Browsing by Subject "Primordial germ cells"

Now showing 1 - 3 of 3
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    In vitro differentiation of primordial germ cells and oocyte-like cells from stem cells
    (Universidad de Murcia. Departamento de Biología Celular e Histología, 2018) Costa, José J.N.; Souza, Glaucinete B.; Soares, Maria A.A.; Ribeiro, Regislane P.; van den Hurk, Robert; Silva, José R.V.
    Infertility is the result of failure due to an organic disorder of the reproductive organs, especially their gametes. Recently, much progress has been made on generating germ cells, including oocytes, from various types of stem cells. This review focuses on advances in female germ cell differentiation from different kinds of stem cells, with emphasis on embryonic stem cells, adult stem cells, and induced pluripotent stem cells. The advantages and disadvantages of the derivation of female germ cells from several types of stem cells are also highlighted, as well as the ability of stem cells to generate mature and functional female gametes. This review shows that stem cell therapies have opened new frontiers in medicine, especially in the reproductive area, with the possibility of regenerating fertility.
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    Induction of pluripotency in primordial germ cells
    (Murcia: F. Hernández, 2011) Kimura, Tohru; Nakano, Toru
    Summary. Primordial germ cells (PGCs) are the founder cells of all gametes. PGCs differentiate from pluripotent epiblasts cells by mesodermal induction signals during gastrulation. Although PGCs are unipotent cells that eventually differentiate into only sperm or oocytes, they dedifferentitate to pluripotent stem cells known as embryonic germ cells (EGCs) in vitro and give rise to testicular teratomas in vivo, which indicates a “metastable” differentiation state of PGCs. We have shown that an appropriate level of phosphoinositide-3 kinase (PI3K)/Akt signaling, balanced by positive and negative regulators, ensures the establishment of the male germ lineage by preventing its dedifferentiation. Specifically, hyper-activation of the signal leads to testicular teratomas and enhances EGC derivation efficiency. In addition, PI3K/Akt signaling promotes PGC dedifferentiation via inhibition of the tumor suppressor p53, a downstream molecule of the PI3K/Akt signal. On the other hand, Akt activation during mesodermal differentiation of embryonic stem cells (ESCs) generates PGC-like pluripotent cells, a process presumably induced through equilibrium between mesodermal differentiation signals and dedifferentiationinducing activity of Akt. The transfer of these cells to ESC culture conditions results in reversion to an ESClike state. The interconversion between ESC and PGClike cells helps us to understand the metastability of PGCs. The regulatory mechanisms of PGC dedifferentiation are discussed in comparison with those involved in the dedifferentiation of testicular stem cells, ESC pluripotency, and somatic nuclear reprogramming.
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    The expression of a novel cxcr4 gene in Xenopus embryo
    (Murcia : F. Hernández, 2009) Alonso, Edurne; Gómez-Santos, Laura; Sáez, F.J.; Madrid Cuevas, Juan Francisco
    The aim of the present work was to identify a homologue of zebrafish cxcr4b in Xenopus, which could be involved in primordial germ cell (PGC) guidance migration. Following a BLAST analysis, the clone gi 27519681, homologous to the zebrafish gene z-cxcr4b, was identified, inserted into pCMV-SPORT6 plasmid and cloned in Escherichia coli. Embryonic expression of x-cxcr4b was analyzed by RT-PCR. X-cxcr4b was weakly expressed maternally but sharply increased after the mid-blastula transition (MBT), declining significantly at stage 45 when PGCs migration is complete. In contrast, RT-PCR of isolated presumptive PGCs showed strong maternal expression at stage 8, which decreased by stage 10 post-MBT and was not detected at stage 14. Whole mount in situ hybridization of x-cxcr4b mRNA showed that this gene is expressed in neural and haematopoietic tissues, and should be linked to important processes during embryonic development of these organs. Although weak staining could be seen in some samples within the anterior endoderm, expression of x-cxcr4b was never coincident with that of Xpat mRNA, which labels PGCs restricted to the posterior endoderm. Therefore, maternal x-cxcr4b is specifically downregulated within PGCs at pre-migratory stages while it is expressed in other tissues.