The Effect and Mechanism of Action of Nuclear Protein 1 (NUPR1) in Spinal Cord Injury

Abstract

Background: The aim of this study was to explore the action and mechanism of action of nuclear protein 1 (NUPR1) in spinal cord injury (SCI). Methods: P12 cells were treated with thapsigargin (TG) and transfected with small interfering RNA targeting NUPR1 (siNUPR1) and CCAAT/enhancer binding protein homologous protein (CHOP) overexpression plasmid. In terms of the determination on cell viability, proliferation and apoptosis, cell counting kit (CCK)-8, 5-ethynyl-2’-deoxyuridine (EdU) and flow cytometry assays were harnessed. NUPR1, CHOP, B-cell lymphoma-2 (Bcl-2) associated X (Bax), B-cell lymphoma-2 (Bcl-2), cleaved (C)-cysteinyl aspartate specific proteinase (caspase)-12, protein disulfide isomerase (PDI), glucose-regulated protein 78 kDa (GRP78) and death receptor 5 (DR5) levels were tested using Western blot as well as quantitative reverse transcription-polymerase chain reaction (qRT-PCR). Results: NUPR1 expression was significantly boosted in TG-stimulated P12 cells. TG significantly repressed cell viability, proliferation and Bcl-2 level yet facilitated apoptosis and expression levels of Bax, CHOP, PDI, GRP78 and DR5. NUPR1 knockdown reversed the above effects of TG, whilst CHOP overexpression impaired the reversing effect of NUPR1 knockdown. Conclusions: NUPR1 knockdown significantly restrains TG-induced P12 cell loss, via inhibition of CHOP/DR5 axis.