PSF1 Is Essential for Early Embryogenesis in Mice

Abstract

Psf1 (partner of sld five 1) forms a novel heterotetramer complex, GINS (Go, Ichi, Nii, and San; five, one, two, and three, respectively, in Japanese), with Sld5, Psf2, and Psf3. The formation of this complex is essential for the initiation of DNA replication in yeast and Xenopus laevis egg extracts. Although all of the components are well conserved in higher eukaryotes, the biological function in vivo is largely unknown. We originally cloned the mouse ortholog of PSF1 from a hematopoietic stem cell cDNA library and found that PSF1 is expressed in blastocysts, adult bone marrow, and testis, in which the stem cell system is active. Here we used the genetargeting technique to determine the physiological function of PSF1 in vivo. Mice homozygous for a nonfunctional mutant of PSF1 died in utero around the time of implantation. PSF1 ؊/؊ blastocysts failed to show outgrowth in culture and exhibited a cell proliferation defect. Our data clearly indicate that PSF1 is required for early embryogenesis.

Both alleles of PSF1 are required for maintenance of pool size of immature hematopoietic cells and acute bone marrow regeneration

“…PSF1 mutant mice and Runx1-deficient mice (Runx1-deficient mice were a gift from Dr T. Watanabe, Tohoku University, Sendai, Japan) were maintained and bred as described. 18,19 All animal studies were approved by the Animal Care Committee of Kanazawa University and the Osaka University Animal Care and Use Committee. For BM ablation studies, 8-week-old wild-type and PSF1 ϩ/Ϫ mice were treated with a single tail vein injection of 5-fluorouracil (5-FU; 150 mg/kg body weight; Kyowa Hakko Kogyo, Tokyo, Japan).…”

“…Loss of PSF1 causes embryonic lethality around the implantation stage. 18 PSF1 Ϫ/Ϫ embryos revealed impaired proliferation of multipotent stem cells, ie, the inner cell mass. In mice, PSF1 is highly expressed in proliferating HSCs and the hematopoietic progenitor cells (HPCs).…”

“…[14][15][16][17] Previously, we cloned the mouse ortholog of PSF1 from an HSC-specific cDNA library. 18 PSF1 is predominantly expressed in highly proliferative tissues, such as testis and BM. Loss of PSF1 causes embryonic lethality around the implantation stage.…”

Isolation of the Cdc45/Mcm2–7/GINS (CMG) complex, a candidate for the eukaryotic DNA replication fork helicase

“…For measuring the lengths of the duplex DNA in the substrates, a dsDNA ladder was labeled with 32 P and separated on the gel in either native or boiled form. in mice (34) …”

Crystal structure of the human GINS complex

“…Psf1 is required for cell proliferation in yeast and mice, and loss of Psf1 leads to early embryonic death (Takayama et al 2003;Ueno et al 2005). Psf2 regulates the chromosome segregation, presumably through its S-phase role in centromere replication (Huang et al 2005).…”