Intercellular signaling via cyclic GMP diffusion through gap junctions restarts meiosis in mouse ovarian follicles
Intercellular signaling via cyclic GMP diffusion through gap junctions restarts meiosis in mouse ovarian follicles
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DOI：
10.1073/pnas.1423598112
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发表时间：
2015-04-28
影响因子：
11.1
通讯作者：
Jaffe, Laurinda A.
中科院分区：
文献类型：
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作者：
Shuhaibar, Leia C.;Egbert, Jeremy R.;Jaffe, Laurinda A.
哺乳动物卵母细胞减数分裂暂停，直到促黄体激素（LH）激活卵泡壁颗粒细胞中的受体。先前的工作已经确定了来自颗粒细胞的环GMP（cGMP）在维持减数分裂停滞中的中心作用，但尚不清楚LH与位于距卵母细胞多达10个细胞层的受体的结合如何降低卵母细胞cGMP并重新开始减数分裂。在这里，通过可视化细胞间的cGMP在实时活卵泡表达FRET传感器的小鼠，我们表明，cGMP通过间隙连接的扩散不仅是负责维持减数分裂停滞，而且还为快速传输的信号，重新启动减数分裂从卵泡表面的卵母细胞。在LH暴露之前，整个卵泡中的cGMP浓度处于类似于2-4 μ M的均匀高水平。然后，在LH应用的1分钟内，外周颗粒细胞中的cGMP开始减少。因此，cGMP从卵母细胞扩散到由大颗粒细胞体积提供的水槽中，使得到20分钟时卵泡中的cGMP浓度均匀地低，类似于100 nM。卵母细胞中cGMP的减少解除了对减数分裂细胞周期的抑制。这种直接证明，由完整组织的一个区域中的刺激引发的生理信号可以通过环核苷酸扩散穿过间隙连接而穿过许多细胞层，这可以为不同的细胞过程提供一般机制。
Meiosis in mammalian oocytes is paused until luteinizing hormone (LH) activates receptors in the mural granulosa cells of the ovarian follicle. Prior work has established the central role of cyclic GMP (cGMP) from the granulosa cells in maintaining meiotic arrest, but it is not clear how binding of LH to receptors that are located up to 10 cell layers away from the oocyte lowers oocyte cGMP and restarts meiosis. Here, by visualizing intercellular trafficking of cGMP in real-time in live follicles from mice expressing a FRET sensor, we show that diffusion of cGMP through gap junctions is responsible not only for maintaining meiotic arrest, but also for rapid transmission of the signal that reinitiates meiosis from the follicle surface to the oocyte. Before LH exposure, the cGMP concentration throughout the follicle is at a uniformly high level of similar to 2-4 mu M. Then, within 1 min of LH application, cGMP begins to decrease in the peripheral granulosa cells. As a consequence, cGMP from the oocyte diffuses into the sink provided by the large granulosa cell volume, such that by 20 min the cGMP concentration in the follicle is uniformly low, similar to 100 nM. The decrease in cGMP in the oocyte relieves the inhibition of the meiotic cell cycle. This direct demonstration that a physiological signal initiated by a stimulus in one region of an intact tissue can travel across many layers of cells via cyclic nucleotide diffusion through gap junctions could provide a general mechanism for diverse cellular processes.