Self-renewal and differentiation of mouse embryonic stem cells as measured by Oct4 expression: the role of the cAMP/PKA pathway |
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Authors: | S Faherty A Fitzgerald M Keohan L R Quinlan |
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Institution: | (1) Department of Physiology, National University of Ireland, Galway, University Road, Galway, Ireland |
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Abstract: | In this study we examined the role of the cAMP/protein kinase A (PKA) pathway in affecting IOUD2 ES cell self-renewal and
differentiation, Oct4 expression, and cell proliferation. Forskolin, the adenylate cyclase agonist, alone had no effect on
ES cell self-renewal. However, when cells were treated with the differentiation-inducing agent retinoic acid, forskolin significantly
promoted ES cell self-renewal. Effectively, forskolin rescued cells from a pathway of differentiation. Culturing ES cells
in the presence of the phosphodiesterase inhibitor IBMX had no effect on ES cell self-renewal but did increase cell proliferation.
In the presence of 100 μM IBMX without LIF, 10 μM forskolin significantly increased ES cell self-renewal. The cell permeable
cAMP analog 8-Br-cAMP (1 and 5 mM) promoted ES cell differentiation in the presence of LIF, while in the absence of LIF, it
promoted ES cell self-renewal. The effect of the PKA specific inhibitors H89 and KT5720 on Oct4 expression was, again, LIF-dependent.
In the presence of LIF, these inhibitors decreased Oct4 expression, while they increased Oct4 expression in the absence of
LIF. In general, ES cells maintained on a self-renewal pathway through the presence of LIF show little effect from altered
cAMP signaling except at higher levels. However, in strict contrast, when ES cell are on a differentiation pathway through
exposure to retinoic acid or the removal of LIF, altering cAMP levels can rescue the self-renewal process promoting Oct4 expression.
This study clearly shows that the cAMP/PKA pathway plays a role in ES cell self-renewal pathways.
This work was partly funded by the Millennium Research Fund National University of Ireland Galway. |
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Keywords: | Mouse Embryonic stem cells Oct4 cAMP PKA Self-renewal |
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