Maternal Pumilio acts together with Nanos in germline development in Drosophila embryos

Nanos (Nos) is one of the evolutionarily conserved proteins known to direct germ-line development. In Drosophila, maternal Nos protein maintains transcriptional quiescence in the germ-line progenitors or pole cells to repress ectopic expression of somatic genes. Here we show that maternal Nos is required to establish and maintain germ-line identity by preventing apoptosis and somatic cell fate. The pole cells lacking maternal Nos were degraded by apoptosis during mid to late embryogenesis. When apoptosis was suppressed by Df(3L)H99, some pole cells lacking Nos adopted somatic cell fates. These pole cells expressed somatic markers ectopically and lost the germ-line marker Vasa. We further found that some Nos-negative pole cells were able to migrate into the gonads, but they failed to develop as functional germ cells during postembryonic stages. We propose a model in which Nos establishes germ-line͞soma dichotomy and is also required to maintain germ-line fate.T he mechanism underlying the segregation of germ line from somatic line is a century-old issue in developmental biology. In many animal groups, maternal factors required for germ-line formation are localized in a histologically remarkable region in egg cytoplasm, or germ plasm, and are inherited in the germ-line progenitors (1, 2). In Drosophila, the germ-line progenitors known as pole cells are first formed at the posterior pole of the blastoderm embryos. During later embryogenesis, the pole cells pass through midgut epithelium into hemocoel and migrate within the embryos to reach the embryonic gonads, where they differentiate as functional germ line (1-4). Previous works have demonstrated that none of the pole cells becomes incorporated into any somatic tissues and contributes to somatic development during embryogenesis (5, 6). However, it remains elusive how the developmental fate of pole cells is regulated by germ plasm components.One of the germ plasm components, Nanos (Nos), is evolutionarily conserved and has a widespread role in germ-line development (7-13). Maternal nos mRNA is enriched in germ plasm, and its protein product is partitioned into pole cells when they are formed and remains detectable in these cells throughout embryogenesis (14). Nos is required in pole cells for their proper migration into the embryonic gonads (15, 16). Within pole cells, Nos is involved in maintaining transcriptional quiescence (17) and is also required for maintenance of a germ-line-specific chromatin status that correlates with transcriptional inactivity (18). In the absence of maternal Nos activity, ectopic expression of somatic genes is detectable in pole cells (17). These results led us to speculate that pole cells lacking Nos may adopt somatic cell fate.Here, we show that pole cells are able to adopt both germ-line and somatic cell fates and undergo apoptosis. Nos is required to repress the pathway leading to somatic differentiation and apoptosis. Thus, we conclude that Nos is essential for germline͞soma dichotomy and for germ-line maintenance. H99-PLH⌬23͞TM3...

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“…However, beginning at stage 9͞10 most pole cells were lost in the embryos derived from nos homozygous mothers (nos embryos) (24) (Fig. 1A).…”

Section: Resultsmentioning

confidence: 99%

“…Immunofluorescent staining of embryos was carried out as described in ref. 24. For Vas staining, the dechorionated embryos were fixed in 2 ml of a 1:1 mixture of heptane and fixative II (4% paraformaldehyde in PBS).…”

Section: Methodsmentioning

confidence: 99%

Nanos suppresses somatic cell fate in Drosophila germ line

Hayashi

Hayashi²,

Kobayashi³

2004

Proc. Natl. Acad. Sci. U.S.A.

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131

155

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“…Thus, based on studies on the DAZ gene family and studies in Drosophila and C. elegans that indicate an essential role of Pumilio in germ cell development (17,(30)(31)(32)(33)(34), we suggest that PUM2 may function in maintenance of the human germ cell lineage. PUM2 is expressed throughout the development of the female and male germ cell lineages.…”

Section: Discussionmentioning

confidence: 99%

“…In model organisms, Pumilio proteins are required for germ line maintenance and differentiation (17,(30)(31)(32)(33)(34). Germ line stem cells are not maintained and instead differentiate prematurely in Drosophila Pumilio mutants (17).…”

Section: Discussionmentioning

confidence: 99%

Human Pumilio-2 is expressed in embryonic stem cells and germ cells and interacts with DAZ (Deleted in AZoospermia) and DAZ-Like proteins

Moore

Jaruzelska

Fox

et al. 2003

Proc. Natl. Acad. Sci. U.S.A.

