Project description:Primary myelofibrosis (PMF) is a myeloproliferative neoplasm prone to leukemic transformation, for which limited treatment is available. Amongst individuals diagnosed with PMF, the most prevalent mutation is the JAK2V617F somatic point mutation that activates the Janus kinase 2 (JAK2) enzyme. Our earlier reports on hyperactivity of β1 integrin and enhanced adhesion activity of the α2β1 complex in JAK2V617F megakaryocytes (MKs) led us to examine the new hypothesis that this mutation leads to post-translational modification via changes in glycosylation. Samples were derived from immunoprecipitation of MKs obtained from Vav1-hJAK2V617F and wild type mice. Immunoprecipitated fractions were separated by SDS-PAGE and analyzed using LC-MS/MS techniques in a bottom-up glycoproteomics workflow. In the immunoprecipitate, glycopeptiforms corresponding to 11 out of the 12 potential N-glycosylation sites of integrin β1, and to all nine potential glycosylation sites of integrin α2, were observed. Glycopeptiforms were compared across WT and JAK2V617F phenotypes for both integrins. The overall trend observed is that JAK2V617F mutation in PMF MKs leads to changes in β1 glycosylation; in most cases, it results in an increase in the integrated area of glycopeptiforms. We also observed that, in mutated MKs, changes in integrin α2 glycosylation were more substantial than those observed for integrin β1 glycosylation, a finding that suggests that altered integrin α2 glycosylation may also affect activation. Additionally, the identification of proteins associated to the cytoskeleton that were co-immunoprecipitated with integrins α2 and β1 demonstrated the potential of the methodology employed in this study to provide some insight, at the peptide level, into the consequences of integrin activation in MKs. The extensive and detailed glycosylation patterns we uncovered provide a basis for future functional studies of each site in control cells as compared to JAK2V617F mutated cells.

Project description:Normal donors BM CD34+ cells were differentiated in thrombopoietin-treated liquid suspension cultures. Briefly, CD34+ cells (80,000 /mL) were resuspended in a serum-free medium in the presence of 100 ng/mL of human recombinant thrombopoietin (TPO; Genzyme, Boston, MA). Every 3 days, viable cells were scored by Trypan blue dye exclusion and cultures were amplified with fresh serum-free medium. Each well was then supplemented with 100 ng/mL TPO. After 14 to 16 days of liquid culture, CD34-derived megakaryocytes (MKs) were purified by means of an anti-CD41a monoclonal antibody (MoAb) (Dako, Milan, Italy) directed against the glycoproteic *IIb-*3 complex and immunobeads (MPC 450 Dynabeads; Dynal, Oslo, Norway), as previously described (27). The purity of MKs was determined for each isolation by indirect immunofluorescence, using an anti-CD41b MoAb which reacts with a different epitope of *IIb-*3 subunit (Immunotech Inc., Westbrook, ME), followed by a goat anti-mouse IgG, covalently linked to fluorescein (Becton Dickinson, San Jose, CA). Essential Throbocytemia BM CD34+ cells were differentiated in thrombopoietin-treated liquid suspension cultures. Briefly, CD34+ cells (80,000 /mL) were resuspended in a serum-free medium in the presence of 100 ng/mL of human recombinant thrombopoietin (TPO; Genzyme, Boston, MA). Every 3 days, viable cells were scored by Trypan blue dye exclusion and cultures were amplified with fresh serum-free medium. Each well was then supplemented with 100 ng/mL TPO. After 14 to 16 days of liquid culture, CD34-derived megakaryocytes (MKs) were purified by means of an anti-CD41a monoclonal antibody (MoAb) (Dako, Milan, Italy) directed against the glycoproteic *IIb-*3 complex and immunobeads (MPC 450 Dynabeads; Dynal, Oslo, Norway), as previously described (27). The purity of MKs was determined for each isolation by indirect immunofluorescence, using an anti-CD41b MoAb which reacts with a different epitope of *IIb-*3 subunit (Immunotech Inc., Westbrook, ME), followed by a goat anti-mouse IgG, covalently linked to fluorescein (Becton Dickinson, San Jose, CA). Keywords: other

Project description:Normal donors BM CD34+ cells were differentiated in thrombopoietin-treated liquid suspension cultures. Briefly, CD34+ cells (80,000 /mL) were resuspended in a serum-free medium in the presence of 100 ng/mL of human recombinant thrombopoietin (TPO; Genzyme, Boston, MA). Every 3 days, viable cells were scored by Trypan blue dye exclusion and cultures were amplified with fresh serum-free medium. Each well was then supplemented with 100 ng/mL TPO. After 14 to 16 days of liquid culture, CD34-derived megakaryocytes (MKs) were purified by means of an anti-CD41a monoclonal antibody (MoAb) (Dako, Milan, Italy) directed against the glycoproteic *IIb-*3 complex and immunobeads (MPC 450 Dynabeads; Dynal, Oslo, Norway), as previously described (27). The purity of MKs was determined for each isolation by indirect immunofluorescence, using an anti-CD41b MoAb which reacts with a different epitope of *IIb-*3 subunit (Immunotech Inc., Westbrook, ME), followed by a goat anti-mouse IgG, covalently linked to fluorescein (Becton Dickinson, San Jose, CA). Essential Throbocytemia BM CD34+ cells were differentiated in thrombopoietin-treated liquid suspension cultures. Briefly, CD34+ cells (80,000 /mL) were resuspended in a serum-free medium in the presence of 100 ng/mL of human recombinant thrombopoietin (TPO; Genzyme, Boston, MA). Every 3 days, viable cells were scored by Trypan blue dye exclusion and cultures were amplified with fresh serum-free medium. Each well was then supplemented with 100 ng/mL TPO. After 14 to 16 days of liquid culture, CD34-derived megakaryocytes (MKs) were purified by means of an anti-CD41a monoclonal antibody (MoAb) (Dako, Milan, Italy) directed against the glycoproteic *IIb-*3 complex and immunobeads (MPC 450 Dynabeads; Dynal, Oslo, Norway), as previously described (27). The purity of MKs was determined for each isolation by indirect immunofluorescence, using an anti-CD41b MoAb which reacts with a different epitope of *IIb-*3 subunit (Immunotech Inc., Westbrook, ME), followed by a goat anti-mouse IgG, covalently linked to fluorescein (Becton Dickinson, San Jose, CA).

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Comparison of gene expression in megakaryocytes derived from primary myelofibrosis or healthy individuals

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