Related Experiment Videos
Vitamin A: overlapping delivery pathways to tissues from the circulation
Jisun Paik1, Silke Vogel, Loredana Quadro
1Department of Medicine, Columbia University, New York, NY 10032, USA.
The Journal of Nutrition
|January 6, 2004
Summary
Retinol-binding protein (RBP) is crucial for vitamin A transport. RBP-deficient mice show impaired vitamin A mobilization and altered beta-carotene cleavage, impacting retinoid actions.
Area of Science:
- Biochemistry
- Molecular Biology
- Nutritional Science
Background:
- Retinol bound to retinol-binding protein (RBP) is the primary circulating retinoid.
- Other retinoid and proretinoid forms are also present in blood.
- The contribution of these forms to cellular and tissue retinoid actions is not fully understood.
Purpose of the Study:
- To investigate the role of RBP in retinoid transport and storage.
- To explore the function of carotene cleavage enzyme (CCE) in beta-carotene metabolism in the testis.
Main Methods:
- Studied RBP-deficient mice to examine retinoid transport and storage.
- Analyzed beta-carotene cleavage by CCE in vitro using pull-down assays and MALDI-MS.
- Investigated interactions between CCE and lactate dehydrogenase-C (LDH-C) in mouse testis.
Main Results:
- RBP-deficient mice exhibit normal vitamin A uptake but accumulate excess vitamin A in the liver.
- These mice show early-life visual impairment, correctable with adequate vitamin A intake.
- Mouse testis CCE interacts with the testis-specific LDH-C isoform, suggesting a collaborative role in beta-carotene cleavage.
Conclusions:
- RBP is essential for efficient mobilization of stored vitamin A from the liver.
- CCE and LDH-C may function together in the testis to catalyze beta-carotene cleavage, contributing to retinoid availability.