Amazing stuff! We are still discovering new types of cells in the human body!
"... And now, scientists have discovered a new kind of fat cell. It’s a subtype of beige fat cells, but it seems to burn energy and generate heat through a completely different mechanism. ...
But scientists began to notice that some beige fat cells didn’t have UCP1 at all. ... They discovered that the new beige fat cells engage in “futile cycles” – biochemical processes that don’t seem to have any specific purpose.
These futile cycles took two forms. In one, the cells break down fats into fatty acids, then quickly reassemble them back into new fats. In another, creatine is converted into another molecule called creatine phosphate, then immediately converted back into creatine. ..."
"In brief
- A newly described type of beige fat cell consumes energy and generates heat by running biochemical processes back and forth, seemingly without purpose.
- Almost all people have this cell type. The more of it a person has, the leaner they tend to be and the better their metabolic health.
- The new findings could help to develop therapies for obesity and metabolic disorders such as diabetes.
..."
From the highlights and abstract:
"Highlights
• snRNA-seq reveals distinct subpopulations of adipocytes in mouse ingWAT at RT and CE
• A novel subpopulation, P2 adipocytes, functions as thermogenic cells
• P2 adipocytes plausibly utilize futile cycles for UCP1-independent thermogenesis
• P2-like human adipocyte is associated with energy expenditure and metabolic health
Summary
Adipose tissue can recruit catabolic adipocytes that utilize chemical energy to dissipate heat. This process occurs either by uncoupled respiration through uncoupling protein 1 (UCP1) or by utilizing ATP-dependent futile cycles (FCs). However, it remains unclear how these pathways coexist since both processes rely on the mitochondrial membrane potential. Utilizing single-nucleus RNA sequencing to deconvolute the heterogeneity of subcutaneous adipose tissue in mice and humans, we identify at least 2 distinct subpopulations of beige adipocytes: FC-adipocytes and UCP1-beige adipocytes. Importantly, we demonstrate that the FC-adipocyte subpopulation is highly metabolically active and utilizes FCs to dissipate energy, thus contributing to thermogenesis independent of Ucp1. Furthermore, FC-adipocytes are important drivers of systemic energy homeostasis and linked to glucose metabolism and obesity resistance in humans. Taken together, our findings identify a noncanonical thermogenic adipocyte subpopulation, which could be an important regulator of energy homeostasis in mammals."
Beige fat cells with a “Sisyphus mechanism” (original news release) "A new class of fat cells makes people healthier. The cells consume energy and produce heat through seemingly pointless biochemical reactions."
Single-nucleus transcriptomics identifies separate classes of UCP1 and futile cycle adipocytes (open access)
Graphical abstract
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