Lipid Droplets/metabolism* ; Bacteria ; Lipid Metabolism

Lipophagy, the selective engulfment of lipid droplets (LDs) by autophagosomes for lysosomal degradation, is critical to lipid and energy homeostasis. Here we show that the lipid transfer protein ORP8 is located on LDs and mediates the encapsulation of LDs by autophagosomal membranes. This function of ORP8 is independent of its lipid transporter activity and is achieved through direct interaction with phagophore-anchored LC3/GABARAPs. Upon lipophagy induction, ORP8 has increased localization on LDs and is phosphorylated by AMPK, thereby enhancing its affinity for LC3/GABARAPs. Deletion of ORP8 or interruption of ORP8-LC3/GABARAP interaction results in accumulation of LDs and increased intracellular triglyceride. Overexpression of ORP8 alleviates LD and triglyceride deposition in the liver of ob/ob mice, and Osbpl8-/- mice exhibit liver lipid clearance defects. Our results suggest that ORP8 is a lipophagy receptor that plays a key role in cellular lipid metabolism.
Animals ; Mice ; Lipid Droplets ; Autophagy ; Autophagosomes ; Homeostasis ; Triglycerides

Lipophagy is a kind of selective autophagy, which can selectively identify and degrade lipid droplets and plays an important role in regulating cellular lipid metabolism and maintaining intracellular lipid homeostasis. Exercise can induce lipophagy and it is also an effective means of reducing body fat. In this review, we summarized the relationship between exercise and lipophagy in the liver, pancreas, adipose tissue, and the possible molecular mechanisms to provide a new clue for the prevention and treatment of fatty liver, obesity and other related metabolic diseases by exercise.
Autophagy/physiology* ; Humans ; Lipid Droplets/metabolism* ; Lipid Metabolism/physiology* ; Liver ; Metabolic Diseases/metabolism*

Camellia oil has become an important plant oil in China in recent years, but its effects on non-alcoholic fatty liver disease (NAFLD) have not been documented. In this study, the effects of camellia oil, soybean oil, and olive oil on NAFLD were evaluated by analyzing the fatty acid profiles of the plant oils, the serum lipids and lipoproteins of rats fed different oils, and by cytological and ultrastructural observation of the rats' hepatocytes. Analysis of fatty acid profiles showed that the polyunsaturated fatty acid (PUFA) n-6/n-3 ratio was 33.33 in camellia oil, 12.50 in olive oil, and 7.69 in soybean oil. Analyses of serum lipids and lipoproteins of rats showed that the levels of total cholesterol and low-density lipoprotein cholesterol in a camellia oil-fed group (COFG) were lower than those in an olive oil-fed group (OOFG) and higher than those in a soybean oil-fed group (SOFG). However, only the difference in total cholesterol between the COFG and SOFG was statistically significant. Cytological observation showed that the degree of lipid droplet (LD) accumulation in the hepatocytes in the COFG was lower than that in the OOFG, but higher than that in the SOFG. Ultrastructural analysis revealed that the size and number of the LDs in the hepatocytes of rats fed each of the three types of oil were related to the degree of damage to organelles, including the positions of nuclei and the integrity of mitochondria and endoplasmic reticulum. The results revealed that the effect of camellia oil on NAFLD in rats was greater than that of soybean oil, but less than that of olive oil. Although the overall trend was that among the three oil diets, those with a lower n-6/n-3 ratio were associated with a lower risk of NAFLD, and the effect of camellia oil on NAFLD was not entirely related to the n-6/n-3 ratio and may have involved other factors. This provides new insights into the effect of oil diets on NAFLD.
Animals ; Camellia/chemistry* ; Fatty Acids/analysis* ; Hepatocytes/ultrastructure* ; Lipid Droplets/physiology* ; Lipids/blood* ; Male ; Non-alcoholic Fatty Liver Disease/pathology* ; Plant Oils/administration & dosage* ; Rats ; Rats, Sprague-Dawley

Adipose tissue is the main energy reserve of the body. When energy is required, adipocyte triglycerides stored in lipid droplets (LDs) are broken down by lipase, and free fatty acids are released to supply the physiological need. Intracellular LDs are active metabolic organelles in mammalian cells, particularly in adipocytes. The present study was aimed to investigate the morphological changes of LDs and the alternation of LD-associated perilipin family proteins during long-term lipolysis stimulated by forskolin. Primary differentiated adipocytes derived from epididymal fat pads of Sprague-Dawley (SD) rats were incubated in the presence or absence of 1 μmol/L forskolin for 24 h. Content of glycerol released to the culture medium was determined by a colorimetric assay and served as an index of lipolysis. Morphological changes of LDs were observed by Nile red staining. The mRNA level of perilipin family genes was detected by quantitative real-time PCR. The protein level and subcellular localization were examined by immunoblotting and immunofluorescence staining, respectively. The results showed that forskolin induced sustained lipolysis in differentiated adipocytes. The morphology of LDs changed in a time-dependent manner. Large clustered LDs became gradually smaller in size and eventually disappeared; in contrast, peripheral micro-LDs increased gradually in number until the cytoplasm was filled with numerous micro-LDs. The protein level of the perilipin family proteins showed obvious alternation. Mature adipocytes physiologically expressed a very low level of Plin2 protein, whereas in adipocytes stimulated with lipolytic forskolin, the protein and mRNA levels of Plin2 were significantly increased, and the increased Plin2 was specifically bound to the surface of LDs. During chronic stimulation of forskolin, the mRNA level of Plin3 was unchanged, but the mRNA levels of Plin1, Plin4 and Plin5 were significantly decreased. These results suggest that the morphology of LDs and perilipin family proteins on the surface of LDs are significantly altered during long-term lipolysis stimulated by forskolin, representing a dynamic process of the remodeling of LDs.
Adipocytes ; drug effects ; Animals ; Cells, Cultured ; Colforsin ; pharmacology ; Lipid Droplets ; Lipolysis ; Perilipin-2 ; metabolism ; Perilipins ; metabolism ; Rats ; Rats, Sprague-Dawley

