Dazl functions in maintenance of pluripotency and genetic and epigenetic programs of differentiation in mouse primordial germ cells in vivo and in vitro.
BACKGROUND
Mammalian germ cells progress through a unique developmental program that encompasses proliferation and migration of the nascent primordial germ cell (PGC) population, reprogramming of nuclear DNA to reset imprinted gene expression, and differentiation of mature gametes. Little is known of the genes that regulate quantitative and qualitative aspects of early mammalian germ cell development both in vivo, and during differentiation of germ cells from mouse embryonic stem cells (mESCs) in vitro.


RESULTS
We used a transgenic mouse system that enabled isolation of small numbers of Oct4DeltaPE:GFP-positive germ cells in vivo, and following differentiation from mESCs in vitro, to uncover quantitate and qualitative phenotypes associated with the disruption of a single translational regulator, Dazl. We demonstrate that disruption of Dazl results in a post-migratory, pre-meiotic reduction in PGC number accompanied by aberrant expression of pluripotency genes and failure to erase and re-establish genomic imprints in isolated male and female PGCs, as well as subsequent defect in progression through meiosis. Moreover, the phenotypes observed in vivo were mirrored by those in vitro, with inability of isolated mutant PGCs to establish pluripotent EG (embryonic germ) cell lines and few residual Oct-4-expressing cells remaining after somatic differentiation of mESCs carrying a Dazl null mutation. Finally, we observed that even within undifferentiated mESCs, a nascent germ cell subpopulation exists that was effectively eliminated with ablation of Dazl.


CONCLUSIONS
This report establishes the translational regulator Dazl as a component of pluripotency, genetic, and epigenetic programs at multiple time points of germ cell development in vivo and in vitro, and validates use of the ESC system to model and explore germ cell biology.
Haston
Kelly M
KM
Department of Obstetrics and Gynecology, Institute for Stem Cell Biology & Regenerative Medicine, Stanford University School of Medicine, Palo Alto, California, United States of America.
Tung
Joyce Y
JY
Reijo Pera
Renee A
RA
D000818:Animals; D017209:Apoptosis; D002454:Cell Differentiation; D049109:Cell Proliferation; D004622:Embryo, Mammalian / Q000166:cytology; D053595:Embryonic Stem Cells / Q000166:cytology / Q000378:metabolism; D044127:Epigenesis, Genetic; D018507:Gene Expression Regulation, Developmental; D018392:Genomic Imprinting; D005854:Germ Cells / Q000166:cytology* / Q000378:metabolism*; D006657:Histones / Q000378:metabolism; D008540:Meiosis; D008745:Methylation; D051379:Mice; D008954:Models, Biological; D009154:Mutation / Q000235:genetics; D009928:Organ Specificity / Q000235:genetics; D039904:Pluripotent Stem Cells / Q000166:cytology* / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000378:metabolism*
C508515:DAZL protein, mouse; D006657:Histones; D016601:RNA-Binding Proteins