Mutation of IDH1 aggravates the fatty acid­induced oxidative stress in HCT116 cells by affecting the mitochondrial respiratory chain.

Increasing evidence has indicated that mutations of isocitrate dehydrogenase 1/2 (IDH1/2) contribute to the metabolic reprogramming of cancer cells; however their functions in lipid metabolism remain unknown. In the present study, the parental and IDH1 (R132H/+) mutant HCT116 cells were treated with various concentrations of oleic acid (OA) or palmitic acid (PA) in the presence or absence of glucose. The results demonstrated that mutation of IDH1 exacerbated the effects of OA and PA on cell viability and apoptosis, and consistently elevated the production of reactive oxygen species in HCT116 cells, particularly in the absence of glucose. Furthermore, mutation of IDH1 inhibited the rate of fatty acid oxidation (FAO), but elevated the glucose consumption in HCT116 cells. The results of immunoblotting and reverse transcription­quantitative polymerase chain reaction (RT­qPCR) indicated that the expression of glucose transporter 1 was upregulated, whereas that of carnitine palmitoyl transferase 1 was downregulated in IDH1 mutant HCT116 cells. Although mitochondrial DNA quantification demonstrated that mutation of IDH1 had no effect on the quantity of mitochondria, immunoblotting and RT­qPCR revealed that mutation of IDH1 in HCT116 cells significantly downregulated the expression of cytochrome c (CYCS) and CYCS oxidase IV, two important components in mitochondrial respiratory chain. These results indicated that mutation of IDH1 aggravated the fatty acid­induced oxidative stress in HCT116 cells, by suppressing FAO and disrupting the mitochondrial respiratory chain. The results of the present study may provide novel insight into therapeutic strategies for the treatment of cancer types with IDH mutation.

Atorvastatin reduces lipid accumulation in the liver by activating protein kinase A-mediated phosphorylation of perilipin 5.

Statins have been proven to be effective in treating non-alcoholic fatty liver disease (NAFLD). Recently, it was reported that statins decreased the hepatic expression of perilipin 5 (Plin5), a lipid droplet (LD)-associated protein, which plays critical roles in regulating lipid accumulation and lipolysis in liver. However, the function and regulation mechanism of Plin5 have not yet been well-established in NAFLD treatment with statins. In this study, we observed that atorvastatin moderately reduced the expression of Plin5 in livers without changing the protein level of Plin5 in the hepatic LD fraction of mice fed with high-fat diet (HFD). Intriguingly, atorvastatin stimulated the PKA-mediated phosphorylation of Plin5 and reduced the triglyceride (TG) accumulation in hepatocytes with overexpression of wide type (Plin5-WT) compared to serine-155 mutant Plin5 (Plin5-S155A). Moreover, PKA-stimulated FA release of purified LDs carrying Plin5-WT but not Plin5-S155A. Glucagon, a PKA activator, stimulated the phosphorylation of Plin5-WT and inhibited its interaction with CGI-58. The results indicated that atorvastatin promoted lipolysis and reduced TG accumulation in the liver by increasing PKA-mediated phosphorylation of Plin5. This new mechanism of lipid-lowering effects of atorvastatin might provide a new strategy for NAFLD treatment.

Cideb Deficiency Aggravates Dextran Sulfate Sodium-induced Ulcerative Colitis in Mice by Exacerbating the Oxidative Burden in Colonic Mucosa.

BACKGROUND: Abnormal lipid metabolism is one of many factors that contribute to the development of ulcerative colitis (UC). As a lipid droplet-associated protein, Cideb facilitated the export of lipids from enterocytes and promoted intestinal lipid absorption. We found that Cideb was upregulated in the colonic mucosa of both UC patients and dextran sodium sulfate (DSS)-induced mouse colitis, but its roles in the pathogenesis of UC are still ill-defined. METHODS: Acute colitis was induced with DSS in Cideb-null and wild-type mice, and the inflammation and oxidative stress were evaluated in the colonic mucosa. Moreover, triglyceride accumulation and oxidative stress were further analyzed in polarized Caco-2 cells with overexpression of Cideb. RESULTS: Our present data indicated that Cideb-null mice were more susceptible to DSS-induced colitis, and consumption of a high-fat diet exacerbated the deterioration of DSS-induced colitis in Cideb-null mice. Moreover, Cideb deficiency increased the colonic oxidative stress in DSS-treated mice and more significant under a high-fat diet condition. In exploring the mechanism, we found that Cideb deficiency elevated the lipid content in both feces and the colonic mucosa of DSS-treated mice, especially those fed with a high-fat diet. The in vitro evidence proved that Cideb expression reduced triglyceride accumulation and oxidative stress in polarized Caco-2 cells in the presence of oleic acid. CONCLUSIONS: Our data suggest that Cideb plays a protective role against the development of UC by reducing the lipid accumulation and oxidative damage in the colonic mucosa. Therefore, Cideb could be a potential therapeutic target for UC.

Synthesis and photophysical properties of phosphorus(V) porphyrins functionalized with axial carbazolylvinylnaphthalimides.

We have synthesized new D-A-D type phosphorus(V) porphyrin derivatives and functionalized with axial carbazolylvinylnaphthalimide units. The absorption bands of the obtained phosphorus(V) porphyrins were in the range 250-640 nm with high molar absorption coefficients, meaning strong light-harvesting abilities. Notably, it is found that the devices based on phosphorus(V) porphyrins with a configuration structure of [ITO/PEDOT : PSS/organic active film/LiF/Al] give an incident-photon-to-current conversion efficiency (IPCE) response. The maximal IPCE value reaches 2.76% for the device based on compound , which is much higher than that of 0.20% for compound . The reason might be due to the low oxidation potential and the strong light-harvesting ability of the enlarged conjugation of the axial units in compound . Therefore, we deduced that photo-induced electron transfer happened in phosphorus(V) porphyrins bearing axial conjugated donor units, which would make them good candidates for photovoltaic materials that could be applied in solar cells.