PPAR-gamma agonists inhibit TGF-beta1-induced chemokine expression in human tubular epithelial cells.
ABSTRACT: AIM: Peroxisome proliferator-activated receptor-gamma (PPAR-gamma) has a wide range of biological functions, including anti-inflammation. In this study, we investigated the inhibitory effects of PPAR-gamma on transforming growth factor beta1 (TGF-beta1)-induced interleukin-8 (IL-8) and monocyte chemoattractant protein-1 (MCP-1) expression in renal tubular epithelial cells (HK-2). METHODS: HK-2 cells were pretreated with 15d-PGJ2 or troglitazone (TGL) and then treated with TGF-beta1. Expression of MCP-1 and IL-8 was measured using real-time PCR and ELISA. RESULTS: Treatment with 5 ng/mL TGF-beta1 for 24 h increased both MCP-1 and IL-8 mRNA and protein levels in HK-2 cells. Both 15d-PGJ2 at 2.5 and 5 micromol/L and TGL at 2.5 micromol/L exhibited inhibitory effects on TGF-beta1-induced MCP-1 expression. Additionally, 15d-PGJ2 at 2.5 and 5 micromol/L and TGL at 2.5 micromol/L inhibited TGF-beta1-induced expression of IL-8. CONCLUSION: PPAR-gamma agonists (15d-PGJ2 and TGL) could inhibit the TGF-beta1-induced expression of chemokines in HK-2 cells. Our results suggest that PPAR-gamma agonists have the potential to be used as a treatment regimen to reduce inflammation in renal tubulointerstitial disease.
Project description:<h4>Background and purpose</h4>Peroxisome proliferator-activated receptor (PPAR)-gamma ligands have been shown to inhibit cardiac fibrosis. However, the underlying mechanisms are poorly understood. We investigated the regulation by PPAR-gamma ligands of angiotensin (Ang) II-induced plasminogen activator inhibitor (PAI)-1, extracellular matrix (ECM) production and cell growth in cardiac fibroblasts.<h4>Experimental approach</h4>The effects of PPAR-gamma ligands on Ang II-induced PAI-1, ECM expression and cell growth were assessed in primary-cultured rat cardiac fibroblasts; cardiac PAI-1 and ECM production was examined in Ang II-infused rats.<h4>Key results</h4>In growth-arrested cardiac fibroblasts, PPAR-gamma ligands rosiglitazone and 15-deoxy-Delta(12,14)-prostaglandin J2 (15d-PGJ2) dose-dependently attenuated Ang II-induced cell proliferation and expression of PAI-1, collagen type-I, collagen type-III and fibronectin. An accompanying increase in PPAR-gamma expression and activation was also observed. These suppressive effects were attenuated by the PPAR-gamma antagonists GW9662 and bisphenol A diglycidyl ether (BADGE). Moreover, rosiglitazone and 15d-PGJ2 inhibited in part the expression and phosphorylation of Ang II-induced transforming growth factor (TGF)-beta1, Smad2/3 and c-Jun NH(2)-terminal kinase (JNK). Ang II infusion in rats markedly increased left ventricular production of PAI-1, collagen and fibronectin, with a concurrent increase in the ratios of heart weight/body weight and left ventricle weight/body weight. Co-treatment with rosiglitazone significantly decreased these levels and upregulated PPAR-gamma expression.<h4>Conclusions and implications</h4>Rosiglitazone and 15d-PGJ2 suppress Ang II-induced production of PAI-1 and ECM probably via interactions between PPAR-gamma and TGF-beta1/Smad2/3 and JNK signalling pathways. It is suggested that PPAR-gamma and its ligands may have potential applications in preventing cardiac fibrosis.
