Inhibition of CRM1-mediated nuclear export of transcription factors by leukemogenic NUP98 fusion proteins.

Abstract

NUP98 is a nucleoporin that plays complex roles in the nucleocytoplasmic trafficking of macromolecules. Rearrangements of the NUP98 gene in human leukemia result in the expression of numerous fusion oncoproteins whose effect on nucleocytoplasmic trafficking is poorly understood. The present study was undertaken to determine the effects of leukemogenic NUP98 fusion proteins on CRM1-mediated nuclear export. NUP98-HOXA9, a prototypic NUP98 fusion, inhibited the nuclear export of two known CRM1 substrates: mutated cytoplasmic nucleophosmin and HIV-1 Rev. In vitro binding assays revealed that NUP98-HOXA9 binds CRM1 through the FG repeat motif in a Ran-GTP-dependent manner similar to but stronger than the interaction between CRM1 and its export substrates. Two NUP98 fusions, NUP98-HOXA9 and NUP98-DDX10, whose fusion partners are structurally and functionally unrelated, interacted with endogenous CRM1 in myeloid cells as shown by co-immunoprecipitation. These leukemogenic NUP98 fusion proteins interacted with CRM1, Ran, and the nucleoporin NUP214 in a manner fundamentally different from that of wild-type NUP98. NUP98-HOXA9 and NUP98-DDX10 formed characteristic aggregates within the nuclei of a myeloid cell line and primary human CD34+ cells and caused aberrant localization of CRM1 to these aggregates. These NUP98 fusions caused nuclear accumulation of two transcription factors, NFAT and NFkappaB, that are regulated by CRM1-mediated export. The nuclear entrapment of NFAT and NFkappaB correlated with enhanced transcription from promoters responsive to these transcription factors. Taken together, the results suggest a new mechanism by which NUP98 fusions dysregulate transcription and cause leukemia, namely, inhibition of CRM1-mediated nuclear export with aberrant nuclear retention of transcriptional regulators.

• Authors: Akiko Takeda, Nayan J Sarma, Anmaar M Abdul-Nabi, Nabeel R Yaseen
• Journal: The Journal of biological chemistry (J Biol Chem) Vol. 285 Issue 21 Pg. 16248-57 (May 21 2010) ISSN: 1083-351X [Electronic] United States
• PMID: 20233715 (Publication Type: Journal Article, Research Support, N.I.H., Extramural)

Chemical References

• Antigens, CD34
• Homeodomain Proteins
• Karyopherins
• NF-kappa B
• NFATC Transcription Factors
• NUP214 protein, human
• NUP98-HOXA9 fusion protein, human
• Nuclear Pore Complex Proteins
• Oncogene Proteins, Fusion
• RAN protein, human
• Receptors, Cytoplasmic and Nuclear
• exportin 1 protein
• rev Gene Products, Human Immunodeficiency Virus
• rev protein, Human Immunodeficiency Virus-1
• Guanosine Triphosphate
• ran GTP-Binding Protein

Topics

• Active Transport, Cell Nucleus (genetics)
• Amino Acid Motifs
• Antigens, CD34
• Cell Nucleus (genetics, metabolism, pathology)
• Guanosine Triphosphate (genetics, metabolism)
• HIV-1 (genetics, metabolism)
• Homeodomain Proteins (genetics, metabolism)
• Humans
• K562 Cells
• Karyopherins (genetics, metabolism)
• Leukemia (genetics, metabolism, pathology)
• Mutation
• NF-kappa B (genetics, metabolism)
• NFATC Transcription Factors (genetics, metabolism)
• Nuclear Pore Complex Proteins (genetics, metabolism)
• Oncogene Proteins, Fusion (genetics, metabolism)
• Promoter Regions, Genetic (genetics)
• Receptors, Cytoplasmic and Nuclear (genetics, metabolism)
• Transcription, Genetic (genetics)
• ran GTP-Binding Protein (genetics, metabolism)
• rev Gene Products, Human Immunodeficiency Virus (genetics, metabolism)