title: Δ40p53 is involved in the inactivation of autophagy and contributes to inhibition of cell death in HCT116-Δ40p53 cells.
abstract: Δ40p53 is an isoform of wild-type p53 (wtp53). Here, we assessed whether Δ40p53 has the same functions as wild-type p53 in the regulation of cell death and autophagy. First, we used HCT116 (p53+/+) and H1299 (p53-free) cells to produce two cell lines (HCT116-Δ40p53 and H1299-Δ40p53) that express exogenous Δ40p53 but not wtp53. By using these cell lines, we determined that Δ40p53 inhibited starvation-induced autophagy, as does wtp53. This inhibition arises from both Δ40p53 and wtp53 having 3'-5' exonuclease activity, which reduces the levels of double-stranded RNA (dsRNA) and then inhibits PKR/eIF2α-induced autophagy in cells exposed to starvation. Like wtp53, the translocation of Δ40p53 to the nucleus increased in cells in response to Methyl methane sulfonate (MMS) treatment-induced DNA damage. Previous studies have shown that nuclear wtp53 can induce DRAM expression and DRAM-induced autophagy in cells in response to DNA damage, thereby contributing to apoptotic cell death as DRAM-induced autophagy is a pro-apoptotic factor. Here, nuclear Δ40p53 did not individually induce DRAM-induced autophagy and cell death in response to DNA damage. However, nuclear Δ40p53 inhibited wtp53-induced DRAM expression and cell death. Thus, Δ40p53 and wtp53 have 3'-5' exonuclease activity and inhibit starvation-induced autophagy in the cytoplasm; however, nuclear Δ40p53 inhibits wtp53-induced cell death by impairing the transactivation activity of wtp53. Because wtp53 inhibits tumor and viral infection by inhibiting autophagy and promoting degradation of viral dsRNA, it is reasonable to believe that Δ40p53 has the similar functions. A deeper study of these functions of Δ40p53 is needed in the future.
authors.affiliation: Capital Medical University affiliated Beijing You An Hospital, Beijing 100069, China.|Organ Transplantation Center, The Affiliated Hospital of Qingdao University, Shandong Province, 266003, China.
authors.forename: Yunjin
authors.initials: Y
authors.lastname: Zang
authors.affiliation: Beijing Institute of Hepatology, Beijing 100069, China.|Capital Medical University affiliated Beijing You An Hospital, Beijing 100069, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Shi
authors.affiliation: Beijing Institute of Hepatology, Beijing 100069, China.|Capital Medical University affiliated Beijing You An Hospital, Beijing 100069, China.
authors.forename: Kai
authors.initials: K
authors.lastname: Liu
authors.affiliation: Beijing Institute of Hepatology, Beijing 100069, China.|Capital Medical University affiliated Beijing You An Hospital, Beijing 100069, China.
authors.forename: Luxin
authors.initials: L
authors.lastname: Qiao
authors.affiliation: Beijing Institute of Hepatology, Beijing 100069, China.|Capital Medical University affiliated Beijing You An Hospital, Beijing 100069, China.
authors.forename: Xianghua
authors.initials: X
authors.lastname: Guo
authors.affiliation: Beijing Institute of Hepatology, Beijing 100069, China.|Capital Medical University affiliated Beijing You An Hospital, Beijing 100069, China.|Organ Transplantation Center, The Affiliated Hospital of Qingdao University, Shandong Province, 266003, China.
authors.forename: Dexi
authors.initials: D
authors.lastname: Chen
mesh_terms: D001343:Autophagy / Q000502:physiology*; D005455:Fluorescent Antibody Technique; D005786:Gene Expression Regulation / Q000502:physiology*; D045325:HCT116 Cells; D006801:Humans; D015151:Immunoblotting; D008565:Membrane Proteins / Q000378:metabolism; D016133:Polymerase Chain Reaction; D020033:Protein Isoforms / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
chemical_list: C512709:DRAM1 protein, human; D008565:Membrane Proteins; D020033:Protein Isoforms; D016159:Tumor Suppressor Protein p53
keywords: autophagy; cell death; wild-type p53; Δ40p53