Perilipin and adipophilin, two significant lipid droplet (LD)-specific proteins, participate in storing fat or ectopic lipid deposition and fat mobilization in many types of mammalian cells. Acylation stimulating protein (ASP) is a novel adipocyte-derived hormone known for a major determinant for triglyceride synthesis (TGS) and lipid metabolism. The present study was aimed to investigate: (1) whether ASP, rather than insulin, is a powerful potentiator which could physiologically and directly influence TGS during 3T3-L1 preadipocyte differentiation; (2) whether ASP exposure at indicated time points during 3T3-L1 preadipocyte differentiation could influence the gene/protein expression of adipophilin and perilipin. 3T3-L1 preadipocytes were differentiated by traditional hormone cocktail and divided into control, ASP and insulin groups according to the treatment of ASP (1 mmol/L) or insulin (100 nmol/L). ASP-stimulated and insulin-stimulated TGS rate at indicated time points (0 d, 3 d, 6 d, 9 d) were assayed by measuring the incorporation of [(3)H]-oleic acid into TG, and the corresponding glucose transport was assayed by [(3)H]-2-DG uptake. The effects of ASP or insulin on gene/protein expression of adipophilin and perilipin at indicated time points were evaluated by semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) and Western blot. The results obtained were as follows: (1) on the 3rd and 6th day of differentiation, ASP dramatically enhanced TGS rate compared with control group (P<0.05, P<0.01); There was no significant difference in TGS rate between insulin group and control group; (2) on the 6th and 9th day of differentiation, both ASP and insulin promoted glucose uptake (P<0.05, P<0.01), and the promoting effect in ASP group was greater than that in insulin group; (3) ASP elevated adipophilin gene and protein expression at the very early stage of differentiation (P<0.05, P<0.001) and had no significant effect from the 4th day of differentiation. Perilipin gene and protein expression increased throughout preadipocyte differentiation and its expression was up-regulated following ASP stimulation from the 3rd day of differentiation (P<0.05, P<0.001) to the end of differentiation (P<0.05); (4) Insulin did not affect gene and protein variation pattern of adipophilin and perilipin. Taken together, this study provides evidence that ASP-evoked changes in gene and protein expression of adipophilin and perilipin correlate with ASP-stimulated TGS acceleration, and adipophilin and perilipin are involved in the molecular mechanism of ASP-induced adipogenesis and LD formation.
3T3-L1 Cells ; Adipocytes ; cytology ; Animals ; Carrier Proteins ; metabolism ; Cell Differentiation ; Complement C3a ; pharmacology ; Gene Expression ; Insulin ; pharmacology ; Membrane Proteins ; metabolism ; Mice ; Perilipin-1 ; Perilipin-2 ; Phosphoproteins ; metabolism

OBJECTIVETo identify the association between PLIN 1237 polymorphism and obesity in Chinese Han adults.

METHODSA total of 994 adults (157 obese subjects, 322 overweight subjects, and 515 normal controls) were recruited from two rural communities. PLIN 1237 polymorphism was genotyped by polymerase chain reaction-restriction-fragment-length-polymorphism (PCR-RFLP). Association between PLIN polymorphisms and obesity status was estimated by ordinal logistic regression.

RESULTSThe three genotypes of PLIN 1237 were detected with a percentage of 54.3%, 37.1%, and 8.6% in TT, TC, and CC genotypes, respectively. For the PLIN 1237 polymorphism locus, the frequency of alleles T and C was 0.73 and 0.27, respectively. The PLIN 1237 polymorphisms were in Hardy-Weinberg equilibrium. PLIN 1237 polymorphism was not associated with obesity. The odds ratio for overweight or obesity for the CC+TC genotype was 0.8 (0.4, 1.4) in women (P = 0.4) and 0.6 (0.3, 1.3) in men (P = 0.2) after adjustment for age, education, household income and alcohol consumption, smoking, and physical activity.

CONCLUSIONChinese Han adults have a lower frequency of variant-allele C in PLIN 1237. PLIN 1237 T > C polymorphism is not significantly associated with obesity in northern Chinese adults.

