Tao L, Shen D, Pandey S, Hao W, Rich K A, Fong H K
Doheny Eye Institute, Los Angeles, CA 90033, USA.
Mol Vis. 1998 Dec 2;4:25.
The aim of this study is to isolate and characterize cDNA clones and the genes that encode mouse RPE retinal G protein-coupled receptor (RGR) and to analyze expression of the RGR gene in the developing mouse retina. The conserved amino acid sequences of RGR from various mammals can be compared to the amino acid sequence motif of G protein-coupled receptors.
Mouse RGR cDNA and gene clones were isolated from a retina cDNA library and 129SV genomic DNA library, respectively. The expression of RGR in the developing C57BL/6J mouse retina was analyzed by immunohistochemical staining with a polyclonal antipeptide antibody.
The deduced amino acid sequence of mouse RGR is 78% and 81% identical to that of bovine and human RGR, respectively. The mouse RGR gene is split into seven exons and extends about 11 kb. Two predominant mRNA transcripts, 1.9 and 1.7 kb in length, and a third, relatively faint, 5.5-kb transcript were detected in mouse eye by hybridization to a RGR cDNA probe. Frozen sections of C57BL/6J mouse retina at various stages of development were incubated with a mouse RGR antipeptide antibody. RGR immunoreactivity was first seen at postnatal day 2 (P2) in centrally located RPE cells. From day P6 to P12, there was an increase in the number and intensity of immunoreactive RPE cells in the central and mid-peripheral regions of the retina, while the most peripheral RPE cells were still negative. By day P16, the length of the RPE monolayer was immunoreactive, and staining of the central RPE cells was markedly more intense than at younger ages.
Mouse and human RGR are highly conserved. A gradient of RGR expression in RPE extends from the central to the peripheral retina during development. In reference to the appearance of melanin-positive differentiated RPE cells, the induction of RGR expression is a relatively late event in the maturation of the retina.
本研究旨在分离并鉴定编码小鼠视网膜色素上皮（RPE）视网膜G蛋白偶联受体（RGR）的cDNA克隆和基因，并分析RGR基因在发育中小鼠视网膜中的表达情况。可将来自各种哺乳动物的RGR保守氨基酸序列与G蛋白偶联受体的氨基酸序列基序进行比较。
分别从视网膜cDNA文库和129SV基因组DNA文库中分离出小鼠RGR cDNA和基因克隆。用多克隆抗肽抗体通过免疫组织化学染色分析RGR在发育中的C57BL/6J小鼠视网膜中的表达。
小鼠RGR的推导氨基酸序列与牛和人RGR的序列分别有78%和81%的同一性。小鼠RGR基因被分成7个外显子，长度约为11kb。通过与RGR cDNA探针杂交，在小鼠眼中检测到两种主要的mRNA转录本，长度分别为1.9kb和1.7kb，以及第三种相对较弱的5.5kb转录本。用小鼠RGR抗肽抗体孵育处于不同发育阶段的C57BL/6J小鼠视网膜冰冻切片。RGR免疫反应性首先在出生后第2天（P2）出现在位于中央的RPE细胞中。从P6到P12天，视网膜中央和中周边区域免疫反应性RPE细胞的数量和强度增加，而最周边的RPE细胞仍为阴性。到P16天，RPE单层的长度有免疫反应性，中央RPE细胞的染色明显比幼年时更强。
小鼠和人RGR高度保守。在发育过程中，RPE中RGR表达从视网膜中央向周边呈梯度分布。参照黑色素阳性分化RPE细胞的出现情况，RGR表达的诱导是视网膜成熟过程中相对较晚发生的事件。
