Cellular retinol-binding proteins are determinants of retinol uptake and metabolism in stably transfected Caco-2 cells.

摘要: The mammalian small intestine contains two related cellular retinol-binding proteins, CRBP and II, which are thought to have distinct functions. human intestinal cell line, Caco-2, was used as a model system for testing the hypothesis that intracellular levels of these proteins directly modulate absorption subsequent metabolism retinol in enterocytes. Immunoblot Northern blot hybridization demonstrated Caco-2 cells express II retinoic acid-binding protein I increasing amounts become more differentiated but do not detectable quantities CRBP. Stably transfected cloned lines over-express or coexpress control line expression vector without an insert were established. Retinol uptake retinyl ester synthesis increased up 2-fold by coexpression over-expression II. No significant differences detected pattern esters synthesized from exogenous [3H]retinol. This suggests fatty acid pools utilized esterification same despite phenotype lines. There no between apical basolateral [3H]retinol filter grown wild type monolayers. Thus, neither nor appear preferentially interact with luminal- plasma-derived retinol. Notably, over-expressed CRBP, endogenous reduced 5-10-fold compared These studies indicate determinants accumulation esterification, they suggest CRBP-bound metabolite can regulate intestine.