An activating mutation in the CSF3R gene induces a hereditary chronic neutrophilia

We identify an autosomal mutation in the CSF3R gene in a family with a chronic neutrophilia. This T617N mutation energetically favors dimerization of the granulocyte colony-stimulating factor (G-CSF) receptor transmembrane domain, and thus, strongly promotes constitutive activation of the receptor and hypersensitivity to G-CSF for proliferation and differentiation, which ultimately leads to chronic neutrophilia. Mutant hematopoietic stem cells yield a myeloproliferative-like disorder in xenotransplantation and syngenic mouse bone marrow engraftment assays. The survey of 12 affected individuals during three generations indicates that only one patient had a myelodysplastic syndrome. Our data thus indicate that mutations in the CSF3R gene can be responsible for hereditary neutrophilia mimicking a myeloproliferative disorder

Combined analysis of cell growth and apoptosis-regulating proteins in HPVs associated anogenital tumors

<p>Abstract</p> <p>Background</p> <p>The clinical course of human papillomavirus (HPV) associated with Bowenoid papulosis and condyloma acuminatum of anogenital tumors are still unknown. Here we evaluated molecules that are relevant to cellular proliferation and regulation of apoptosis in HPV associated anogenital tumors.</p> <p>Methods</p> <p>We investigated the levels of telomerase activity, and inhibitor of apoptosis proteins (IAPs) family (c-IAP1, c-IAP2, XIAP) and c-Myc mRNA expression levels in 20 specimens of Bowenoid papulosis and 36 specimens of condyloma acuminatum in anogenital areas. Overall, phosphorylated (p-) AKT, p-ribosomal protein S6 (S6) and p-4E-binding protein 1 (4EBP1) expression levels were examined by immunohistochemistry in anogenital tumors both with and without positive telomerase activity.</p> <p>Results</p> <p>Positive telomerase activity was detected in 41.7% of Bowenoid papulosis and 27.3% of condyloma acuminatum compared to normal skin (<it>p </it>< 0.001). In contrast, the expression levels of Bowenoid papulosis indicated that c-IAP1, c-IAP2 and XIAP mRNA were significantly upregulated compared to those in both condyloma acuminatum samples (<it>p </it>< 0.001, <it>p </it>< 0.001, <it>p </it>= 0.022, respectively) and normal skin (<it>p </it>< 0.001, <it>p </it>= 0.002, <it>p </it>= 0.034, respectively). Overall, 30% of Bowenoid papulosis with high risk HPV strongly promoted IAPs family and c-Myc but condyloma acuminatum did not significantly activate those genes. Immunohistochemically, p-Akt and p-S6 expressions were associated with positive telomerase activity but not with p-4EBP1 expression.</p> <p>Conclusion</p> <p>Combined analysis of the IAPs family, c-Myc mRNA expression, telomerase activity levels and p-Akt/p-S6 expressions may provide clinically relevant molecular markers in HPV associated anogenital tumors.</p

MEIS1-mediated transactivation of synaptotagmin-like 1 promotes CXCL12/CXCR4 signaling and leukemogenesis

The TALE-class homeoprotein MEIS1 specifically collaborates with HOXA9 to drive myeloid leukemogenesis. Although MEIS1 alone has only a moderate effect on cell proliferation in vitro, it is essential for the development of HOXA9-induced leukemia in vivo. Here, using murine models of leukemogenesis, we have shown that MEIS1 promotes leukemic cell homing and engraftment in bone marrow and enhances cell-cell interactions and cytokine-mediated cell migration. We analyzed global DNA binding of MEIS1 in leukemic cells as well as gene expression alterations in MEIS1-deficent cells and identified synaptotagmin-like 1 (Sytl1, also known as Slp1) as the MEIS1 target gene that cooperates with Hoxa9 in leukemogenesis. Replacement of SYTL1 in MEIS1-deficent cells restored both cell migration and engraftment. Further analysis revealed that SYTL1 promotes cell migration via activation of the CXCL12/CXCR4 axis, as SYTL1 determines intracellular trafficking of CXCR4. Together, our results reveal that MEIS1, through induction of SYTL1, promotes leukemogenesis and supports leukemic cell homing and engraftment, facilitating interactions between leukemic cells and bone marrow stroma

Meis1 regulates self-renewal of HSCs in a cell autonomous manner.

