Obesity is a major human health problem, as it is extremely common and increases the risk for diabetes, cardiovascular disease, and many other pathologies, including some forms of cancer. Obesity occurs when the energy a person consumes offsets the energy that they expend, causing excess energy to be stored, most often in adipose tissue. Research in the Lynes laboratory is aimed at understanding how adipose tissue functions to regulate the balance of energy, and we study humans, mice and cells to ask questions about how this process is controlled.
Adipose Tissue In Action
Adipose tissue is a sink for excess energy, taking up nutrients from the blood to store them for use in metabolism. In this video, cells in the mouse's adipose tissue called adipocytes have a special enzyme which produces light when they absorb lipids from circulation. At the beginning of the movie, lipids are injected into the mouse's tail vein and rapidly cleared from the blood by the brown adipose tissue located along the spine, which produces the glow that we measure with a camera.
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Credit for this movie belongs to the authors of Lynes et al., Nat Med 2017.
What Are Adipocytes Doing?
Adipocytes are specialized to handle lipids in relatively large quantities. Adipocytes store lipids in discrete droplets, which are the white circles inside of the cell in this movie. Lipid droplet management is a complex process requiring cellular machinery that supports the shepherding of the droplets around the cell, and in this video you can see droplets coalescing and splitting from one another.
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Credit for this movie belongs to the authors of Xue et al., Nat Med 2015.
Where Do Adipocytes Come From?
Everyday, adipocytes in our bodies need to be replaced by new cells in a process called adipogenesis. Adipocytes develop from cells called preadipocytes that change their cellular identity to take on the role of the mature adipocyte. Different kinds of preadipocytes live in adipose tissue, and in this movie cells that are part of a cellular lineage that express the Trpv1 gene are green, while other cellular lineages are red. The cells that makeup the long, thing green vasculature structure have acted as preadipocytes, undergoing adipogenesis to form the green fat cells on the top and bottom of the movie.
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Credit for this movie belongs to B. Morrill and the authors of Shamsi et al., Nat Metab 2021.