PURPOSE: Obesity is a major health problem of global significance because it is clearly associated with an increased risk of health problems, such as nonalcoholic fatty liver disease (NAFLD), diabetes, cardiovascular diseases, and cancer. Lonicera caerulea (LC) originates from high mountains or wet areas and has been used as a traditional medicine in northern Russia, China, and Japan. LC contains a range of bioactive constituents, such as vitamins, minerals, and polyphenols. This study examined the anti-obesity effects of LC during differentiation in preadipocytes. METHODS: The cell viability assay was performed after the differentiation of 3T3-L1 cells for 7 days. Oil Red O staining was used to visualize the changes in lipid droplets in 3T3-L1 cells and mouse adipose-derived stem cells (MADSCs). The mRNA expression of obesity-related genes was determined by quantitative real-time PCR. RESULTS: According to the results of Oil Red O staining, the lipid levels and size of lipid droplets in the adipocytes were reduced and the LC extract (LCE, 0.25–1 mg/mL) markedly inhibited adipogenesis in a dose-dependent manner. The treatment of LCE also decreased the mRNA expression of peroxisome proliferator-activated receptor γ (PPARγ), CCAAT/enhancer binding protein-α (C/EBPα), and sterol regulatory element binding protein 1 (SREBP1) in 3T3-L1 cells. Western blot analysis showed that the PPARγ, C/EBPα, and SREBP1 protein levels in both 3T3-L1 and MADSC were reduced in a dose-dependent manner. CONCLUSION: These results suggest that LCE can inhibit adipogenic differentiation through the regulation of adipogenesis-related markers.
3T3-L1 Cells ; Adipocytes ; Adipogenesis ; Animals ; Blotting, Western ; Cardiovascular Diseases ; Cell Survival ; China ; Japan ; Lipid Droplets ; Lonicera ; Medicine, Traditional ; Mice ; Minerals ; Miners ; Non-alcoholic Fatty Liver Disease ; Obesity ; Peroxisomes ; Polyphenols ; Real-Time Polymerase Chain Reaction ; RNA, Messenger ; Russia ; Stem Cells ; Sterol Regulatory Element Binding Protein 1 ; Vitamins

Trypanosoma cruzi infection results in debilitating cardiomyopathy, which is a major cause of mortality and morbidity in the endemic regions of Chagas disease (CD). The pathogenesis of Chagasic cardiomyopathy (CCM) has been intensely studied as a chronic inflammatory disease until recent observations reporting the role of cardio-metabolic dysfunctions. In particular, we demonstrated accumulation of lipid droplets and impaired cardiac lipid metabolism in the hearts of cardiomyopathic mice and patients, and their association with impaired mitochondrial functions and endoplasmic reticulum (ER) stress in CD mice. In the present study, we examined whether treating infected mice with an ER stress inhibitor can modify the pathogenesis of cardiomyopathy during chronic stages of infection. T. cruzi infected mice were treated with an ER stress inhibitor 2-Aminopurine (2AP) during the indeterminate stage and evaluated for cardiac pathophysiology during the subsequent chronic stage. Our study demonstrates that inhibition of ER stress improves cardiac pathology caused by T. cruzi infection by reducing ER stress and downstream signaling of phosphorylated eukaryotic initiation factor (P-elF2α) in the hearts of chronically infected mice. Importantly, cardiac ultrasound imaging showed amelioration of ventricular enlargement, suggesting that inhibition of ER stress may be a valuable strategy to combat the progression of cardiomyopathy in Chagas patients.
2-Aminopurine ; Animals ; Cardiomyopathies ; Chagas Disease ; Endoplasmic Reticulum ; Endoplasmic Reticulum Stress ; Heart ; Humans ; Lipid Droplets ; Lipid Metabolism ; Mice ; Mortality ; Pathology ; Peptide Initiation Factors ; Trypanosoma cruzi ; Ultrasonography

