Diverse inhibitors of de novo purine synthesis promote AICAR-induced AMPK activation and glucose uptake in L6 myotubes

Dolinar, Klemen (author), Miš, Katarina (author), Šopar, Katja (author), Šutar, Mateja (author), Božič, Meta (author), Kolar, Matic (author), Hropot, Tim (author), Garcia-Roves, Pablo Miguel (author), Chibalin, Alexander V. (author), Pirkmajer, Sergej (author)

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.

• Language: English
• Keywords: AMP‐activated protein kinase, AMPK, folate metabolism, glucose uptake, insulin signaling, purine metabolism, skeletal muscle cells
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: MF - Faculty of Medicine
• Publication status: Published
• Publication version: Version of Record
• Year: 2025
• Number of pages: 15 str.
• Numbering: Vol. 51, iss. 4, art. e70037
• PID: 20.500.12556/RUL-176849
• UDC: 616-092
• ISSN on article: 0951-6433
• DOI: 10.1002/biof.70037
• COBISS.SI-ID: 248413955
• Publication date in RUL: 11.12.2025

Record is a part of a journal

• Title: BioFactors
• Shortened title: BioFactors
• Publisher: Wiley, International Union of Biochemistry and Molecular Biology
• ISSN: 0951-6433
• COBISS.SI-ID: 530453

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Slovenian
• Keywords: AMP-aktivirana proteinska kinaza, AMPK, presnova folatov, privzem glukoze, signalizacija insulina, presnova purinov, celice skeletnih mišic