Jin-Feng Zhao

Essential role of transient receptor potential vanilloid type 1 in evodiamine-mediated protection against atherosclerosis

We investigated whether transient receptor potential vanilloid type 1 (TRPV1) was involved in the therapeutic effect of evodiamine, a main bioactive component in the fruit of Evodiae rutaecarpa, on the development of atherosclerosis in apolipoprotein E‐deficient (ApoE−/−) mice and ApoE−/−TRPV1−/− mice.

AMP-activated protein kinase mediates erythropoietin-induced activation of endothelial nitric oxide synthase†

We investigated whether AMP‐activated protein kinase (AMPK), a multi‐functional regulator of energy homeostasis, participates in the regulation of erythropoietin (EPO)‐mediated activation of endothelial nitric oxide synthase (eNOS) in endothelial cells (ECs) and mice. In ECs, treatment with EPO increased the phosphorylation of AMPK, acetyl‐CoA carboxylase (ACC), and eNOS, as revealed by Western blot analysis. Inhibition of AMPK activation by compound C or dominant‐negative AMPK mutant abrogated the EPO‐induced increase in the phosphorylation of AMPK, ACC, and eNOS, as well as nitric oxide (NO) production. Additionally, suppression of AMPK activation abolished EPO‐induced EC proliferation, migration and tube formation. Immunoprecipitation analysis demonstrated that AMPK mediated the EPO‐induced increase in the phosphorylation of β common receptor (βCR) and the formation of a βCR–AMPK–eNOS complex. In mice, inhibition of AMPK activation by compound C markedly decreased EPO‐elicited angiogenesis in Matrigel plugs. Furthermore, the phosphorylation of AMPK and eNOS was significantly higher in aortas from EPO transgenic mice than wild‐type mice. Moreover, treatment with EPO neutralizing antibody greatly reduced the exercise training‐induced increase in phosphorylation of AMPK and eNOS in aortas of wild‐type mice. Taken together, EPO may trigger AMPK‐dependent signaling, which leads to enhanced phosphorylation of βCR and eNOS, increased βCR–AMPK–eNOS complex formation, NO production, and, ultimately, angiogenesis. J. Cell. Physiol. 227: 3053–3062, 2012.

Activation of TRPV1 Prevents OxLDL-Induced Lipid Accumulation and TNF-α-Induced Inflammation in Macrophages: Role of Liver X Receptor α

The transient receptor potential vanilloid type 1 (TRPV1) is crucial in the pathogenesis of atherosclerosis; yet its role and underlying mechanism in the formation of macrophage foam cells remain unclear. Here, we show increased TRPV1 expression in the area of foamy macrophages in atherosclerotic aortas of apolipoprotein E-deficient mice. Exposure of mouse bone-marrow-derived macrophages to oxidized low-density lipoprotein (oxLDL) upregulated the expression of TRPV1. In addition, oxLDL activated TRPV1 and elicited calcium (Ca2+) influx, which were abrogated by the pharmacological TRPV1 antagonist capsazepine. Furthermore, oxLDL-induced lipid accumulation in macrophages was ameliorated by TRPV1 agonists but exacerbated by TRPV1 antagonist. Treatment with TRPV1 agonists did not affect the internalization of oxLDL but promoted cholesterol efflux by upregulating the efflux ATP-binding cassette (ABC) transporters ABCA1 and ABCG1. Moreover, the upregulation of ABC transporters was mainly through liver X receptor α- (LXRα-) dependent regulation of transcription. Moreover, the TNF-α-induced inflammatory response was alleviated by TRPV1 agonists but aggravated by the TRPV1 antagonist and LXRα siRNA in macrophages. Our data suggest that LXRα plays a pivotal role in TRPV1-activation-conferred protection against oxLDL-induced lipid accumulation and TNF-α-induced inflammation in macrophages.

The essential role of transient receptor potential vanilloid 1 in simvastatin-induced activation of endothelial nitric oxide synthase and angiogenesis

We investigated the role of transient receptor potential vanilloid receptor type 1 (TRPV1) in simvastatin‐mediated activation of endothelial nitric oxide synthase (eNOS) and angiogenesis.

