VASA encodes a putative ATP dependent helicase
(EC:3.6.1.-) involved in pole cell determination which is localised to the cytoplasm; it is expressed in the adult (egg
chamber and testis ), embryo (pole cell and pole granule ), larva (pole cell ), ovary (female germline stem cell ,
germarium , nurse cell , oocyte,etc ), cyst cell , male germline stem cell and spermatocyte ) and
pole granule ). Similar sequences have been identified in Caenorhabditis elegans , Homo sapiens , Mus musculus ,
Mus , Saccharomyces cerevisiae and unknown . It has been sequenced and its amino acid sequence contains a
DEAD-box subfamily ATP-dependent helicases signature .
General function
Cytoskeleton, Microtubule binding, Cell organization, Cell death/survival, DNA Replication
Comment
Ikenishi K reviewed genes in the germ plasm in Caenorhabditis elegans, Drosophila and Xenopus. Special cytoplasm, called germ plasm, that is essential for the differentiation of
germ cells is localized in a particular region of Caenorhabditis elegans,
Drosophila and Xenopus eggs. The mode of founder cell formation of germline,
the origin and behavior of the germline granules, and the molecules localized in
germline cells are compared in these organisms. The common characteristics of
the organisms are mainly as follows. First, the founder cells of germline are
established before the initiation of gastrulation. Second, the germline granules or
their derivatives are always present in germline cells or germ cells throughout the
life cycle in embryos, larvae, and adults. Lastly, among the proteins localized in
the germ plasm, only Vasa protein or its homolog is detected in the germline cells
or germ cells throughout the life cycle. As the protein of vasa homolog has been
reported to be also localized in the germline-specific structure or nuage in some
of the organisms without the germ plasm, the possibility that the mechanism for
differentiation of primordial germ cells is basically common in all organisms with
or without the germ plasm is discussed.
Cellular localization
Nuclear
Comment
Ovarian function
Germ cell development
Comment
Ikenishi K, et al 2000 reported spatio-temporal expression of Xenopus vasa homolog, XVLG1, in oocytes and
embryos: the presence of XVLG1 RNA in somatic cells as well as germline cells.
Ikenishi K et al reported the involvement of the protein of Xenopus vasa homolog (Xenopus vasa-like gene 1,
XVLG1) in the differentiation of primordial germ cells.
Expression regulated by
Comment
Ovarian localization
Oocyte
Comment
Komiya T et al reported the isolation and characterization of a novel gene of the DEAD box
protein family which is specifically expressed in germ cells of Xenopus laevis.
They have isolated a cDNA of the DEAD protein family from a Xenopus ovary
cDNA library. Northern hybridization revealed that the mRNA corresponding to
the cDNA [XVLG1 (Xenopus vasa-like gene)] was specifically expressed in adult
testis and ovary. The deduced amino acid sequence of XVLG1 was relatively
homologous to that of Drosophila vasa. XVLG1 protein was found to be
expressed exclusively in adult testis and ovary by immunoblotting with a
monoclonal antibody against XVLG1 protein. Immunocytological study showed
that XVLG1 protein was expressed in oogonia, oocytes, spermatogonia,
spermatocytes, and also in primordial germ cells in stage 46 tadpoles.
Follicle stages
Comment
Regulation of Injury-Induced Ovarian Regeneration by Activation of Oogonial Stem Cells. Erler P et al. (2016) Some animals have the ability to generate large numbers of oocytes throughout life. This raises the question whether persistent adult germline stem cell populations drive continuous oogenesis and whether they are capable of mounting a regenerative response after injury. Here we demonstrate the presence of adult oogonial stem cells (OSCs) in the adult axolotl salamander ovary and show that ovarian injury induces OSC activation and functional regeneration of the ovaries to reproductive capability. Cells that have morphological similarities to germ cells were identified in the developing and adult ovaries via histological analysis. Genes involved in germ cell maintenance including Vasa, Oct4, Sox2, Nanog, Bmp15, Piwil1, Piwil2, Dazl, and Lhx8 were expressed in the presumptive OSCs. Colocalization of Vasa protein with H3 mitotic marker showed that both oogonial and spermatogonial adult stem cells were mitotically active. Providing evidence of stemness and viability of adult OSCs, enhanced green fluorescent protein (EGFP) adult OSCs grafted into white juvenile host gonads gave rise to EGFP OSCs, and oocytes. Last, the axolotl ovaries completely regenerated after partial ovariectomy injury. During regeneration, OSC activation resulted in rapid differentiation into new oocytes, which was demonstrated by Vasa(+) /BrdU(+) coexpression. Furthermore, follicle cell proliferation promoted follicle maturation during ovarian regeneration. Overall, these results show that adult oogenesis occurs via proliferation of endogenous OSCs in a tetrapod and mediates ovarian regeneration. This study lays the foundations to elucidate mechanisms of ovarian regeneration that will assist regenerative medicine in treating premature ovarian failure and reduced fertility. Stem Cells 2017;35:236-247.//////////////////
Phenotypes
Mutations
1 mutations
Species: D. melanogaster
Mutation name: None
type: null mutation fertility: infertile - ovarian defect Comment: Loss-of-function mutations of Vas have been isolated which affect the egg
and the embryonic abdominal segment and are maternal effect male sterile, maternal effect female sterile and maternal
effect recessive lethal.