Project description:PPAR? belongs to the peroxisome proliferator-activated receptor (PPAR) family of nuclear receptors. Upon activation by an agonist, PPAR? controls a variety of physiological processes via regulation of its target genes. 15-Deoxy-?12,14-prostaglandin J2 (15d-PGJ2) is a cyclopentenone prostaglandin that features an electrophilic, ?,?-unsaturated ketone (an enone) in the cyclopentenone ring. Many of 15d-PGJ2's biological effects result from covalent interaction between C9 and the thiol group of a catalytic cysteine (Cys) in target proteins. In this study, we investigated whether 15d-PGJ2 activates PPAR? by forming a covalent adduct. Our data show that 15d-PGJ2 activates PPAR?'s transcriptional activity through formation of a covalent adduct between its endocyclic enone at C9 and Cys249 in the receptor's ligand-binding domain. As expected, no adduct formation was seen following a Cys-to-Ser mutation at residue 249 (C249S) of PPAR? or with a PGD2/PGJ2 analogue that lacks the electrophilic C9. Furthermore, the PPAR? C249S mutation weakened induction of the receptor's DNA binding activity by 15d-PGJ2, which highlights the biological significance of our findings. Calculated chemical properties as well as data from molecular orbital calculations, reactive molecular dynamics simulations, and intrinsic reaction coordinate modeling also supported the selectivity of 15d-PGJ2's C9 toward PPAR?'s Cys thiol. In summary, our results provide the molecular, chemical, and structural basis of 15d-PGJ2-mediated PPAR? activation, designating 15d-PGJ2 as the first covalent PPAR? ligand to be identified.
Project description:An endogenous anticancer agent, 15-deoxy -?12,14-prostaglandin J2 (15d-PGJ2) induces apoptosis in the chemoresistant renal cell carcinoma (RCC). Peroxisome proliferator-activated receptor-? (PPAR?) is a nuclear receptor for 15d-PGJ2, and mediates the cytotoxicity of 15d-PGJ2 in many cancerous cells. However, 15d-PGJ2 induces apoptosis independently of PPAR? in human RCC cell line such as Caki-2. In the present study, we found that 15d-PGJ2 ameliorated the chemoresistance to one of anthracycline antibiotics, doxorubicin, in Caki-2 cells. Doxorubicin alone exhibited weak cytotoxicity at the concentrations effective for other cancer cells such as Hela cells. In addition, it did not activate caspase 3. However, the cytotoxicity of doxorubicin was increased remarkably and accompanied with the caspase- 3 activation in the presence of 15d-PGJ2. Doxorubicin alone damaged plasma membrane, and the combined application of 15d-PGJ2 with doxorubicin increased the membrane permeability slightly. PPAR? was involved in neither the anti-tumor activity nor the synergistic effect of 15d-PGJ2. 15d-PGJ2 induces apoptosis in Caki-2 cells via suppressing the phosphoinositide 3-kinase (PI3K)-Akt pathway. The effect of PI3K inhibitor on the cytotoxicity of doxorubicin was additive, but not synergistic. Although the PI3K inhibitor mimicked the cytotoxicity of 15d-PGJ2, it might not be involved in the synergism between 15d-PGJ2 and doxorubicin. In conclusion, 15d-PGJ2 enhanced the chemosensitivity of doxorubicin via the pathway independent of PPAR? and PI3K.
Project description:We have previously identified four novel isoforms of PPAR-gamma transcripts in monkey macrophages (J. Zhou, K.M. Wilson, J.D. Medh, Genetic analysis of four novel peroxisome proliferator receptor-gamma splice variants in monkey macrophages. Biochem. Biophys. Res. Commun., 293 (2002) 274-283). The purpose of this study was to ascertain that these isoforms are also present in humans. Specific primers were designed to amplify individual isoform transcripts. The presence of PPAR-gamma4, PPAR-gamma5, and PPAR-gamma7 transcripts in human THP-1 macrophages was confirmed by RT-PCR and sequencing. A transcript corresponding to PPAR-gamma6 was not detected. The presence of novel full-length transcripts and protein was also ascertained by Northern and Western blot analysis. Treatment of THP-1 cells with 15-deoxy-Delta12,14-prostaglandin J2 (15d-PGJ2) resulted in more than 20% induction in the expression of PPAR-gamma5 and PPAR-gamma7 transcripts by both Northern blot analysis and RT-PCR. Another PPAR-gamma ligand, troglitazone, induced expression of only PPAR-gamma5. Both ligands inhibited the expression of PPAR-gamma1 and PPAR-gamma2. Additionally, 15d-PGJ2 and troglitazone increased the level of apolipoprotein E transcript by 60% but decreased lipoprotein lipase expression by 15% in THP-1 cells. The differential regulation of PPAR-gamma transcripts suggests that each transcript isoform may contribute to macrophage function.
