Stard 3 (Steroidogenic Acute Regulatory-Related Lipid Transfer Domain-Containing Protein 3) Play Important Role in Preadipocyte Differentiation

Aim: To evaluate Stard 3’s effects and relative mechanisms in preadipocyto differentiation by vitro study. Materials and Methods: The 3T3-L1 cell were divided into 5 groups as NC, si-Stard 3, ROS agonist, ROS inhibitor and si-Stard 3+ROS agonist groups. The cell of different groups were evaluated by Oil red O staining and Triglyceride. Evaluating ROS production by DHE and NBT assay. Using RT-qPCR and WB methods to evaluate gene and protein expressions. Results: Compared with NC group, Triglyceride, DHE fluorescence intensity and NBT positive rate were significantly down-regulation in si-Stard 3 and ROS inhibitor groups (P < 0.001, respectively), and were significantly up-regulation in ROS agonist group (P < 0.001, respectively); However, with si-Stard 3 transfection and ROS agonist treatment, compared with si-Stard 3 group, Triglyceride, DHE fluorescence intensity and NBT positive rate were significantly increased in si-Stard 3+ROS agonist group (P < 0.001, respectively). With RT-qPCR and WB assay, Compared with NC group, Stard 3 gene and protein expressions of si-Stard 3 and si-Stard 3+ROS agonist group were significantly depressed (P < 0.001, respectively), AMPK, PPARγ, CEBPα and FABP4 gene expressions were significantly differences in si-Stard 3, ROS agonist and ROS inhibitor groups (P < 0.001, respectively) and p-AMPK, PPARγ, CEBPα and FABP4 protein expressions were significantly differences in si-Stard 3, ROS agonist and ROS inhibitor groups (P < 0.001, respectively), with si-Stard 3 transfection and ROS agonist the relative gene and protein expressions were significantly resumed compared with si-Stard 3 group (P < 0.001, respectively). Conclusion: Stard 3 knockdown had effects to suppress 3T3-L1 cells transformation into adipocytes in vitro study.

The role and possible mechanism of the long noncoding RNA LINC01260 in nonalcoholic fatty liver disease

Objective To investigate the differential expression profile of lncRNAs in the nonalcoholic fatty liver disease (NAFLD) model induced by oleic acid (OA) and to further explore the role of LINC01260 (ENST00000255183) in NAFLD, providing theoretical support for the clinical value of lncRNAs in NAFLD. Methods OA (50 μg/mL) was used to induce steatosis in normal human LO2 hepatocytes for 48 h and was verified by Oil red O staining. Differential expression profiles of lncRNAs were obtained by eukaryotic circular sequencing (RNA/lncRNA/circRNA-seq) techniques. A gain-of-function (GOF) strategy for LINC01260 was adopted, Oil red O staining and semiquantitative analysis were combined to explore whether the GOF of LINC01260 affects LO2 cell steatosis. CeRNA-based bioinformatics analysis of lncRNAs was performed, and the enriched mRNAs were further verified. RXRB siRNAs were applied and verify its role in LINC01260 regulated OA-induced hepatocytes steatosis. Results Lipid droplets of different sizes were observed in the cells of the OA group. Absorbance in the OA group was significantly increased after isopropanol decolorization (P < 0.05). Compared with those in the control group, there were 648 lncRNAs with differential expression greater than 1 time in the OA group, of which 351 were upregulated and 297 were downregulated. Fluorescence quantitative PCR showed that the expression of LINC01260 in the OA group was downregulated by 0.35 ± 0.07-fold (P < 0.05). The formation of lipid droplets in LO2 cells of the LINC01260 GOF group decreased significantly (P < 0.05). CeRNA analysis indicated that the mRNA levels of RXRB, RNPEPL1, CD82, MADD and KLC2 were changed to different degrees. Overexpression of LINC01260 significantly induced RXRB transcription (P < 0.05) and translation, and RXRB silence attenuated the lipids decrease induced by LINC01260 overexpression. Conclusion The OA-induced NAFLD cell model has a wide range of lncRNA differential expression profiles. LINC01260 participates in the regulation of the lipid droplet formation process of NAFLD, and its overexpression can significantly inhibit the steatosis process of LO2 cells. Mechanistically, LINC01260 may act as a ceRNA to regulate the expression of RXRB, thereby affecting the adipocytokine signaling pathway.

