Inositol 1,4,5-trisphosphate receptors are essential for fetal-maternal connection and embryo viability
Inositol 1,4,5-trisphosphate receptors are essential for fetal-maternal connection and embryo viability
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DOI：
10.1371/journal.pgen.1008739
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发表时间：
2020-04-01
期刊：
影响因子：
4.5
通讯作者：
Ouyang Kunfu
中科院分区：
文献类型：
--
作者：
Yang Feili;Huang Lei;Ouyang Kunfu
肌醇1，4，5-三磷酸受体（IP（3）Rs）是位于ER膜上的细胞内钙释放通道家族，在哺乳动物中由3种不同的亚型（IP（3）R1、IP（3）R2和IP（3）R3）组成。已提出IP 3 R介导的Ca 2+信号传导在调节心血管发育中发挥重要作用，IP（3）R1和IP（3）R2双敲除（DKO）小鼠已被证明会出现心血管缺陷和胚胎致死。然而，我们目前的研究使用条件细胞特异性基因缺失策略显示，在小鼠心肌细胞、内皮/造血细胞和心血管谱系的早期前体细胞中缺失这两种基因不能导致相似的致死表型。相比之下，我们观察到DKO胚胎中的尿囊-胎盘缺陷，包括脐血管尺寸减小和胎盘迷路深度减小，这可能独立于DKO胚胎中的其他表型而发生。我们进一步发现，上胚层IP（3）R1和IP（3）R2的缺失也会导致胚胎死亡和类似的尿囊-胎盘缺陷。三磷酸肌醇受体（Inositol 1，4，5-trisphosphate receptor，IP（3）Rs）是位于雌激素受体（ER）膜上的一类细胞内钙离子释放通道，在哺乳动物中有3种不同的亚型（IP（3）R1，IP（3）R2，IP（3）R3，IP（3）R4，IP（3）R5，IP（3）R6），IP（3）R7，IP（3）R8，IP（3）R9），IP（3）R1，IP（3）R2），IP（3）R1，IP（3和IP（3）R3）分别由3个基因Itpr 1、Itpr 2和Itpr 3编码。利用基因敲除小鼠模型的研究表明，IP（3）R对胚胎存活是必需的。IP（3）R1和IP（3）R2的缺失已被证明会导致心血管缺陷和胚胎死亡。然而，尚不清楚哪种细胞类型导致IP（3）R1和IP（3）R2双敲除（DKO）小鼠的心血管缺陷。在这项研究中，我们建立了条件性IP（3）R1和IP（3）R2敲除小鼠模型，这两种基因在特定的心血管细胞谱系中缺失。我们的结果显示，TnT-Cre在心肌细胞中缺失IP（3）R1和IP（3）R2，Tie 2-Cre和Flk 1-Cre在内皮/造血细胞中缺失IP（3）R1和IP（3）R2，或Mesp 1-Cre在心血管谱系的早期前体细胞中缺失IP（3）R1和IP（3）R2，导致没有表型。这表明，心血管细胞谱系中两个IP 3R基因的缺失不能解释在DKO小鼠中观察到的心血管缺陷和胚胎致死性。然后，我们重新访问并在DKO胚胎中进行了更详细的表型分析，发现DKO胚胎在胚胎第9.5天出现了心血管缺陷，包括心血管体积缩小，心腔扩大以及生长迟缓，但严重程度不同。有趣的是，我们还观察到DKO胚胎中的尿囊-胎盘缺陷，包括脐血管尺寸减小和胎盘迷路深度减小，这可能独立于DKO胚胎中的其他表型发生，即使没有明显的生长迟缓。此外，IP（3）R1和IP（3）R2被外胚层特异性Meox 2-Cre（其靶向所有胎儿组织和胚外中胚层但不靶向胚外滋养层细胞）缺失也导致胚胎致死和类似的尿囊-胎盘缺陷。综上所述，我们的研究结果表明，IP（3）R1和IP（3）R2在维持胎儿-母体连接的完整性和胚胎活力方面发挥着重要和冗余的作用。
Author summaryInositol 1,4,5-trisphosphate receptors (IP(3)Rs) are a family of intracellular Ca2+ release channels located on the ER membrane, which in mammals consist of 3 different subtypes (IP(3)R1, IP(3)R2, and IP(3)R3). IP3R-mediated Ca2+ signaling has been proposed to play an essential role in regulating cardiovascular development, and IP(3)R1 and IP(3)R2 double knockout (DKO) mice has been shown to develop cardiovascular defects and embryonic lethality. However, our present study using conditional cell-specific gene deletion strategy revealed that deletion of both genes in cardiomyocytes, endothelial / hematopoietic cells, and early precursors of the cardiovascular lineages in mice could not result in similar lethal phenotypes. By contrast, we observed allantoic-placental defects including reduced sizes of umbilical vessels and reduced depth of placental labyrinth in DKO embryos, which could occur independently from other phenotypes in DKO embryos. We further found that deletion of both IP(3)R1 and IP(3)R2 in epiblast also resulted in embryonic lethality and similar allantoic-placental defects. Our results demonstrated that IP(3)R1 and IP(3)R2 play an essential and redundant role in maintaining the integrity of fetal-maternal connection and embryonic viability.Inositol 1,4,5-trisphosphate receptors (IP(3)Rs) are a family of intracellular Ca2+ release channels located on the ER membrane, which in mammals consist of 3 different subtypes (IP(3)R1, IP(3)R2, and IP(3)R3) encoded by 3 genes, Itpr1, Itpr2, and Itpr3, respectively. Studies utilizing genetic knockout mouse models have demonstrated that IP(3)Rs are essential for embryonic survival in a redundant manner. Deletion of both IP(3)R1 and IP(3)R2 has been shown to cause cardiovascular defects and embryonic lethality. However, it remains unknown which cell types account for the cardiovascular defects in IP(3)R1 and IP(3)R2 double knockout (DKO) mice. In this study, we generated conditional IP(3)R1 and IP(3)R2 knockout mouse models with both genes deleted in specific cardiovascular cell lineages. Our results revealed that deletion of IP(3)R1 and IP(3)R2 in cardiomyocytes by TnT-Cre, in endothelial / hematopoietic cells by Tie2-Cre and Flk1-Cre, or in early precursors of the cardiovascular lineages by Mesp1-Cre, resulted in no phenotypes. This demonstrated that deletion of both IP3R genes in cardiovascular cell lineages cannot account for the cardiovascular defects and embryonic lethality observed in DKO mice. We then revisited and performed more detailed phenotypic analysis in DKO embryos, and found that DKO embryos developed cardiovascular defects including reduced size of aortas, enlarged cardiac chambers, as well as growth retardation at embryonic day (E) 9.5, but in varied degrees of severity. Interestingly, we also observed allantoic-placental defects including reduced sizes of umbilical vessels and reduced depth of placental labyrinth in DKO embryos, which could occur independently from other phenotypes in DKO embryos even without obvious growth retardation. Furthermore, deletion of both IP(3)R1 and IP(3)R2 by the epiblast-specific Meox2-Cre, which targets all the fetal tissues and extraembryonic mesoderm but not extraembryonic trophoblast cells, also resulted in embryonic lethality and similar allantoic-placental defects. Taken together, our results demonstrated that IP(3)R1 and IP(3)R2 play an essential and redundant role in maintaining the integrity of fetal-maternal connection and embryonic viability.