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Relationship between perinatal appearance of cellular retinol-binding protein, type II and retinal reductase activity
1Department of Nutrition, School of Food and Nutritional Sciences, The University of Shizuoka, Japan.
Insights
Cellular retinol-binding protein, type II (CRBP(II)) in chick liver is transiently expressed during the perinatal period. This protein appears to play a key role in metabolizing beta-carotene and retinol.
Area of Science:
- Biochemistry
- Developmental Biology
- Nutritional Science
Background:
- Cellular retinol-binding protein, type II (CRBP(II)) is involved in retinoid metabolism.
- Its role during the perinatal period, particularly in avian species, is not well understood.
Purpose of the Study:
- To investigate the role of transiently expressed hepatic CRBP(II) in perinatal chick liver.
- To examine the relationship between CRBP(II) levels, retinal reductase activity, and beta-carotene concentrations during chick development.
Main Methods:
- Northern blot analysis was used to detect CRBP(II) mRNA levels.
- Hepatic CRBP(II) protein levels, retinal reductase activity, and beta-carotene concentrations in liver and serum were measured.
Main Results:
- CRBP(II) mRNA and protein showed transient expression in chick liver around hatching, peaking 1-3 days post-hatch.
- Retinal reductase activity increased significantly at hatching, paralleling CRBP(II) expression.
- Serum and liver beta-carotene levels also showed similar developmental patterns.
Conclusions:
- Hepatic CRBP(II) transiently expressed during the perinatal period is likely involved in beta-carotene metabolism.
- CRBP(II) may facilitate the conversion of beta-carotene to retinol and its subsequent esterification.
Abstract:
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.