Insulin prevents fatty acid induced increase of adipocyte size

Molecular mechanism of Gan-song Yin inhibiting the proliferation of renal tubular epithelial cells by regulating miR-21-5p in adipocyte exosomes

ETHNOPHARMACOLOGICAL RELEVANCE

Gan-song Yin is derived from the classic ancient prescription " Gan-song pill " for the treatment of wasting-thirst in Ningxia combined with the characteristic "fragrant medicine". It is clinically used for the treatment of early renal fibrosis caused by diabetic nephropathy. Previous studies have shown that it has a good effect and great potential in the prevention and treatment of diabetic nephropathy, but its mechanism research is still limited.

AIM OF THE STUDY

To investigate the mechanism of GSY to improve DN by interfering with miR-21-5p and glycolipid metabolism in adipocyte exosomes using 3T3-L1 and TCMK-1 co-culture system.

MATERIALS AND METHODS

The co-culture system of 3T3-L3 and TCMK-1 was established, the IR model was established, and the stability, lipid drop change, glucose consumption, triglyceride content, cell viability, cell cycle and apoptosis level, protein content and mRNA expression of the IR model were detected.

RESULTS

GSY inhibited 3T3-L1 activity, increased glucose consumption and decreased TG content. Decreased TCMK-1 cell viability, inhibited apoptosis, cell cycle arrest occurred in G0/G1 phase and S phase. Adipocyte IR model and co-culture system were stable within 48 h. After GSY intervention, lipid droplet decomposition and glucose consumption increased. The TG content of adipocytes increased, while the TG content of co-culture system decreased. GSY can regulate the expression of TGF-β1/SMAD signaling pathway protein in IR state. After GSY intervention, the expression of miR-21-5p was increased in 3T3-L1 and Exo cells, and decreased in TCMK-1 cells.

CONCLUSIONS

GSY can regulate TGF-β1/SMAD signaling pathway through the secretion of miR-21-5p from adipocytes, protect IR TCMK-1, regulate the protein and mRNA expression levels of PPARγ, GLUT4, FABP4, and improve glucose and lipid metabolism.

In vitro and in vivo toxicity of carbon dots with different chemical compositions

Carbon dots (CDs) are easy-obtained nanoparticles with wide range of biological activity; however, their toxicity after prolonged exposure is poorly investigated. So, in vitro and in vivo toxicity of CDs with the surfaces enriched with hydroxylated hydrocarbon chains and methylene groups (CD_GE), carboxyl and phenol groups accompanied with nitrogen (CD_3011), trifluoromethyl (CDF19) or toluidine and aniline groups (CDN19) were aimed to be discovered. CDs' in vitro toxicity was assessed on A549 cells (real-time cell analysis of impedance, fluorescence microscopy) after 24 h of incubation, and we observed no changes in cell viability and morphology. CDs' in vivo toxicity was assessed on C57Bl6 mice after multiple dosages (5 mg/kg subcutaneously) for 14 days. Lethality (up to 50%) was observed in CDN19 and CD_3011 groups on different days of dosing, accompanied by toxicity signs in case of CD_3011. There were no changes in serum biochemical parameters except Urea (increased in CDF19 and CD_3011 groups), nor substantial kidney, liver, and spleen injuries. The most impactful for all organs were also CD_3011 and CDF19, causing renal tubule injury and liver blood supply violation. Thus, CDs with a surface enriched with oxygen- and nitrogen-containing functional groups might be toxic after multiple everyday dosing, without, however, significant damages of internal organs in survived animals.

FABP4 Controls Fat Mass Expandability (Adipocyte Size and Number) through Inhibition of CD36/SR-B2 Signalling

Adipose tissue hypertrophy during obesity plays pleiotropic effects on health. Adipose tissue expandability depends on adipocyte size and number. In mature adipocytes, lipid accumulation as triglycerides into droplets is imbalanced by lipid uptake and lipolysis. In previous studies, we showed that adipogenesis induced by oleic acid is signed by size increase and reduction of FAT/CD36 (SR-B2) activity. The present study aims to decipher the mechanisms involved in fat mass regulation by fatty acid/FAT-CD36 signalling. Human adipose stem cells, 3T3-L1, and its 3T3-MBX subclone cell lines were used in 2D cell cultures or co-cultures to monitor in real-time experiments proliferation, differentiation, lipolysis, and/or lipid uptake and activation of FAT/CD36 signalling pathways regulated by oleic acid, during adipogenesis and/or regulation of adipocyte size. Both FABP4 uptake and its induction by fatty acid-mediated FAT/CD36-PPARG gene transcription induce accumulation of intracellular FABP4, which in turn reduces FAT/CD36, and consequently exerts a negative feedback loop on FAT/CD36 signalling in both adipocytes and their progenitors. Both adipocyte size and recruitment of new adipocytes are under the control of FABP4 stores. This study suggests that FABP4 controls fat mass homeostasis.