Nakao Nobuhiro, Ono Hiroko, Yamamura Takashi, Anraku Tsubasa, Takagi Tsuyoshi, Higashi Kumiko, Yasuo Shinobu, Katou Yasuhiro, Kageyama Saburo, Uno Yumiko, Kasukawa Takeya, Iigo Masayuki, Sharp Peter J, Iwasawa Atsushi, Suzuki Yutaka, Sugano Sumio, Niimi Teruyuki, Mizutani Makoto, Namikawa Takao, Ebihara Shizufumi, Ueda Hiroki R, Yoshimura Takashi
Division of Biomodelling, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan.
Nature. 2008 Mar 20;452(7185):317-22. doi: 10.1038/nature06738.
Molecular mechanisms regulating animal seasonal breeding in response to changing photoperiod are not well understood. Rapid induction of gene expression of thyroid-hormone-activating enzyme (type 2 deiodinase, DIO2) in the mediobasal hypothalamus (MBH) of the Japanese quail (Coturnix japonica) is the earliest event yet recorded in the photoperiodic signal transduction pathway. Here we show cascades of gene expression in the quail MBH associated with the initiation of photoinduced secretion of luteinizing hormone. We identified two waves of gene expression. The first was initiated about 14 h after dawn of the first long day and included increased thyrotrophin (TSH) beta-subunit expression in the pars tuberalis; the second occurred approximately 4 h later and included increased expression of DIO2. Intracerebroventricular (ICV) administration of TSH to short-day quail stimulated gonadal growth and expression of DIO2 which was shown to be mediated through a TSH receptor-cyclic AMP (cAMP) signalling pathway. Increased TSH in the pars tuberalis therefore seems to trigger long-day photoinduced seasonal breeding.
调节动物对光周期变化作出季节性繁殖反应的分子机制尚未完全明确。在日本鹌鹑（Coturnix japonica）的中基底下丘脑（MBH）中，甲状腺激素激活酶（2型脱碘酶，DIO2）基因表达的快速诱导是光周期信号转导途径中迄今记录到的最早事件。在此，我们展示了鹌鹑MBH中与光诱导促黄体生成素分泌起始相关的基因表达级联反应。我们识别出两波基因表达。第一波在首个长日照黎明后约14小时启动，包括结节部促甲状腺激素（TSH）β亚基表达增加；第二波大约在4小时后发生，包括DIO2表达增加。向短日照鹌鹑脑室内（ICV）注射TSH可刺激性腺生长和DIO2表达，且已证明这是通过TSH受体 - 环磷酸腺苷（cAMP）信号通路介导的。因此，结节部TSH增加似乎触发了长日照光诱导的季节性繁殖。
