Submitted to: Poultry Science
Publication Type: Abstract Only
Publication Acceptance Date: 3/17/2005
Publication Date: 7/1/2005
Citation: Proszkowiec-Weglarz, M., Richards, M.P. 2005. Identification and characterization of the AMP-activated protein kinase pathway in chickens [abstract]. Poultry Science. 84(Supplement 1):56. Paper No. T44.
Technical Abstract: In mammals, AMP-activated protein kinase (AMPK) is an enzyme complex that plays a key role in sensing cellular energy (AMP/ATP) levels and maintaining intracellular energy balance. The AMPK protein complex is hetero-trimeric consisting of one catalytic (alpha) subunit and two regulatory (beta and gamma) subunits. AMPK is activated through phosphorylation by an upstream kinase (LKB1). Activated AMPK phosphorylates a variety of protein targets that affect carbohydrate, lipid and protein metabolism. In general, AMPK acts to increase cellular energy levels by reducing the activity of ATP-utilizing metabolic pathways and increasing those that generate ATP. Since there have been no prior studies of AMPK in birds, the objective of this work was to identify and characterize the AMPK pathway in chickens. Total RNA was isolated from 3-wk-old male broiler chicken tissues and used to identify specific transcripts for and to determine the level of expression of AMPK subunit and LKB1 genes by RT-PCR. An LKB1 gene homologue was expressed in all tissues examined, with the highest levels in duodenum and skeletal muscle and the lowest levels in pancreas and liver. Gene transcripts corresponding to AMPK alpha-1 and -2 and beta-1 and -2 subunits were identified. Although 3 different subunit genes for gamma exist in mammals, we found only 2 in chickens. One was located on chromosome 2 corresponding to gamma-1&2 in mammals and the other on chromosome 7 corresponding to gamma-3. All tissues, except for heart and skeletal muscle, expressed alpha-1, beta-2 and gamma 1&2 preferentially. Heart preferentially expressed alpha-2, beta-2 and gamma-1&2, whereas skeletal muscle expressed alpha-2, beta-2 and gamma-3. The gamma-3 gene was only expressed in heart and skeletal muscle. This is the first report to identify avian LKB1 and AMPK subunit gene homologues and to determine tissue-specific expression of AMPK subunit genes. Our data indicates the existence of the AMPK pathway in chickens which presumably functions in maintaining cellular energy balance.