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. Author manuscript; available in PMC: 2022 Nov 1.
Published in final edited form as: Trends Cell Biol. 2021 Jun 29;31(11):912–923. doi: 10.1016/j.tcb.2021.06.003

Figure 2: An explanation of runaway lipolysis.

Figure 2:

Left: As lipogenesis proceeds in wild type cells, lipase activity is low favoring fat storage, promoting adipocyte maturation. Right: In seipin-deficient cells, lipase activity is stimulated which could lead to an increase in free fatty acids (FFA). The small lipid droplets seen in seipin-null cells may promote microlipophagy, as larger droplets are poor cargo, contributing to the pool of free fatty acids. These can promote cAMP production through several pathways, including FFAR4, which would further stimulate lipolysis. The high concentration of fatty acids could cause lipotoxicity and death of the cells. Note that FFA levels and lipotoxicity have yet to be assessed in seipin-deficient adipocytes. p-ATGL, p-HSL, and p-PLIN1: phosphorylated adipose triglyceride lipase, hormone-sensitive lipase, and perilipin 1, respectively.