Treatment of the rat hepatic stellate cell line, PAV-1, by retinol and palmitic acid leads to a convenient model to study retinoids metabolism

Abstract

The main site of vitamin A storage in the liver is the hepatic stellate cells (HSC). Involvement of HSC in vitamin A metabolism has mainly been studied using primary culture, which represents the most physiological model but technically suffers several drawbacks (yield, low reproducibility, etc.). To circumvent these problems, we have previously established and characterised an immortalised rat HSC line named PAV-1. This study aimed to investigate in PAV-1 and in primary HSC (i) the incorporation of retinol and its esterification, (ii) the cellular retinol-binding protein (CRBP) content, (iii) the acid retinyl ester hydrolase activity (aREH), (iv) the thermal susceptibility and (v) the lipid composition of the membranes, which may play a crucial role in retinol transport across cellular membrane. In routine conditions of culture, the rate of retinol esterification in PAV-1 was low (5.2%) compared to that obtained with primary HSC (69.9%). Retinol pre-treatment doubled this esterification rate (10.7%) and the CRBP content in PAV-1. The co-incubation with retinol and palmitic acid enabled PAV-1 to esterify retinol with a rate close to that of primary HSC (66.2% vs. 69.9%) and with similar retinyl ester profiles. aREH activity was higher in primary HSC than in PAV-1. Thermal susceptibility and phospholipid composition of membranes in PAV-1 treated cells were similar to those of primary HSC. In conclusion, our study shows that PAV-1 cells treated with retinol and palmitic acid is a sound and convenient model for studying vitamin A mobilisation, a fundamental physiological event occurring in HSC.