AICAR

AICAR (5-Aminoimidazole-4-carboxamide ribonucleoside, Acadesine, AICA riboside) is a cell-permeable nucleoside analogue that pharmacologically activates AMP-activated protein kinase (AMPK) by accumulating its intracellular phosphorylated metabolite ZMP (AICAR monophosphate). ZMP mimics AMP at the gamma subunit regulatory domains of AMPK, allosterically activating the kinase and promoting LKB1-mediated phosphorylation at the critical Thr172 activation loop site. AICAR is the most widely published pharmacological AMPK activator in the research literature, with over 3,000 peer-reviewed publications documenting its use across metabolic, cancer, cardiovascular, and immunological research.

AMPK is the master cellular energy sensor — a heterotrimeric serine/threonine kinase composed of catalytic alpha, scaffold beta, and regulatory gamma subunits. It is activated when the AMP/ATP ratio rises under energetic stress (exercise, hypoxia, glucose deprivation, ischaemia) and functions to restore energy homeostasis by simultaneously activating catabolic pathways and suppressing energy-consuming anabolic pathways. AICAR provides a specific pharmacological means of activating AMPK in the absence of genuine energetic stress, enabling researchers to study AMPK's downstream consequences independently of the metabolic state changes that accompany real energy deficit.

The downstream signalling consequences of AICAR/AMPK activation are extensive. Phosphorylation and inactivation of acetyl-CoA carboxylase (ACC) at Ser79 reduces malonyl-CoA production, relieving CPT1-mediated inhibition of long-chain fatty acid import into mitochondria — the committed step of mitochondrial fatty acid oxidation. AMPK phosphorylates TSC2 (Thr1227, Ser1345) and Raptor (Ser722, Ser792), suppressing mTORC1 activity and reducing protein synthesis and cell growth. AMPK activates PGC-1alpha through direct phosphorylation (Ser177, Ser538), initiating the mitochondrial biogenesis transcriptional programme — upregulating TFAM, NRF1, NRF2, and ultimately mtDNA replication and OXPHOS subunit gene expression. In skeletal muscle, AMPK promotes GLUT4 vesicle translocation to the plasma membrane via AS160 phosphorylation, increasing glucose uptake independently of insulin.

The mechanistic connection between AICAR and MOTS-c (mitochondrial-derived peptide) is important for comparative research design. MOTS-c has been proposed to activate AMPK indirectly by inhibiting ATIC — the enzyme that converts AICAR to IMP in the purine synthesis pathway. ATIC inhibition causes endogenous AICAR accumulation, which is then phosphorylated to ZMP and activates AMPK by the identical mechanism as exogenous AICAR. Using both AICAR (direct ZMP provision) and MOTS-c (upstream ATIC inhibition) in parallel research designs, with Compound C or dorsomorphin as AMPK inhibitor controls, allows dissection of AMPK-dependent versus AMPK-independent MOTS-c biology.

Research applications span: skeletal muscle fatty acid oxidation (14C-palmitate oxidation, oxygen consumption rate by Seahorse XF); hepatic gluconeogenesis suppression (phospho-ACC, PEPCK, G6Pase expression); mitochondrial biogenesis (mtDNA copy number by qPCR, TFAM and PGC-1alpha by Western blot); cancer cell proliferation inhibition via mTORC1 suppression (phospho-S6K1, phospho-4E-BP1); anti-inflammatory signalling (NFkB pathway suppression); and AMPK pathway comparison with metformin (Complex I inhibitor, indirect AMPK activator) to distinguish AMPK-specific from broader metabolic effects.

MW: 338.23 g/mol. CAS: 2627-69-2. Molecular formula: C9H14N4O5. Freely water-soluble — prepare 100mM stocks in sterile water or PBS. Working concentration in cell culture: 0.5-2 mM. Stable at -20°C for months. For laboratory and analytical research purposes only.

AICAR is freely water-soluble — prepare 100mM stocks in sterile water or PBS. Working concentrations in cell culture: 0.5-2 mM for reliable AMPK activation. At these concentrations, ZMP accumulates within 30-60 minutes, producing detectable phospho-AMPK (Thr172) and phospho-ACC (Ser79) by Western blot within 1-2 hours. Serum-containing media is compatible — AICAR's nucleoside structure is not a substrate for peptidases. At 2mM, AICAR adds approximately 2 mOsm/kg to culture medium — negligible compared to the approximately 300 mOsm/kg of standard DMEM. MW: 338.23 g/mol. CAS: 2627-69-2. Store lyophilised at -20°C. For laboratory and analytical research purposes only.