SETDB1 is essential for mouse primordial germ cell fate determination by ensuring BMP signaling

Abstract

In mouse embryos, primordial germ cells (PGCs) are fate-determined from epiblast cells. Signaling pathways involved in PGC formation have been identified, but their epigenetic mechanisms remain poorly understood. Here, we show that the histone methyltransferase SETDB1 is an epigenetic regulator of PGC fate determination. Setdb1-deficient embryos exhibit drastic reduction of nascent PGCs. Dppa2, Otx2 and Utf1 are de-repressed whereas mesoderm development-related genes, including BMP4 signaling-related genes, are downregulated by Setdb1 knockdown during PGC-like cell (PGCLC) induction. In addition, binding of SETDB1 is observed at the flanking regions of Dppa2, Otx2 and Utf1 in cell aggregates containing PGCLCs, and trimethylation of lysine 9 of histone H3 is reduced by Setdb1 knockdown at those regions. Furthermore, DPPA2, OTX2 and UTF1 binding is increased in genes encoding BMP4 signaling-related proteins, including SMAD1. Finally, overexpression of Dppa2, Otx2 and Utf1 in cell aggregates containing PGCLCs results in the repression of BMP4 signalingrelated genes and PGC determinant genes. We propose that the localization of SETDB1 to Dppa2, Otx2 and Utf1, and subsequent repression of their expression, are crucial for PGC determination by ensuring BMP4 signaling.

Molecular and epigenetic pathogenesis of germ cell tumors

“…This induction of PGC specification occurs through signaling pathways from extraembryonic tissue, such as BMP2, BMP4, BMP8b and SMAD1 [ 11 ]. SMAD1 activity is dependent on SETDB1, which catalyzes H3K9 trimethylation leading to repression of negative SMAD1 regulators DPPA2, OTX2, and UTF1 [ 12 ]. Subsequently, expression of BLIMP1/PRDM1, the key factor of PGC specification, is triggered, causing the PGC precursors to escape the somatic differentiation program [ 1 , 8 , 10 ].…”

“…Lately, Mochizuki et al. [ 12 ] revealed a Prdm1-dependent enrichment of Hdac3 and deacetylation of H3 and H4 histones in murine epiblast-like cells, which is crucial for repression of somatic gene expression of Hoxa1 , Dnmt3b , Crabp2 , and Meis2 . Upon E10.5–11.5, PGCs arrive at the genital ridge.…”

The control of gene expression and cell identity by H3K9 trimethylation

“…In mice, a population of epiblast cells in the post-implantation embryo forms primordial germ cells (PGCs): the precursors of oocytes and spermatozoa. SetDB1 depletion at early stages of development ( prior to E6.5 by Sox2Cre cKO and at E9.5 by TnapCre cKO) was shown to repress PGC formation and lead to gonadal hypotrophy in adults (Liu et al, 2014;Mochizuki et al, 2018). During PGC-like cell induction, SetDB1 was suggested to directly repress several transcription factors involved in mesoderm cell fate, thereby maintaining proper cell identity (Mochizuki et al, 2018).…”

“…SetDB1 depletion at early stages of development ( prior to E6.5 by Sox2Cre cKO and at E9.5 by TnapCre cKO) was shown to repress PGC formation and lead to gonadal hypotrophy in adults (Liu et al, 2014;Mochizuki et al, 2018). During PGC-like cell induction, SetDB1 was suggested to directly repress several transcription factors involved in mesoderm cell fate, thereby maintaining proper cell identity (Mochizuki et al, 2018). In E13.5 PGCs, SetDB1 was shown to control H3K9me3 levels and repress a subset of retrotransposons from the ERV and LINE1 classes, as well as a number of host genes (Liu et al, 2014).…”

The Histone Methyltransferase SETDB1 Modulates Survival of Spermatogonial Stem/Progenitor Cells Through NADPH Oxidase

“…The role of SETDB1 has been explored extensively in the development of male germ lines ( An et al, 2014 ; Liu et al, 2015 , 2017 ; Hirota et al, 2018 ; Mochizuki et al, 2018 ). SETDB1 is recruited to repress ERVs transcription via H3K9me3 in primordial germ cells ( Liu et al, 2015 ), and suppresses the expression of Dppa2 , Otx2 , and Utf1 during PGC determination ( Mochizuki et al, 2018 ). Setdb1 knockout disrupts spermatogenesis and expression of meiosis-related genes ( Hirota et al, 2018 ).…”