Project description:15-Deoxy-?-12,14-prostaglandin J2 (15d-PGJ2), a natural peroxisome proliferator-activated receptor-? (PPAR-?) agonist, has been explored in some detail over the last 20 years. By triggering the PPAR-? signalling pathway, it plays many roles and exerts antitumour, anti-inflammatory, antioxidation, antifibrosis, and antiangiogenesis effects. Although many synthetic PPAR-? receptor agonists have been developed, as an endogenous product of PPAR-? receptors, 15d-PGJ2 has beneficial characteristics including rapid expression and the ability to contribute to a natural defence mechanism. In this review, we discuss the latest advances in our knowledge of the biological role of 15d-PGJ2 mediated through PPAR-?. It is important to understand its structure, synthesis, and functional mechanisms to develop preventive agents and limit the progression of associated diseases.
Project description:Urinary obstruction is associated with inflammation and oxidative stress, leading to renal dysfunction. Previous studies have shown that 15-deoxy-?12,14-prostaglandin J2 (15d-PGJ2) has both antioxidant and anti-inflammatory effects. Using a unilateral ureteral obstruction (UUO) mouse model, we examined the effects of 15d-PGJ2 on oxidative stress and inflammation in the kidney. Mice were subjected to UUO for 3 days and treated with 15d-PGJ2. Protein and RNA expression were examined using immunoblotting and qPCR. 15d-PGJ2 increased NF-E2-related nuclear factor erythroid-2 (Nrf2) protein expression in response to UUO, and heme oxygenase 1 (HO-1), a downstream target of Nrf2, was induced by 15d-PGJ2. Additionally, 15d-PGJ2 prevented protein carbonylation, a UUO-induced oxidative stress marker. Inflammation, measured by nuclear NF-?B, F4/80, and MCP-1, was increased in response to UUO and further increased by 15d-PGJ2. Renal injury was aggravated by 15d-PGJ2 treatment as measured by kidney injury molecule-1 (KIM-1) and cortical caspase 3 content. No effect of 15d-PGJ2 was observed on renal function in mice subjected to UUO. This study illustrates differentiated functioning of 15d-PGJ2 on inflammation and oxidative stress in response to obstructive nephropathy. High concentrations of 15d-PGJ2 protects against oxidative stress during 3-day UUO in mice; however, it aggravates the associated inflammation.
Project description:BACKGROUND: Circadian rhythms are endogenous, self-sustained oscillations with approximately 24-hr rhythmicity that are manifested in various physiological and metabolic processes. The circadian organization of these processes in mammals is governed by the master oscillator within the suprachiasmatic nuclei (SCN) of the hypothalamus. Recent findings revealed that circadian oscillators exist in most organs, tissues, and even in immortalized cells, and that the oscillators in peripheral tissues are likely to be coordinated by SCN, the master oscillator. Some candidates for endogenous entrainment factors have sporadically been reported, however, their details remain mainly obscure. RESULTS: We developed the in vitro real-time oscillation monitoring system (IV-ROMS) by measuring the activity of luciferase coupled to the oscillatory gene promoter using photomultiplier tubes and applied this system to screen and identify factors able to influence circadian rhythmicity. Using this IV-ROMS as the primary screening of entrainment factors for circadian clocks, we identified 12 candidates as the potential entrainment factor in a total of 299 peptides and bioactive lipids. Among them, four candidates (endothelin-1, all-trans retinoic acid, 9-cis retinoic acid, and 13-cis retinoic acid) have already been reported as the entrainment factors in vivo and in vitro. We demonstrated that one of the novel candidates, 15-deoxy-Delta12,14-prostaglandin J2 (15d-PGJ2), a natural ligand of the peroxisome proliferator-activated receptor-gamma (PPAR-gamma), triggers the rhythmic expression of endogenous clock genes in NIH3T3 cells. Furthermore, we showed that 15d-PGJ2 transiently induces Cry1, Cry2, and Roralpha mRNA expressions and that 15d-PGJ2-induced entrainment signaling pathway is PPAR-gamma--and MAPKs (ERK, JNK, p38MAPK)-independent. CONCLUSION: Here, we identified 15d-PGJ2 as an entrainment factor in vitro. Using our developed IV-ROMS to screen 299 compounds, we found eight novel and four known molecules to be potential entrainment factors for circadian clocks, indicating that this assay system is a powerful and useful tool in initial screenings.
