BRG1 Deficiency Promotes Cardiomyocyte Inflammation and Apoptosis by Activating the cGAS-STING Signaling in Diabetic Cardiomyopathy.

Brahma-related gene 1 (BRG1) has been implicated in the repair of DNA double-strand breaks (DSBs). Downregulation of BRG1 impairs DSBs repair leading to accumulation of double-stranded DNA (dsDNA). Currently, the role of BRG1 in diabetic cardiomyopathy (DCM) has not been clarified. In this study, we aimed to explore the function and molecular by which BRG1 regulates DCM using mice and cell models. We found that BRG1 was downregulated in the cardiac tissues of DCM mice and in cardiomyocytes cultured with high glucose and palmitic acid (HG/PA), which was accompanied by accumulation of dsDNA and activation of the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) signaling pathway. shRNA-mediated Brg1 knockdown aggravated DCM mice cardiac functions, enhanced dsDNA accumulation, cGAS-STING signaling activation, which induced inflammation and apoptosis. In addition, the results were further verified in HG/PA-treated primary neonatal rat cardiomyocytes (NRCMs). Overexpression of BRG1 in NRCMs yielded opposite results. Furthermore, a selective cGAS inhibitor RU.521 or STING inhibitor C-176 partially reversed the BRG1 knockdown-induced inflammation and apoptosis in vitro. In conclusion, our results demonstrate that BRG1 is downregulated during DCM in vivo and in vitro, resulting in cardiomyocyte inflammation and apoptosis due to dsDNA accumulation and cGAS-STING signaling activation. Therefore, targeting the BRG1-cGAS-STING pathway may represent a novel therapeutic strategy for improving cardiac function of patients with DCM.

DHODH inhibition represents a therapeutic strategy and improves abiraterone treatment in castration-resistant prostate cancer.

Castration-resistant prostate cancer (CRPC) is an aggressive disease with poor prognosis, and there is an urgent need for more effective therapeutic targets to address this challenge. Here, we showed that dihydroorotate dehydrogenase (DHODH), an enzyme crucial in the pyrimidine biosynthesis pathway, is a promising therapeutic target for CRPC. The transcript levels of DHODH were significantly elevated in prostate tumors and were negatively correlated with the prognosis of patients with prostate cancer. DHODH inhibition effectively suppressed CRPC progression by blocking cell cycle progression and inducing apoptosis. Notably, treatment with DHODH inhibitor BAY2402234 activated androgen biosynthesis signaling in CRPC cells. However, the combination treatment with BAY2402234 and abiraterone decreased intratumoral testosterone levels and induced apoptosis, which inhibited the growth of CWR22Rv1 xenograft tumors and patient-derived xenograft organoids. Taken together, these results establish DHODH as a key player in CRPC and as a potential therapeutic target for advanced prostate cancer.

Naringenin protects pancreatic ß cells in diabetic rat through activation of estrogen receptor ß.

Naringenin is a citrus flavonoid that potently improves metabolic parameters in animal models of metabolic disorders, such as type 2 diabetes. Estrogen receptor (ER) activation promotes ß cell function and survival, thereby improving systemic glucose metabolism. In this study, we used a luciferase reporter assay, isolated rat islets and a diabetic rat model to investigate the effects of naringenin on ER signaling and the underlying mechanism of naringenin-mediated improvement of islet function in diabetes. Naringenin specifically activated ERß without affecting the activity of ERα, G protein-coupled estrogen receptor (GPER) or estrogen-related receptor (ERR) α/ß/γ. Additionally, treatment with naringenin enhanced glucose-stimulated insulin secretion in isolated rat islets. This effect was abrogated by PHTPP, an ERß antagonist. Transcriptomic analysis revealed that naringenin upregulated the expression of genes, such as Pdx1 and Mafa, which are closely linked to improved ß-cell function. In consistence, single administration of naringenin to normal rats elevated plasma insulin levels and improved glucose responses. These beneficial effects were blocked by PHTPP. In streptozocin-nicotinamide induced diabetic rats, treatment for 2 weeks with naringenin alone, but not in combination with PHTPP, significantly restored pancreatic ß cell mass and improved glucose metabolism. Collectively, these data support that naringenin specifically activate ERß to improve insulin secretion in the primary rat islets. Furthermore, naringenin administration also protected ß cell function and reversed glucose dysregulation in diabetic rats. These beneficial effects are at least partially dependent on the ERß pathway.