Trapa japonica Flerov Extract Prevents Obesity by Regulating Adipogenesis and Lipolysis in Differentiated 3T3-L1 Cells

Our study investigated that the anti-obesity effect of the Trapa japonica Flerov extract (TJ) in differentiated 3T3-L1 adipocytes. To this end, 3T3-L1 cells were treated with TJ during their differentiation period. On the last day of the cell culture, we tested intracellular cAMP, FA, glycerol release, TG, and performed Oil Red O staining and Western blot assays. On the part of adipogenesis, lipogenesis, and lipolysis mechanism, TJ increased the cAMP (maximum 125.4%) levels and glycerol release (maximum four times) and decreased FA (maximum 35.1%) and TG (maximum 35.7%) levels. Furthermore, the protein expression levels of each mechanism-related factor were regulated in a dose-dependent manner. These results indicate that TJ reduced lipid accumulation by max 53.6% and 47.9%, respectively, in adipogenesis and lipolysis mechanisms. We expect this effect of TJ to be due to its component, ellagic acid. In conclusion, we found that TJ inhibits TG synthesis during adipogenesis and lipogenesis, promotes lipolysis, and thus, indicating its potential as a functional food for obesity prevention.

Knockdown of CDC20 Promotes Adipogenesis of Bone Marrow-derived Stem Cells

Background: Bone is a rigid organ that provides support and physical protection to vital organs of the body. Several bone loss disorders are commonly associated with increased bone marrow adipose tissue. Bone marrow mesenchymal stromal/stem cells (BMSCs) are multipotent progenitors differentiating into osteoblasts, adipocytes, and chondrocytes. CDC20 is a co-activator of APC/C, required for full ubiquitin ligase activity. In our previous study, CDC20 promoted the osteogenic commitment of BMSCs and Cdc20 conditional knockout mice suggested a decline in bone mass. In this study, we investigated the function of CDC20 in the adipogenic differentiation of BMSCs and provided a new clue between adipogenesis and osteogenesis. Methods: Lentivirus containing CDC20 shRNA was used for CDC20 knockdown in hBMSCs. Primary mBMSCs were isolated from Cdc20f/f and Sp7-Cre;Cdc20f/f mice. Adipogenesis was examined by qRT-PCR and western blot analysis of adipogenic regulators, Oil Red O staining and transplantation into nude mice. The CDC20 knockout efficiency was determined through immunochemistry, qRT-PCR and western blot of bone marrow. Accumulation of adiposity was measured through histology and staining of bone sections. Results: CDC20 expression in hBMSCs was significantly decreased during adipogenic differentiation. Knockdown of CDC20 enhanced adipogenic differentiation of hBMSCs in vitro. CDC20-knockdown hBMSCs showed more adipose tissue–like constructs in H&E staining and Oil Red O staining. Sp7-Cre;Cdc20f/f mice presented increased adipocytes in bone marrow compared with control mice. mBMSCs from Sp7-Cre;Cdc20f/f mice exerted upregulated adipogenic differentiation. Conclusions: Our findings showed that knockdown of CDC20 enhanced adipogenesis of h(m)BMSCs in vitro and in vivo. Overall, CDC20 regulated both adipogenesis and osteogenesis of BMSCs, and may lead to the development of new therapeutic target for “fatty bone” and osteoporosis.

Impaired Proliferation, Apoptosis, and Angiogenesis of Adipose-Derived Stem Cells Isolated from Rats during the Course of Diabetes

Background: To characterize the impaired of proliferation, apoptosis, and angiogenic activity in ASCs isolated at different stages of the disease course from rats with type 1 diabetes mellitus (T1DM) rats induced by streptozotocin (STZ). Methods: Adipose tissues of the epididymis were harvested at 0, 4, 8, 12, and 16 weeks after the induction of T1DM in rats and from normal rats at the same time points and the morphological variations were detected by Oil red O staining. ASCs were collected from adipose tissues. Cell proliferation, apoptosis, vascular endothelial growth factor (VEGF), and basic fibroblast growth factor (bFGF) expression were assessed. Results: With the prolongation of the disease course, the size and the morphology of adipocytes were distorted, and intracellular lipid droplets became smaller. After 4 weeks, the proliferation of ASCs was decreased, while apoptosis in ASCs was increased. Furthermore, as the disease proceeded, proliferation decreased and apoptosis increased. VEGF and bFGF expression in ASCs from diabetic rats was downregulated at 8 weeks. Conclusion: At 4 weeks after T1DM induction, the proliferation of ASCs decreased and apoptosis increased. The expression of angiogenic factors in ASCs declined at 8 weeks after T1DM induction. The changes in the proliferation, apoptosis, and angiogenic activity are related to the prolongation of disease course.

