ABSTRACT
NUP98-HOXA9 [t(7;11) (p15;p15)] is associated with inferior prognosis in de novo and treatment-related acute myeloid leukaemia (AML) and contributes to blast crisis in chronic myeloid leukaemia (CML). We have engineered an inducible transgenic zebrafish harbouring human NUP98-HOXA9 under the zebrafish spi1(pu.1) promoter. NUP98-HOXA9 perturbed zebrafish embryonic haematopoiesis, with upregulated spi1 expression at the expense of gata1a. Markers associated with more differentiated myeloid cells, lcp1, lyz, and mpx were also elevated, but to a lesser extent than spi1, suggesting differentiation of early myeloid progenitors may be impaired by NUP98-HOXA9. Following irradiation, NUP98-HOXA9-expressing embryos showed increased numbers of cells in G2-M transition compared to controls and absence of a normal apoptotic response, which may result from an upregulation of bcl2. These data suggest NUP98-HOXA9-induced oncogenesis may result from a combination of defects in haematopoiesis and an aberrant response to DNA damage. Importantly, 23% of adult NUP98-HOXA9-transgenic fish developed a myeloproliferative neoplasm (MPN) at 19-23 months of age. In summary, we have identified an embryonic haematopoietic phenotype in a transgenic zebrafish line that subsequently develops MPN. This tool provides a unique opportunity for high-throughput in vivo chemical modifier screens to identify novel therapeutic agents in high risk AML.
Subject(s)
Cell Transformation, Neoplastic/genetics , Homeodomain Proteins/genetics , Leukemia, Experimental/genetics , Myeloid Cells/pathology , Myeloproliferative Disorders/genetics , Nuclear Pore Complex Proteins/genetics , Oncogene Proteins, Fusion/genetics , Animals , Animals, Genetically Modified , Apoptosis , Cell Cycle , Cell Lineage , DNA Damage , GATA1 Transcription Factor/physiology , Gene Expression Regulation, Developmental , Gene Expression Regulation, Leukemic , Genes, Reporter , Hematopoiesis/genetics , Homeodomain Proteins/physiology , Humans , Leukemia, Experimental/pathology , Leukemia, Radiation-Induced/genetics , Leukemia, Radiation-Induced/pathology , Myeloid Cells/radiation effects , Myeloproliferative Disorders/pathology , Nuclear Pore Complex Proteins/physiology , Oncogene Proteins, Fusion/physiology , Phenotype , Promoter Regions, Genetic , Proto-Oncogene Proteins/genetics , Recombinant Fusion Proteins/physiology , Trans-Activators/genetics , Transgenes , Zebrafish/embryology , Zebrafish Proteins/physiologyABSTRACT
The aqueous extract of the edible green microalgae Chlorella pyrenoidosa is of interest because of its immunostimulatory activity. Some components in the extract have been identified previously, namely a unique type of arabinogalactan and a galactofuran. Further fractionation of this extract was accomplished by treating the aqueous solution of the fraction precipitated by addition of 1.5vol of 95% ethanol with cetyltrimethylammonium bromide. The residue obtained by concentration of the supernatant was fractionated further by anion-exchange chromatography and size-exclusion chromatography on Sephadex G-100. Two fractions from the latter column were retained, of which one was a starch-like alpha-(1-->4)-linked d-glucan with some alpha-(1-->6) branches, and the other contained a starch plus a mixture of beta-(1-->2)-d-glucans. ESI mass spectrometry was used to show that the mixture contained both cyclic and linear beta-(1-->2)-d-glucans in a cyclic:linear ratio of 64:36, based on intensities of mass spectral peaks. For the cyclic beta-(1-->2)-d-glucans, ring sizes ranged from 18 to 35 monosaccharides with the ring containing 21 glucose units (54% of the cyclic glucans) being greater than three times more abundant than the next most abundant component, the ring containing 22 glucose units (15%). No rings containing 20 glucose units were present. This is the first observation of cyclic beta-(1-->2)-d-glucans in algae, as far as we are aware. For the linear beta-(1-->2)-d-glucans, the component containing 20 glucoses was most abundant (35% of the linear glucans), while the component containing 21 glucose units was the next most abundant (17%). These relatively low-molecular-weight glucans had low immunostimulatory activity.