AICAR

Corton et al. (Eur J Biochem, 1995) established the molecular basis for AICAR's use as an AMPK-pathway probe: the compound requires functional nucleoside transporters for cellular uptake and adenosine kinase activity for conversion to ZMP, the intracellularly active AMP-mimetic species. Blocking either step with pharmacological inhibitors eliminates AMPK-pathway activation, confirming the uptake-phosphorylation-ZMP cascade and defining the methodological controls that subsequent AICAR experiments depend on. Steinberg and Hardie (Nat Rev Mol Cell Biol, 2023) and Hardie, Ross and Hawley (Nat Rev Mol Cell Biol, 2012) provide the most comprehensive reviews of AMPK structure, regulation, and the pharmacological use of AICAR across the literature. Because ZMP also interacts with other AMP-regulated enzymes, and some cellular responses to AICAR proceed through AMPK-independent mechanisms, AICAR is characterised in the research literature as a probe whose on-target activity requires mechanistic controls rather than as a fully selective AMPK agonist.

Xiao et al. (Nature, 2007) reported the crystal structure of the AMPK regulatory fragment carrying three occupied nucleotide sites on the γ-subunit, providing atomic-resolution insight into how AMP-mimetic ligands engage the Bateman (CBS-domain) module. Xiao et al. (Nature, 2011) extended this to the full mammalian AMPK heterotrimer, defining the structural basis by which ADP, in addition to AMP, protects the activation-loop threonine from dephosphorylation. These structures underpin the mechanistic framework in which ZMP's action on AMPK is interpreted. Steinberg and Carling (Nat Rev Drug Discov, 2019) and Hardie (Nat Rev Mol Cell Biol, 2007) review how AMPK structural knowledge informs drug-discovery efforts targeting this kinase. Marie et al. (Am J Hum Genet, 2004) examined individuals with loss-of-function mutations in ATIC (AICAR transformylase/IMP cyclohydrolase), the enzyme immediately downstream of ZMP in purine biosynthesis, characterising the inherited condition AICA-ribosuria and establishing that endogenous AICAR is detectable in urine under normal physiological conditions.

The use of AICAR as a metabolic-research tool in isolated tissues was established in the mid-1990s. Sullivan et al. (FEBS Lett, 1994) examined AICAR in isolated rat adipocytes, measuring its effects on both lipolysis and lipogenesis pathways. Merrill et al. (Am J Physiol, 1997) demonstrated AICAR-associated AMPK activation in rat skeletal muscle and examined changes in fatty-acid oxidation and glucose-uptake parameters. Kurth-Kraczek et al. (Diabetes, 1999) subsequently examined GLUT4 transporter translocation in skeletal muscle, using AICAR alongside contraction stimuli to dissect AMPK-dependent and AMPK-independent transporter-trafficking mechanisms. Mu et al. (Mol Cell, 2001) extended this line using a dominant-negative AMPK construct, showing that AICAR-stimulated glucose uptake requires AMPK, whereas contraction-stimulated uptake only partially depends on it. These studies collectively positioned AICAR as a standard pharmacological probe for AMPK-dependent metabolic flux assays in tissue-level preparations.

Narkar et al. (Cell, 2008) examined the effects of AICAR treatment on oxidative metabolic gene expression and transcriptional and functional parameters in sedentary rodents, characterising the transcriptional landscape associated with AMPK activation in skeletal muscle. The study also examined a PPARδ agonist both alone and in combination with AICAR, comparing transcriptional and functional outcomes across treatment conditions in rodent treadmill models. This work became a reference point for studying AICAR's role in the PGC-1α-driven transcriptional network and its relationship to mitochondrial biogenesis programs in muscle tissue.

Campàs et al. (Blood, 2003) investigated AICAR in B-cell chronic lymphocytic leukemia (B-CLL) cell preparations alongside T lymphocytes, examining AMPK activation and apoptosis-pathway engagement. The study characterised cellular uptake and intracellular ZMP formation as required steps and established that the response is p53-independent, providing a cell-line model for studying AICAR in hematological malignancy contexts. Santidrián et al. (Blood, 2010) further examined the apoptotic mechanism in CLL cells and found that under certain conditions the response proceeds independently of both AMPK and p53, proceeding instead through upregulation of the BH3-only proteins BIM and NOXA — underscoring that not all AICAR-associated cellular responses are attributable to AMPK. Van Den Neste et al. (Cancer Chemother Pharmacol, 2013) reported on a Phase I/II multicenter study (NCT00559624) that examined AICAR in patients with relapsed or refractory chronic lymphocytic leukemia, characterising biological parameters in a patient cohort. A further Phase I/II study (NCT01813838) examined AICAR in patients with higher-risk myelodysplastic syndrome and acute myeloid leukemia.

AICAR has been studied in clinical research programs examining cardiac protection during coronary artery bypass graft surgery. The McSPI Research Group (Anesthesiology, 1995) conducted an early randomized trial in the perioperative cardiac surgery setting. Mangano (JAMA, 1997) presented a meta-analysis of five international randomized trials examining AICAR in the perioperative cardiac surgery setting, assessing combined cardiovascular endpoints. Mangano et al. (JACC, 2006) reported on long-term cardiovascular endpoints in a pooled analysis of data from this trial series. Newman et al. (JAMA, 2012) conducted the RED-CABG trial (NCT00872001), a large randomized controlled trial enrolling intermediate-to-high-risk patients undergoing coronary artery bypass graft surgery and assessing a composite cardiovascular endpoint.