Impact of Adenosine Analogue, Adenosine-5 ′ -N-Ethyluronamide (NECA), on Insulin Signaling in Skeletal Muscle Cells

Abstract

Background and Objectives. To investigate whether there are molecular interactions between adenosine analogue (NECA) and insulin signaling pathways at multiple nuclear receptors and at the metabolic and inflammatory levels. Materials and Methods. Rat L6 skeletal muscle cells were cultured in 25 cm2 flasks. These differentiated cells were treated, and then, quantitative reverse transcription-polymerase chain reaction (qRT-PCR) (probe-based) was used to measure the relative mRNA expression level for metabolic, inflammatory, and nuclear receptor genes including peroxisome proliferator-activated receptor gamma (PGC-1α), carnitine palmitoyl transferase 1 beta (CPT1B), long-chain acyl-CoA de hydrogenase (LCAD), acetyl-CoA carboxylase beta (ACCβ), pyruvate dehydrogenase kinase 4 (PDK4), hexokinase II (HKII), phosphofructokinase (PFK), interleukin-6 (IL-6), and nuclear receptor subfamily 4, group A (NR4A) at different treatment conditions. Results. Adenosine-5 ${}^{\prime }$ -N-ethyluronamide (NECA), a stable adenosine analogue, significantly stimulate inflammatory mediator (IL-6) ( $p<0.001$ ) and nuclear receptors (NR4A) ( $p<0.05$ ) and significantly modulate metabolic (PFK, LCAD, PGC-1α, and CPT1B) gene expressions in skeletal muscle cells ( $p<0.05$ , $p<0.05$ , $p<0.001$ , and $p<0.01$ , respectively). This present study shows that there is a noteworthy crosstalk between NECA and insulin at various metabolic levels including glycolysis (HKII), fatty acid oxidation (ACCβ), and insulin sensitivity (PDK4). Conclusions. A novel crosstalk between adenosine analogue and insulin has been demonstrated for the first time; evidence has been gathered in vitro for the effects of NECA and insulin treatment on intracellular signaling pathways, in particular glycolysis and insulin sensitivity in skeletal muscle cells.