The objective of this study was to examine effects of spontaneous adipocyte generation on osteogenic differentiation of porcine skin-derived stem cells (pSSCs). Correlation between osteogenic differentiation and adipocyte differentiation induced by osteocyte induction culture was determined using different cell lines. Osteogenic differentiation efficiency of pSSCs was then analyzed by controlling the expression of adipocyte-specific transcription factors during osteogenic induction culture. Among four cell lines, pSSCs-II had the lowest lipid droplet level but the highest calcium content (p < 0.05). It also expressed significantly low levels of peroxisome proliferator-activated receptor gamma 2 (PPARγ2) and adipocyte protein 2 (aP2) mRNAs but very high levels of runt-related transcription factor 2 (Runx2) and alkaline phosphatase (ALP) mRNAs as osteogenic makers (p < 0.05). Oil red O extraction was increased by 0.1 µM troglitazone (TGZ) treatment but decreased by 50 µM bisphenol A diglycidyl ether (BADGE) (p < 0.05). Calcium content was drastically increased after BADGE treatment compared to that in osteogenic induction control and TGZ-treated pSSCs (p < 0.05). Relative expression levels of PPARγ2 and aP2 mRNAs were increased by TGZ but decreased by BADGE. Expression levels of Rucx2 and ALP mRNAs, osteoblast-specific marker genes, were significantly increased by BADGE treatment (p < 0.05). The expression level of BCL2 like 1 was significantly higher in BADGE-treated pSSCs than that in TGZ-treated ones (p < 0.05). The results demonstrate that spontaneous adipocyte generation does not adversely affect osteogenic differentiation. However, reducing spontaneous adipocyte generation by inhibiting PPARγ2 mRNA expression can enhance in vitro osteogenic differentiation of pSSCs.
Adipocytes ; Alkaline Phosphatase ; Calcium ; Cell Line ; Ether ; In Vitro Techniques ; Lipid Droplets ; Osteocytes ; Osteogenesis ; PPAR gamma ; RNA, Messenger ; Stem Cells ; Transcription Factors

Differentiation of preadipocyte, also named adipogenesis, leads to the phenotype of mature adipocyte that is filled with many lipid droplets. Excessive lipid accumulation in adipocytes leads to the development of obesity. In this study, we investigated the effect of 11 different natural compounds on lipid accumulation during the differentiation of 3T3-L1 preadipocytes into 3T3-L1 adipocytes. Strikingly, among the natural compounds, cryptotanshinone at 10 µM most strongly reduced triglyceride (TG) contents in 3T3-L1 cells after 8 days of the differentiation. Furthermore, cryptotanshinone at 10 µM significantly suppressed lipid accumulation in 3T3-L1 cells after 8 days of the differentiation. Cryptotanshinone at 1 to 10 µM tested did not affect the survival of 3T3-L1 cells after 8 days of the differentiation. On mechanistic levels, cryptotanshinone time-differentially decreased the expression levels of CCAAT/enhancer-binding protein-α (C/EBP-α), peroxisome proliferator-activated receptor-γ (PPAR-γ), fatty acid synthase (FAS), and perilipin A but also the phosphorylation levels of signal transducer and activator of transcription-3 (STAT-3) during the 3T3-L1 cell differentiation. Taken together, these findings demonstrate that cryptotanshinone inhibits lipid accumulation in differentiating 3T3-L1 cells, which appears to be mediated through the reduced expression and/or phosphorylation levels of C/EBP-α, PPAR-γ, FAS, Perilipin A, and STAT-3.
3T3-L1 Cells ; Adipocytes ; Adipogenesis ; Lipid Droplets ; Obesity ; Peroxisomes ; Phenotype ; Phosphorylation ; Transducers ; Triglycerides

Betula platyphylla var. japonica (Betulaceae), also known as Asian white birch, is an endemic medicinal tree, the bark of which has been used in Chinese traditional medicine for the treatment of various inflammatory diseases. In our continuing search for bioactive compounds from Korean natural resources, a phytochemical investigation of the bark of B. platyphylla var. japonica led to the isolation of 7-oxo-β-sitosterol (1) and soyacerebroside I (2) from its ethanol extract as main components by liquid chromatography (LC)/mass spectrometry (MS)-based analysis. The structures of isolates were identified by comparison of ¹H and ¹³C nuclear magnetic resonance spectroscopic data and physical data with the previously reported values and LC/MS analyses. To the best of our knowledge, this is the first study to demonstrate that the isolated compounds, 7-oxo-β-sitosterol and soyacerebroside I, were isolated in B. platyphylla var. japonica. We examined the effects of the isolates on the regulation of adipocytes and osteoblast differentiation. These isolates (1 and 2) produced fewer lipid droplets compared to the untreated negative control in Oil Red O staining of the mouse mesenchymal stem cell line without altering the amount of alkaline phosphatase staining. The results demonstrated that both compounds showed marginal inhibitory effects on adipocyte differentiation but did not affect osteoblast differentiation.
Adipocytes ; Alkaline Phosphatase ; Animals ; Asian Continental Ancestry Group ; Betula ; Chromatography, Liquid ; Ethanol ; Humans ; Lipid Droplets ; Magnetic Resonance Spectroscopy ; Medicine, Chinese Traditional ; Mesenchymal Stromal Cells ; Mice ; Natural Resources ; Osteoblasts ; Spectrum Analysis ; Trees