Adult ; Asian Continental Ancestry Group ; genetics ; Carrier Proteins ; Female ; Genetic Predisposition to Disease ; Humans ; Male ; Obesity ; genetics ; Perilipin-1 ; Phosphoproteins ; genetics ; metabolism ; Polymorphism, Single Nucleotide ; genetics

To explore the effect of chronic high dose of insulin on lipolysis in porcine adipocytes and the underlying molecular regulation mechanisms, we cultured primary porcine adipocytes and incubated them with different concentrations of insulin (0, 200, 400, 800, 1600 nmol/L) for 24-96 h in the absence or presence of specific protein kinase A (PKA) inhibitor or extracellular signal-related kinase (ERK) inhibitor. Then, we measured the glycerol release into the culture media as an indicator of the lipolysis, and observed the lipid accumulation morphology by phase-contrast microscopy. Further, we analyzed the gene expressions of perilipin A and peroxisome proliferator-activated receptor-gamma 2 (PPAR gamma 2) with semi-quantitative RT-PCR and Western blotting, respectively. The results showed that chronic high dose of insulin stimulated lipolysis in differentiated porcine adipocytes in a dose- and time-dependent manner, and significantly attenuated the lipolytic response to isoprenaline. Meanwhile, the protein and mRNA expressions of PPAR gamma 2 and perilipin A were significantly reduced. In addition, both PKA and ERK inhibitors significantly suppressed insulin-stimulated lipolysis, however, only ERK inhibitor reversed the insulin-induced down-regulation of perilipin A. These findings imply that chronic high dose of insulin stimulates lipolysis in porcine adipocytes by repressing perilipin A, which is involved in ERK pathway.
Adipocytes ; cytology ; drug effects ; metabolism ; Animals ; Carrier Proteins ; Dose-Response Relationship, Drug ; Down-Regulation ; drug effects ; Insulin ; pharmacology ; Lipolysis ; drug effects ; Perilipin-1 ; Phosphoproteins ; metabolism ; Swine

We used CRISPR/Cas9 to delete plin1 of 3T3-L1 preadipocyte, to observe its effect on lipolysis in adipocytes and to explore regulatory pathways. We cultured 3T3-L1 preadipocytes, and the plin1 knockout vectors were transfected by electroporation. Puromycin culture was used to screen successfully transfected adipocytes, and survival rates were observed after transfection. The optimized "cocktail" method was used to differentiate 3T3-L1 preadipocytes. The glycerol and triglyceride contents were determined by enzymatic methods. The changes in lipid droplet form and size were observed by Oil red O staining. The protein expression of PLIN1, PPARγ, Fsp27, and lipases was measured by Western blotting. RT-PCR was used to measure the expression of PLIN1 and lipases mRNA. After the adipocytes in the control group were induced to differentiate, the quantity of tiny lipid droplets was decreased, and the quantity of unilocular lipid droplets was increased and arranged in a circle around the nucleus. Compared with the control group, the volume of unilocular lipid droplets decreased, and the quantity of tiny lipid droplets increased after induction of adipocytes in the knockout group. The expression of PLIN1 mRNA and protein in the adipocytes was significantly inhibited (P<0.05); glycerol levels increased significantly (0.098 4±0.007 6), TG levels decreased significantly (0.031 0±0.005 3); mRNA and protein expression of HSL and ATGL increased (P<0.05); PPARγ and Fsp27 expression unchanged in adipocytes. The above results indicate that the knockout of plin1 enhances the lipolysis of 3T3-L1 adipocytes by exposing lipids in lipid droplets and up-regulating lipases effects.
3T3-L1 Cells ; Adipocytes ; metabolism ; Animals ; CRISPR-Cas Systems ; Gene Knockout Techniques ; Lipase ; metabolism ; Lipolysis ; genetics ; Mice ; Perilipin-1 ; genetics ; metabolism

Humans ; Diabetes Mellitus, Type 2/genetics* ; Hyperlipidemias ; Mutation ; Insulin Resistance/genetics* ; Metabolic Diseases ; Proto-Oncogene Proteins c-akt ; Perilipin-1/genetics*

OBJECTIVETo investigate the effects of hypoxia on lipid metabolism in the normal human hepatic cell line L02 and to investigate the underlying molecular mechanisms.

