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Retinyl ester hydrolysis and retinol efflux from BFC-1beta adipocytes
1Institute of Human Nutrition, Columbia University, New York, New York 10032, USA.
The Journal of Biological Chemistry
|May 30, 1997
Summary
This study shows that cyclic AMP (cAMP) stimulates retinol mobilization from fat cells by activating hormone-sensitive lipase (HSL) to hydrolyze stored retinyl esters. This finding reveals a key mechanism for regulating vitamin A levels in the body.
Area of Science:
- Biochemistry
- Cell Biology
- Endocrinology
Background:
- Adipose tissue serves as a primary reservoir for retinol (vitamin A).
- Mechanisms governing retinol mobilization from adipose stores remain largely uncharacterized.
- Understanding retinol release is crucial for regulating vitamin A homeostasis.
Purpose of the Study:
- To investigate the effects of cyclic AMP (cAMP) on retinol efflux from adipocytes.
- To elucidate the enzymatic pathways involved in cAMP-mediated retinol mobilization.
- To determine the role of hormone-sensitive lipase (HSL) in retinyl ester hydrolysis.
Main Methods:
- Murine BFC-1beta adipocytes were treated with dibutyryl cAMP to stimulate retinol efflux.
- High-performance liquid chromatography (HPLC) was used to quantify retinol and retinyl esters.
- HSL activity was assessed using purified fractions and overexpressing cell lines.
Main Results:
- cAMP significantly increased retinol accumulation in the culture media in a time- and dose-dependent manner.
- Cellular retinyl ester concentrations decreased following cAMP stimulation.
- HSL was identified as a key enzyme hydrolyzing retinyl palmitate, facilitating retinol release.
Conclusions:
- cAMP-dependent retinol mobilization from adipocytes is mediated by the hydrolysis of retinyl esters.
- Hormone-sensitive lipase (HSL) plays a critical role in releasing retinol from adipose stores.
- These findings provide novel insights into the regulation of vitamin A metabolism and storage.