Inhibitory Effects of Pinostilbene on Adipogenesis in 3T3-L1 Adipocytes: A Study of Possible Mechanisms

Resveratrol is a phytoalexin with multiple bioactive properties, including antioxidative, neuroprotective, cardioprotective, and anticancer effects. However, resveratrol exhibits structural instability in response to UV irradiation, alkaline pH, and oxygen exposure. Thus, resveratrol derivatives have attracted considerable research interest. In this study, we aimed to evaluate the anti-adipogenic effects of pinostilbene hydrate (PH), a methylated resveratrol derivative, in 3T3-L1 cells. We also evaluated the mechanisms underlying the effects of PH on adipogenesis in 3T3-L1 adipocytes. Oil Red O staining, lipid accumulation assay, and triglyceride (TG) content assay revealed that PH significantly inhibited lipid and TG accumulation without cytotoxicity. In addition, we determined that PH decreased the expression of adipogenesis-related transcription factors, such as PPARγ, C/EBPα, SREBP-1c, and FABP4, and the phosphorylation of MAPK and protein kinase B (AKT). Moreover, PH attenuated the expression of CREB and C/EBPβ, while increasing the phosphorylation of AMPK and ACC, and decreasing the expression of fatty acid synthase and FABP4. Based on these results, we suggest that PH suppresses adipogenesis in 3T3-L1 cells via the activation of the AMPK signaling pathway and the inhibition of the MAPK and AKT insulin-dependent signaling pathways.

Influences of Unmodified and Carboxylated Carbon Nanotubes on Lipid Profiles in THP-1 Macrophages: A Lipidomics Study

Since the possible roles of surface modifications in determining multi-walled carbon nanotube (MWCNT)–promoted endoplasmic reticulum (ER) stress-mediated lipid-laden macrophage foam cell formation are still in debate, we compared unmodified and carboxylated MWCNT-induced cytotoxicity, lipid profile changes, and expression of ER stress genes in THP-1 macrophages. Particularly, we focused on lipid profile changes by using lipidomics approaches. We found that unmodified and carboxylated MWCNTs significantly decreased cellular viability and appeared to damage the cellular membrane to a similar extent. Likewise, the results from Oil Red O staining showed that both types of MWCNTs slightly but significantly induced lipid accumulation. In keeping with Oil Red O staining results, lipidomics data showed that both types of MWCNTs up-regulated most of the lipid classes. Interestingly, almost all lipid classes were relatively higher in carboxylated MWCNT-exposed THP-1 macrophages compared with unmodified MWCNT-exposed cells, indicating that carboxylated MWCNTs more effectively changed lipid profiles. But in contrast to our expectation, none of the MWCNTs significantly induced the expression of ER stress genes. Even, compared with carboxylated MWCNTs, unmodified MWCNTs induced higher expression of lipid genes, including macrophage scavenger receptor 1 and fatty acid synthase. Combined, our results suggested that even though carboxylation did not significantly affect MWCNT-induced lipid accumulation, carboxylated MWCNTs were more potent to alter lipid profiles in THP-1 macrophages, indicating the need to use omics techniques to understand the exact nanotoxicological effects of MWCNTs. However, the differential effects of unmodified and carboxylated MWCNTs on lipid profiles might not be related with the induction of ER stress.

Effect of Metformin and Simvastatin in Inhibiting Proadipogenic Transcription Factors

Obesity is a multifactorial chronic disease characterized by the excessive accumulation of fat in adipose tissue driven by hypertrophy and hyperplasia of adipocytes through adipogenesis. Adipogenesis plays a key role in the development of obesity and related metabolic disorders, which makes it potential target for the therapeutic approach to obesity. An increasing number of studies confirm the pleiotropic action of the combined treatment with metformin and statins, suggesting their anti-hypertensive, anti-inflammatory, and anti-adipogenic effect. The aim of this study was to analyze the effect of different doses of metformin (MET) and simvastatin (SIM) on the expression of key transcription factors of adipogenesis. Mouse 3T3-L1 preadipocytes were induced to differentiation in adipogenic medium with sustained MET and SIM treatment to assess the effect on adipogenesis. Nine days after initiating adipogenesis, the cells were prepared for further experiments, including Oil Red O staining, RT-PCR, Western blotting, and immunocytochemistry. Treating the cells with the combination of MET and SIM slightly reduced the intensity of Oil Red O staining compared with the control group, and down-regulated mRNA and protein expression of PPARγ, C/EBPα, and SREBP-1C. In conclusion, the inhibitory effect of MET and SIM on adipocyte differentiation, as indicated by decreased lipid accumulation, appears to be mediated through the down-regulation of adipogenic transcription factors, peroxisome proliferator-activated receptor γ (PPARγ), CCAAT/enhancer binding pro-tein α (C/EBPα), and sterol regulatory element-binding protein 1 (SREBP-1C).

