title: Hypoxic stress induces, but cannot sustain trophoblast stem cell differentiation to labyrinthine placenta due to mitochondrial insufficiency.
abstract: Dysfunctional stem cell differentiation into placental lineages is associated with gestational diseases. Of the differentiated lineages available to trophoblast stem cells (TSC), elevated O2 and mitochondrial function are necessary to placental lineages at the maternal-placental surface and important in the etiology of preeclampsia. TSC lineage imbalance leads to embryonic failure during uterine implantation. Stress at implantation exacerbates stem cell depletion by decreasing proliferation and increasing differentiation. In an implantation site O2 is normally ~2%. In culture, exposure to 2% O2 and fibroblast growth factor 4 (FGF4) enabled the highest mouse TSC multipotency and proliferation. In contrast, hypoxic stress (0.5% O2) initiated the most TSC differentiation after 24h despite exposure to FGF4. However, hypoxic stress supported differentiation poorly after 4-7 days, despite FGF4 removal. At all tested O2 levels, FGF4 maintained Warburg metabolism; mitochondrial inactivity and aerobic glycolysis. However, hypoxic stress suppressed mitochondrial membrane potential and maintained low mitochondrial cytochrome c oxidase (oxidative phosphorylation/OxPhos), and high pyruvate kinase M2 (glycolysis) despite FGF4 removal. Inhibiting OxPhos inhibited optimum differentiation at 20% O2. Moreover, adding differentiation-inducing hyperosmolar stress failed to induce differentiation during hypoxia. Thus, differentiation depended on OxPhos at 20% O2; hypoxic and hyperosmolar stresses did not induce differentiation at 0.5% O2. Hypoxia-limited differentiation and mitochondrial inhibition and activation suggest that differentiation into two lineages of the labyrinthine placenta requires O2>0.5-2% and mitochondrial function. Stress-activated protein kinase increases an early lineage and suppresses later lineages in proportion to the deviation from optimal O2 for multipotency, thus it is the first enzyme reported to prioritize differentiation.
authors.affiliation: CS Mott Center for Human Growth and Development, Department of Ob/Gyn, Reproductive Endocrinology and Infertility, Wayne State University School of Medicine, Detroit, MI 48201, USA.
authors.forename: Yufen
authors.initials: Y
authors.lastname: Xie
authors.affiliation: CS Mott Center for Human Growth and Development, Department of Ob/Gyn, Reproductive Endocrinology and Infertility, Wayne State University School of Medicine, Detroit, MI 48201, USA; Program for Reproductive Sciences, Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, USA.
authors.forename: Sichang
authors.initials: S
authors.lastname: Zhou
authors.affiliation: CS Mott Center for Human Growth and Development, Department of Ob/Gyn, Reproductive Endocrinology and Infertility, Wayne State University School of Medicine, Detroit, MI 48201, USA.
authors.forename: Zhongliang
authors.initials: Z
authors.lastname: Jiang
authors.affiliation: CS Mott Center for Human Growth and Development, Department of Ob/Gyn, Reproductive Endocrinology and Infertility, Wayne State University School of Medicine, Detroit, MI 48201, USA.
authors.forename: Jing
authors.initials: J
authors.lastname: Dai
authors.affiliation: CS Mott Center for Human Growth and Development, Department of Ob/Gyn, Reproductive Endocrinology and Infertility, Wayne State University School of Medicine, Detroit, MI 48201, USA; Program for Reproductive Sciences, Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, USA.
authors.forename: Elizabeth E
authors.initials: EE
authors.lastname: Puscheck
authors.affiliation: College of Medicine, Dankook University, Cheonan-si, Chungcheongnam-do 330-714, Republic of Korea.
authors.forename: Icksoo
authors.initials: I
authors.lastname: Lee
authors.affiliation: Department of Pediatrics and Children's Hospital of Michigan, Wayne State University School of Medicine, USA.
authors.forename: Graham
authors.initials: G
authors.lastname: Parker
authors.affiliation: Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, USA.
authors.forename: Maik
authors.initials: M
authors.lastname: Hüttemann
authors.affiliation: CS Mott Center for Human Growth and Development, Department of Ob/Gyn, Reproductive Endocrinology and Infertility, Wayne State University School of Medicine, Detroit, MI 48201, USA; Program for Reproductive Sciences, Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, USA; Karmanos Cancer Institute, Wayne State University School of Medicine, USA; Institutes for Environmental Health Science, Wayne State University School of Medicine, USA; Department of Biology, University of Windsor, Windsor, ON N9B 3P4, Canada. Electronic address: drappole@med.wayne.edu.
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Rappolee
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects; D015687:Cell Hypoxia; D019070:Cell Lineage; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D004268:DNA-Binding Proteins; D003576:Electron Transport Complex IV / Q000378:metabolism; D005260:Female; D051519:Fibroblast Growth Factor 4 / Q000494:pharmacology; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D051379:Mice; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D048055:Mitogen-Activated Protein Kinase 8 / Q000037:antagonists & inhibitors / Q000378:metabolism; D009479:Neuropeptides / Q000378:metabolism; D010920:Placenta / Q000166:cytology; D011247:Pregnancy; D011257:Pregnancy Proteins / Q000378:metabolism; D011770:Pyruvate Kinase / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D013234:Stem Cells / Q000166:cytology* / Q000378:metabolism; D014157:Transcription Factors; D014327:Trophoblasts / Q000166:cytology*
chemical_list: D000255:Adenosine Triphosphate; D051792:Basic Helix-Loop-Helix Proteins; D004268:DNA-Binding Proteins; D003576:Electron Transport Complex IV; D051519:Fibroblast Growth Factor 4; D048055:Mitogen-Activated Protein Kinase 8; D009479:Neuropeptides; D011257:Pregnancy Proteins; D011770:Pyruvate Kinase; D017382:Reactive Oxygen Species; D014157:Transcription Factors; C101631:Gcm1 protein, mouse; C095572:Hand1 protein, mouse; C558404:Tpbpa protein, mouse