Pak2 reduction induces a failure of early embryonic development in mice

Abstract

Background The quality of the early embryo is vital to embryonic development and implantation. As a highly conserved serine/threonine kinase, p21-activated kinase 2 (Pak2) participates in diverse biologic processes, especially in cytoskeleton remodeling and cell apoptosis. In mice, Pak2 knock out and endothelial depletion of Pak2 showed embryonic lethality. However, the role of Pak2 in preimplantation embryos remains unelucidated. Methods In the present work, Pak2 was reduced using a specific small interfering RNA in early mouse embryos, validating the unique roles of Pak2 in spindle assembly and DNA repair during mice early embryonic development. We also employed immunoblotting, immunostaining, in vitro fertilization (IVF) and image quantification analyses to test the Pak2 knockdown on the embryonic development progression, spindle assembly, chromosome alignment, oxidative stress, DNA lesions and blastocyst cell apoptosis. Areas in chromatin with γH2AX were detected by immunofluorescence microscopy and serve as a biomarker of DNA damages. Results We found that Pak2 knockdown significantly reduced blastocyst formation of early embryos. In addition, Pak2 reduction led to dramatically increased abnormal spindle assembly and chromosomal aberrations in the embryos. We noted the overproduction of reactive oxygen species (ROS) with Pak2 knockdown in embryos. In response to DNA double strand breaks (DSBs), the histone protein H2AX is specifically phosphorylated at serine139 to generate γH2AX, which is used to quantitative DSBs. In this research, Pak2 knockdown also resulted in the accumulation of phosphorylated γH2AX, indicative of increased embryonic DNA damage. Commensurate with this, a significantly augmented rate of blastocyst cell apoptosis was detected in Pak2-KD embryos compared to their controls. Conclusions Collectively, our data suggest that Pak2 may serve as an important regulator of spindle assembly and DNA repair, and thus participate in the development of early mouse embryos.

Pak2 is essential for meiotic progression and meiotic apparatus assembly in mouse oocytes

“…APC/C Cdh1 -mediated proteolysis of Plk1 was reported in some somatic cells and oocytes after DNA damage, and led to withdrawal from the cell cycle [27,46] . Our recent data also veri ed that Pak2-KD in early mouse embryos led to distinct embryonic DNA damage [41] . Pak2-KD oocytes exhibited a phenotype highly similar to that with Plk1 inhibition [25] , and Plk1 was depicted to be a direct target of the G2 DNAdamage checkpoint [47] .…”

“…3). Our previous investigation also revealed that silencing of Pak2 in early embryos of mice precipitated defects in spindle assembly and in chromosomal alignment [41] . As faithful chromosome separation is ensured by the bioriented interaction of chromosomes to the spindle through the end-on attachment of microtubules to kinetochores [42] , it is conceivable that the high percentage of spindle/chromosome abnormalities in Pak2-KD oocytes is a consequence of K-MT misattachments.…”

“…Investigators recently noted that inactivation of Pak2 caused oxidative stress and DNA lesions [41,44] .…”

PAK2 is essential for chromosome alignment in metaphase I oocytes

“…3 ). Our previous investigation also revealed that silencing of Pak2 in early embryos of mice precipitated defects in spindle assembly and in chromosomal alignment [ 41 ]. As faithful chromosome separation is ensured by the bi-oriented interaction of chromosomes to the spindle through the end-on attachment of microtubules to kinetochores [ 42 ], it is conceivable that the high percentage of spindle/chromosome abnormalities in Pak2 -KD oocytes is a consequence of K-MT misattachments.…”

PAK Inhibitor FRAX486 Represses Metastatic Potential of Triple-negative Breast Cancer Cells by Blocking Autophagy

“…In TNBC cells, PAK2 was verified as an inhibition target of FRAX486 in our study here. PAK2 plays important roles in embryogenesis and in the etiology of autism [43,44]. Besides, PAK2 regulates cell survival [45,46].…”