The SQSTM1-NUP214 fusion protein interacts with Crm1, activates Hoxa and Meis1 genes, and drives leukemogenesis in mice

• Published in: PloS one 2020-04, Vol.15 (4), p.e0232036
• Main Authors: Lavau, Catherine P, Aumann, Waitman K, Sze, Sei-Gyung K, Gupta, Veerain, Ripple, Katelyn, Port, Sarah A, Kehlenbach, Ralph H, Wechsler, Daniel S
• Format: Article
• Language: English
• Subjects: Amino Acid Motifs; Amino acids; Animals; B cells; Biology and Life Sciences; Blood diseases; Cancer; Cell Line; Chromatin; Exportin 1 Protein; Fusion protein; Gene expression; Gene Expression Regulation, Neoplastic; Gene mutation; Genes; Genetic aspects; Glycine; Hemopoiesis; Homeodomain Proteins - genetics; HOXA gene; Immunoprecipitation; Karyopherins - metabolism; Leukemia; Leukemia - genetics; Leukemia - metabolism; Leukemia - pathology; Leukemogenesis; Liver transplants; Medicine and Health Sciences; Mice; Molecular biology; Mutagenesis, Site-Directed; Mutation; Myeloid Ecotropic Viral Integration Site 1 Protein - genetics; Myeloid leukemia; Neoplasm Transplantation; Nuclear Pore Complex Proteins - chemistry; Nuclear Pore Complex Proteins - genetics; Nuclear transport; Nucleoporins; Oncogene Proteins, Fusion - chemistry; Oncogene Proteins, Fusion - genetics; Oncogene Proteins, Fusion - metabolism; Pathogenesis; Pediatrics; Phenylalanine; Point Mutation; Protein binding; Proteins; Receptors, Cytoplasmic and Nuclear - metabolism; Sequestosome-1 Protein - genetics; Stem cell transplantation; Transcription factors; Up-Regulation
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0232036

The NUP98 and NUP214 nucleoporins (NUPs) are recurrently fused to heterologous proteins in leukemia. The resulting chimeric oncoproteins retain the phenylalanine-glycine (FG) repeat motifs of the NUP moiety that mediate interaction with the nuclear export receptor Crm1. NUP fusion leukemias are characterized by HOXA gene upregulation; however, their molecular pathogenesis remains poorly understood. To investigate the role of Crm1 in mediating the leukemogenic properties of NUP chimeric proteins, we took advantage of the Sequestosome-1 (SQSTM1)-NUP214 fusion. SQSTM1-NUP214 retains only a short C-terminal portion of NUP214 which contains FG motifs that mediate interaction with Crm1. We introduced point mutations targeting these FG motifs and found that the ability of the resulting SQSTM1-NUP214FGmut protein to interact with Crm1 was reduced by more than 50% compared with SQSTM1-NUP214. Mutation of FG motifs affected transforming potential: while SQSTM1-NUP214 impaired myeloid maturation and conferred robust colony formation to transduced hematopoietic progenitors in a serial replating assay, the effect of SQSTM1-NUP214FGmut was considerably diminished. Moreover, SQSTM1-NUP214 caused myeloid leukemia in all transplanted mice, whereas none of the SQSTM1-NUP214FGmut reconstituted mice developed leukemia. These oncogenic effects coincided with the ability of SQSTM1-NUP214 and SQSTM1-NUP214FGmut to upregulate the expression of Hoxa and Meis1 genes in hematopoietic progenitors. Indeed, chromatin immunoprecipitation assays demonstrated that impaired SQSTM1-NUP214 interaction with Crm1 correlated with impaired binding of the fusion protein to Hoxa and Meis1 genes. These findings highlight the importance of Crm1 in mediating the leukemogenic properties of SQSTM1-NUP214, and suggest a conserved role of Crm1 in recruiting oncoproteins to their effector genes.