Activation of transient receptor potential vanilloid 1 decreases endothelial nitric oxide synthase phosphorylation at Thr497 by protein phosphatase 2B‐dependent dephosphorylation of protein kinase C

We investigated the effects and underlying molecular mechanism of transient receptor potential vanilloid 1 (TRPV1), a calcium (Ca2+)‐permeable non‐selective cation channel, on phosphorylation of endothelial nitric oxide synthase (eNOS) at threonine 497 (Thr497) in bovine aortic endothelial cells (BAECs) and in mice.

Activation of soluble guanylyl cyclase prevents foam cell formation and atherosclerosis.

Soluble guanylyl cyclase (sGC) is a key modulator in the regulation of vascular tone. However, its role and involving mechanism in cholesterol metabolism of macrophages and atherosclerosis remain unclear.

Novel Effect of Paeonol on the Formation of Foam Cells: Promotion of LXRα-ABCA1–Dependent Cholesterol Efflux in Macrophages

Paeonol, a phenolic component purified from Paeonia suffruticosa (Cortex Moutan), is used in traditional Chinese medicine to treat inflammatory diseases. However, little is known about the effect of paeonol on cholesterol metabolism. We investigated the efficacy of paeonol on cholesterol metabolism and the underlying mechanism in macrophages and apolipoprotein E deficient (apoE(-/-)) mice. Treatment with paeonol markedly attenuated cholesterol accumulation induced by oxidized LDL in macrophages, which was due to increased cholesterol efflux. Additionally, paeonol enhanced the mRNA and protein expression of ATP-binding membrane cassette transport protein A1 (ABCA1) but did not alter the protein level of ABCG1 or other scavenger receptors. Inhibition of ABCA1 activity with a pharmacological inhibitor, neutralizing antibody or small interfering RNA (siRNA), negated the effects of paeonol on cholesterol efflux and cholesterol accumulation. Furthermore, paeonol induced the nuclear translocation of liver X receptor α (LXRα) by increasing its activity. siRNA knockdown of LXRα abolished the paeonol-induced upregulation of ABCA1, promotion of cholesterol efflux and suppression of cholesterol accumulation. Moreover, atherosclerotic lesions, hyperlipidemia and systemic inflammation were reduced and the protein expression of ABCA1 was increased in aortas of paeonol-treated apoE(-/-) mice. Paeonol may alleviate the formation of foam cells by enhancing LXRα-ABCA1-dependent cholesterol efflux.

Maternal exposure to di-(2-ethylhexyl) phthalate exposure deregulates blood pressure, adiposity, cholesterol metabolism and social interaction in mouse offspring

Long-term exposure to di-(2-ethylhexyl) phthalate (DEHP) is highly associated with carcinogenicity, fetotoxicity, psychological disorders and metabolic diseases, but the detrimental effects and mechanisms are not fully understood. We investigated the effect of exposing mouse mothers to DEHP, and the underlying mechanism, on blood pressure, obesity and cholesterol metabolism as well as psychological and learning behaviors in offspring. Tail-cuff plethysmography was used for blood pressure measurement; Western blot used was for phosphorylation and expression of protein; hematoxylin and eosin staining, Nissl staining and Golgi staining were used for histological examination. The serum levels of cholesterol, triglycerides and glucose were measured by blood biochemical analysis. Hepatic cholesterol and triglyceride levels were assessed by colorimetric assay kits. Offspring behaviors were evaluated by open-field activity, elevated plus maze, social preference test and Morris water maze. Maternal DEHP exposure deregulated the phosphorylation of endothelial nitric oxide synthase and upregulated angiotensin type 1 receptor in offspring, which led to increased blood pressure. It led to obesity in offspring by increasing the size of adipocytes in white adipose tissue and number of adipocytes in brown adipose tissue. It increased the serum level of cholesterol in offspring by decreasing the hepatic capacity for cholesterol clearance. The impaired social interaction ability induced by maternal DEHP exposure might be due to abnormal neuronal development. Collectively, our findings provide new evidence that maternal exposure to DEHP has a lasting effect on the physiological functions of the vascular system, adipose tissue and nerve system in offspring.

