title: PKC-delta inhibitors sustain self-renewal of mouse embryonic stem cells under hypoxia in 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-1 alpha (HIF-1 alpha). Previous studies have demonstrated that PKC-delta is activated by hypoxia and increases the protein stability and transcriptional activity of HIF-1 alpha in human cancer cells. Furthermore, activation of PKC-delta mediates cardiac differentiation of ESCs and hematopoietic stem cells. However, the role of PKC-delta in hypoxia-induced early differentiation of mESCs remains largely unknown. Here, we show the inhibition of PKC-delta activity prevents the early differentiation of mESCs under hypoxia using PKC-delta inhibitors, GF 109203X and rottlerin. Reduction of PKC-delta activity under hypoxia effectively decreased HIF-1 alpha protein levels and substantially recovered the expression of LIF-specific receptor (LIFR) and phosphorylated-STAT3 in mESCs. Furthermore, PKC-delta 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-delta inhibitors block the early differentiation of mESCs via destabilization of HIF-1 alpha under hypoxia.
authors.affiliation: Research Institute of Pharmaceutical Sciences, NeuroVascular Coordination Research Center, College of Pharmacy, Seoul National University, Seoul 151-742, Korea.
authors.forename: Hyo-Jong
authors.initials: HJ
authors.lastname: Lee
authors.forename: Chul-Ho
authors.initials: CH
authors.lastname: Jeong
authors.forename: Jong-Ho
authors.initials: JH
authors.lastname: Cha
authors.forename: Kyu-Won
authors.initials: KW
authors.lastname: Kim
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects; D015687:Cell Hypoxia / Q000187:drug effects; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D015536:Down-Regulation / Q000187:drug effects; D053595:Embryonic Stem Cells / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology*; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism; D053680:Leukemia Inhibitory Factor Receptor alpha Subunit / Q000378:metabolism; D051379:Mice; D011493:Protein Kinase C / Q000037:antagonists & inhibitors* / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D050796:STAT3 Transcription Factor / Q000378:metabolism
chemical_list: D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D053680:Leukemia Inhibitory Factor Receptor alpha Subunit; C507841:Lifr protein, mouse; D047428:Protein Kinase Inhibitors; D050796:STAT3 Transcription Factor; D011493:Protein Kinase C