AICAR AMPK Research: AMP-Activated Protein Kinase Activation in Cell Models
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AICAR AMPK Research Overview
AICAR (5-aminoimidazole-4-carboxamide ribonucleoside, acadesine, MW 258.23 g/mol, CAS 2627-69-2) is a synthetic AMP analogue and AMP-activated protein kinase (AMPK) activator extensively studied in cell-based metabolic pathway research. This nucleoside analog serves as a valuable research tool for investigating cellular energy sensing mechanisms and metabolic signaling cascades in various in vitro experimental systems.
Molecular Properties
| Property | Value |
|----------|-------|
| Molecular Formula | C₉H₁₄N₄O₅ |
| Molecular Weight | 258.23 g/mol |
| CAS Number | 2627-69-2 |
| Active metabolite | ZMP (AICA ribonucleotide monophosphate) |
AMPK Activation Mechanism Research
Intracellular Phosphorylation Pathway
AICAR is phosphorylated intracellularly to ZMP (AICA ribonucleotide monophosphate) by adenosine kinase, creating an active metabolite that mimics AMP within cellular systems. This phosphorylation step is essential for AMPK activation, as ZMP accumulation triggers conformational changes in the AMPK heterotrimer complex. Research demonstrates that ZMP binding to the γ-subunit of AMPK promotes allosteric activation and enhances phosphorylation at Thr172 on the α-subunit by upstream kinases including LKB1 and CaMKKβ.
Receptor Binding Characteristics
In vitro binding studies reveal that ZMP exhibits high affinity for the adenine nucleotide-binding sites within the AMPK complex. Radioligand binding assays demonstrate competitive displacement of AMP by ZMP, with binding affinity values (Kd) typically ranging from 10-50 μM depending on the specific AMPK isoform and experimental conditions. The γ-subunit contains four cystathionine β-synthase (CBS) domains that form two Bateman domains, creating binding sites for adenine nucleotides where ZMP competes with AMP and ATP.
Cell-Based Assay Applications
Primary Cell Models
AICAR demonstrates consistent AMPK activation across multiple primary cell types in controlled in vitro environments. Hepatocyte cultures show dose-dependent AMPK phosphorylation following AICAR treatment, with optimal activation observed at concentrations between 0.5-2.0 mM. Skeletal muscle cell cultures exhibit similar activation patterns, making these models valuable for studying tissue-specific AMPK signaling responses.
Immortalized Cell Lines
Various immortalized cell lines provide reproducible platforms for AICAR-mediated AMPK research. HepG2 hepatocellular carcinoma cells demonstrate robust AMPK activation with AICAR treatment, showing increased phosphorylation of downstream targets including acetyl-CoA carboxylase (ACC) and 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR). C2C12 myoblast cells offer additional models for investigating skeletal muscle-specific AMPK signaling pathways.
Signaling Pathway Analysis
Downstream Target Phosphorylation
AMPK activation by AICAR triggers phosphorylation cascades affecting multiple metabolic enzymes. Key downstream targets include ACC (Ser79), HMGR (Ser872), and eukaryotic elongation factor 2 kinase (eEF2K). These phosphorylation events can be quantified using specific antibodies in Western blot analyses or high-content imaging assays to measure pathway activation kinetics.
Metabolic Enzyme Regulation
AICAR-activated AMPK modulates enzyme activity through both direct phosphorylation and transcriptional regulation. Phosphofructokinase-2 (PFK2) activity increases following AMPK-mediated phosphorylation, while fatty acid synthase (FAS) activity decreases. These enzymatic changes can be measured using colorimetric or fluorometric enzyme activity assays in cell lysates.
Experimental Considerations
Concentration-Response Relationships
Dose-response studies typically employ AICAR concentrations ranging from 0.1-5.0 mM in cell culture media. Time-course experiments reveal initial AMPK phosphorylation within 15-30 minutes, with peak activation occurring at 1-2 hours post-treatment. Sustained activation can be maintained for 6-12 hours depending on cellular uptake and ZMP accumulation rates.
Assay Optimization Parameters
Cell culture conditions significantly influence AICAR uptake and AMPK activation. Serum-free media enhance compound uptake, while glucose concentrations affect baseline AMPK activity. Temperature, pH, and incubation duration require optimization for specific cell types and experimental objectives.
Research Summary
AICAR represents a valuable pharmacological tool for investigating AMPK signaling pathways in vitro through its conversion to the active metabolite ZMP. The compound demonstrates consistent activation across diverse cell models, enabling researchers to study metabolic enzyme regulation, signaling cascade kinetics, and pathway interactions. Optimal experimental conditions typically involve 0.5-2.0 mM AICAR concentrations with 1-4 hour treatment periods, providing robust and reproducible AMPK activation for mechanistic studies in cellular energy sensing and metabolic regulation research.
All content is intended for in vitro laboratory research purposes only. Not for human or animal consumption. Not intended to diagnose, treat, cure, or prevent any condition.
