Liou G I, Wang M, Matragoon S
Department of Ophthalmology, Medical College of Georgia, Augusta 30912.
Invest Ophthalmol Vis Sci. 1994 Mar;35(3):1083-8.
To determine if the time course for the onset of gene and protein expression for interphotoreceptor binding protein (IRBP) precedes that of opsin in the developing mouse retina.
Relative mRNA levels of the IRBP and opsin genes were determined in prenatal and postnatal retinal RNA with RNase protection analysis (RPA). To determine if IRBP and opsin protein expressions are differentially regulated, dissociated retinal cells from postnatal (P) days 2 and 3 mice, that were injected with BrdU, were then double-labeled with antibodies against BrdU and either opsin or IRBP.
With RPA, IRBP mRNA was detected on embryonic (E) day 11 at the time of cone formation, whereas opsin mRNA was not detected until P0. It took until P3 for opsin expression to reach significant levels, whereas rods already appear during embryonic development. IBRP transcription preceded that of opsin because it rapidly increased from E13 to an early postnatal day. By P20, the expression levels of IRBP and opsin achieved constancy. Double antibody labeling revealed positive staining for both IRBP and BrdU as soon as 2 hours after injection, but it took until 40 hours for double positive staining for opsin and BrdU.
Because only IRBP protein expression was observed before the last mitosis of the photoreceptor precursor cells, IRBP could be essential for retinal development.
确定在发育中的小鼠视网膜中，光感受器间结合蛋白（IRBP）的基因和蛋白表达开始的时间进程是否早于视蛋白。
采用核糖核酸酶保护分析（RPA）测定产前和产后视网膜RNA中IRBP和视蛋白基因的相对mRNA水平。为了确定IRBP和视蛋白的蛋白表达是否受到不同调控，对出生后（P）第2天和第3天注射了BrdU的小鼠的视网膜解离细胞，用抗BrdU抗体和抗视蛋白或抗IRBP抗体进行双重标记。
通过RPA，在胚胎（E）第11天视锥细胞形成时检测到IRBP mRNA，而视蛋白mRNA直到出生后第0天才被检测到。视蛋白表达直到出生后第3天才达到显著水平，而视杆细胞在胚胎发育期间就已出现。IRBP的转录早于视蛋白，因为它从E13迅速增加到出生后早期。到出生后第20天，IRBP和视蛋白的表达水平达到稳定。双重抗体标记显示，注射后2小时IRBP和BrdU就出现阳性染色，但视蛋白和BrdU的双重阳性染色直到40小时才出现。
由于仅在光感受器前体细胞的最后一次有丝分裂之前观察到IRBP蛋白表达，因此IRBP可能对视网膜发育至关重要。
