We recently found that orphan G-protein-coupled receptor (GPR)153 is expressed in the anterior pituitary (AP) of heifers, leading us to speculate that GPR153 colocalizes with gonadotropin-releasing hormone receptor (GnRHR) in the plasma membrane of gonadotrophs and is expressed at specific times of the reproductive cycle. To test this hypothesis, we examined the coexpression of GnRHR, GPR153, and either luteinizing hormone or follicle-stimulating hormone in AP tissue and cultured AP cells by immunofluorescence microscopy. GPR153 was detected in the gonadotrophs, and was colocalized with GnRHR in the plasma membrane. GPR153 was also detected in the cytoplasm of cultured gonadotrophs. Real-time PCR and western blot analyses found that expression was lower (P < 0.05) in AP tissues during early luteal phase as compared to pre-ovulation or late luteal phases. The 5'-flanking region of the GPR153 gene contained a consensus response element sequence for estrogen, but not for progesterone. These data suggest that some, but not all GPR153 colocalizes with GnRHR in the plasma membrane of gonadotrophs, and its expression changes stage-dependently in the bovine AP.

中文翻译：

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小母牛以垂体前叶依赖的方式在垂体前叶促性腺激素中表达G蛋白偶联受体153。

我们最近发现，孤儿G蛋白偶联受体（GPR）153在小母牛的垂体前叶（AP）中表达，这使我们推测GPR153与促性腺激素释放激素受体（GnRHR）共同定位于促性腺激素的质膜和在生殖周期的特定时间表达。为了验证该假设，我们通过免疫荧光显微镜检查了AP组织和培养的AP细胞中GnRHR，GPR153和促黄体生成素或促卵泡激素的共表达。在促性腺激素中检测到GPR153，并在质膜中与GnRHR共定位。在培养的促性腺激素的细胞质中也检测到了GPR153。实时PCR和Western印迹分析发现表达较低（P <0。05）与排卵前或黄体形成后期相比，黄体形成早期处于AP组织中。GPR153基因的5'侧翼区域包含雌激素而不是孕激素的共有应答元件序列。这些数据表明，部分但不是全部GPR153与GnRHR在性腺营养膜质上共定位，并且其表达在牛AP中呈阶段依赖性变化。