METHODSL02 cells were exposed to hypoxic conditions (experimental groups: at 1% O2, 5% CO2, 94% N2 for 3, 6, 12, 24, or 48 hours) or normoxic conditions (control group: at 21% O2). Lipid droplet accumulation and triglyceride content were measured in each group by oil red O staining and biochemical assay, respectively. The mRNA expression levels of hypoxia-inducible factor (HIF)-2a and sterol regulatory element binding protein (SREBP)-1c were detected by reverse transcription-polymerase chain reaction. Protein expression levels of HIF-2a, adipose differentiation-related protein (ADRP), and Fas were tested by Western blot analysis.

RESULTSLipid droplet accumulation and the triglyceride content were significantly higher in the hypoxia group than the normoxia group. In addition, the hypoxia groups had significantly down-regulated mRNA expression of SREBP-1c (12h: 0.236+/-0.043, 24 h: 0.287+/-0.044, 48 h: 0.342+/-0.049 vs. normoxia: 0.503+/-0.037; F = 28.37, P less than 0.01) and FAS protein (12 h: 0.562+/-0.054, 24 h: 0.674+/-0.062, 48 h: 0.682+/-0.057 vs normoxia: 0.857+/-0.069; F = 16.08, P less than 0.01). In normoxic cells, little or no expression of HIF-2a protein was detected by Western blot. In hypoxic cells, HIF-2a protein expression peaked at 6h (0.973+/-0.067). ADRP protein expression was significantly higher in hypoxia groups than in the normoxia group (12 h: 0.319+/-0.043, 24 h: 0.732+/-0.056 and 48 h: 0.873+/-0.066 vs. 0.211+/-0.019; all, P less than 0.05.

CONCLUSIONExposure to hypoxic conditions might induce lipidosis in normal human hepatic cells by stimulating HIF-2a and ADRP expression.

Basic Helix-Loop-Helix Transcription Factors ; metabolism ; Cell Hypoxia ; Cell Line ; Down-Regulation ; Hepatocytes ; metabolism ; Humans ; Lipid Metabolism ; Membrane Proteins ; metabolism ; Oxygen ; metabolism ; Perilipin-2 ; Sterol Regulatory Element Binding Protein 1 ; metabolism

OBJECTIVETo observe the effect of coptis root extract (CRE) on the gene expressions of perilipin and peroxisome proliferator activated receptor gamma (PPAR-gamma) in atherosclerotic plaque of ApoE-gene knockout mice for exploring its plaque stabilizing action and possible mechanism.

METHODSThirty-three ApoE knockout mice, 6-8 weeks old, were fed with high-fat diet for 13 weeks. After mature atherosclerotic plaques being formed, the animals were randomly allocated into the control group, the CRE group, and the simvastatin group (as positive control) , 11 in each group. They were continuously fed with high-fat diet and to the two drug-treated groups, respective drugs in clinically recommended dose were given for another 13 weeks. Then all mice were sacrificed by the end of experiment. The morphology and composition of atherosclerotic plaques in 4 sections of aortic roots were examined with HE and Movat stain, the average number of fibrous caps buried in the plaque was observed and counted, and the gene expressions of perilipin and PPAR-gamma mRNA were determined by Real-time fluorescent quantitative PCR technology.

RESULTSAfter treatment for 13 weeks, the number of fibrous caps and the gene expression of perilipin mRNA in the CRE group was significantly lower (P<0.05), but gene of PPAR-gamma mRNA was higher (P<0.01) than those in the model group.

CONCLUSIONIn a clinically recommended dose, CRE can significantly decrease the frequency of plaque rupture in aorta of ApoE-gene knockout mice and do favour to plaque stability, its mechanism may be related to the promotion of PPAR-gamma mRNA expression and the inhibition of perilipin mRNA expression.

Animals ; Aorta ; pathology ; Apolipoproteins E ; deficiency ; genetics ; Atherosclerosis ; genetics ; pathology ; Carrier Proteins ; Coptis ; chemistry ; Drugs, Chinese Herbal ; pharmacology ; Gene Expression Regulation ; drug effects ; Gene Knockout Techniques ; Male ; Mice ; Mice, Inbred C57BL ; Mice, Knockout ; PPAR gamma ; genetics ; Perilipin-1 ; Phosphoproteins ; genetics ; Plant Roots ; chemistry ; RNA, Messenger ; genetics ; metabolism ; Time Factors