20.500.12556/DiRROS-28856 Diverse inhibitors of de novo purine synthesis promote AICAR-induced AMPK activation and glucose uptake in L6 myotubes Methotrexate, an immunosuppressant and anticancer drug, promotes glucose uptake and lipid oxidation in skeletal muscle via activation of AMP-activated protein kinase (AMPK). Methotrexate promotes AMPK activation by inhibiting 5-aminoimidazole-4-carboxamide ribonucleotide (ZMP) formyltransferase/inosine monophosphate (IMP) cyclohydrolase (ATIC), which converts ZMP, an endogenous purine precursor and an active form of the pharmacological AMPK activator AICAR, to IMP during de novo purine synthesis. In addition to methotrexate, inhibition of purine synthesis underpins the therapeutic effects of a number of commonly used immunosuppressive, anticancer, and antimicrobial drugs, raising the question of whether activation of AMPK in skeletal muscle could be a recurrent feature of these drugs. Using L6 myotubes, we found that AICAR-induced AMPK activation and glucose uptake were enhanced by inhibitors of the conversion of IMP to GMP (mycophenolate mofetil) or of IMP to AMP (alanosine) as well as by indirect inhibitors of human (trimetrexate) and bacterial ATIC (sulfamethoxazole). 6-Mercaptopurine, which inhibits the conversion of IMP to GMP and AMP, activated AMPK, increased glucose uptake, and suppressed insulin signaling, but did not enhance the effect of AICAR. As determined by measuring oxygen consumption rate, none of these agents suppressed mitochondrial function. Overall, our results indicate that IMP metabolism is a gateway for the modulation of AMPK and its metabolic effects in skeletal muscle cells. AMP‐activated protein kinase (AMPK) folate metabolism glucose uptake insulin signaling purine metabolism skeletal muscle cells AMP-aktivirana proteinska kinaza (AMPK) presnova folatov privzem glukoze signalizacija insulina presnova purinov celice skeletnih mišic true false true Angleški jezik Slovenski jezik Neznano 2026-04-09 13:38:02 2026-04-09 13:38:02 2026-04-10 03:55:40 0000-00-00 00:00:00 2025 0 0 str. 1-15 iss. 4, [Article no.] e70037 Vol. 51 2025 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 616-092 0951-6433 10.1002/biof.70037 248413955 RAZ_Dolinar_Klemen_2025.pdf RAZ_Dolinar_Klemen_2025.pdf 1 24ACB96C274A904D8A5CFBF380F72104 5730687529d8ff70970f2874198872ee968545bebb77723580b932dbfa4ea169 b7244d54-3408-11f1-b941-001a4af901a5 https://dirros.openscience.si/Dokument.php?lang=slv&id=43008 https://iubmb.onlinelibrary.wiley.com/doi/10.1002/biof.70037 1 9ac3b18a-3408-11f1-b941-001a4af901a5 https://dirros.openscience.si/Dokument.php?lang=slv&id=43007 Univerzitetni klinični center Ljubljana 0 0 0