The clathrin-binding domain of CALM-AF10 alters the phenotype of myeloid neoplasms in mice

• Published in: Oncogene Vol. 31; no. 4; pp. 494 - 506
• Main Authors: Stoddart, A, Tennant, T R, Fernald, A A, Anastasi, J, Brodsky, F M, Le Beau, M M
• Format: Journal Article
• Language: English
• Published: England Nature Publishing Group 26.01.2012
• Subjects: Acute myeloid leukemia; Animal models; Animals; CalM gene; Cancer; Chromosome translocations; Clathrin; Clathrin - physiology; Diagnosis; Endocytosis; fluorescence resonance energy transfer; Fusion protein; Gene expression; Genetic aspects; Genotype & phenotype; Growth factor receptors; Growth factors; Histone H3; Histones - metabolism; Humans; Leukemia; Leukemia, Myeloid, Acute - etiology; Leukemia, Myeloid, Acute - metabolism; Leukemia, Myeloid, Acute - pathology; Leukemogenesis; Lysine; Mice; Mice, Inbred BALB C; MLL protein; Myeloproliferative diseases; Nuclei; Oncogene Proteins, Fusion - chemistry; Oncogene Proteins, Fusion - physiology; Phenotype; Protein Multimerization; Protein Structure, Tertiary; Proteins; Proto-Oncogene Proteins c-kit - metabolism; Receptors, Growth Factor - metabolism; Risk factors; Transcription factors; United States
• ISSN: 0950-9232; 1476-5594
• DOI: 10.1038/onc.2011.251

The PICALM (CALM) gene, whose product is involved in clathrin-mediated endocytosis, has been identified in two recurring chromosomal translocations, involving either MLL or MLLT10 (AF10). We developed a mouse model of CALM-AF10(+) leukemia to examine the hypothesis that disruption of endocytosis contributes to leukemogenesis. Exclusion of the C-terminal portion of CALM from the fusion protein, which is required for optimal binding to clathrin, resulted in the development of a myeloproliferative disease, whereas inclusion of this domain led to the development of acute myeloid leukemia and changes in gene expression of several cancer-related genes, notably Pim1 and Crebbp. Nonetheless, the development of leukemia could not be attributed directly to interference with endocytosis or consequential changes in proliferation and signaling. In leukemia cells, full-length CALM-AF10 localized to the nucleus with no consistent effect on growth factor endocyctosis, and suppressed histone H3 lysine 79 methylation regardless of the presence of clathrin. Using fluorescence resonance energy transfer analysis, we show that CALM-AF10 has a propensity to homo-oligomerize, raising the possibility that the function of endocytic proteins involved in chimeric fusions may be to provide dimerization properties, a recognized mechanism for unleashing oncogenic properties of chimeric transcription factors, rather than disrupting the internalization of growth factor receptors.