Division of Cell Signalling and Immunology, Sir James Black Centre, School of Life Sciences, University of Dundee, Dundee DD1 5EH, U.K.
Centre for Targeted Protein Degradation, School of Life Sciences, University of Dundee, 1 James Lindsay Place, Dundee DD1 5JJ, U.K.
Biochem J. 2024 Sep 18;481(18):1203-1219. doi: 10.1042/BCJ20240425.
The AMP-activated protein kinase (AMPK) is a sensor of cellular energy status that is expressed in almost all eukaryotic cells. In the canonical activation mechanism, it is activated by increases in AMP:ATP and ADP:ATP ratios that signify declining cellular energy status. Once activated, AMPK phosphorylates numerous targets that promote catabolic pathways generating ATP, while inhibiting anabolic and other processes that consume ATP, thus acting to restore energy homeostasis. Pharmacological agents that activate AMPK have been useful in identifying downstream targets and have potential as drugs for treatment of metabolic disorders such as Type 2 diabetes and non-alcoholic fatty liver disease. One such agent is C13, a pro-drug with a phosphonate bis(isobutyryloxymethyl) ester moiety, with the isobutyryloxymethyl groups increasing membrane permeability. Following cellular uptake, C13 is cleaved to release C2, an AMP analogue and potent AMPK activator that is specific for complexes containing the α1 (but not the α2) catalytic subunit isoform. This has previously been assumed to be the sole mechanism by which C13 activates AMPK, with potential roles for the isobutyryloxymethyl groups being ignored. We now report that, following cleavage from C13, these protective groups are metabolized to formaldehyde, an agent that inhibits mitochondrial function and increases cellular AMP:ATP ratios, thus providing additional AMPK activation by the canonical mechanism.
腺苷酸活化蛋白激酶（AMPK）是细胞能量状态的传感器，几乎存在于所有真核细胞中。在典型的激活机制中，它被 AMP:ATP 和 ADP:ATP 比值的增加所激活，这表明细胞能量状态下降。一旦被激活，AMPK 磷酸化许多促进产生 ATP 的分解代谢途径的靶标，同时抑制消耗 ATP 的合成代谢和其他过程，从而作用于恢复能量稳态。激活 AMPK 的药理学制剂已被用于鉴定下游靶标，并具有作为治疗代谢紊乱如 2 型糖尿病和非酒精性脂肪性肝病的药物的潜力。一种这样的制剂是 C13，一种带有膦酸双（异丁酰氧甲基）酯部分的前药，异丁酰氧甲基基团增加了膜通透性。在细胞摄取后，C13 被切割释放 C2，C2 是一种 AMP 类似物和强效的 AMPK 激活剂，专门针对含有 α1（但不是 α2）催化亚基同工型的复合物。这以前被认为是 C13 激活 AMPK 的唯一机制，而忽略了异丁酰氧甲基基团的潜在作用。我们现在报告，在从 C13 切割后，这些保护基团被代谢为甲醛，甲醛抑制线粒体功能并增加细胞 AMP:ATP 比值，从而通过典型机制提供额外的 AMPK 激活。
