PAK2 is essential for chromosome alignment in metaphase I oocytes

Abstract

As a highly conserved and ubiquitously expressed serine/threonine kinase, p21-activated kinase 2 (PAK2) participates in diverse biologic events. However, its roles in mouse oocyte meiotic maturation remain unclear. The present study revealed that mouse oocytes depleted of Pak2 were unable to completely progress through meiosis and that a majority were arrested at metaphase I. Pak2 depletion thus prompted MI arrest and induced meiotic chromosome alignment defects in mouse oocytes, in part due to a reduction in polo-like kinase (PLK1). We demonstrated that PAK2’s interaction with PLK1 protected it from degradation by APC/CCdh1, and that it promoted meiotic progression and bipolar spindle formation. Our data collectively display critical functions for PAK2 in meiotic progression and chromosome alignment in mouse oocytes.

NET1 is a critical regulator of spindle assembly and actin dynamics in mouse oocytes

“…As reliable chromosomal separation is ensured by the bi-oriented interaction of chromosomes with the spindle through the end-on attachment of microtubules to kinetochores [ 32 ], it is conceivable that the high percentage of spindle/chromosomal defects in Net1 -depleted oocytes is a consequence of K-MT misattachments. If these attachment errors are not corrected prior to anaphase in normal oocyte maturation, they may cause chromosome-separation defects [ 16 ]; and consistent with this concept, the frequency of aneuploidy was significantly increased in Net1 -depleted oocytes relative to controls (Fig. 4 C).…”

“…These phenotypes contrasted sharply with control oocytes that exhibited a typical barrel-shaped spindle and well-aligned chromosomes at the cellular equator. In order for chromosomes to be properly aligned and segregated, kinetochores must be attached to microtubules emanating from the opposite spindle pole [ 16 ]; however, we noted that Net1 -KD oocytes exhibited spindle/chromosome disorganization and hypothesized that NET1 may be required for correct kinetochore-microtubule (K-MT) assembly. CREST was used to detect kinetochores, anti-α-tubulin antibody was used to visualize spindles, and Hoechst 33,342 was used to visualize chromosomes in MI oocytes (Fig.…”

“…Chromosomal spreads were created as described previously [ 16 ]. Briefly, the zonae pellucidae of oocytes were removed with Tyrode’s acid solution (Cat# T1788-100ML; Sigma, St. Louis, USA) and transferred to M2 medium for recovery.…”

“…For example, to produce a healthy oocyte, spindle assembly and chromosomal alignment must be properly controlled during meiotic progression [ 15 ]. Aneuploid eggs can be generated by any error in the oocyte maturation process [ 16 ], and several studies have shown that fertilization of aneuploid eggs in mammals leads to pregnancy loss, which—if the fetuses survive to term—results in developmental disabilities [ 17 ]. Spindle assembly and asymmetric-division defects are major causes—particularly in women of advanced maternal age—of infertility, miscarriages, or birth defects [ 18 ].…”

A Stapled Peptide Inhibitor of METTL3-METTL14 for Cancer Therapy

“…According to previous reports, METTL3 function as tumor-promoting factors in many cancer types or METTL3 inhibiting hinders tumor growth cancer growth, etc. liver cancer (HepG2) and cervical cancer (HeLa) [24] ; colorectal cancer (HCT116) [25] ; leucocythemia (CCRF-CEM, K562, MDSL, HL60) [14] , PCa cell(DU145, PC3) [26] .The results showed that both RSM3 and RM3 exhibited broad toxicity towards various cancer cells including PC3, DU145, HeLa, HepG2, HCT116, A549, K562, MDS-L, CCRF-CEM ( Fig. S8 ).…”