KHDC3L mutation causes recurrent pregnancy loss by inducing genomic instability of human early embryonic cells.

Weidao Zhang,Dengfeng Zhang,Zhongliang Chen,Bo Zhao,Zhengyuan Xie,Ping Zheng,Lu Liu,Yonggang Yao,Tanya Paull

doi:10.1371/journal.pbio.3000468

Abstract

Recurrent pregnancy loss (RPL) is an important complication in reproductive health. About 50% of RPL cases are unexplained, and understanding the genetic basis is essential for its diagnosis and prognosis. Herein, we report causal KH domain containing 3 like (KHDC3L) mutations in RPL. KHDC3L is expressed in human epiblast cells and ensures their genome stability and viability. Mechanistically, KHDC3L binds to poly(ADP-ribose) polymerase 1 (PARP1) to stimulate its activity. In response to DNA damage, KHDC3L also localizes to DNA damage sites and facilitates homologous recombination (HR)-mediated DNA repair. KHDC3L dysfunction causes PARP1 inhibition and HR repair deficiency, which is synthetically lethal. Notably, we identified two critical residues, Thr145 and Thr156, whose phosphorylation by Ataxia-telangiectasia mutated (ATM) is essential for KHDC3L’s functions. Importantly, two deletions of KHDC3L (p.E150_V160del and p.E150_V172del) were detected in female RPL patients, both of which harbor a common loss of Thr156 and are impaired in PARP1 activation and HR repair. In summary, our study reveals both KHDC3L as a new RPL risk gene and its critical function in DNA damage repair pathways.

Highlights

Recurrent pregnancy loss (RPL) is defined as two or more spontaneous clinical pregnancy losses, according to the American Society for Reproductive Medicine [1]
We knocked out KH domain containing 3 like (KHDC3L) at both alleles in human embryonic stem cells (ESCs) (hESC) using a CRISPR/Cas9-mediated strategy to investigate the function of KHDC3L in these cells (S1B Fig)
We examined whether KHDC3L participated in the replication-associated DNA double-strand break (DSB) repair to safeguard the genomic stability of epiblast cells. hESCs were treated with etoposide to induce DNA DSBs

Summary

Introduction

Recurrent pregnancy loss (RPL) is defined as two or more spontaneous clinical pregnancy losses, according to the American Society for Reproductive Medicine [1]. Khdc is highly transcribed in oocytes and epiblast cells of pre- and postimplantation early embryos [20,21] It is expressed in mouse embryonic stem cells (ESCs) [22]. Using mouse ESCs as a model, we further revealed that zygotic Khdc, which is expressed in epiblast cells between the blastocyst stage and embryonic day (E) 5.5 [21], safeguards the genomic stability of epiblast cells in pre- and postimplantation embryos. KHDC3L mRNAs were predominantly detected in epiblast cells by single-cell RNA sequencing in monkey embryos [23,25], and its expression level remained high until E14 at the onset of gastrulation [23] These expression patterns suggest that KHDC3L may play a role during postimplantation embryogenesis. We revealed the divergent molecular mechanisms of human KHDC3L compared to mouse Filia

Results

Discussion

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