The crucial role of ATGL for energy supply of muscles

Mobilization of FAs from triglycerides (TGs) in intracellular lipid droplets was for many years considered to be accomplished through carefully regulated activity of hormone sensitive lipase (HSL). To the great surprise of several investigators in the field, inactivation of the HSL gene in mice (HSL-ko) did not lead to low plasma FAs, major derangements of energy metabolism, and overweight, as expected (1–3). Instead, HSL-ko mice accumulated diglycerides in several tissues, indicating that HSL was mainly rate-limiting for diglyceride hydrolysis (4).