Project description:Activation of peroxisome proliferator-activated receptor ? (PPAR?) serves as a key factor in the proliferation and invasion of breast cancer cells and is a potential therapeutic target for breast cancer. However, the mechanisms underlying this effect remain largely unknown. Heme oxygenase-1 (HO-1) is induced and overexpressed in various cancers and is associated with features of tumor aggressiveness. Recent studies have shown that HO-1 is a major downstream target of PPAR?. In this study, we investigated the effects of induction of HO-1 by PPAR? on TPAinduced MMP-9 expression and cell invasion using MCF-7 breast cancer cells. TPA treatment increased NF-?B /AP-1 DNA binding as well as MMP-9 expression. These effects were significantly blocked by 15d-PGJ2, a natural PPAR? ligand. 15d-PGJ2 induced HO-1 expression in a dose-dependent manner. Interestingly, HO-1 siRNA significantly attenuated the inhibition of TPA-induced MMP-9 protein expression and cell invasion by 15d-PGJ2. These results suggest that 15d-PGJ2 inhibits TPA-induced MMP- 9 expression and invasion of MCF-7 cells by means of a heme oxygenase-1-dependent mechanism. Therefore, PPAR?/HO-1 signaling- pathway inhibition may be beneficial for prevention and treatment of breast cancer. [BMB Reports 2020; 53(4): 212-217].
Project description:Renal fibrosis is an inevitable outcome of all kinds of progressive chronic kidney disease (CKD). Recently, asiatic acid (AA), a triterpenoid compound from Chinese medicine Centella asiatica, has been found to attenuate renal fibrosis. In the current study, we explored the mechanisms underlying antifibrotic effect of AA on UUO model. SD rats and ICR mice were subjected to unilateral ureteral occlusion (UUO) surgery. Prior the surgery, rats were administered AA (10?mg·kg-1 per day, ig) for 7 days, whereas the mice received AA (15?mg·kg-1 per day, ig) for 3 days. UUO group displayed significant degree of renal dysfunction, interstitial fibrosis, oxidative stress, and activation of the TGF-?/Smad and Wnt/?-catenin signaling pathway in the kidney, these pathological changes were greatly ameliorated by pretreatment with AA. In addition, we found that co-treatment with GW9662, a selective PPAR-? antagonist (1?mg·kg-1 per day, ip) for 7 days, abolished the protective effects of AA. We further revealed that AA pretreatment did not significantly change the expression levels of PPAR-? in the kidney, but markedly increase the plasma levels of 15d-PGJ2, an endogenous ligand of PPAR-?. In UUO mice, pretreatment with 15d-PGJ2 (24??g·kg-1 per day, ip, for 7 days) produced similar protective effect as AA. Moreover, AA pretreatment upregulated the expression levels of active, nuclear-localized SREBP-1 (nSREBP-1), whereas fatostatin, a specific inhibitor of SREBP-1, decreased the expression of nSREBP-1, as well as the level of 15d-PGJ2. These results provide new insight into the antifibrotic mechanism of AA and endogenous metabolites might become a new clue for investigation of drug mechanism.
Project description:Peroxisome proliferator-activated receptors (PPARs) have been originally thought to be restricted to lipid metabolism or glucose homeostasis. Recently, evidence is growing that PPAR? ligands have inhibitory effects on tumor growth. To shed light on the potential therapeutic effects on melanoma we tested a panel of PPAR agonists on their ability to block tumor proliferation in vitro. Whereas ciglitazone, troglitazone and WY14643 showed moderate effects on proliferation, 15d-PGJ2 displayed profound anti-tumor activity on four different melanoma cell lines tested. Additionally, 15d-PGJ2 inhibited proliferation of tumor-associated fibroblasts and tube formation of endothelial cells. 15d-PGJ2 induced the tumor suppressor gene p21, a G(2)/M arrest and inhibited tumor cell migration. Shot gun proteome analysis in addition to 2D-gel electrophoresis and immunoprecipitation of A375 melanoma cells suggested that 15d-PGJ2 might exert its effects via modification and/or downregulation of Hsp-90 (heat shock protein 90) and several chaperones. Applying the recently established CPL/MUW database with a panel of defined classification signatures, we demonstrated a regulation of proteins involved in metastasis, transport or protein synthesis including paxillin, angio-associated migratory cell protein or matrix metalloproteinase-2 as confirmed by zymography. Our data revealed for the first time a profound effect of the single compound 15d-PGJ2 on melanoma cells in addition to the tumor-associated microenvironment suggesting synergistic therapeutic efficiency.