Role of neutrophils in different stages of atherosclerosis.

Neutrophils constitute the first line of defense in human immunity and can be attracted to inflamed and infected sites by various chemokines. As essential players in immune processes, neutrophils theoretically play integral roles in the course of chronic inflammation-induced atherosclerosis. However, because neutrophils are rarely found in atherosclerotic lesions, their involvement in the pathophysiological progression of atherosclerosis has been largely underestimated or ignored. Recent research has revealed convincing evidence showing the presence of neutrophils in atherosclerotic lesions and has revealed neutrophil contributions to different atherosclerosis stages in mice and humans. This review describes the underlying mechanisms of neutrophils in different stages of atherosclerosis and highlights potential neutrophil-targeted therapeutic strategies relevant to atherosclerosis. An in-depth understanding of neutrophils' roles in atherosclerosis pathology will promote exploration of new methods for the prevention and treatment of atherogenesis and atherothrombosis.

DT-010 Exerts Cardioprotective Effects by Regulating the Crosstalk between the AMPK/PGC-1α Pathway and ERp57.

The AMP-activated protein kinase (AMPK)/peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) pathway performs a crucial role in energy metabolism and mitochondrial network. Our previous study found that DT-010, a novel danshensu (DSS) and tetramethylpyrazine (TMP) conjugate, had significant cardioprotective properties in vitro and in vivo. We also reported that ERp57 served as a major target of DSS using the chemical proteomics approach. In this article, we focus on exploring the interrelationship between the regulation of the AMPK/PGC-1α pathway and promoting ERp57 expression induced by DT-010 in tert-butylhydroperoxide- (t-BHP-) induced H9c2 cell injury. The results showed that DT-010 activated the AMPK/PGC-1α pathway and increased ERp57 protein expression. Importantly, the above phenomenon as well as the mitochondrial function can be partially reversed by siRNA-mediated ERp57 suppression. Meanwhile, silencing AMPK significantly inhibited the ERp57 expression induced by DT-010. In addition, molecular docking and kinase assay in vitro revealed that DT-010 had no direct regulation effects on AMPK activity. Taken together, DT-010 exerted cardioprotective effects by regulating the crosstalk of AMPK/PGC-1α pathway and ERp57, representing a potential therapeutic agent for ischemic heart disease.

Thymoquinone induces apoptosis in temozolomide-resistant glioblastoma cells via the p38 mitogen-activated protein kinase signaling pathway.

Temozolomide (TMZ) can cross the blood-brain barrier (BBB) and deliver methyl groups to the purine (guanine) bases of DNA, leading to mispairing during DNA replication and subsequent cell death. However, increased expression of the repair enzyme methyl guanine methyltransferase (MGMT), which removes methyl groups from purine bases, counteracts methylation by TMZ. We evaluated the anticancer potential of thymoquinone (TQ), a hydrophobic flavonoid that inhibits resistance and induces apoptosis in various cancer cells, both in vitro and in vivo. In vitro experiments showed that compared with the Hs683 and M059J cell lines, U251 cells were more sensitive to TMZ. Compared to U251 cells, U251R cells, a TMZ drug-resistant strain established in this study, are characterized by increased expression of phosphorylated extracellular signal-regulated kinase (p-ERK) and MGMT. TQ treatments induced apoptosis in all cell lines. The p38 mitogen-activated protein kinase signal pathway was mainly activated in U251 and U251R cells; however, p-ERK and MGMT upregulation could not suppress TQ effects. Furthermore, si-p38 pretreatment of U251R cells in TQ treatments inhibited cell apoptosis. We speculate that TQ contributed to the phosphorylation and activation of p38, but not of ERK-induced apoptosis (irrespective of TMZ resistance). In vivo, U251R-derived tumors subcutaneously inoculated in nude mice exhibited significant tumor volume reduction after TQ or TQ + TMZ cotreatments. High-performance liquid chromatography assay confirmed the presence of TQ in murine brain tissues. Our findings demonstrate that TQ can effectively cross the BBB and function alone or in combination with TMZ to treat glioblastoma.

Niacin exacerbates ß cell lipotoxicity in diet-induced obesity mice through upregulation of GPR109A and PPARγ2: Inhibition by incretin drugs.

The widely used lipid-lowering drug niacin was reported to increase blood glucose in diabetes. How does niacin regulate ß Cell function in diabetic patients remains unclear. This study aimed to investigate the effect of niacin on ß cell lipotoxicity in vitro and in vivo. Niacin treatment sensitized the palmitate-induced cytotoxicity and apoptosis in INS-1 cells. In addition, palmitate significantly increased the niacin receptor GPR109A and PPARγ2 levels, which could be further boosted by niacin co-treatment, creating a vicious cycle. In contrast, knocking down of GPR109A could reverse both PPARγ2 expression and niacin toxicity in the INS-1 cells. Interestingly, we found that GLP-1 receptor agonist exendin-4 showed similar inhibitive effects on the GPR109A/PPARγ2 axis and was able to reverse niacin induced lipotoxicity in INS-1 cells. In diet-induced obesity (DIO) mouse model, niacin treatment resulted in elevated blood glucose, impaired glucose tolerance and insulin secretion, accompanied by the change of islets morphology and the decrease of ß cell mass. The combination of niacin and DPP-4 inhibitor sitagliptin can improve glucose tolerance, insulin secretion and islet morphology and ß cell mass, even better than sitagliptin alone. Our results show that niacin increased ß cell lipotoxicity partially through upregulation of GPR109A and PPARγ2, which can be alleviated by incretin drugs. We provide a new mechanism of niacin toxicity, and suggest that the combination of niacin and incretin may have better blood glucose and lipid control effect in clinical practice.

UPRmt and coordinated UPRER in type 2 diabetes.

The mitochondrial unfolded protein response (UPRmt) is a molecular mechanism that maintains mitochondrial proteostasis under stress and is closely related to various metabolic diseases, such as type 2 diabetes (T2D). Similarly, the unfolded protein response of the endoplasmic reticulum (UPRER) is responsible for maintaining proteomic stability in the endoplasmic reticulum (ER). Since the mitochondria and endoplasmic reticulum are the primary centers of energy metabolism and protein synthesis in cells, respectively, a synergistic mechanism must exist between UPRmt and UPRER to cooperatively resist stresses such as hyperglycemia in T2D. Increasing evidence suggests that the protein kinase RNA (PKR)-like endoplasmic reticulum kinase (PERK) signaling pathway is likely an important node for coordinating UPRmt and UPRER. The PERK pathway is activated in both UPRmt and UPRER, and its downstream molecules perform important functions. In this review, we discuss the mechanisms of UPRmt, UPRER and their crosstalk in T2D.

Erk phosphorylation reduces the thymoquinone toxicity in human hepatocarcinoma.

Although enormous achievements have been made in targeted molecular therapies against hepatocellular carcinoma (HCC), the treatments can only prolong the life of patients with extrahepatic metastases. We evaluated thymoquinone (TQ), a compound from Nigella sativa Linn., for its anti-cancer effect on SK-Hep1 cells and HCC-xenograft nude mice. TQ effectively triggered cell death    and activated p38 and extracellular signal-regulated kinases (Erk) pathways up to 24 h after treatment in cells. TQ-induced cell death was reversed by p38 inhibitor; however, it was enhanced by si-Erk. The caspase3 activation and TUNEL assay revealed a stronger toxic effect upon co-treatment with TQ and si-Erk. Our study suggested that phosphorylation of p38 in SK-Hep1 cells constituted the major factor leading to cell apoptosis, whereas phosphorylation of Erk led to drug resistance. Furthermore, TQ therapeutic effect was improved upon Erk inhibition in HCC-xenograft nude mice. TQ could present excellent anti-HCC potential under suitable p-Erk inhibiting conditions.

Multi-Omics Characterization of Circular RNA-Encoded Novel Proteins Associated With Bladder Outlet Obstruction.

Bladder outlet obstruction (BOO) is a common urologic disease associated with poorly understood molecular mechanisms. This study aimed to investigate the possible involvements of circRNAs (circular RNAs) and circRNA-encoded proteins in BOO development. The rat BOO model was established by the partial bladder outlet obstruction surgery. Differential expression of circRNA and protein profiles were characterized by deep RNA sequencing and iTRAQ quantitative proteomics respectively. Novel proteins encoded by circRNAs were predicted through ORF (open reading frame) selection using the GETORF software and verified by the mass spectrometry in proteomics, combined with the validation of their expressional alterations by quantitative RT-PCR. Totally 3,051 circRNAs were differentially expressed in bladder tissues of rat BOO model with widespread genomic distributions, including 1,414 up-regulated, and 1,637 down-regulated circRNAs. Our following quantitative proteomics revealed significant changes of 85 proteins in rat BOO model, which were enriched in multiple biological processes and signaling pathways such as the PPAR and Wnt pathways. Among them, 21 differentially expressed proteins were predicted to be encoded by circRNAs and showed consistent circRNA and protein levels in rat BOO model. The expression levels of five protein-encoding circRNAs were further validated by quantitative RT-PCR and mass spectrometry. The circRNA and protein profiles were substantially altered in rat BOO model, with great expressional changes of circRNA-encoded novel proteins.

Metformin scavenges formaldehyde and attenuates formaldehyde-induced bovine serum albumin crosslinking and cellular DNA damage.

Formaldehyde (FA) can be produced in the environment and by cell metabolism and has been classified as a carcinogen in animals and humans. Metformin is the most commonly used drug for the treatment of type 2 diabetes. Metformin also has potential benefit in cancer prevention and treatment. The aim of this study was to determine whether metformin can directly react with FA and attenuate its toxicity in vitro. Metformin was incubated at pH 7.4 and 37°C in the presence of FA, and the reaction mixture was analyzed by UV spectrophotometry, high-performance liquid chromatography (HPLC), and mass spectrometry. Fluorescence spectrophotometry, immunofluorescence, and western blot were used to measure FA-induced bovine serum albumin (BSA) crosslinking and DNA damage in HepG2 cells treated with or without metformin. According to the HPLC and mass spectrometry data, we speculate that the reaction of metformin with FA (1:1) initially results in the formation of a conjugated intermediate followed by the subsequent generation of a stable six-membered ring structure. Correspondingly, metformin attenuated FA-induced fluorescence in BSA as well as the aggregation of γH2AX in HepG2 cells. These results suggest that metformin can protect protein and DNA damage induced by FA at least partly through a direct reaction process.

PPARα and NCOR/SMRT corepressor network in liver metabolic regulation.

Peroxisome proliferator-activated receptor alpha (PPARα, NR1C1) belongs to a large family of ligand-dependent nuclear receptors (NRs). It is one of the best studied NRs which controls the lipid metabolism (mainly fatty acid oxidation) and inflammation, and has been a promising target for treating metabolic disorders such as fatty liver and cardiometabolic diseases. The function of PPARα relies on its interaction with various coregulators upon different stimulating contexts, and, thereby, activates or represses its transcription targets in a gene-selective manner. Understanding the transcription factor and coregulator network underlying the PPARα regulation is prerequisite to decipher its gene- and context-selectivity for designing better therapeutic ligands. In this review, we will summarize current knowledge of PPARα coregulator network, with major focus on a relatively well-studied corepressor complex containing core subunits of nuclear receptor corepressor (NCOR or NCOR1), silencing mediator of retinoic acid and thyroid hormone receptor (SMRT or NCOR2), G-protein suppressor 2 (GPS2), transducin ß-like protein 1 (TBL1 or TBL1X), TBL-related 1 (TBLR1 or TBL1XR1), and the catalytic core of histone deacetylase 3 (HDAC3). We will mainly review the molecular events of the complex and sub-complexes in controlling the liver metabolism. We will also discuss the potential perturbation of the subunit expression in human livers during liver metabolic disorder progression which potentially defines the patient disease susceptibility and drug responses.

F0F1 ATP synthase regulates extracellular calcium influx in human neutrophils by interacting with Cav2.3 and modulates neutrophil accumulation in the lipopolysaccharide-challenged lung.

BACKGROUND: Neutrophils form the first line of innate host defense against invading microorganisms. We previously showed that F0F1 ATP synthase (F-ATPase), which is widely known as mitochondrial respiratory chain complex V, is expressed in the plasma membrane of human neutrophils and is involved in regulating cell migration. Whether F-ATPase performs cellular functions through other pathways remains unknown. METHODS: Blue native polyacrylamide gel electrophoresis followed by nano-ESI-LC MS/MS identification and bioinformatic analysis were used to identify protein complexes containing F-ATPase. Then, the identified protein complexes containing F-ATPase were verified by immunoblotting, immunofluorescence colocalization, immunoprecipitation, real-time RT-PCR and agarose gel electrophoresis. Immunoblotting, flow cytometry and a LPS-induced mouse lung injury model were used to assess the effects of the F-ATPase-containing protein complex in vitro and in vivo. RESULTS: We found that the voltage-gated calcium channel (VGCC) α2δ-1 subunit is a binding partner of cell surface F-ATPase in human neutrophils. Further investigation found that the physical connection between the two proteins may exist between the F1 part (α and ß subunits) of F-ATPase and the α2 part of VGCC α2δ-1. Real-time RT-PCR and PCR analyses showed that Cav2.3 (R-type) is the primary type of VGCC expressed in human neutrophils. Research on the F-ATPase/Cav2.3 functional complex indicated that it can regulate extracellular Ca2+ influx, thereby modulating ERK1/2 phosphorylation and reactive oxygen species production, which are typical features of neutrophil activation. In addition, the inhibition of F-ATPase can reduce neutrophil accumulation in the lungs of mice that were intratracheally instilled with lipopolysaccharide, suggesting that the inhibition of F-ATPase may prevent neutrophilic inflammation-induced tissue damage. CONCLUSIONS: In this study, we identified a mechanism by which neutrophil activity is modulated, with simultaneous regulation of neutrophil-mediated pulmonary damage. These results show that surface F-ATPase of neutrophils is a potential innate immune therapeutic target.

Hyperglycemia induces NF-κB activation and MCP-1 expression via downregulating GLP-1R expression in rat mesangial cells: inhibition by metformin.

Hyperglycemia impairs glucagon-like peptide-1 receptor (GLP-1R) signaling in multiple cell types and thereby potentially attenuates the therapeutic effects of GLP-1R agonists. We hypothesized that the downregulation of GLP-1R by hyperglycemia might reduce the renal-protective effects of GLP-1R agonists in diabetic nephropathy (DN). In this study, we examined the effects of high glucose on the expression of GLP-1R and its signaling pathways in the HBZY-1 rat mesangial cell line. We found that high glucose reduced GLP-1R messenger RNA (mRNA) levels in HBZY-1 cells and in the renal cortex in db/db mice comparing with control groups. In consistence, GLP-1R agonist exendin-4 induced CREB phosphorylation was attenuated by high glucose but not low glucose treatment, which is paralleled with abrogated anti-inflammatory functions in HBZY-1 cells linked with nuclear factor-κB (NF-κB) activation. In consistence, GLP-1R inhibition aggravated the high glucose-induced activation of NF-κB and MCP-1 protein levels in cultured HBZY-1 cells while overexpression of GLP-1R opposite effects. We further proved that metformin restored high glucose-inhibited GLP-1R mRNA expression and decreased high glucose evoked inflammation in HBZY-1 cells. On the basis of these findings, we conclude that high glucose lowers GLP-1R expression and leads to inflammatory responses in mesangial cells, which can be reversed by metformin. These data support the rationale of combinative therapy of metformin with GLP-1R agonists in DN.

The F0F1 ATP synthase regulates human neutrophil migration through cytoplasmic proton extrusion coupled with ATP generation.

Cytoplasmic alkalinization and extracellular adenosine triphosphate (ATP) signals are required for migration of chemokineactivated neutrophils, but the precise functions remain unclear. In this work, the effect of the plasma membrane-expressed F0F1-ATP synthase (FATPase) on human neutrophils was examined. We found F-ATPase to be involved in cytoplasm proton extrusion and extracellular ATP generation. Oligomycin A, an F-ATPase inhibitor that blocks proton transfer, inhibited cytoplasmic alkalinization, extracellular ATP generation, adhesion and chemotaxis in N-formyl-Met-Leu-Phe (fMLP)-stimulated neutrophils; however, adenosine diphosphate (ADP), a substrate and activator of F-ATPase, had the opposite effect. Further analysis revealed that cell surface F-ATPase can translocate to the leading edge of directional fMLP-stimulated neutrophils toward ADP hydrolyzed from pannexin 1 channel-released ATP, followed by F-ATPase-catalyzed ATP regeneration using ADP and protons transferred from the cytoplasm. Therefore, the membrane-expressed F-ATPase regulates human neutrophil migration via cytoplasm proton extrusion and extracellular ATP generation.

