Ku80 is required but not sufficient for Gα13-mediated endodermal differentiation in P19 embryonic carcinoma cells

Abstract

We have shown that a constitutively active Galpha13 (Galpha13Q226L) induces differentiation in P19 embryonic carcinoma cells to an endodermal phenotype. In this report, we demonstrate that Ku, a heterodimer of p80 (Ku80) and p70 (Ku70), is upregulated in P19 cells overexpressing Galpha13Q226L. Ku is the regulatory subunit of the DNA-dependent protein kinase and is primarily involved in DNA repair and recombination. Ku80 also is a somatostatin receptor. We show that while overexpression of Ku80 drastically reduced P19 cell proliferation, it was not sufficient to induce endodermal differentiation. However, coexpression of Galpha13Q226L and an antisense Ku80 abrogated the retarded growth rate and endodermal differentiation observed in cells expressing only Galpha13Q226L. Overexpression of Galpha13Q226L or Ku80 downregulated RNA polymerase I-mediated transcriptional activity and overexpression of antisense Ku80 restored the activity to control level. These results suggest that Ku80 is required for Galpha13-mediated endodermal differentiation in P19 cells.

Menin induces endodermal differentiation in aggregated P19 stem cells by modulating the retinoic acid receptors

“…Previous studies have shown Gα12 and Gα13 suppressing P19 cell growth [40]. However Gα12- and Gα13-overexpressing cells undergoing endodermal differentiation in monolayers [31–33] stands in contrast to our finding.…”

Retinoic Acid and the Development of the Endoderm

“…This signaling axis has expanded to include other players and it is now generally accepted that extensive crosstalk between disparate signaling pathways are necessary for patterning ExEn. One of these pathways involves heterotrimeric G-protein signaling activated by RA in F9 cells [201,202] and in P19 cells [203][204][205][206][207]. Other gene networks induced by RA include, but are not limited to thyroid hormone signaling involving monocarboxylate transporters [185] and to the positive and negative regulation imparted on the non-canonical and canonical Wnt pathways [30,179,201,[208][209][210][211][212][213]; the latter also linked to Snail1 stabilization.…”

Puromycin-resistant lentiviral control shRNA vector, pLKO.1 induces unexpected cellular differentiation of P19 embryonic stem cells

“…When treated with low dose (10 nM) RA, P19 ES cells cultured in monolayers undergo endodermal differentiation [18,19]. Previously, it has been shown that P19 ES cells retain their stemness when transfected with various plasmid vectors alone that are neomycin- and hygromycin-resistant [25,26,28,30,32]. In compliance, this study shows that the pCDNA3 plasmid vector which is neomycin-resistant does not alter the P19 ES cell phenotype.…”