<p>(A) Experimental strategy for analyzing the function of Meis1 in HSCs. Mice with chimeric BM were generated by transplanting CD34⁻ LSK cells (50 cells/mouse) from <i>Mx1-Cre</i>⁺<i>Meis1</i>^fl/fl or control <i>Meis1</i>^fl/fl mice (CD45.2) and an equal number of CD34⁻ LSK cells from wild-type mice (CD45.1/CD45.2) with CD45.1 BM supports cells in lethally irradiated CD45.1 recipient mice. A subset of mice was treated with poly(I:C) three months after transplantation. (B) Mean percentages of CD45.2⁺ cells ± SD in the peripheral blood derived from <i>Meis1</i>^fl/fl (n = 6; open circles) and <i>Mx1-Cre⁺ Meis1</i>^fl/fl (n = 6; closed circles) CD34⁻ LSK cells after poly(I:C) treatment. Initial engraftment of CD45.2⁺ was normalized to 100% for each mouse. *p<0.05 and **p<0.01. (C) Histogram represents mean (± SD) contribution of the indicated splenic cell populations derived from <i>Meis1</i>^fl/fl (n = 6; open bars) and <i>Mx1-Cre</i>⁺<i>Meis1</i>^fl/fl (n = 6; solid bars) CD34⁻ LSK cells three months after poly(I:C) treatment. *p<0.05 and **p<0.01. (D) Mean percentages of CD45.2⁺ cells ± SD in the peripheral blood derived from <i>Meis1</i>^fl/fl (n = 6; open circles) or <i>Mx1-Cre⁺ Meis1</i>^fl/fl (n = 6; closed circles) CD34⁻ LSK cells after secondary transplantation. *p<0.05 and **p<0.01. (E) Total numbers (left) and proportions (right) of different colony types produced by CD34⁻ LSK cells from poly(I:C)-treated <i>Mx1-Cre⁺ Meis1</i>^fl/fl and control <i>Meis1</i>^fl/fl mice (n = 3 per each group). Cultures were assessed on day 14 for granulocyte (CFU-G), monocytes (CFU-M), granulocyte-monocyte (CFU-GM), erythroid (BFU-E) and mixed (CFU-GEMM) colony formation. The data are the means of three-independent experiments. (F) Representative photographs of 14 day colonies derived from CD34⁻ LSK cells from poly(I:C)-treated <i>Mx1-Cre⁺ Meis1</i>^fl/fl- and control <i>Meis1</i>^fl/fl mice (×40 magnification).</p

Meis1 regulates cell cycle of the HSC compartment.

<p>(A) Representative flow cytometric profiles showing Annexin V and 7-AAD staining of LSK cells from <i>Mx1-Cre⁺ Meis1</i>^fl/fl and control mice one week after poly(I:C) treatment. Bar graphs on the right represent the percentages of apoptotic LSK cells (anexin V⁺ 7-AAD⁻) cells from poly(I:C)–treated <i>Mx1-Cre</i>⁺<i>Meis1</i>^fl/fl (solid bars) and control <i>Meis1</i>^fl/fl (open bars) mice (mean and SD; n = 3). (B) Representative flow cytometric profiles showing BrdU incorporation and 7-AAD staining of LSK cells from <i>Mx1-Cre Meis1</i>^fl/fl and control mice one week after poly(I:C) treatment. Bar graphs shown on the right represent the percentages of cells in G0/G1-, S- and G2/M-phase of the cell cycle in the LSK cell population from poly(I:C)–treated <i>Mx1-Cre</i>⁺<i>Meis1</i>^fl/fl (solid bars) and control <i>Meis1</i>^fl/fl (open bars) mice (mean and SD; n = 3). **p<0.01.</p