PKC-δ inhibitors sustain self-renewal of mouse embryonic stem cells under hypoxiain vitro

Abstract

Under hypoxia, mouse embryonic stem cells (mESCs) lose their self-renewal activity and display an early differentiated morphology mediated by the hypoxia-inducible factor-1α (HIF-1α). Previous studies have demonstrated that PKC-δ is activated by hypoxia and increases the protein stability and transcriptional activity of HIF-1α in human cancer cells. Furthermore, activation of PKC-δ mediates cardiac differentiation of ESCs and hematopoietic stem cells. However, the role of PKC-δ in hypoxia-induced early differentiation of mESCs remains largely unknown. Here, we show the inhibition of PKC-δ activity prevents the early differentiation of mESCs under hypoxia using PKC-δ inhibitors, GF 109203X and rottlerin. Reduction of PKC-δ activity under hypoxia effectively decreased HIF-1α protein levels and substantially recovered the expression of LIF-specific receptor (LIFR) and phosphorylated-STAT3 in mESCs. Furthermore, PKC-δ inhibitors aid to sustain the expression of self-renewal markers and suppress the expression of early differentiation markers in mESCs under hypoxia. Taken together, these results suggest that PKC-δ inhibitors block the early differentiation of mESCs via destabilization of HIF-1α under hypoxia.

Self-Renewal Versus Lineage Commitment of Embryonic Stem Cells: Protein Kinase C Signaling Shifts the Balance

“…S7B). We chose PKCδ because of a recent report 27 that implicated PKCδ inhibition in maintaining mESCs self-renewal in vitro . Compared to the PKCζkd cells, the expression of pluripotency genes, Oct4, Nanog and Sox2, were significantly induced when both PKCζ and PKCδ were knocked-down (Figure S7C).…”

“…In investigating the role of PKC during endothelial differentiation, however, we serendipitously found that inhibition of PKC signaling is sufficient to maintain, derive, and propagate pluripotent ES cells and also facilitates reprogramming of differentiated cells to induce pluripotency. Prior to this study, PKC isoforms have been studied during ES cell differentiation in different perspectives 12–16 . However, the involvement of the PKC signaling pathway in ES cell pluripotency is largely unknown.…”

Chlorogenic acid inhibits hypoxia-induced angiogenesis via down-regulation of the HIF-1α/AKT pathway

“…erythropoiesis, cell proliferation and angiogenesis [2][3][4]. HIF expression is profound in primary tumor tissues and correlates with a poor prognosis in patients with various cancers [5][6][7][8].…”

Suppression of HIF-1α by Valproic Acid Sustains Self-Renewal of Mouse Embryonic Stem Cells under Hypoxia In Vitro

“…Rex1 and Fgf4 are representative markers for mESC stemness and self-renewal activity, whereas Fgf5 and Stat5a are markers for early differentiation (Lee et al , 2010). Expression levels of Rex1 and Fgf4 decreased under hypoxia; treatment with VPA blocked the suppression of the Rex1 and Fgf4 in a dose-dependent manner (Fig.…”

“…Furthermore, we reported that PKC-δ inhibitors block the early differentiation of mESCs under hypoxia via the destabilization of HIF-1α (Lee et al , 2010). HDACIs effectively inhibited HIF-1α stability in cancer cells; however, the relevance of the HDACIs as regulators of self-renewal activity in hypoxia-induced differentiation in mESCs is largely unknown.…”