AKT signaling promotes derivation of embryonic germ cells from primordial germ cells. Export

@article{citeulike:2294869, abstract = {Primordial germ cells (PGCs) are embryonic germ cell precursors. Although the developmental potency of PGCs is restricted to the germ lineage, PGCs can acquire pluripotency, as verified by the in vitro establishment of embryonic germ (EG) cells and the in vivo production of testicular teratomas. PGC-specific inactivation of PTEN, which is a lipid phosphatase antagonizing phosphoinositide-3 kinase (PI3K), enhances both EG cell production and testicular teratoma formation. Here, we analyzed the effect of the serine/threonine kinase AKT, one of the major downstream effectors of PI3K, on the developmental potency of PGCs. We used transgenic mice that expressed an AKT-MER fusion protein, the kinase activity of which could be regulated by the ligand of modified estrogen receptor (MER), 4-hydroxytamoxifen. We found that hyperactivation of AKT signaling in PGCs at the proliferative phase dramatically augmented the efficiency of EG cell establishment. Furthermore, AKT signaling activation substituted to some extent for the effects of bFGF, an essential growth factor for EG cell establishment. By contrast, AKT activation had no effect on germ cells that were in mitotic arrest or that began meiosis at a later embryonic stage. In the transgenic PGCs, AKT activation induced phosphorylation of GSK3, which inhibits its kinase activity; enhanced the stability and nuclear localization of MDM2; and suppressed p53 phosphorylation, which is required for its activation. The p53 deficiency, but not GSK3 inhibition, recapitulated the effects of AKT hyperactivation on EG cell derivation, suggesting that p53 is one of the crucial downstream targets of the PI3K/AKT signal and that GSK3 is not.}, author = {Kimura, Tohru and Tomooka, Maya and Yamano, Noriko and Murayama, Kazushige and Matoba, Shogo and Umehara, Hiroki and Kanai, Yoshiakira and Nakano, Toru}, citeulike-article-id = {2294869}, citeulike-linkout-0 = {http://dx.doi.org/10.1242/dev.013474}, citeulike-linkout-1 = {http://view.ncbi.nlm.nih.gov/pubmed/18216173}, citeulike-linkout-2 = {http://www.hubmed.org/display.cgi?uids=18216173}, day = {23}, doi = {10.1242/dev.013474}, issn = {0950-1991}, journal = {Development}, keywords = {akt, gsk3, mdm2, p53, pgc, pi3k}, month = {January}, posted-at = {2008-01-27 12:34:43}, priority = {2}, title = {AKT signaling promotes derivation of embryonic germ cells from primordial germ cells.}, url = {http://dx.doi.org/10.1242/dev.013474}, year = {2008} }

TY - JOUR ID - citeulike:2294869 L3 - citeulike-article-id:2294869 N2 - Primordial germ cells (PGCs) are embryonic germ cell precursors. Although the developmental potency of PGCs is restricted to the germ lineage, PGCs can acquire pluripotency, as verified by the in vitro establishment of embryonic germ (EG) cells and the in vivo production of testicular teratomas. PGC-specific inactivation of PTEN, which is a lipid phosphatase antagonizing phosphoinositide-3 kinase (PI3K), enhances both EG cell production and testicular teratoma formation. Here, we analyzed the effect of the serine/threonine kinase AKT, one of the major downstream effectors of PI3K, on the developmental potency of PGCs. We used transgenic mice that expressed an AKT-MER fusion protein, the kinase activity of which could be regulated by the ligand of modified estrogen receptor (MER), 4-hydroxytamoxifen. We found that hyperactivation of AKT signaling in PGCs at the proliferative phase dramatically augmented the efficiency of EG cell establishment. Furthermore, AKT signaling activation substituted to some extent for the effects of bFGF, an essential growth factor for EG cell establishment. By contrast, AKT activation had no effect on germ cells that were in mitotic arrest or that began meiosis at a later embryonic stage. In the transgenic PGCs, AKT activation induced phosphorylation of GSK3, which inhibits its kinase activity; enhanced the stability and nuclear localization of MDM2; and suppressed p53 phosphorylation, which is required for its activation. The p53 deficiency, but not GSK3 inhibition, recapitulated the effects of AKT hyperactivation on EG cell derivation, suggesting that p53 is one of the crucial downstream targets of the PI3K/AKT signal and that GSK3 is not. JF - Development SN - 0950-1991 TI - AKT signaling promotes derivation of embryonic germ cells from primordial germ cells. KW - akt KW - gsk3 KW - mdm2 KW - p53 KW - pgc KW - pi3k AU - Kimura, Tohru AU - Tomooka, Maya AU - Yamano, Noriko AU - Murayama, Kazushige AU - Matoba, Shogo AU - Umehara, Hiroki AU - Kanai, Yoshiakira AU - Nakano, Toru PY - 2008/01/23/ UR - http://dx.doi.org/10.1242/dev.013474 ER -