Expression and splicing of FGF receptor mRNAs during APRE-19 cell differentiation in vitro

PURPOSE. The expression and alternative splicing of the four FGF receptor ( FGFR) mRNAs are regulated in a developmental- and tissue-specific fashion. Capability of differentiation in vitro of the retinal pigment epithelial ce ll line ARPE-19 has been previously demonstrated. In this study, the hypoth esis that FGF receptor gene expression and the alternative splicing of the FGFR1 mRNA is regulated as a function of ARPE-19 differentiation in vitro w as tested. METHODS. ARPE-19 cells were plated at sparse or confluent densities and mai ntained in culture up to 14 months. The expression of FGF receptors and the ratio of the FGFR1 beta to FGFR1 alpha splice variants of the FGFR1 transc ript were quantified by a published PCR technique. Two in vivo samples of h uman RPE served as controls. RESULTS. Sparse cultures of ARPE-19 cells predominantly express FGFR1. When these cultures are allowed to differentiate, FGFR2 is also expressed. Samp les of mRNA from RPE cells in vivo exhibit FGFR1 and FGFR2 expression as we ll as FGFR3 expression, a form that is minimally apparent in vitro. The rat io of the FGFR1 beta to FGFR1 alpha splice variant decreases as a function of cell differentiation in vitro and approaches the ratio observed in human RPE cells in vivo. Stimulation of cultures in vitro with FGF2 as a prototy pical differentiation agent does not regulate the ratio of the FGFR1 beta t o FGFR1 alpha splice variant. CONCLUSIONS. Differentiation of the ARPE-19 cell line in vitro recapitulate s many but not all the in vivo patterns of FGFR expression and splicing. Th is in vitro system may be useful for selected studies on how cellular diffe rentiation regulates FGF receptor gene expression and splicing.