intake impairs transient receptor potential channel M5 (TRPM5)-mediated aversion to high salt concentrations, consequently promoting high salt intake and hypertension; however, it remains unknown whether TRPM5 activation ameliorates cardiovascular dysfunction. Herein we found that bitter melon extract (BME) and cucurbitacin E (CuE), a major compound in BME, lowered high salt-induced hypertension. Long-term BME intake significantly enhanced the aversion to high salt concentrations by upregulating TRPM5 expression and function, eventually decreasing excessive salt consumption in mice. Moreover, dietary BME ameliorated high salt-induced cardiovascular dysfunction and angiotensin II-induced hypertension in vivo. The mechanistic evidence demonstrated that dietary BME inhibited high salt-induced RhoA/Rho kinase pathway overactivation, leading to reduced phosphorylation levels of myosin light chain kinase and myosin phosphatase targeting subunit 1. Furthermore, CuE inhibited vasoconstriction by attenuating L-type Ca2+ channel-induced Ca2+ influx in vascular smooth muscle cells. To summarize, our findings indicate that dietary BME has a beneficial role in antagonizing excessive salt consumption and thus appears promising for the prevention of high salt-induced cardiovascular dysfunction.

Transient Receptor Potential Channel Canonical Type 3 Deficiency Antagonizes Myofibroblast Transdifferentiation In Vivo.

OBJECTIVE: Myofibroblast transformation has been shown to be associated with the reactive oxygen species- (ROS-) producing enzyme NADPH oxidase (Nox4). Inhibition of transient receptor potential channel canonical type 3 (TRPC3) attenuates mitochondrial calcium handling and ROS production in the vasculature of hypertensive rats. However, it remains elusive whether TRPC3 regulates mitochondrial calcium and ROS production and participates in myofibroblast transdifferentiation during wound healing. METHODS AND RESULTS: In this study, we demonstrated that activation of TRPC3 by transforming growth factor ß (TGFß (TGFαSMA). Inhibition of TRPC3 with its specific inhibitor, Pyr3, significantly decreased TGFß (TGFαSMA). Inhibition of TRPC3 with its specific inhibitor, Pyr3, significantly decreased TGFß (TGFß (TGFTrpc3-/- mice exhibited significantly attenuated myofibroblast transdifferentiation, as demonstrated by decreased αSMA). Inhibition of TRPC3 with its specific inhibitor, Pyr3, significantly decreased TGFß (TGFß (TGFTrpc3-/- mice exhibited significantly attenuated myofibroblast transdifferentiation, as demonstrated by decreased Trpc3+/+ mice. In addition, Trpc3-/- mice exhibited significantly attenuated myofibroblast transdifferentiation, as demonstrated by decreased. CONCLUSIONS: Our data indicate that TGFß1-mediated activation of TRPC3 enhances mitochondrial calcium and ROS production, which promotes myofibroblast transdifferentiation and HTS formation. Inhibition of the TRPC3-mediated Nox4/pSmad2/3 pathway may be a useful strategy to limit HTS formation after injury.ß (TGF.

Activation of TRPV1 channel antagonizes diabetic nephropathy through inhibiting endoplasmic reticulum-mitochondria contact in podocytes.

The impairment of podocyte protein filtration function caused by excessive mitochondrial calcium intake is a critical feature of diabetic nephropathy (DN). Ca2+ channel transient receptor potential cation channel subfamily V member 1 (TRPV1) has been reported to protect against ischemia-reperfusion induced acute renal injury, but there is no report about its role in DN. Here, we report that dietary capsaicin potently inhibits and reverses chronic renal structural and functional damages in db/db or streptozotocin (STZ)-induced diabetic mice in a TRPV1-dependent manner. Activation of TRPV1 by capsaicin alleviated hyperglycemia-induced mitochondrial dysfunction in podocytes, accompanied by reduced mitochondria-associated membranes (MAMs) formation and fewer Ca2+ transport from endoplasmic reticulum (ER) to mitochondria. Mechanistically, TRPV1-mediated transient Ca2+ influx activated 5' AMP-activated protein kinase (AMPK) that reduced the transcription of Fundc1, a key molecule participating in MAMs formation. Inhibition of AMPK or overexpression of Fundc1 obviously blocked the inhibitory effect of capsaicin on MAMs formation and functional decline in podocytes. These findings emphasize the critical role of mitochondrial Ca2+ homeostasis in the maintenance of normal renal function and suggest an effective intervention method to counteract DN.

High-salt intake increases TRPC3 expression and enhances TRPC3-mediated calcium influx and systolic blood pressure in hypertensive patients.

Enhanced transient receptor potential canonical subtype 3 (TRPC3) expression and TRPC3-mediated calcium influx in monocytes from hypertensive rats and patients are associated with increased blood pressure. Daily salt intake is closely related to hypertension, but the relationship between TRPC3 expression and salt intake has not yet been evaluated in hypertensive patients. Using reverse transcription-polymerase chain reaction, we studied the expression of TRPC3 and TRPC3-related store-operated calcium entry (SOCE) in peripheral blood mononuclear cells (PBMCs) from hypertensive and normotensive control subjects. Measurement of SOCE was performed using the fluorescent dye Fura-2 AM. Participants were divided into a low-salt group (<9 g) and a high-salt group (≥9 g) based on 24-h urinary sodium excretion. Increased TRPC3 mRNA expression levels and SOCE were observed in THP-1 cells after high-NaCl treatment. However, administration of the TRPC3-specific inhibitor Pyr3 significantly decreased the effect. Furthermore, the TRPC3 mRNA expression levels in PBMCs from high-salt intake patients with essential hypertension were significantly higher than those in low-salt intake patients compared with those in normotensive control subjects. We also observed significantly increased TRPC3-mediated SOCE in PBMCs from hypertensive subjects (but not from normotensive control subjects), with calcium concentration correlating with salt intake. More importantly, TRPC3 mRNA levels showed a significant correlation with salt intake and systolic blood pressure in patients with essential hypertension. This study demonstrated, for the first time, that increased TRPC3 mRNA levels are associated with elevated salt intake and systolic blood pressure in hypertensive patients.

Inhibition of Mitochondrial Calcium Overload by SIRT3 Prevents Obesity- or Age-Related Whitening of Brown Adipose Tissue.

The whitening and loss of brown adipose tissue (BAT) during obesity and aging promote metabolic disorders and related diseases. The imbalance of Ca2+ homeostasis accounts for the dysfunction and clearance of mitochondria during BAT whitening. Capsaicin, a dietary factor activating TRPV1, can inhibit obesity induced by high-fat diet (HFD), but whether capsaicin inhibits BAT loss and the underlying mechanism remain unclear. In this study, we determined that the inhibitory effects of capsaicin on HFD-induced obesity and BAT whitening were dependent on the participation of SIRT3, a critical mitochondrial deacetylase. SIRT3 also mediated all of the beneficial effects of capsaicin on alleviating reactive oxygen species generation, elevating mitochondrial activity, and restricting mitochondrial calcium overload induced by HFD. Mechanistically, SIRT3 inhibits mitochondrial calcium uniporter (MCU)-mediated mitochondrial calcium overload by reducing the H3K27ac level on the MCU promoter in an AMPK-dependent manner. In addition, HFD also inhibits AMPK activity to reduce SIRT3 expression, which could be reversed by capsaicin. Capsaicin intervention also inhibited aging-induced BAT whitening through this mechanism. In conclusion, this study emphasizes a critical role of the AMPK/SIRT3 pathway in the maintenance of BAT morphology and function and suggests that intervention in this pathway may be an effective target for preventing obesity- or age-related metabolic diseases.