Biology subjects

Csomos, I.

Publications and source records attributed to Csomos, I..

3 recordsLinked to original sources

bioRxiv2022

Mitophagy mediates beige to white transition of human primary subcutaneous adipocytes ex vivo

Brown and beige adipocytes have multilocular lipid droplets, express uncoupling protein (UCP) 1, and promote energy expenditure. In rodents, when the stimulus of browning subsides, parkin-dependent mitophagy is activated and dormant beige adipocytes persist. In humans, however, the molecular events during beige to white transition were not studied in detail. In this study, human primary subcutaneous abdominal preadipocytes were differentiated to beige for 14 days, then either the beige culture conditions were applied for additional 14 days or it was replaced by a white medium. Control white adipocytes were differentiated by their specific cocktail for 28 days. Peroxisome proliferator-activated receptor {gamma}-driven beige differentiation resulted in increased mitochondrial biogenesis, UCP1 expression, fragmentation, and respiration as compared to white. Morphology, UCP1-content, mitochondrial fragmentation, and basal respiration of the adipocytes that underwent transition, along with the induction of mitophagy, were similar to control white adipocytes. However, white converted beige adipocytes had a stronger responsiveness to dibutyril-cAMP, which mimics adrenergic stimulus, than the control white ones. Gene expression patterns showed that removal of mitochondria in transitioning adipocytes may involve both parkin-dependent and independent pathways. Preventing entry of beige adipocytes into white transition can be a feasible way to maintain elevated thermogenesis and energy expenditure.

cell biology↗

bioRxiv2021

BMP7 increases UCP1-dependent and independent thermogenesis with a unique gene expression program in human neck area derived adipocytes

White adipocytes contribute to energy storage accumulating lipid droplets, whereas brown and beige adipocytes mainly function in dissipating energy as heat primarily via the action of uncoupling protein 1 (UCP1). Bone morphogenic protein 7 (BMP7) has been shown to drive brown adipocyte differentiation in mice. In this study, we have performed global RNA-sequencing and functional assays on adipocytes obtained from subcutaneous (SC) and deep-neck (DN) depots of human neck and differentiated with or without BMP7. We found that BMP7 did not influence differentiation but upregulated browning markers, including UCP1 mRNA and protein. BMP7 also enhanced mitochondrial DNA content, fragmentation, and levels of oxidative phosphorylation complex subunits along with PGC1 and p-CREB upregulation. Furthermore, both UCP1-dependent proton leak and UCP1-independent, creatine driven substrate cycle coupled thermogenesis were augmented upon BMP7 treatment in SC and DN derived adipocytes. The gene expression analysis shed light also on possible role of genes unrelated to thermogenesis so far, including ACAN, CRYAB, and ID1, which were amongst the highest upregulated ones by BMP7 treatment in both types of adipocytes. Together, our study shows that BMP7 strongly upregulates thermogenesis in human neck area derived adipocytes, along with genes, which might have a supporting role in energy expenditure.

cell biology↗

bioRxiv2021

Irisin stimulates the release of CXCL1 from differentiating human subcutaneous and deep-neck derived adipocytes via upregulation of NFκB pathway

Thermogenic brown and beige adipocytes play an important role in combating obesity. Recent studies in rodents and humans have indicated that these adipocytes release cytokines, termed "batokines". Irisin was discovered as a polypeptide regulator of beige adipocytes released by myocytes, primarily during exercise. We performed global RNA sequencing on adipocytes derived from human subcutaneous and deep-neck precursors, which were differentiated in the presence or absence of irisin. Irisin did not exert an effect on the expression of characteristic thermogenic genes, while upregulated genes belonging to various cytokine signaling pathways. Out of the several upregulated cytokines, CXCL1, the highest upregulated, was released throughout the entire differentiation period, and predominantly by differentiated adipocytes. Deep-neck area tissue biopsies also showed a significant release of CXCL1 during 24 hours irisin treatment. Gene expression data indicated upregulation of the NF[kcy]B pathway upon irisin treatment, which was validated by an increase of p50 and decrease of I[kcy]B protein level, respectively. Continuous blocking of the NF{kappa}B pathway, using a cell permeable inhibitor of NF{kappa}B nuclear translocation, significantly reduced CXCL1 release. The released CXCL1 exerted a positive effect on the adhesion of endothelial cells. Together, our findings demonstrate that irisin stimulates the release of a novel "batokine", CXCL1, via upregulation of NF{kappa}B pathway in neck area derived adipocytes, which might play an important role in improving tissue vascularization.

cell biology↗