title: Reduction of the neuroprotective transcription factor Npas4 results in increased neuronal necrosis, inflammation and brain lesion size following ischaemia.
abstract: Stroke is the second leading cause of death and the most frequent cause of adult disability. Neuronal Per-Arnt-Sim domain protein 4 (Npas4) is an activity-dependent transcription factor whose expression is induced in various brain insults, including cerebral ischaemia. Although previous studies have demonstrated that Npas4 plays a critical role in protecting neurons against neurodegenerative insults, the neuroprotective effect of Npas4 in response to ischaemic brain injury remains unknown. In this study, we used a loss-of-function approach to examine the neuroprotective potential of Npas4 in the context of ischaemic damage. Using oxygen and glucose deprivation, we demonstrated that the knockdown of Npas4 in mouse cortical neurons resulted in increased susceptibility to cell death. The protective effect of Npas4 was further investigated in vivo using a photochemically-induced stroke model in mice. We found a significantly larger lesion size and increased neurodegeneration in Npas4 knockout mice as compared to wild-type mice. Moreover, we also showed that ablation of Npas4 caused an increase in activated astrocytes and microglia, pro-inflammatory cytokines interleukin-6 and tumour necrosis factor alpha levels and a switch from apoptotic to necrotic cell death. Taken together, these data suggest that Npas4 plays a neuroprotective role in ischaemic stroke by limiting progressive neurodegeneration and neuroinflammation.
authors.affiliation: School of Biological Sciences, The University of Adelaide, Adelaide, SA, Australia.
authors.forename: Fong Chan
authors.initials: FC
authors.lastname: Choy
authors.affiliation: School of Biological Sciences, The University of Adelaide, Adelaide, SA, Australia.
authors.forename: Thomas S
authors.initials: TS
authors.lastname: Klarić
authors.affiliation: School of Biological Sciences, The University of Adelaide, Adelaide, SA, Australia.
authors.forename: Wai Khay
authors.initials: WK
authors.lastname: Leong
authors.affiliation: School of Medicine, The University of Adelaide, Adelaide, SA, Australia.
authors.forename: Simon A
authors.initials: SA
authors.lastname: Koblar
authors.affiliation: School of Biological Sciences, The University of Adelaide, Adelaide, SA, Australia School of Medicine, The University of Adelaide, Adelaide, SA, Australia South Australian Health & Medical Research Institute, North Terrace, Adelaide, SA, Australia martin.lewis@sahmri.com.
authors.forename: Martin D
authors.initials: MD
authors.lastname: Lewis
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics* / Q000378:metabolism; D015153:Blotting, Western; D001921:Brain / Q000276:immunology / Q000378:metabolism* / Q000473:pathology*; D002545:Brain Ischemia / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D003470:Culture Media; D055786:Gene Knockout Techniques; D005947:Glucose / Q000378:metabolism; D007150:Immunohistochemistry; D007249:Inflammation / Q000378:metabolism / Q000473:pathology; D008297:Male; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009474:Neurons / Q000276:immunology / Q000378:metabolism* / Q000473:pathology*; D010100:Oxygen / Q000378:metabolism; D061251:Primary Cell Culture; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D003470:Culture Media; D005947:Glucose; D010100:Oxygen; C481603:NPAS4 protein, human
keywords: Brain ischaemia; Npas4; inflammation; necrosis; neuroprotection