Excess Nitric Oxide Impairs LXR(α)-ABCA1-Dependent Cholesterol Efflux in Macrophage Foam Cells

Excess nitric oxide (NO) promotes the progression of atherosclerosis by increasing the oxidation of low‐density lipoprotein (LDL) and inflammatory responses. However, little is known about the impact of NO and its underlying molecular mechanism on lipid metabolism of macrophage foam cells. In this study, Oil‐red O staining, cholesterol and triglyceride assay, Dil‐oxidized LDL (oxLDL) binding assay, cholesterol efflux assay, real‐time RT‐PCR and Western blot analysis were used for in vitro experiments. Apolipoprotein E‐deficient (apoE−/−) and apoE and inducible nitric oxide synthase‐deficient (apoE−/−iNOS−/−) mice were as our in vivo models. Treatment with S‐nitroso‐N‐acetyl‐D,L‐penicillamine (SNAP), an NO donor, exacerbated oxLDL‐induced cholesterol accumulation in macrophages, because of reduced efficacy of cholesterol efflux. In addition, SNAP decreased the protein level of ATP‐binding cassette transporter A1 (ABCA1) without affecting scavenger receptor type A (SR‐A), CD36, ABCG1, or SR‐B1 levels. This SNAP‐mediated downregulation of ABCA1 was mainly through the effect of NO but not peroxynitrite. Furthermore, the SNAP‐downregulated ABCA1 was due to the decrease in the liver X receptor α (LXRα)‐dependent transcriptional regulation. Moreover, genetic deletion of iNOS increased the serum capacity of reverse cholesterol efflux and protein expression of LXRα, ABCA1, and SR‐BI in aortas and retarded atherosclerosis in apoE−/− mice. Our findings provide new insights in the pro‐atherogenic effect of excess NO on cholesterol metabolism in macrophages. J. Cell. Physiol. 229: 117–125, 2014.

Transient receptor potential vanilloid type 1 is vital for (-)-epigallocatechin-3-gallate mediated activation of endothelial nitric oxide synthase.

SCOPE Epigallocatechin-3-gallate (EGCG), the most abundant catechin of green tea, has beneficial effects on physiological functions of endothelial cells (ECs), yet the detailed mechanisms are not fully understood. In this study, we investigated the role of transient receptor potential vanilloid type 1 (TRPV1), a ligand-gated nonselective calcium channel, in EGCG-mediated endothelial nitric oxide (NO) synthase (eNOS) activation and angiogenesis. METHODS AND RESULTS In ECs, treatment with EGCG time-dependently increased the intracellular level of Ca(2+) . Removal of extracellular calcium (Ca(2+) ) by EGTA or EDTA or inhibition of TRPV1 by capsazepine or SB366791 abrogated EGCG-increased intracellular Ca(2+) level in ECs or TRPV1-transfected HEK293 cells. Additionally, EGCG increased the phsophorylation of eNOS at Ser635 and Ser1179, Akt at Ser473, calmodulin-dependent protein kinase II (CaMKII) at Thr286 and AMP-activated protein kinase (AMPK) at Thr172, all abolished by the TRPV1 antagonist capsazepine. EGCG-induced NO production was diminished by pretreatment with LY294002 (an Akt inhibitor), KN62 (a CaMKII inhibitor), and compound C (an AMPK inhibitor). Moreover, blocking TRPV1 activation prevented EGCG-induced EC proliferation, migration, and tube formation, as well as angiogenesis in Matrigel plugs in mice. CONCLUSION EGCG may trigger activation of TRPV1-Ca(2+) signaling, which leads to phosphorylation of Akt, AMPK, and CaMKII; eNOS activation; NO production; and, ultimately, angiogenesis in ECs.