Alizadeh M, Gelfman C M, Bench S R, Hjelmeland L M
Section of Molecular and Cellular Biology, University of California, Davis 95616-8794, USA.
Invest Ophthalmol Vis Sci. 2000 Jul;41(8):2357-62.
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 cell line ARPE-19 has been previously demonstrated. In this study, the hypothesis that FGF receptor gene expression and the alternative splicing of the FGFR1 mRNA is regulated as a function of ARPE-19 differentiation in vitro was tested.
ARPE-19 cells were plated at sparse or confluent densities and maintained in culture up to 14 months. The expression of FGF receptors and the ratio of the FGFR1beta to FGFR1alpha splice variants of the FGFR1 transcript were quantified by a published PCR technique. Two in vivo samples of human RPE served as controls.
Sparse cultures of ARPE-19 cells predominantly express FGFR1. When these cultures are allowed to differentiate, FGFR2 is also expressed. Samples of mRNA from RPE cells in vivo exhibit FGFR1 and FGFR2 expression as well as FGFR3 expression, a form that is minimally apparent in vitro. The ratio of the FGFR1beta to FGFR1alpha 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 prototypical differentiation agent does not regulate the ratio of the FGFR1beta to FGFR1alpha splice variant.
Differentiation of the ARPE-19 cell line in vitro recapitulates many but not all the in vivo patterns of FGFR expression and splicing. This in vitro system may be useful for selected studies on how cellular differentiation regulates FGF receptor gene expression and splicing.
四种成纤维细胞生长因子受体（FGFR）mRNA的表达及可变剪接以发育和组织特异性方式受到调控。视网膜色素上皮细胞系ARPE-19的体外分化能力先前已得到证实。在本研究中，对FGFR基因表达及FGFR1 mRNA可变剪接受ARPE-19体外分化调控这一假说进行了验证。
将ARPE-19细胞以稀疏或汇合密度接种，培养长达14个月。通过一种已发表的PCR技术对FGFR的表达以及FGFR1转录本中FGFR1β与FGFR1α剪接变体的比例进行定量。两份人视网膜色素上皮的体内样本用作对照。
ARPE-19细胞的稀疏培养物主要表达FGFR1。当这些培养物进行分化时，FGFR2也会表达。体内视网膜色素上皮细胞的mRNA样本显示出FGFR1和FGFR2的表达以及FGFR3的表达，FGFR3这种形式在体外几乎不明显。FGFR1β与FGFR1α剪接变体的比例随着体外细胞分化而降低，并接近在人视网膜色素上皮细胞体内观察到的比例。以FGF2作为典型分化剂对体外培养物进行刺激并不会调节FGFR1β与FGFR1α剪接变体的比例。
ARPE-19细胞系的体外分化概括了FGFR表达和剪接的许多但并非全部体内模式。这个体外系统可能对某些关于细胞分化如何调控FGFR基因表达和剪接的研究有用。
