Inhibition of lipolysis and lipogenesis in isolated rat adipocytes with AICAR, a cell-permeable activator of AMP-activated protein kinase

• Published in: FEBS letters Vol. 353; no. 1; pp. 33 - 36
• Main Authors: Sullivan, Jane E., Brocklehurst, Katy J., Marley, Anna E., Carey, Frank, Carling, David, Beri, Raj K.
• Format: Journal Article
• Language: English
• Published: England Elsevier B.V 10-10-1994
• Subjects: ACC, acetyl-CoA carboxylase; Acetyl-CoA carboxylase; Acetyl-CoA Carboxylase - antagonists & inhibitors; Adipocyte (rat); Adipocytes - drug effects; Adipocytes - metabolism; AICAR, 5-amino-4-imidazolecarboxamide ribonucleoside; Aminoimidazole Carboxamide - analogs & derivatives; Aminoimidazole Carboxamide - pharmacology; AMP-activated protein kinase; AMP-Activated Protein Kinases; AMPK, AMP-activated protein kinase; Animals; Enzyme Activation; Hormone-sensitive lipase; HSL, hormone-sensitive lipase; In Vitro Techniques; Lipids - biosynthesis; Lipogenesis; Lipolysis; Lipolysis - drug effects; Multienzyme Complexes - metabolism; OkA, okadaic acid; PKA, cAMP-dependent protein kinase; Protein Kinases - metabolism; Protein-Serine-Threonine Kinases; Rats; Ribonucleotides - pharmacology; Adipocyte (rat); ACC, acetyl-CoA carboxylase; Acetyl-CoA carboxylase; HSL, hormone-sensitive lipase; PKA, cAMP-dependent protein kinase; Hormone-sensitive lipase; AMPK, AMP-activated protein kinase; AICAR, 5-amino-4-imidazolecarboxamide ribonucleoside; AMP-activated protein kinase; Lipogenesis; Lipolysis; OkA, okadaic acid
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1016/0014-5793(94)01006-4

In vivo, hormone-sensitive lipase (HSL) is known to be phosphorylated on two sites termed the regulatory and basal sites. However, the intracellular role of the basal site or the identity of the protein kinase phosphorylating this site has not been established. We show that 5-amino-4-imidazolecarboxamide ribonucleoside (AICAR) markedly activates cellular AMP-activated protein kinase (AMPK) in a time- and dose-dependent manner. As expected for an agent that activates AMPK intracellularly, AICAR had no effect on the basal activity of HSL. However, preincubation of adipocytes with AICAR led to a reduced response of these cells to the lipolytic agent isoprenaline. AICAR was also shown to profoundly inhibit lipogenesis through increased phosphorylation of acetyl-CoA carboxylase (ACC). Thus it appears that in addition to regulating lipogenesis, AMPK also plays an important antilipolytic role by regulating HSL in rat adipocytes.