Hypoxia-inducible factor-1 alpha is involved in RIP-induced necroptosis caused by in vitro and in vivo ischemic brain injury

Sci Rep. 2017 Jul 19;7(1):5818. doi: 10.1038/s41598-017-06088-0.

Abstract

Necroptosis, a novel type of programmed cell death, is involved in stroke-induced ischemic brain injury. Although studies have sought to explore the mechanisms of necroptosis, its signaling pathway has not yet to be completely elucidated. Thus, we used oxygen-glucose deprivation (OGD) and middle cerebral artery occlusion (MCAO) models mimicking ischemic stroke (IS) conditions to investigate mechanisms of necroptosis. We found that OGD and MCAO induced cell death, local brain ischemia and neurological deficit, while zVAD-fmk (zVAD, an apoptotic inhibitor), GSK'872 (a receptor interacting protein kinase-3 (RIP3) inhibitor), and combined treatment alleviated cell death and ischemic brain injury. Moreover, OGD and MCAO upregulated protein expression of the triggers of necroptosis: receptor interacting protein kinase-1 (RIP1), RIP3 and mixed lineage kinase domain-like protein (MLKL). The upregulation of these proteins was inhibited by GSK'872, combination treatments and RIP3 siRNA but not zVAD treatment. Intriguingly, hypoxia-inducible factor-1 alpha (HIF-1α), an important transcriptional factor under hypoxic conditions, was upregulated by OGD and MCAO. Similar to their inhibitory effects on aforementioned proteins upregulation, GSK'872, combination treatments and RIP3 siRNA decreased HIF-1α protein level. These findings indicate that necroptosis contributes to ischemic brain injury induced by OGD and MCAO and implicate HIF-1α, RIP1, RIP3, and MLKL in necroptosis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Chloromethyl Ketones
  • Animals
  • Apoptosis*
  • Brain Injuries / complications
  • Brain Injuries / metabolism*
  • Brain Injuries / pathology*
  • Brain Ischemia / complications
  • Brain Ischemia / metabolism*
  • Brain Ischemia / pathology*
  • Cell Line
  • Down-Regulation / drug effects
  • GTPase-Activating Proteins / metabolism*
  • Glucose / deficiency
  • Hypoxia-Inducible Factor 1, alpha Subunit / metabolism*
  • Infarction, Middle Cerebral Artery / complications
  • Infarction, Middle Cerebral Artery / metabolism
  • Infarction, Middle Cerebral Artery / pathology
  • Male
  • Mice, Inbred C57BL
  • Necrosis
  • Oxygen
  • RNA, Small Interfering / metabolism
  • Receptor-Interacting Protein Serine-Threonine Kinases / metabolism*
  • Reperfusion Injury / metabolism
  • Reperfusion Injury / pathology

Substances

  • Amino Acid Chloromethyl Ketones
  • GTPase-Activating Proteins
  • Hypoxia-Inducible Factor 1, alpha Subunit
  • RNA, Small Interfering
  • Ralbp1 protein, mouse
  • benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone
  • Receptor-Interacting Protein Serine-Threonine Kinases
  • Ripk3 protein, mouse
  • Glucose
  • Oxygen