Relationship between perinatal appearance of cellular retinol-binding protein, type II and retinal reductase activity in chick liver.

摘要

To explore a role of the transiently appearing cellular retinol-binding protein, type II (CRBP(II)) in perinatal chick liver, we have examined whether the relationships exist among the perinatal changes in hepatic CRBP(II) protein and mRNA levels, retinal reductase activity and beta-carotene levels in liver and serum. Northern blot analysis for hepatic CRBP(II) revealed a transient expression of CRBP(II) mRNA around hatching. The protein of CRBP(II) was also expressed transiently and the highest levels of CRBP(II) were found in the livers 1-3 days after birth. The retinal reductase activity was very low at embryonic age, but its activity rapidly rose at hatching, peaking at 1 day after birth, followed by a gradual decrease to a lower level in 7-day-old chicks. This perinatal pattern of the retinal reductase activities was similar to the pattern of transient appearance of the hepatic CRBP(II), and was also paralleled to the developmental changes in serum and liver beta-carotene concentrations. These findings suggest that hepatic CRBP(II) transiently appearing during the perinatal period may involve in metabolizing hepatic beta-carotene, directing the retinal to the retinal reductase and leading further to the subsequent esterification of the converted retinol.