Cloning and gene expression of hexokinase I and II in the chicken skeletal muscle

To elucidate the distinctive regulatory mechanisms of glucose homeostasis in the skeletal muscles of broiler chickens, hexokinase (HK)I and HKII gene expressions were characterized by northern blot analysis. Chicken HKI and HKII full-length cDNA sequences were identified and the deduced amino acid sequences were 87.4 and 85.9% identical to that of human HKI and HKII, respectively. Using reverse transcription-polymerase chain reaction analysis, chicken HKI mRNA was detected in the skeletal muscle, brain, heart, kidney and testis. Chicken HKII mRNA was highly expressed in the skeletal muscle and heart, whereas a lower expression was observed in the liver, brain and kidney. Fasting for 48 h or refeeding for 24 h in chickens significantly increased the skeletal muscle HKI and HKII mRNA levels in contrast to unchanged or decreased expressions in mammals. The present findings suggest that HKI and HKII have a unique role in the glucose homeostasis regulatory mechanism of chicken skeletal muscles and their role in chickens is not similar to that in mammals.