Putative Role of Nuclear Factor-Kappa B But Not Hypoxia-Inducible Factor-1? in Hypoxia-Dependent Regulation of Oxidative Stress in Hematopoietic Stem and Progenitor Cells.

ABSTRACT: Aims: Adaptation to low oxygen of hematopoietic stem cells (HSCs) in the bone marrow has been demonstrated to depend on the activation of hypoxia-inducible factor (HIF)-1? as well as the limited production of reactive oxygen species (ROS). In this study, we aimed at determining whether HIF-1? is involved in protecting HSCs from ROS. Results: Oxidative stress was induced by DL-buthionine-(S,R)-sulfoximine (BSO)-treatment, which increases the mitochondrial ROS level. Hypoxia rescued Lineage-Sca-1+c-kit+ (LSK) cells from BSO-induced apoptosis, whereas cells succumbed to apoptosis in normoxia. Apoptosis in normoxia was inhibited with the antioxidant N-acetyl-L-cysteine or by overexpression of anti-apoptotic BCL-2. Moreover, stabilized expression of oxygen-insensitive HIFs could not protect LSK cells from oxidative stress-induced apoptosis at normoxia, neither could short hairpin RNA to Hif-1? inhibit the protective effects by hypoxia in LSK cells. Likewise, BSO treatment of LSK cells from Hif-1? knockout mice did not suppress the effects seen in hypoxia. Microarray analysis identified the nuclear factor-kappa B (NF-?B) pathway as a pathway induced by hypoxia. By using NF-?B lentiviral construct and DNA-binding assay, we found increased NF-?B activity in cells cultured in hypoxia compared with normoxia. Using an inhibitor against NF-?B activation, we could confirm the involvement of NF-?B signaling as BSO-mediated cell death was significantly increased in hypoxia after adding the inhibitor. Innovation: HIF-1? is not involved in protecting HSCs and progenitors to elevated levels of ROS on glutathione depletion during hypoxic conditions. Conclusion: The study proposes a putative role of NF-?B signaling as a hypoxia-induced regulator in early hematopoietic cells.

SUBMITTER: Halvarsson C 

PROVIDER: S-EPMC6590716 | biostudies-literature | 2019 Jul

REPOSITORIES: biostudies-literature