207

211

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Early in development, a part of the embryo is set aside to become the germ cell lineage that will ultimately differentiate to form sperm and eggs and transmit genetic information to the next generation. Men with deletions encompassing the Y-chromosome DAZ genes have few or no germ cells but are otherwise healthy, indicating they harbor specific defects in formation or maintenance of germ cells. A DAZ homolog, DAZL (DAZ-Like), is found in diverse organisms, including humans and is required for germ cell development in males and͞or females. We identified proteins that interact with DAZ proteins to better understand their function in human germ cells. Here, we show that PUM2, a human homolog of Pumilio, a protein required to maintain germ line stem cells in Drosophila and Caenorhabditis elegans, forms a stable complex with DAZ through the same functional domain required for RNA binding, protein-protein interactions and rescue of Pumilio mutations in flies. We also show that PUM2 is expressed predominantly in human embryonic stem cells and germ cells and colocalizes with DAZ and DAZL in germ cells. These data implicate PUM2 as a component of conserved cellular machinery that may be required for germ cell development.A ll stem cells have potential to differentiate or proliferate mitotically. These potentials must be balanced for the stem cell population to be maintained. If differentiation exceeds proliferation, the stem cell population is not maintained. Evidence in humans suggests that the DAZ genes function early in the germ line stem cells. Men with deletions encompassing the Y-chromosome DAZ gene cluster have defects in spermatogenesis that are detected initially in the stem cell population. These men frequently lack all germ cells, including the spermatogonial stem cells, and only somatic cells are present in testicular tissue (1-3). In addition, expression of the DAZ gene and its ancestral, autosomal homolog, DAZL, only occurs in germ cells; DAZ is expressed in males, and DAZL is expressed in males and females (4, 5). Evidence from model organisms also suggests the DAZ genes function in germ cell maintenance. The Xenopus homolog of DAZ, Xdazl, is expressed in a region of the early oocyte that contains the germ plasm that is required for formation and maintenance of the germ cell lineage (6, 7). Inhibition of Xdazl leads to loss of the primordial germ cells (6, 7). Finally, the DAZ homolog in mice, Dazl, is most abundantly expressed in premeiotic germ cells; disruption of this gene causes depletion of germ cells beginning prenatally (8-10). DAZ and DAZL homologs may function interchangeably as suggested by the observation that a human DAZ transgene can partially rescue a mouse Dazl mutation (11). To shed light on how DAZ genes might function in human germ cells, we sought to identify proteins that interact with DAZ proteins. Materials and MethodsTwo-Hybrid Screening of DAZ-Interacting Proteins. The yeast two-hybrid system was used to identify proteins that interact with a DAZ:GAL4 DNA-binding domain fusion prot...

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“…The interactions between hNanos1 and several partners could be essential for the functions of this molecule. In Drosophila, nanos is recruited by pumilio to bind to nanos-responsive elements located in the 3 0 untranslated region of target transcripts, for example, hunchback and cyclin B mRNAs (Murata and Wharton, 1995;Asaoka-Taguchi et al, 1999;Sonoda and Wharton, 2001). The structure of pumilio reveals the presence of a Puf domain containing helical repeats (PUM repeats) and showing homology with armadillo-repeat domains (Edwards et al, 2001).…”

Section: Regulation Of Mt1-mmp By Hnanos1mentioning

confidence: 99%

The E-cadherin-repressed hNanos1 gene induces tumor cell invasion by upregulating MT1-MMP expression

et al. 2008

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In this study, we examined the role of the E-cadherinrepressed gene human Nanos1 (hNanos1) in tumor invasion process. First, our in vivo study revealed that hNanos1 mRNAs were overexpressed in invasive lung carcinomas. Moreover, hNanos1 was co-localized with MT1-MMP (membrane type 1-matrix metalloproteinase) in E-cadherin-negative invasive lung tumor clusters. Using an inducible Tet-on system, we showed that induction of hNanos1 expression in DLD1 cells increased their migratory and invasive abilities in a three-dimensional migration and in a modified Boyden chamber assay. Accordingly, we demonstrated that hNanos1 upregulated MT1-MMP expression at the mRNA and protein levels. Inversely, using an RNA interference strategy to inhibit hNanos1 expression in invasive Hs578T, BT549 and BZR cancer cells, we observed a downregulation of MT1-MMP mRNA and protein and concomitantly a decrease of the invasive capacities of tumor cells in a modified Boyden chamber assay. Taken together, our results demonstrate that hNanos1, by regulating MT1-MMP expression, plays an important role in the acquisition of invasive properties by epithelial tumor cells.

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Maternal Pumilio acts together with Nanos in germline development in Drosophila embryos

Cited by 460 publications

References 43 publications

Nanos suppresses somatic cell fate in Drosophila germ line

Nanos suppresses somatic cell fate in Drosophila germ line

Human Pumilio-2 is expressed in embryonic stem cells and germ cells and interacts with DAZ (Deleted in AZoospermia) and DAZ-Like proteins

The E-cadherin-repressed hNanos1 gene induces tumor cell invasion by upregulating MT1-MMP expression

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