Ontogenic Profile of Hexokinase and Glucokinase mRNA Expressions in Embryonic Chicken Liver and Muscle

The present study describes ontogenic profile of mRNA expressions of hexokinase (HK; EC 2.7.1.1) and glucokinase (GK; EC 2.7.1.2, otherwise known as HKIV) that catalyze the first step of glucose metabolism by cells. The liver and the skeletal muscle were collected from 11 to 21 day embryos (n=6) of the White Leghorn chicken and the mRNAs of HKI and II, two HKs known in the chicken, and GK were measured by semi-quantitative reverse transcription PCR. In the liver, HKI mRNAs gradually decreased during the experimental period, while GK mRNAs gradually increased. In the skeletal muscle, HKI increased on day 13 and was almost stable thereafter, while GK gradually decreased. HKII expression tended to increase on day 13 and remained stable thereafter in both the organs. These results suggest a possibility that the well-established domination of GK to HK in the liver is gradually acquired during embryogenesis. Whether embryonic skeletal muscle expresses active GK protein should be studied further.