440 publications from this institution
JNK were not causally linked to the upregulation of Flt1 and Angpt2.We demonstrated that PKCinduced transcription of Angpt2 and Flt1 involved the transcription factor Ets1, as a combined knockdown of Fzd5 and Ets1 completely blocked the enhanced Angpt2 expression, and reduced the upregulation of Flt1 by almost 50% (both n¼4, P<0.05).In addition, an intervention with knockdown of Ets1 on top of the Fzd5 knockdown also partially rescued the poor angiogenic phenotype observed in the 3D co-culture model (n¼6, P<0.05), indicating that this transcription factor was critically involved in suppressing angiogenesis in absence of Fzd5.Conclusions: The current study provides evidence for a pro-angiogenic role of Fzd5, which was shown to be involved in endothelial tubule formation, cell cycle progression and migration, and does so by repression of PKC/Ets1-mediated transcription of Flt1 and Angpt2.
Abstract While intrinsic changes in aging hematopoietic stem cells (HSCs) are well characterized, it remains unclear how extrinsic factors affect HSC aging. Here, we demonstrate that cells in the niche—endothelial cells (ECs) and CXCL12‐abundant reticular cells (CARs)—highly express the heme‐degrading enzyme, heme oxygenase 1 (HO‐1), but then decrease its expression with age. HO‐1‐deficient animals (HO‐1 −/− ) have altered numbers of ECs and CARs that produce less hematopoietic factors. HSCs co‐cultured in vitro with HO‐1 −/− mesenchymal stromal cells expand, but have altered kinetic of growth and differentiation of derived colonies. HSCs from young HO‐1 −/− animals have reduced quiescence and regenerative potential. Young HO‐1 −/− HSCs exhibit features of premature exhaustion on the transcriptional and functional level. HO‐1 +/+ HSCs transplanted into HO‐1 −/− recipients exhaust their regenerative potential early and do not reconstitute secondary recipients. In turn, transplantation of HO‐1 −/− HSCs to the HO‐1 +/+ recipients recovers the regenerative potential of HO‐1 −/− HSCs and reverses their transcriptional alterations. Thus, HSC‐extrinsic activity of HO‐1 prevents HSCs from premature exhaustion and may restore the function of aged HSCs.