Expression of Lhx9 Isoforms in the Developing Gonads of Rana rugosa
Expression of Lhx9 Isoforms in the Developing Gonads of Rana rugosa
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DOI：
10.2108/zsj.24.798
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发表时间：
2007-08
期刊：
影响因子：
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通讯作者：
Yuki Oshima;Koki Noguchi;Masahisa Nakamura
中科院分区：
文献类型：
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作者：
Yuki Oshima;Koki Noguchi;Masahisa Nakamura
Lhx9是一种lim同源结构域（HD）转录因子。Lhx9基因的转录本存在于小鼠胚胎的泌尿生殖嵴中。在缺乏lhx9的小鼠中，没有形成独立的性腺（Birk等，2000）。然而，迄今为止，Lhx9在性腺形成中的作用还没有在小鸡和老鼠以外的动物中进行过研究。因此，本研究旨在确定Lhx9是否在两栖动物发育性腺中表达。我们首先从蛙蛙（Rana rugosa）中分离出Lhx9和Lhx9α、β、γ和δ四个亚型的cdna。所有同工型都缺少HD （dna结合基序）的最后14个氨基酸。RT-PCR分析显示，Lhx9和Lhx9α在成年蛙的卵巢、睾丸、大脑和心脏中均有高表达。然而，Lhx9和这四种亚型中的任何一种都没有在胰腺和肾脏中表达。用RT-PCR方法检测了它们在红毛瓢虫发育性腺中的表达，结果显示Lhx9和Lhx9α转录本在性别鉴定过程中未发现性别二态性。Lhx9γ和Lhx9δ也有表达，但表达量较低。相比之下，Lhx9β转录本几乎未被检测到。此外，原位杂交分析表明，rugosa Lhx9早在性别决定之前就在性腺和中肾发育的体细胞中表达。综上所述，Lhx9及其四种同工异构体可能参与了红毛鼠的器官发生。所有同种异构体在该物种中都可能作为Lhx9的内源性显性阴性形式发挥作用。
Abstract Lhx9 is a LIM-homeodomain (HD) transcription factor. Transcripts of the Lhx9 gene are present in the urogenital ridges of mouse embryos. In Lhx9-deficient mice, a discrete gonad is not formed (Birk et al., 2000). To date, however, the role of Lhx9 in gonad formation has not been studied in animals other than chicks and mice. Thus, this study was aimed at determining whether or not Lhx9 is expressed in the developing gonads of amphibians. We first isolated cDNAs of Lhx9 and four isoforms, named Lhx9α, β, γ and δ, from the frog Rana rugosa. All the isoforms lacked the last 14 amino acids of the HD (the DNA-binding motif). RT-PCR analysis revealed that Lhx9 and Lhx9α were highly expressed in the ovary, testis, brain and heart of adult frogs. However, neither Lhx9 nor any of the four isoforms was expressed in the pancreas and kidney. When their expression in the developing gonads of R. rugosa was examined by RT-PCR, transcripts of Lhx9 and Lhx9α were detected with no sexual dimorphism during sex determination. Lhx9γ and Lhx9δ were also expressed, but at a low level. In contrast, the Lhx9β transcript was hardly detected. In addition, in situ hybridization analysis showed that R. rugosa Lhx9 was expressed in somatic cells in the developing gonad and mesonephros far before sex determination. Taken together, Lhx9 and its four isoforms are probably involved in organogenesis in R. rugosa. All the isoforms may function as an endogenous dominant-negative form of Lhx9 in this species.