Chow M M, Kight K E, Gothilf Y, Alok D, Stubblefield J, Zohar Y
Center of Marine Biotechnology, University of Maryland Biotechnology Institute, Suite 236, 701 East Pratt Street, Baltimore, Maryland 21202, USA.
J Mol Endocrinol. 1998 Dec;21(3):277-89. doi: 10.1677/jme.0.0210277.
GnRH is a neuropeptide which plays an essential role in the control of reproductive fitness for all vertebrates. Increasing evidence suggests that multiple forms of GnRH may exist in most vertebrate brains. Southern blot analysis of the three GnRHs known to be present in perciform fish, the seabream (sb)GnRH, the salmon(s) GnRH and the chicken (c) GnRH-II, demonstrates that each is present as a single gene copy in the genome of the striped bass, Morone saxatilis. In order to investigate the physiological consequences of multiple GnRHs in a single vertebrate species, we have isolated and characterized two of the GnRH genes, those for sbGnRH and cGnRH-II. Computer analysis of 3.5 kb of sequence upstream of the sbGnRH gene reveals a number of consensus DNA binding sites which implicate steroids, such as estrogen and glucocorticoids, and the steroidogenic transcription factor, SF-1, as being involved in the regulation of sbGnRH gene expression. Sequence analysis of the cGnRH-II gene reveals evidence of multiple promoters. Expression studies using (1) solution hybridization-RNAse protection mapping with several RNA probes directed at various regions of the proGnRH gene, (2) primer extension assays using two specific oligonucleotide primers, and (3) reverse transcription PCR with several oligonucleotide primers on cGnRH-II transcripts demonstrate that the cGnRH-II gene initiates transcription at numerous sites using a TATA-less promoter within the brains of sexually mature striped bass. This study is the first to characterize and compare the promoter structures of two GnRH genes present in a single vertebrate species.
促性腺激素释放激素（GnRH）是一种神经肽，在所有脊椎动物的生殖适应性控制中起着至关重要的作用。越来越多的证据表明，大多数脊椎动物的大脑中可能存在多种形式的GnRH。对鲈形目鱼类中已知存在的三种GnRH，即黑鲷（sb）GnRH、鲑鱼（s）GnRH和鸡（c）GnRH-II进行Southern印迹分析，结果表明，在条纹鲈（Morone saxatilis）的基因组中，每种GnRH都以单基因拷贝形式存在。为了研究单一脊椎动物物种中多种GnRH的生理后果，我们分离并鉴定了其中两个GnRH基因，即sbGnRH和cGnRH-II的基因。对sbGnRH基因上游3.5 kb序列的计算机分析揭示了许多共有DNA结合位点，这表明类固醇，如雌激素和糖皮质激素，以及类固醇生成转录因子SF-1参与了sbGnRH基因表达的调控。cGnRH-II基因的序列分析揭示了多个启动子的证据。使用（1）溶液杂交-RNA酶保护图谱法，用几种针对proGnRH基因不同区域的RNA探针；（2）引物延伸试验，使用两种特异性寡核苷酸引物；（3）逆转录PCR，用几种寡核苷酸引物对cGnRH-II转录本进行表达研究，结果表明，在性成熟条纹鲈的大脑中，cGnRH-II基因使用无TATA框的启动子在多个位点启动转录。本研究首次对单一脊椎动物物种中存在的两个GnRH基因的启动子结构进行了表征和比较。
