title: Sall2 is required for proapoptotic Noxa expression and genotoxic stress-induced apoptosis by doxorubicin.
abstract: The Sall2 transcription factor is deregulated in several cancers; however, little is known about its cellular functions, including its target genes. Recently, we demonstrated that p53 directly regulates Sall2 expression under genotoxic stress. Here, we investigated the role of Sall2 in the context of cellular response to genotoxic stress. In addition, we further examined the Sall2-p53 relationship during genotoxic stress in primary mouse embryo fibroblasts (MEFs), which are derived from Sall2 knockout mice separately, or in combination with the p53ERTAM knock-in mice. We found that the levels of Sall2 mRNA and protein are dynamically modulated in response to doxorubicin. At early times of stress, Sall2 is downregulated, but increases under extension of the stress in a p53-independent manner. Based on caspase-3/7 activities, expression of cleaved poly (ADP-ribose) polymerase, expression of cleaved caspase-3 and induction of proapoptotic proteins, Sall2 expression was correlated with cellular apoptosis. Consequently, Sall2-/- MEFs have decreased apoptosis, which relates with increased cell viability in response to doxorubicin. Importantly, Sall2 was required for apoptosis even in the presence of fully activated p53. Searching for putative Sall2 targets that could mediate its role in apoptosis, we identified proapoptotic NOXA/PMAIP1 (phorbol-12-myristate-13-acetate-induced protein 1). We demonstrated that Sall2 positively regulates Noxa promoter activity. Conserved putative Sall2-binding sites at the NOXA promoter were validated in vitro by electrophoretic mobility shift assay and in vivo by ChIP experiments, identifying NOXA as a novel Sall2 target. In agreement, induction of Noxa protein and mRNA in response to doxorubicin was significantly decreased in Sall2-/- MEFs. In addition, studies in leukemia Jurkat T cells support the existence of the Sall2/Noxa axis, and the significance of this axis on the apoptotic response to doxorubicin in cancer cells. Our study highlights the relevance of Sall2 in the apoptotic response to extended genotoxic stress, which is important for understanding its role in normal physiology and disease.
authors.affiliation: Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile.
authors.forename: D
authors.initials: D
authors.lastname: Escobar
authors.affiliation: Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile.
authors.forename: M I
authors.initials: MI
authors.lastname: Hepp
authors.affiliation: Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile.
authors.forename: C
authors.initials: C
authors.lastname: Farkas
authors.affiliation: Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile.
authors.forename: T
authors.initials: T
authors.lastname: Campos
authors.affiliation: Department of Biochemistry, University of Cambridge, Cambridge, UK.
authors.forename: N M
authors.initials: NM
authors.lastname: Sodir
authors.affiliation: Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile.
authors.forename: M
authors.initials: M
authors.lastname: Morales
authors.affiliation: Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile.
authors.forename: C I
authors.initials: CI
authors.lastname: Álvarez
authors.affiliation: Helen Diller Family Comprehensive Cancer Center, University of California San Francisco, San Francisco, CA 94115, USA.
authors.forename: L
authors.initials: L
authors.lastname: Swigart
authors.affiliation: Department of Biochemistry, University of Cambridge, Cambridge, UK.
authors.forename: G I
authors.initials: GI
authors.lastname: Evan
authors.affiliation: Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile.
authors.forename: J L
authors.initials: JL
authors.lastname: Gutiérrez
authors.affiliation: Department of Kidney Development, Institute of Molecular Embryology and Genetics, Kumamoto University, Kumamoto, Japan.
authors.forename: R
authors.initials: R
authors.lastname: Nishinakamura
authors.affiliation: Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile.
authors.forename: A F
authors.initials: AF
authors.lastname: Castro
authors.affiliation: Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile.
authors.forename: R
authors.initials: R
authors.lastname: Pincheira
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D004249:DNA Damage; D004268:DNA-Binding Proteins; D004317:Doxorubicin / Q000008:administration & dosage; D005347:Fibroblasts / Q000473:pathology; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics* / Q000378:metabolism; D019169:Jurkat Cells; D007938:Leukemia / Q000235:genetics* / Q000473:pathology; D051379:Mice; D018345:Mice, Knockout; D011485:Protein Binding; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics* / Q000378:metabolism; D014157:Transcription Factors; D016159:Tumor Suppressor Protein p53 / Q000235:genetics* / Q000378:metabolism
chemical_list: D004268:DNA-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; C408009:Pmaip1 protein, mouse; D019253:Proto-Oncogene Proteins c-bcl-2; C403266:Sall2 protein, mouse; D014157:Transcription Factors; D016159:Tumor Suppressor Protein p53; D004317:Doxorubicin