![]() ![]() Genomic DNAs were prepared from purified PE tg pro-B cells and five leukemic PE tg mice and subjected to quantitative PCR to quantify D HJ H and V HD HJ H rearrangements using primers that bind the indicated gene segments. The locus is composed of ∼200 V H (red boxes), ∼12 D H (blue), and 4 J H (green) segments that undergo recombination in B-cell precursors to produce a functional V HD HJ H unit. ( A) Schematic of the mouse IgH locus ( Upper). Clonal selection in PAX5-ELN–induced B-ALL. ![]() Clonal Transformation and Collaborating Events with PAX5-ELN Oncoprotein.įig. Immunophenotypic characterization showed that BM, spleen, and lymph nodes (LNs) of leukemic PE tg mice contained an aberrant proportion of CD19 + B cells associated with an aberrant and variable expression of CD23 and Igκ/λ markers ( Fig. This observation indicates that the reported effects on PE tg mice cannot be ascribed to high expression levels of PAX5-ELN fusion protein. Importantly, although the expression of PAX5-ELN was driven by IgH regulatory sequences, immunoblot analysis of protein extracts with a PAX5 paired domain-specific antibody revealed that the abundance of PAX5-ELN was not higher than that of endogenous PAX5 ( Fig. 1 C, Lower) and exhibited blast cells in the bone marrow (BM) ( Fig. Moreover, PE tg mice developed a lymphadenopathy ( Fig. 1 C, Upper) characterized by a massive infiltration of B220 + cells and a dramatic perturbation of the spleen architecture ( Fig. Leukemic development was associated with a splenomegaly ( Fig. Mutant mice that constitutively expressed PAX5-ELN (hereafter PE tg mice) efficiently developed leukemia with a penetrance of 80% at 300 d ( Fig. 39) were immunophenotyped using the B220, CD19, CD23, and Igκ/λ markers. ( G) Total cells from the BM, spleen, and LNs of WT ( Left) and leukemic PE tg ( Right) mouse (no. 83) was subjected to immunoblotting with anti–N-terminal Pax5 (N19) antibody for the detection of PAX5-ELN and endogenous Pax5 and with anti-ELN antibody for the detection of PAX5-ELN and endogenous Eln. ( F) Protein extract of leukemic cells from a B-ALL PE tg mouse (no. ( E) Pictures of May-Grünwald–Giemsa–stained cytospin of BM cells from WT and leukemic PE tg mice. ( D) Staining with hematoxylin and eosin (HE) and immunohistochemistry of B220 are shown of spleens from WT and leukemic PE tg mice. ( C) Pictures of spleens ( Upper) and LNs ( Lower) from WT and leukemic PE tg mice are shown. ( C– E) PAX5-ELN induces B-ALL development characterized by leukemic cell invasion in the bone marrow, spleen, and lymph nodes. ( B) Kaplan–Meier curves of the time to leukemia for cohorts of PE tg mice ( n = 28). Desmos, Desmosine HD, homeodomain OP, octapeptide pVH, VH gene promoter. ![]() The sequence encoding the human PAX5-ELN fusion protein was inserted downstream of Eμ enhancer. ( A) Generation of knockin mouse model expressing PAX5-ELN fusion protein. Human PAX5-ELN expression induces efficient B-ALL development. Hence, our study provides a new in vivo model of human B-ALL and strongly implicates PAX5 fusion proteins as potent oncoproteins in leukemia development.įig. Finally, our molecular and computational approaches identified PAX5-ELN–regulated gene candidates that establish the molecular bases of the preleukemic state to drive B-ALL initiation. Our functional studies demonstrate that PAX5-ELN affected B-cell development in vitro and in vivo featuring an aberrant expansion of the pro-B cell compartment at the preleukemic stage. Leukemic transformation was associated with recurrent secondary mutations on Ptpn11, Kras, Pax5, and Jak3 genes affecting key signaling pathways required for cell proliferation. PAX5-ELN–expressing mice efficiently developed B-ALL with an incidence of 80%. To study the function of the resulting PAX5-ELN fusion protein in B-ALL development, we generated a knockin mouse model in which the PAX5-ELN transgene is expressed specifically in B cells. We previously reported a new recurrent t(7 9)(q11 p13) chromosomal translocation in human B-ALL that juxtaposed PAX5 to the coding sequence of elastin ( ELN). However, the role of PAX5 fusion proteins in B-ALL initiation and transformation is ill-known. PAX5 is a well-known haploinsufficient tumor suppressor gene in human B-cell precursor acute lymphoblastic leukemia (B-ALL) and is involved in various chromosomal translocations that fuse a part of PAX5 with other partners. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |