High Glucose-induced Lipid Accumulation Research Articles

Inhibition of EZH2 mitigates peritoneal fibrosis and lipid precipitation in peritoneal mesothelial cells mediated by klotho

Background Peritoneal fibrosis caused by long-term peritoneal dialysis (PD) is the main reason why patients withdraw from PD treatment. Lipid accumulation in the peritoneum was shown to participate in fibrosis, and klotho is a molecule involved in lipid metabolism. GSK343 (enhancer of zeste 2 polycomb repressive complex 2 subunit (EZH2) inhibitor) has been verified to inhibit epithelial mesenchymal transdifferentiation (EMT) and peritoneal fibrosis, but its related mechanism remains unclear. This study aimed to investigate whether lipid accumulation was involved in the effect of GSK343 and its related mechanism. Materials and Methods First, the expression of EZH2, klotho and EMT indices in human peritoneal mesothelial cells (HMrSV5) incubated with high glucose (HG) levels was detected. After EZH2 was inhibited by GSK343, Western blot (WB), wound healing and Transwell assays were used to explore the effect of GSK343. EZH2 and klotho expression was also detected. Oil red O and Nile red staining and triglyceride (TG) detection kits were used to detect lipid accumulation. A rescue experiment with small interfering RNA specific for klotho (si-klotho) on the basis of GSK343 was also conducted to verify that GSK343 exerted its effect via klotho. In in vivo experiments, rats were administered GSK343, and the related index was assessed. Results In our study, we revealed that the expression of EZH2 was significantly upregulated and klotho was significantly downregulated in HMrSV5 cells induced by high glucose. With the aid of GSK343, we found that lipid deposition caused by HG was significantly decreased. In addition, EMT and fibrosis were also significantly alleviated. Moreover, GSK343 could also restore the downregulation of klotho. To further verify whether klotho mediated the effect of EZH2, a rescue experiment with si-klotho was also conducted. The results showed that si-klotho could counteract the protective effect of GSK343 on high glucose-induced lipid accumulation and fibrosis. In vivo experiments also revealed that GSK343 could relieve peritoneal fibrosis, lipid deposition and EMT by mitigating EZH2 and restoring klotho expression. Conclusions Combining these findings, we found that EZH2 regulated lipid deposition, peritoneal fibrosis, and EMT mediated by klotho. To our knowledge, this is the first study to demonstrate the effect of the EZH2-klotho interaction on peritoneal fibrosis. Hence, EZH2 and klotho could act as potential targets for the treatment of peritoneal fibrosis.

C1q/tumour necrosis factor-related protein-3 alleviates high-glucose-induced lipid accumulation and necroinflammation in renal tubular cells by activating the adenosine monophosphate-activated protein kinase pathway.

Lipid accumulation and progressive necroinflammation play pivotal roles in the development of diabetic nephropathy. C1q tumour necrosis factor-related protein-3 (CTRP3) is an adipokine with pleiotropic functions in cell proliferation, glucose and lipid metabolism, and inflammation. However, the mechanism and involvement of CTRP3 in lipid metabolism and the necroinflammation of renal tubular cells remain unclear. Here, we report that CTRP3 expression decreased in a time- and concentration-dependent manner in high glucose-stimulated HK-2 cells. We noted that the overexpression of CTRP3 or recombinant CTRP3 (rCTRP3) treatment prevented high glucose-induced lipid accumulation by inhibiting the expression of sterol regulatory element-binding protein-1 and increasing the expression of peroxisome proliferator-activated receptor-α and ATP-binding cassette A1. Moreover, the nucleotide-binding oligomerisation domain-like receptor protein 3-mediated inflammatory response and mixed lineage kinase domain-like protein-dependent necroinflammation were inhibited by CTRP3 overexpression or rCTRP3 treatment in HK-2 cells cultured in high glucose. Furthermore, lipotoxicity-induced by palmitic acid was found to be involved in necroinflammation in HK-2 cells, and CTRP3 displayed the same protective effect. CTRP3 also activated the adenosine monophosphate-activated protein kinase (AMPK) pathway, whereas adenine 9-β-D-arabinofuranoside, an AMPK inhibitor, replicated the protective effects of CTRP3. Besides, using kidney biopsies from patients with diabetes, we found that decreased CTRP3 expression was accompanied by increased lipid deposition, as well as the structural and functional injury of renal tubular cells. Our findings demonstrate that CTRP3 affects lipid metabolism and necroinflammation in renal tubular cells via the AMPK signalling pathway. Thus, CTRP3 may be a potential therapeutic target in diabetic renal injury.

Berberine Reduces Lipid Accumulation by Promoting Fatty Acid Oxidation in Renal Tubular Epithelial Cells of the Diabetic Kidney.

Abnormal lipid metabolism in renal tubular epithelial cells contributes to renal lipid accumulation and disturbed mitochondrial bioenergetics which are important in diabetic kidney disease. Berberine, the major active constituent of Rhizoma coptidis and Cortex phellodendri, is involved in regulating glucose and lipid metabolism. The present study aimed to investigate the protective effects of berberine on lipid accumulation in tubular epithelial cells of diabetic kidney disease. We treated type 2 diabetic db/db mice with berberine (300 mg/kg) for 12 weeks. Berberine treatment improved the physical and biochemical parameters of the db/db mice compared with db/m mice. In addition, berberine decreased intracellular lipid accumulation and increased the expression of fatty acid oxidation enzymes CPT1, ACOX1 and PPAR-α in tubular epithelial cells of db/db mice. The mitochondrial morphology, mitochondrial membrane potential, cytochrome c oxidase activity, mitochondrial reactive oxygen species, and mitochondrial ATP production in db/db mice kidneys were significantly improved by berberine. Berberine intervention activated the AMPK pathway and increased the level of PGC-1α. In vitro berberine suppressed high glucose-induced lipid accumulation and reversed high glucose-induced reduction of fatty acid oxidation enzymes in HK-2 cells. Importantly, in HK-2 cells, berberine treatment blocked the change in metabolism from fatty acid oxidation to glycolysis under high glucose condition. Moreover, berberine restored high glucose-induced dysfunctional mitochondria. These data suggested that berberine alleviates diabetic renal tubulointerstitial injury through improving high glucose-induced reduction of fatty acid oxidation, alleviates lipid deposition, and protect mitochondria in tubular epithelial cells.

Metformin reduces lipid accumulation in HepG2 cells via downregulation of miR-33b

Introduction Here, we aimed to investigate whether the beneficial effects of metformin on lipid accumulation is mediated through regulation of miR-33b. Methods The expression of the genes and miRNAs and protein levels were evaluated using real-time PCR and western blot, respectively. To investigate the potential role of miR-33b in lipid accumulation, the mimic of the miR-33b was transfected into HepG2 cells. Results We found that metformin reduces high glucose-induced lipid accumulation in HepG2 cells through inhibiting of SREBP1c and FAS and increasing the expression of CPT1 and CROT. Overexpression of miR-33b significantly prevented the decreasing effect of metformin on lipid content and intra and extra triglyceride levels. Importantly, miR-33b mimic inhibited the increasing effects of metformin on the expression of CPT1 and CROT. Conclusion These findings suggest that metformin attenuates high glucose-induced lipid accumulation in HepG2 cell by downregulating the expression of miR-33b.

Hydrogen sulfide protects against high glucose‑induced lipid metabolic disturbances in 3T3‑L1 adipocytes via the AMPK signaling pathway.

Aberrant lipid metabolism contributes to the development of type 2 diabetes mellitus. The mechanisms by which hydrogen sulfide (H2S), an endogenous gasotransmitter, regulates lipid metabolism remain unclear. The aim of the present study was to investigate if the protective effects of H2S during high glucose (HG)-induced lipid accumulation in 3T3-L1 adipocytes may be mediated by AMP-activated protein kinase (AMPK). Triglyceride (TG) content and the production of H2S were determined using adipogenesis colorimetric assay kits and H2S synthesis methods. The levels of monocyte chemoattractant protein-1 and adiponectin were evaluated by ELISA. Total AMPK and phosphorylated AMPK levels were assessed by western blot analysis. HG increased the cellular level of TG and decreased H2S production in 3T3-L1 adipocytes. The H2S donor, sodium hydrosulfide (NaHS) protected against the HG-induced accumulation of TG in 3T3-L1 adipocytes. Furthermore, NaHS suppressed HG-induced TG accumulation by activating AMPK. Collectively, the findings of the present study suggested that HG induced lipid accumulation in 3T3-L1 adipocytes, and AMPK activation may underlie the lipid-lowering effects of H2S.

1α,25(OH)2 D3 alleviates high glucose-induced lipid accumulation in rat renal tubular epithelial cells by inhibiting SREBPs.

Lipid accumulation is a vital event in the progression of diabetic nephropathy. 1,25-Dihydroxyvitamin D3 (1α,25(OH)2 D3 ) is considered to have a protective effect on diabetic nephropathy. However, it remains unclear whether 1α,25(OH)2 D3 can inhibit lipid accumulation, and the potential mechanisms responsible for lipid metabolism are incompletely understood. In this study, we evaluated the effects of 1α,25(OH)2 D3 on lipid metabolism in high glucose-exposed rat renal tubular epithelial NRK-52E cells. Results indicated that high glucose-enhanced lipid accumulation in NRK-52E cells and 1α,25(OH)2 D3 can remarkably decrease high glucose-induced lipid accumulation. Western blot showed that 1α,25(OH)2 D3 alleviated high glucose-induced upregulation of sterol regulatory element-binding protein-1c (SREBP-1c) and SREBP2, along with their established target genes fatty acid synthase (FASN) and hydroxymethylglutaryl CoA reductases (HMGCR). Overall, these findings suggest that 1α,25(OH)2 D3 downregulated the expressions of SREBPs to inhibit high glucose-induced lipid accumulation, which provides new sights into the protective effects of 1α,25(OH)2 D3 on diabetic nephropathy.

Nobiletin Inhibits Hepatic Lipogenesis via Activation of AMP-Activated Protein Kinase.

We aimed to investigate the effects of nobiletin on hepatic lipogenesis in high glucose-induced lipid accumulation in HepG2 cells. Nobiletin, a citrus polymethoxyflavonoid with six methoxy groups, is present abundantly in the peels of citrus fruits. HepG2 cells were incubated in Dulbecco's modified Eagle's medium containing high glucose (25 mM) and subsequently treated with nobiletin at different concentrations (5, 25, and 50 μM). Results showed that nobiletin markedly inhibited high glucose-induced hepatic lipid accumulation in HepG2 cells. In addition, it reduced the protein expression of lipogenic factors, including sterol regulatory element-binding protein 1c (SREBP-1c) and fatty acid synthase (FAS). Nobiletin significantly increased the phosphorylation of AMP-activated protein kinase (AMPK) and acetyl-CoA carboxylase. Pretreatment with compound C, an AMPK inhibitor, abolished the inhibitory effects of nobiletin on SREBP-1c and FAS expression. These results suggested that nobiletin might attenuate high glucose-induced lipid accumulation in HepG2 hepatocytes via modulation of AMPK signaling pathway. Therefore, nobiletin might be useful for the prevention and treatment of nonalcoholic fatty liver diseases.

Role of salt inducible kinase 1 in high glucose-induced lipid accumulation in HepG2 cells and metformin intervention

AimsTo investigate the roles of salt inducible kinase (SIK1) in high glucose-induced triglyceride accumulation in human hepatoma HepG2 cells as well as in the molecular mechanism by which metformin, a drug to treat diabetes, suppresses high glucose-induced lipogenesis. Main methodsA cell model for high glucose-induced hepatic steatosis was prepared by exposing HepG2 cells to high glucose (25mmol) in the absence or presence of metformin (0.5mmol). Intracellular triglycerides were visualized by Oil Red O and measured using a triglyceride assay kit. Cell viability was evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide method. SIK1 overexpression in HepG2 cells was achieved by transient transfection, and the mRNA and protein levels of SIK1 and lipogenic factors were measured using a reverse transcription-polymerase chain reaction and western blotting, respectively. Key findingsLipid accumulation in HepG2 cells was obvious after treatment with high glucose for 24h. In response to high glucose, SIK1 expression was negatively correlated with that of lipogenic factors and lipid accumulation in HepG2 cells. We observed that overexpression of SIK1, or treatment with metformin, suppressed lipogenesis, even in high glucose conditions. Furthermore, treatment with metformin upregulated SIK1 mRNA and protein levels, as well as the active form of SIK1. SignificanceSIK1 plays a vital role in high glucose-induced lipid accumulation, and metformin suppresses lipogenesis via the induction and activation of SIK1.

Unsaponifiable Matter from Rice Bran Attenuates High Glucose-Induced Lipid Accumulation by Activating AMPK in HepG2 Cells

Rice bran, a major by-product of rice milling, has a variety of health benefits, including antioxidant, anti-inflammatory, and cholesterol-lowering effects. However, the effects of rice bran unsaponifiable matter (USM) on hepatic lipid metabolism remain unclear. In this study, the effects of rice bran USM in the prevention of high glucose-induced lipid accumulation and its putative mechanism in HepG2 cells were investigated. USM significantly inhibited high glucose-induced lipid accumulation and suppressed fatty acid synthase and sterol regulatory element-binding protein-1c expression in HepG2 cells. It also increased the phosphorylation of AMP-activated protein kinase (AMPK) and acetyl coenzyme A carboxylase. Moreover, a specific inhibitor of AMPK attenuated the effects of USM on lipid accumulation. These results demonstrate that rice bran USM prevents hepatic lipid accumulation via an AMPK-dependent signaling pathway and provides a promising approach for novel lipid-lowering therapies. Practical Application Rice bran is known to be rich in phytosterols, tocopherols, tocotrienols, and γ-oryzanol, all of which have health benefits. In recent years, the recognition of the health benefits of rice bran has resulted in its increased use in a range of food products, which far exceeds its usage as a dietary supplement. This study provides biological evidence that supports the use of rice bran unsaponifiable matter in the prevention of hepatic lipid accumulation.

<i>Ixeris dentata</i> (Thunb) Nakai Ethylacetate Extract Attenuates Sterol Regulatory Element-Binding Proteins-1c via AMP-Activated Protein Kinase Activation

Purpose: To investigate the molecular mechanisms underlying the role of Ixeris dentataa extract (IDE) in the prevention of high glucose induced lipid accumulation in human HepG-2 hepatocytes.Methods: IDE extract was prepared by maceration in ethyl acetate. Its fractionation was carried out by column chromatography. HepG-2 cells were pretreated with various concentration of IDE (0, 10, 20, 40 and 80 μg/mL) and then treated with serum-free medium with normal glucose (5 mM) for 1 h, followed by exposure to high glucose (30 mM D-glucose) for 24 h. Cell viability and cytotoxicity parameters were measured using lactate dehydrogenase (LDH) and MTT assay while triglyceride and total cholesterol levels were evaluated using respective enzymatic reagent kits. Protein expressional levels were analyzed by Western blotting.Results: IDE did not influence the cell viability (up to 200 μg/mL) and did not show any signs of cytotoxicity (up to 80 μg/mlL. IDE significantly attenuated lipid accumulation in human HepG2 hepatocytes when exposed to high glucose (30 mM D-glucose) in a dose-dependent manner (p < 0.05, 0.01 and 0.001 at 20, 40 and 80 μg/mL concentrations, respectively). Nile red staining showed that 10, 20, 40 and 80 μg/mL concentrations of IDE reduced lipid accumulation by 23.4, 34.8 (p < 0.05), 46.5 (p < 0.01) and 53.2 % (p < 0.001), respectively. The increased levels of triglycerides and total cholesterol were also attenuated by IDE (p < 0.001 at 80 μg/mL). Further, IDE attenuated the expression of fatty acid synthase and sterol regulatory element-binding protein-1. Adenosine monophosphate-activated protein kinase was also activated by IDE treatment when exposed to high glucose level (30 mM Dglucose) in human HepG2 hepatocytes.Conclusion: The findings indicate that IDE exerts hypolipidemic effect by inhibiting lipid biosynthesis, mediated via AMPK signaling. This probably explains the extract’s beneficial effect in various inflammation disorders.Keywords: Ixeris dentata extract, Lipogenesis, AMP-activated protein kinase, Sterol regulatory element-binding protein 1 -1, Anti-obesity, HepG-2 cell

Nobiletin Attenuates High Glucose‐induced Lipid Accumulation in HepG2 Hepatocytes through Activation of AMP‐activated Protein Kinase‐dependent Signaling

Nobiletin, a citrus polymethoxyflavonoid with six methoxy groups, is found abundantly in the peels of citrus fruits. Although nobiletin has been reported to display anti‐inflammatory, anti‐tumor, and anti‐diabetes activities, its effect on lipid modulation remained unclear. In the present study, we investigated the effect of nobiletin on hepatic lipogenesis in high glucose‐induced HepG2 cells. HepG2 cells were incubated in either normal (5.5 mmol/L) or high (25 mmol/L) glucose and subsequently treated with different concentrations of nobiletin (5, 25 and 50 μM). The results revealed that nobiletin markedly inhibited hepatic lipid accumulation in HepG2 cells. Nobiletin also reduced the expression of lipogenic factors, including sterol regulatory element‐binding protein 1c (SREBP‐1c) and fatty acid synthase (FAS). Moreover, nobiletin significantly increased AMP‐activated protein kinase (AMPK) phosphorylation and acetyl‐CoA carboxylase (ACC) phosphorylation. Pretreatment with compound C, an AMPK inhibitor, abolished the inhibitory effects of nobiletin on SREBP‐1c and FAS expressions. These results suggest that nobiletin may attenuate the high glucose‐induced lipid accumulation in HepG2 hepatocytes through modulation of AMPK signaling pathway, therefore preventing hepatic steatosis.

<i>Olea europaea</i> Linn (Oleaceae) Fruit Pulp Extract Suppresses Sterol Regulatory Element-Binding Proteins-1c via AMP-Activated Protein Kinase Activation in Human Hepatic Cells

Purpose: To investigate the molecular mechanisms underlying the role of Olea europaea Linn (Oleaceae) fruit pulp extract (OPF) in the prevention of high glucose-induced lipid accumulation in human HepG2 hepatocytes.Methods: HepG2 cells were pretreated with various concentration of OPF (0, 10, 20, 40 and 80 µg/ml) and then treated with serum-free medium with normal glucose (5 mM) for 1 h, followed by exposure to high glucose (25 mM D-glucose) for 24 h. Cell viability and cytotoxicity parameters were measured using LDH and MTT assay while triglyceride and total cholesterol levels were evaluated using respective enzymatic reagent kits. Protein expressional levels were analyzed by Western blotting.Results: OPF did not influence the cell viability (up to 200 µg/ml) and showed any signs of cytotoxicity (up to 80 µg/ml). OPF significantly attenuated lipid accumulation in human HepG2 hepatocytes whenexposed to high glucose (25 mM D-glucose) in a dose-dependently (p < 0.05, 0.01 and 0.001 at 20, 40 and 80 µg/ml concentrations, respectively). Nile red staining showed that 10, 20, 40 and 80 µg/ml concentrations of OPF reduced lipid accumulation by 25, 33.7 (p< 0.05), 43.7 (p attenuated by OPF (p < 0.001 at 80 µg/ml). Further, OPF attenuated the expression of fatty acid synthase and sterol regulatory element-binding protein-1. Adenosine monophosphate-activated protein kinase was also activated by OPF treatment when exposed to high glucose (25 mM D-glucose) inhuman HepG2 hepatocytes.Conclusion: This study indicates that OPF has hypolipidemic effects by inhibiting lipid biosynthesis mediated via AMPK signaling. Thus, this extract can be potentially developed into an anti-obesity agent.Keywords: Olea europaea, Fruit pulp extract, Lipogenesis, AMPK SREBP-1, Anti-obesity; HepG2 cells

Houttuynia cordata attenuates lipid accumulation via activation of AMP-activated protein kinase signaling pathway in HepG2 cells.

Houttuynia cordata (H. cordata) from the family Saururaceae is a perennial herb native to Southeast Asia. It possesses a range of medicinal properties to treat several disease symptoms including allergic inflammation and anaphylaxis. In the present investigation, we provided the molecular mechanisms underlying the role of H. cordata extract (HCE) in the prevention of high glucose-induced lipid accumulation in human HepG2 hepatocytes. HepG2 cells were pre-treated with various concentrations of HCE (0, 10, 20, 40, and 80 μg/mL) and treated with serum-free medium with normal glucose (5 mM) for 1 h, followed by exposure to high glucose (25 mM D-glucose) for 24 h. HCE significantly and dose-dependently attenuated lipid accumulation in human HepG2 hepatocytes when exposed to high glucose (25 mM D-glucose) (p < 0.05, p < 0.01 and p < 0.001 at 20, 40, and 80 μg/mL concentrations, respectively). Further, HCE attenuated the expression of fatty acid synthase (FAS), sterol regulatory element-binding protein-1 and glycerol 3-phosphate acyltransferases (GPATs). The adenosine monophosphate-activated protein kinase (AMPK) was also activated by HCE treatment when exposed to high glucose (25 mM D-glucose) in human HepG2 hepatocytes. This study suggests the hypolipidemic effects of HCE by the inhibition of lipid biosynthesis mediated through AMPK signaling, which may play an active role and can be developed as an anti-obesity agent.

3‐Caffeoyl, 4‐dihydrocaffeoylquinic acid from Salicornia herbacea attenuates high glucose‐induced hepatic lipogenesis in human HepG2 cells through activation of the liver kinase B1 and silent information regulator T1/AMPK‐dependent pathway

Increasing evidence indicates that polyphenols may protect against metabolic disease through activating AMP-activated protein kinase (AMPK). The aims of our study were to provide new data on the molecular mechanism(s) underlying the role of the phenolic compound, 3-caffeoyl, 4-dihydrocaffeoylquinic acid (CDCQ) from Salicornia herbacea, in the prevention of high glucose-induced lipogenesis in human HepG2 cells. Nile red staining assays were used to demonstrate lipid accumulation in the cells. Expression of sterol regulatory element-binding protein-1c (SREBP-1c) and fatty acid synthase (FAS) gene at the levels of promoter activity, mRNA, and protein was demonstrated using transient transfection assays, quantitative RT-PCR, and Western blot analyses, respectively. We found that CDCQ suppressed high glucose-induced lipid accumulation in HepG2 cells. CDCQ strongly inhibited high glucose-induced FAS expression by modulating SREBP-1c activation. Moreover, the use of both a specific inhibitor and liver kinase B1 (LKB1)-siRNA transfected HepG2 cells showed that CDCQ activated AMPK via silent information regulator T1 (SIRT1) or LKB1 in HepG2 cells. These results indicate that CDCQ prevented lipid accumulation by blocking the expression of SREBP-1c and FAS through LKB1/SIRT1 and AMPK activation in HepG2 cells, suggesting that CDCQ plays a potential role in the prevention of lipogenesis by AMPK activation.

Phillyrin attenuates high glucose-induced lipid accumulation in human HepG2 hepatocytes through the activation of LKB1/AMP-activated protein kinase-dependent signalling

Phillyrin, an active constituent found in many medicinal plants and certain functional foods, has anti-obesity activity in vivo. The aim of our study was to provide new data on the molecular mechanism(s) underlying the role of phillyrin in the prevention of high glucose-induced lipid accumulation in human HepG2 hepatocytes. We found that phillyrin suppressed high glucose-induced lipid accumulation in HepG2 cells. Phillyrin strongly inhibited high glucose-induced fatty acid synthase (FAS) expression by modulating sterol regulatory element-binding protein-1c (SREBP-1c) activation. Moreover, use of the pharmacological AMP-activated protein kinase (AMPK) inhibitor compound C revealed that AMPK is essential for suppressing SREBP-1c expression in phillyrin-treated cells. Finally, we found that liver kinase B1 (LKB1) phosphorylation is required for the phillyrin-enhanced activation of AMPK in HepG2 hepatocytes. These results indicate that phillyrin prevents lipid accumulation in HepG2 cells by blocking the expression of SREBP-1c and FAS through LKB1/AMPK activation, suggesting that phillyrin is a novel AMPK activator with a role in the prevention and treatment of obesity.

PI3K/Akt pathway mediates high glucose‐induced lipid accumulation in human renal proximal tubular cells via spliced XBP‐1

In the present study, we investigated the effect of X-box-binding protein-1 (XBP-1) splicing on lipogenesis in high glucose-stimulated human renal proximal tubular cell line (HKC). The results revealed that high glucose promoted the splicing of XBP-1, concomitant with up-regulation of lipogenic genes including fatty acid synthase, acetyl-CoA carboxylase, adipocyte differentiation-related protein, and cellular triglyceride. Again, silence of XBP-1 with shRNA vector inhibited high glucose-caused increased lipogenesis. Furthermore, we confirmed that the inhibition of phosphotidyl inositol 3-kinase (PI3K)/Akt pathway with LY294002 or Akt shRNA vector blocked the effect of high glucose on XBP-1 splicing and cellular triglyceride. These above data suggest that spliced XBP-1 mediates high glucose-induced lipid accumulation in HKC cells and PI3K/Akt pathway may be involved in high glucose-caused XBP-1 splicing.