ABSTRACT
Adiponectin, which is expressed exclusively in adipose tissue, has been shown to increase fatty acid oxidation via activation of AMP-activated kinase (AMPK) and phosphorylation of acetyl CoA carboxylase (ACC). ACC phosphorylation and carnitine palmitoyl-transferase-1 (CPT1) activity have been shown to be rate controlling factors in fatty acid oxidation. In high fat diet (HFD)-induced obese mice, we analyzed the time-course of changes in the expression of adiponectin and lipid oxidative enzymes induced by treatment with bisphenol A diglycidyl ether (BADGE) or caffeine for 8 weeks, and investigated whether the changes of adiponectin and lipid oxidative enzymes expression correlated with reduced adiposity or steatosis after 8 weeks of treatment. After 8 weeks of treatment, BADGE and caffeine had reduced body weight and epididymal adipose tissue weight in mice fed HFD, and markedly reduced the number of fatty droplets in the liver. Interestingly, the expression of adiponectin and lipid oxidative enzymes significantly increased after 2 weeks of treatment. These results indicate that the expression of adiponectin and lipid oxidative enzymes in the early stages of BADGE or caffeine treatment correlated well with the long-term anti-obesity effects.
Subject(s)
Acetyl-CoA Carboxylase/metabolism , Adiponectin/analysis , Biphenyl Compounds/pharmacology , Caffeine/pharmacology , Carnitine O-Palmitoyltransferase/metabolism , Dietary Fats/administration & dosage , Fatty Liver/metabolism , Obesity/metabolism , Animals , Male , Mice , Mice, Inbred C57BL , Time FactorsABSTRACT
Prp19p is an integral component of the heteromeric protein complex (the NineTeen complex) in the nucleus, and it is essential for the structural integrity of NineTeen complex and its subsequent activation of the spliceosome. We identified Prp19p, which has never been reported in relation to any function outside of the nucleus, as a member of proteins associated with lipid droplets. Down-regulation of Prp19p expression with RNA interference in 3T3-L1 cells repressed lipid droplet formation with the reduction in the level of expression of perilipin and S3-12. The levels of expression of SCD1 (stearoyl-CoA desaturase-1), DGAT-1 (acyl-CoA diacylglycerol acyltransferase-1), and glycerol-3-phosphate acyltransferase were also reduced in Prp19p down-regulated cells, and a significant decrease in triglycerides was observed. Unlike perilipin, which is one of the most extensively studied lipid droplet-associated proteins, Prp19p is not essential for cAMP- and hormone-sensitive lipase-dependent lipolysis pathways, even though Prp19p is a component of the lipid droplet phospholipid monolayer, and down-regulation of Prp19p represses fat accretion significantly. These results suggest that Prp19p or Prp19-interacting proteins during lipid droplet biogenesis in adipocytes may be considered as another class of potential targets for attacking obesity and obesity-related problems.
Subject(s)
Inclusion Bodies/metabolism , Lipid Metabolism , Nuclear Proteins/metabolism , Saccharomyces cerevisiae Proteins , 3T3-L1 Cells , Adipocytes/metabolism , Adipocytes/ultrastructure , Animals , Carrier Proteins , Diacylglycerol O-Acyltransferase/metabolism , Down-Regulation , Glycerol-3-Phosphate O-Acyltransferase/metabolism , Lipolysis , Male , Membrane Proteins/antagonists & inhibitors , Mice , Mice, Inbred C57BL , Nuclear Matrix-Associated Proteins , Perilipin-1 , Perilipin-4 , Phosphoproteins/antagonists & inhibitors , RNA Interference , RNA Splicing Factors , Spliceosomes , Stearoyl-CoA Desaturase/metabolismABSTRACT
Matrix Metalloproteinases (MMPs) are crucial enzymes for ultraviolet irradiation-induced photoaging in human skin. Ultraviolet B (UVB) stimulates dermal fibroblasts to increase MMP-1 and -3 expression and extracellular matrix (ECM) degradation in photoaging. We investigated whether phosphatase and tensin homolog (PTEN)/Akt pathway is involved in secretions of MMP-1 and -3 in human dermal fibroblasts. The increase in MMP-1 and -3 expression and secretion occurred along with the increase in PTEN and Akt phosphorylation by UVB irradiation in a dose- and time-dependent manner. However, treatment with a casein kinase 2 inhibitor, 5,6-dichloro-1-beta-D-ribofuranosyl-benzimidazole, inhibited their phosphorylations and MMP-1 and -3 secretions. Transfection of wild-type PTEN (Wt-PTEN) decreased basal and UVB-induced MMP-1 and -3 secretions, as well as activator protein-1 (AP-1) activity, while transfection of small interference RNA of PTEN (siRNA-PTEN), phosphatase-inactive PTEN (C124S-PTEN), or lipid phosphatase-inactive PTEN (G129E-PTEN) increased basal or UVB-induced MMP-1 and -3 secretions and AP-1 activity. Transfection of constitutively active Akt (Myr-Akt) also increased basal or UVB-induced MMP-1 and -3 secretions, as well as AP-1 activity. However, transfection of kinase-inactive Akt (K179M-Akt) decreased their secretions, but showed no significant change of AP-1 activity without UVB irradiation, and a significant increase of AP-1 activity with UVB irradiation. Treatment with the phosphatidylinositol 3-kinase inhibitors, LY294002 or wortmannin, downregulated basal and UVB-induced MMP-1 and -3 secretions. In conclusion, UVB irradiation increases PTEN and Akt phosphorylation in human dermal fibroblasts, and these inhibition of PTEN and activation of Akt by phosphorylation are involved in UVB-induced MMP-1 and -3 secretions partly through upregulation of AP-1 activity.
