title: WT1 protein is cleaved by caspase-3 in apoptotic leukemic cells.
abstract: The aberrant overexpression of Wilms' tumor-1 gene (WT1) plays an important role in blast cell survival and resistance to chemotherapy in acute myeloid leukemia (AML). Here, we found in chemotherapeutic drug etoposide-induced apoptosis, WT1 protein was cleaved into smaller fragment by caspase-3 in leukemic cells. The cleavage was blocked by pan-caspase inhibitor and special caspase-3 inhibitor, suggesting that caspase-3 might cleave WT1 protein. Furthermore, recombinant active caspase-3 cleaved the Flag-WT1 and GST-WT1 proteins in vitro. However, site-directed mutagenesis analyses failed to identify caspase-3-targeted sites in WT1 protein, indicating that caspase-3 cleaved uncommon sites but not classical motifs (DXXD) and non-classical motifs (XXXD). Finally, Eto decreased c-Myc and Bcl-2 expression via reducing the binding of WT1 to the promoter and Eto-induced apoptosis was partially prevented by overexpression of WT1. Collectively, we identify a new substrate for caspase-3 and shed new light on understanding the complicated biology of WT1 in leukemia.
authors.affiliation: a Department of Hematology , the Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University , Wenzhou , Zhejiang Province , China.
authors.forename: Jichen
authors.initials: J
authors.lastname: Ruan
authors.affiliation: b Laboratory of Internal Medicine , the First Affiliated Hospital of Wenzhou Medical University , Wenzhou , Zhejiang Province , China.
authors.forename: Shenmeng
authors.initials: S
authors.lastname: Gao
authors.affiliation: c Department of Laboratory Medicine , the Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University , Wenzhou , Zhejiang Province , China.
authors.forename: Junjun
authors.initials: J
authors.lastname: Yang
authors.affiliation: b Laboratory of Internal Medicine , the First Affiliated Hospital of Wenzhou Medical University , Wenzhou , Zhejiang Province , China.
authors.forename: Haiying
authors.initials: H
authors.lastname: Li
authors.affiliation: a Department of Hematology , the Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University , Wenzhou , Zhejiang Province , China.
authors.forename: He
authors.initials: H
authors.lastname: Huang
authors.affiliation: c Department of Laboratory Medicine , the Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University , Wenzhou , Zhejiang Province , China.
authors.forename: Xiaoqun
authors.initials: X
authors.lastname: Zheng
mesh_terms: D000595:Amino Acid Sequence; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D053148:Caspase 3 / Q000378:metabolism*; D045744:Cell Line, Tumor; D015973:Gene Expression Regulation, Leukemic; D006801:Humans; D007938:Leukemia / Q000378:metabolism*; D059748:Proteolysis; D011993:Recombinant Fusion Proteins; D014158:Transcription, Genetic; D025721:WT1 Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D011993:Recombinant Fusion Proteins; D025721:WT1 Proteins; D053148:Caspase 3
keywords: WT1; caspase-3; cleavage