Insemination or phosphatidic acid induces an outwardly spiraling disk of elevated Ca2+ to produce the Ca2+ wave during Xenopus laevis fertilization.
Insemination or phosphatidic acid induces an outwardly spiraling disk of elevated Ca2+ to produce the Ca2+ wave during Xenopus laevis fertilization.
复制标题
授精或磷脂酸会诱导Ca2+向外螺旋盘升高，从而在非洲爪蟾受精过程中产生Ca2+波。
DOI：
10.1016/j.ydbio.2019.01.004
复制
发表时间：
2019
影响因子：
2.7
通讯作者：
Stith,BradleyJ
中科院分区：
文献类型：
--
作者：
Fees,ColbyP;Stith,BradleyJ
在异种受精过程中，在精子-卵子结合位点（热点）的初始细胞内钙（（Ca ~（2+）i））释放在没有使用抑制剂的情况下没有被描述，也没有与潜在的ER结构相关。在没有抑制剂的情况下，我们现在报告说，精子在加入Xenopuseggs后诱导了一个约25 µm的初始热点。该区域与ER斑块和活性增强的IP 3受体簇的大小一致。此外，我们发现了受精（Ca 2+）i波的一种新机制;我们发现该波不是由肌醇1，4，5-三磷酸（IP 3）向外扩散产生的，而是由一个约63 µm的升高的（Ca 2+）i盘以约65 µm/s的速度快速向外顺时针旋转产生的。我们还提出了一种新的机制，为加速受精（Ca 2+）i波的磁盘加速，并加入了其他旋转磁盘（一些逆时针旋转）的时间时，（Ca 2+）i波的速度增加。为了研究磷脂酸（PA）在异种受精过程中（Ca ~（2+））释放中的作用，我们发现两种PA产生抑制剂使受精热点的出现延迟约9-12 min，但不能减小热点的大小，反而加速了后期的（Ca ~（2+））i波。令人惊讶的是，全球除了PA toXenopuseggs诱导局部热点的时间和大小是类似的精子添加后诱导。相比之下，精子在热点出现后约30 s内诱导快速（Ca 2+）i波（约4 µm/s），而PA诱导的热点需要约32 min才能诱导非常缓慢（约1 µm/s）的（Ca 2+）i波，（Ca 2+）i峰较低。因此，PA可能不需要在精卵结合位点处初始释放（Ca 2+）i，但通过诱导类似大小的局部（Ca 2+）i释放来模拟精子。与精子相比，PA可通过缓慢增加IP 3受体聚集而诱发弱而慢的（Ca ~（2+））i波。向异种卵母细胞中加入PA，或向异种卵母细胞或卵中加入Ca 2+离子载体，均未诱导热点，但可诱导以~12 µm/s快速移动的全局（Ca 2+）i波。
DuringXenopusfertilization, the initial intracellular calcium ((Ca2+)i) release at the sperm-egg binding site (hot spot) has not been described without the use of inhibitors, nor related to underlying ER structure. Without inhibitors, we now report that sperm induce an initial hot spot after sperm addition toXenopuseggs that was ~25 µm. This area is consistent with the size of ER patches and clusters of IP3 receptors that have enhanced activity. Furthermore, we find a new mechanism for the fertilization (Ca2+)iwave; instead of outward diffusion of inositol 1,4,5-trisphosphate (IP3), we find that the wave was generated by an outward, clockwise rotation of a ~63 µm disk of elevated (Ca2+)imoving very rapidly at ~65 µm/s. We also suggest a new mechanism for the acceleration of the fertilization (Ca2+)iwave as the disk accelerated and was joined by other rotating disks (some rotating counterclockwise) at a time when the speed of the (Ca2+)iwave increases. To examine the role of phosphatidic acid (PA) in the release of (Ca2+)iduringXenopusfertilization, we find that two inhibitors of PA production delayed the appearance of fertilization hot spots by ~9–12 min but did not reduce the size of hot spots and actually accelerated the later (Ca2+)iwave. Surprisingly, global addition of PA toXenopuseggs induced localized hot spots at a time and size that was similar to those induced after sperm addition. In contrast, sperm induce a rapid (Ca2+)iwave (~4 µm/s) within ~30 s after hot spot appearance, whereas hot spots induced by PA required an ~32 min to induce a very slow (~1 µm/s) (Ca2+)iwave with a lower peak of (Ca2+)i. Thus, PA may not be required for the initial release of (Ca2+)iat the sperm-egg binding site, but mimics sperm by inducing a similarly sized localized (Ca2+)irelease. As compared with sperm, PA may induce a weak, slow (Ca2+)iwave by slowly increasing IP3 receptor clustering. Addition of PA toXenopusoocytes, or Ca2+ionophore to eitherXenopusoocytes or eggs, did not induce hot spots but a global (Ca2+)iwave that rapidly moved at ~12 µm/s.