X-Linked Huwe1 Is Essential for Oocyte Maturation and Preimplantation Embryo Development

Abstract

Summary HUWE1 is a HECT-domain ubiquitin E3 ligase expressed in various tissues. Although HUWE1 is known to promote degradation of the tumor suppressor p53, given a growing list of its substrates, in vivo functions of HUWE1 remain elusive. Here, we investigated the role of HUWE1 in the female reproductive system. Homozygous deletion of Huwe1 in mouse oocytes of primary follicles caused oocyte death and female infertility, whereas acute depletion of HUWE1 protein by Trim-Away technology did not impact oocytes from antral follicles. Interestingly, oocytes from Huwe1 heterozygous females matured and fertilized normally, but the majority of embryos that lacked maternal Huwe1 were arrested at the morula stage after fertilization. Consequently, Huwe1 heterozygous females only produced wild-type pups. Concomitant knockout of p53 did not recover fertility of the Huwe1 knockout females. These findings make HUWE1 a unique and critical maternal factor indispensable for maintaining the quality of oocytes and embryos.

Intracellular fraction of zona pellucida protein 3 is required for the oocyte to embryo transition in mice

“…Live-cell protein masking by antibodies was introduced in the 1980s to show the effects of disrupting the cytokeratin filament network in mouse embryos 42 , while the antibody-based proteasomal degradation of proteins is more recent. Known as ‘ Trim-away’ , it was introduced in 2017 and it has been applied by several laboratories 14,43-47 including our own 15,16 to tackle various proteins of the mammalian oocyte or embryo. In many of those cases the degradation of target protein was partial 43,44,48,49 , yet a knockdown was sufficient to produce a bold effect, as seen here also with ZP3.…”

“…Known as ‘ Trim-away’ , it was introduced in 2017 and it has been applied by several laboratories 14,43-47 including our own 15,16 to tackle various proteins of the mammalian oocyte or embryo. In many of those cases the degradation of target protein was partial 43,44,48,49 , yet a knockdown was sufficient to produce a bold effect, as seen here also with ZP3. In fact, the phenotype of the ZP3 knockdown - pronuclear arrest - was even more severe than that incurred after epitope masking of ZP3: the zygotes not only arrested but also died.…”

A Critical Role for The COP9 Signalosome Subunit 3 as A Gatekeeper of Genome Integrity in 2-Cell Mouse Embryos

“…Together, these two answers predict that a complete depletion by TRIM21-mediated proteasomal degradation may not work, and may not be required to work (depending on one's aim), for every protein. Indeed, it may be noted that out of thirteen studies which applied the TRIM21-mediated proteasomal degradation on oocytic or embryonic proteins in mammals 21,22,27,[65][66][67][68][69][70][71][72][73][74] , four studies reported complete depletion (ITPR1 67 ; SNAP23 27 ; G6PD, PKM, GFPT1 65 ; EG5 also known as KIF11 21 ), four studies reported almost complete depletion (BTG4 68 ; TACC3 69 ; RACGAP1 also known as CYK4 and PLK1 70 ; SMC3 72 ) and five studies reported incomplete depletion (RCC1 66 ; CENPF 71 ; TEAD4 22 ; aPKC also known as PRKC 73 ; HUWE1 74 ). Thus, complete removal of the protein of interest seems to be more the exception than the rule (with current technology).…”

The giant E3 ligase HUWE1 is linked to tumorigenesis, spermatogenesis, intellectual disability, and inflammatory diseases

“…These studies collectively revealed that HUWE1 plays important roles in spermatogonial differentiation by orchestrating DNA damage responses. During oocyte maturation and preimplantation embryo development, oocyte-specific HUWE1 deletion was found to cause oocyte death and female infertility in mice, which were not rescued by p53 deletion, suggesting that another HUWE1 substrate might contribute to this pathway (Eisa et al, 2020).…”