A Novel Age-Related Circular RNA Circ-ATXN2 Inhibits Proliferation, Promotes Cell Death and Adipogenesis in Rat Adipose Tissue-Derived Stromal Cells

Adipose tissue-derived stromal cells are promising candidates investigating the stem cell-related treatment. However, their proportion and utility in the human body decline with time, rendering stem cells incompetent to complete repair processes in vivo. The involvement of circRNAs in the aging process is poorly understood. Rat subcutaneous adipose tissue from 10-week-old and 27-month-old rats were used for hematoxylin and eosin (H and E) staining, TUNEL staining, and circRNA sequencing. Rat adipose tissue-derived stromal cells were cultured and overexpressed with circ-ATXN2. Proliferation was examined using xCELLigence real-time cell analysis, EdU staining, and cell cycle assay. Apoptosis was induced by CoCl2 and examined using flow cytometry. RT-PCR assay and Oil Red O staining were used to measure adipogenesis at 48 h and 14 days, respectively. H and E staining showed that the diameter of adipocytes increased; however, the number of cells decreased in old rats. TUNEL staining showed that the proportion of apoptotic cells was increased in old rats. A total of 4,860 and 4,952 circRNAs was detected in young and old rats, respectively. Among them, 67 circRNAs exhibited divergent expression between the two groups (fold change ≥2, p ≤ 0.05), of which 33 were upregulated (49.3%) and 34 were downregulated (50.7%). The proliferation of circ-ATXN2-overexpressing cells decreased significantly in vitro, which was further validated by xCELLigence real-time cell analysis, EdU staining, and cell cycle assay. Overexpression of circ-ATXN2 significantly increased the total apoptotic rate from 5.78 ± 0.46% to 11.97 ± 1.61%, early apoptotic rate from 1.76 ± 0.22% to 5.50 ± 0.66%, and late apoptosis rate from 4.02 ± 0.25% to 6.47 ± 1.06% in adipose tissue-derived stromal cells. Furthermore, in circ-ATXN2-overexpressing cells, RT-PCR assay revealed that the expression levels of adipose differentiation-related genes PPARγ and CEBP/α were increased and the Oil Red O staining assay showed more lipid droplets. Our study revealed the expression profile of circRNAs in the adipose tissue of old rats. We found a novel age-related circular RNA—circ-ATXN2—that inhibits proliferation and promotes cell death and adipogenesis in rat adipose tissue-derived stromal cells.

Visceral Fat Inflammation and Fat Embolism are associated with Lung's Lipidic Hyaline Membranes in COVID-19 patients

Background: Visceral obesity is a critical determinant of severe coronavirus disease-2019 (COVID-19). Methods: In this study, we performed a comprehensive histomorphologic analysis of autoptic visceral adipose tissues (VAT), lungs and livers of 19 COVID-19 and 23 non-COVID-19 subjects. Results: Although there were no between-groups differences in body-mass-index and adipocytes size, higher prevalence of CD68+ macrophages in COVID-19 subjects VAT was detected (p=0.005) and accompanied by crown-like structures presence, signs of adipocytes stress and death. Consistently, human adipocytes were successfully infected by SARS-CoV2 in vitro and displayed lower cell viability. Being VAT inflammation associated with lipids spill-over from dead adipocytes, we studied lipids distribution employing Oil-Red-O staining (ORO). Lipids were observed within lungs and livers interstitial spaces, macrophages, endothelial cells, and vessels lumen, features suggestive of fat embolism syndrome, more prevalent among COVID-19 individuals (p<0.001). Notably, signs of fat embolism were more prevalent among obese (p=0.03) independently of COVID-19 diagnosis, suggesting that such condition may be an obesity complication, exacerbated by SARS-CoV2 infection. Importantly, all infected subjects lungs presented lipids-rich (ORO+) hyaline membranes, formations associated with COVID-19-related pneumonia, present only in one control with non-COVID-19 pneumonia. Conclusions: This study describes for the first time novel COVID-19-related features possibly underlying the unfavorable prognosis in obese SARS-CoV2-infected-subjects.