Exendin-4 improves blood glucose control in both young and aging normal non-diabetic mice, possible contribution of beta cell independent effects.

AIMS: Type 2 diabetes is highly prevalent in the elderly population. Glucagon like Peptide-1 mimetic such as exendin-4 augments post-prandial insulin secretion. However, the potential influence of aging on the therapeutic effects of this peptide has not been well studied. In this study, we examined the glucose regulatory effects of exendin-4 in mice with different ages. METHODS: We treated 3-month and 20 to 22-month old C57/DBA mice with 10 nM/kg exendin-4 for 10 days with measurements of blood glucose and body weight. We performed OGTT and ITT to evaluate the glucose response and insulin sensitivity. Islet morphology and beta cell mass were measured by immuno-staining and beta cell proliferation was evaluated by BrdU incorporation and PCNA staining. Real-time PCR and western blot were used to measure protein changes in the liver tissue after exendin-4 treatment. RESULTS: Exendin-4 treatment improved glycemic control in both 3-month and 20 to 22-month old mice. In both groups of mice, the blood glucose lowering effect was independent of beta cell function as indicated by unchanged beta cell proliferation, insulin secretion or beta cell mass. Moreover, we found that exendin-4 treatment increased hepatic AKT and FOXO1 phosphorylation and inhibited glucose-6-phosphotase (G6P) and Phosphoenolpyruvate carboxykinase (PEPCK) expression in young mice, but this effect was attenuated in aging mice while the insulin sensitivity showed no change in the young group but significantly improved in aging mice. CONCLUSION: Based on these data, we conclude that the glucose lowering effect of exendin-4 in normal non-diabetic mice was not blunted by aging. We further showed that although there was slight difference in the glucose modulating mechanism of exendin-4 therapy in young and aged mice, the improved glucose control seemed uncorrelated with increased beta cell mass or insulin secretion.

Tocotrienol enriched palm oil prevents atherosclerosis through modulating the activities of peroxisome proliferators-activated receptors.

Palm oil is enriched in vitamin E in the form of alpha-, gamma-, and delta-tocotrienols. Dietary tocotrienol supplements have been shown to prevent atherosclerosis development in patients and preclinical animal models. However, the mechanistic basis for this health beneficial effect is not well established. Peroxisome proliferator-activated receptors alpha, gamma, and delta (PPARalpha, PPARgamma, and PPARdelta) are ligand regulated transcription factors that play essential preventive roles in the development of atherosclerosis through regulating energy metabolism and inflammation. In this study, we presented data that the tocotrienol rich fraction (TRF) of palm oil activated PPARalpha, PPARgamma, and PPARdelta in reporter based assays. Importantly, TRF attenuated the development of atherosclerosis in ApoE-/- mice through inducing PPAR target gene liver X receptor alpha (LXRalpha) and its down-stream target genes apolipoproteins and cholesterol transporters, suggesting that modulating the activities of PPARs is a key aspect of the in vivo action of tocotrienols.

Vitamin E tocotrienols improve insulin sensitivity through activating peroxisome proliferator-activated receptors.

Vitamin E is comprised of two classes of compounds: tocopherols and tocotrienols. Tocotrienol-enriched palm oil has been shown to help reduce blood glucose levels in patients and preclinical animal models. However, the mechanistic basis for tocotrienol action is not well established. Peroxisome proliferator-activated receptors alpha, gamma, and delta (PPARalpha, PPARgamma, and PPARdelta) are ligand-regulated transcription factors that play essential roles in energy metabolism. Importantly, synthetic PPARalpha and PPARgamma ligands are currently used for treating hyperlipidemia and diabetes. In this study, we present data that tocotrienols within palm oil functioned as PPAR modulators. Specifically, both alpha- and gamma-tocotrienol activated PPARalpha, while delta-tocotrienol activated PPARalpha, PPARgamma, and PPARdelta in reporter-based assays. Tocotrienols enhanced the interaction between the purified ligand-binding domain of PPARalpha with the receptor-interacting motif of coactivator PPARgamma coactivator-1alpha. In addition, the tocotrienol-rich fraction of palm oil improved whole body glucose utilization and insulin sensitivity of diabetic Db/Db mice by selectively regulating PPAR target genes. These lines of evidence collectively suggested that PPARs represent a set of molecular targets of tocotrienols.