Functional reconstruction of NANOS3 expression in the germ cell lineage by a novel transgenic reporter reveals distinct subcellular localizations of NANOS3.
Mutations of RNA-binding proteins such as NANOS3, TIAL1, and DND1 in mice have been known to result in the failure of survival and/or proliferation of primordial germ cells (PGCs) soon after their fate is specified (around embryonic day (E) 8.0), leading to the infertility of these animals. However, the mechanisms of actions of these RNA-binding proteins remain largely unresolved. As a foundation to explore the role of these RNA-binding proteins in germ cells, we established a novel transgenic reporter strain that expresses NANOS3 fused with EGFP under the control of Nanos3 regulatory elements. NANOS3-EGFP exhibited exclusive expression in PGCs as early as E7.25, and continued to be expressed in female germ cells until around E14.5 and in male germ cells throughout the fetal period with declining expression levels after E16.5. NANOS3-EGFP resumed strong expression in postnatal spermatogonia and continued to be expressed in undifferentiated spermatogonial cells in adults. Importantly, the Nanos3-EGFP transgene rescued the sterile phenotype of Nanos3 homozygous mutants, demonstrating the functional equivalency of NANOS3-EGFP with endogenous NANOS3. We found that throughout germ cell development, a predominant amount of NANOS3-EGFP co-localized with TIAL1 (also known as TIAR) and phosphorylated eukaryotic initiation factor 2alpha, markers for the stress granules, whereas a fraction of it showed co-localization with DCP1A, a marker for the processing bodies. On the other hand, NANOS3-EGFP did not co-localize with Tudor domain-containing protein 1, a marker for the intermitochondrial cements, in spermatogenic cells. These findings unveil the presence of distinct posttranscriptional regulations in PGCs soon after their specification, for which RNA-binding proteins such as NANOS3 and TIAL1 would play critical functions.
Laboratory for Mammalian Germ Cell Biology, RIKEN Center for Developmental Biology, 2-2-3 Minatojima-Minamimachi, Chuo-ku, Kobe 650-0047, Japan.
Masashi
M
Yamaji
Takashi
T
Tanaka
Mayo
M
Shigeta
Shinichiro
S
Chuma
Yumiko
Y
Saga
Mitinori
M
Saitou
D000818:Animals; D018797:Cell Cycle Proteins; D019070:Cell Lineage; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D004722:Endoribonucleases; D015852:Eukaryotic Initiation Factor-2 / Q000378:metabolism; D005260:Female; D018507:Gene Expression Regulation, Developmental; D005838:Genotype; D005865:Gestational Age; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D007246:Infertility / Q000235:genetics / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D009154:Mutation; D010063:Ovum / Q000378:metabolism*; D010641:Phenotype; D010766:Phosphorylation; D012313:RNA / Q000378:metabolism*; D012323:RNA Processing, Post-Transcriptional; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D017411:Ribonucleoproteins, Small Nuclear / Q000378:metabolism; D013094:Spermatozoa / Q000378:metabolism*; D015534:Trans-Activators / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; C462180:Dppa3 protein, mouse; D015852:Eukaryotic Initiation Factor-2; C477342:Nanos3 protein, mouse; C531066:Prdm14 protein, mouse; D016601:RNA-Binding Proteins; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D017411:Ribonucleoproteins, Small Nuclear; C488681:Tdrd1 protein, mouse; C489665:Tial1 protein, mouse; D015534:Trans-Activators; D014157:Transcription Factors; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins; D012313:RNA; D004722:Endoribonucleases; C466280:smad4-interacting protein SMIF, mouse