A mechanistic study on thrombus formation in JAK2 V617F and CALR mutated chronic myeloproliferative neoplasia (CMN)
Final Report Abstract
The study explored how JAK2-V617F and CALR genetic mutations contribute to blood clot formation in chronic myeloproliferative neoplasms (MPNs), which include essential thrombocythemia (ET), polycythemia vera (PV), and primary myelofibrosis (PMF). Both mutations significantly increase the risk of thrombosis in MPNs. JAK2-VF mutations enhance interactions between platelets and white blood cells (WBCs), activating the immune system and raising the likelihood of clot formation, while CALR mutations also contributes, though to a lesser extent. This study investigated how these mutations affect blood cells, especially neutrophils (a type of WBCs) and calcium signaling pathways essential for cell function and survival. Mouse model with neutrophil-specific JAK2-VF expression showed significant changes, including increased platelet counts and elevated levels of inflammatory molecules like IL-1α. Neutrophils showed reduced motility, with reduced migration distance and speed, but increased adherence to the endothelium, promoting a pro-thrombotic state. In contrast, CALR mutations did not induce significant cytokine changes and increased adhesion. Using Vav-Cre mouse model with CALR and JAK2-VF mutations where sterile inflammation was induced by inferior vena cava (IVC) stenosis, we found that CALR-mutated mice developed larger blood clots, though less pronounced than in mice with the JAK2-VF mutation. The role of integrin proteins mediating cell interactions in promoting clot formation was also investigated. Blocking integrins resulted in smaller clots and reduced inflammation, suggesting that targeting integrin pathways might reduce thrombosis risk in MPN patients. Further, this study also examined how these mutations affect calcium signaling, crucial for many cellular processes. Cells with the JAK2-VF mutation showed increased calcium influx upon stimulation with erythropoietin (EPO) (a hormone promoting red blood cell production), leading to prolonged cell survival. In contrast, CALR-mutated cells showed reduced calcium signaling. Importantly, inhibiting calcium signaling in JAK2-VF-mutated cells reduced their growth and induced cell death, suggesting that targeting calcium pathways could offer a new therapeutic approach for MPNs. Overall, this study provides key insights into the molecular mechanisms of thrombosis in MPNs, potentially leading to more targeted therapies and improved patient outcomes.
Publications
-
P1004: ACTIVATING MUTATIONS IN JAK2 AND CALR DIFFERENTIALLY AFFECT INTRACELLULAR CALCIUM LEVELS AND CALCIUM FLUX. HemaSphere, 7(S3), e21609c8.
Bhuria, Vikas; Franz, Tobias; Baldauf, Conny; Böttcher, Martin; Chatain, Nicolas; Koschmieder, Steffen; Brümmendorf, Tim H.; Mougiakakos, Dimitrios; Schraven, Burkhart; Kahlfuß, Sascha & Fischer, Thomas
-
Proteomic Profiling and Cytokine Analysis Reveals Molecular Signatures and Inflammatory Factors Associated with Thrombosis in JAK2-V617F Positive Myeloproliferative Neoplasm (MPN) Cohorts. Blood, 142(Supplement 1), 6340-6340.
Bhuria, Vikas; van Ham, Marco; Vogel, Katrin; Waldleben, Ana; Zeremski, Vanja; Böttcher, Martin; Brunner-Weinzierl, Monika; Mougiakakos, Dimitrios; Schraven, Burkhart; Jänsch, Lothar & Fischer, Thomas
-
Activating mutations in JAK2 and CALR differentially affect intracellular calcium flux in store operated calcium entry. Cell Communication and Signaling, 22(1).
Bhuria, Vikas; Franz, Tobias; Baldauf, Conny; Böttcher, Martin; Chatain, Nicolas; Koschmieder, Steffen; Brümmendorf, Tim H.; Mougiakakos, Dimitrios; Schraven, Burkhart; Kahlfuß, Sascha & Fischer, Thomas
-
Neutrophil-specific expression of JAK2-V617F or CALRmut induces distinct inflammatory profiles in myeloproliferative neoplasia. Journal of Hematology & Oncology, 17(1).
Haage, Tobias Ronny; Charakopoulos, Emmanouil; Bhuria, Vikas; Baldauf, Conny K.; Korthals, Mark; Handschuh, Juliane; Müller, Peter; Li, Juan; Harit, Kunjan; Nishanth, Gopala; Frey, Stephanie; Böttcher, Martin; Fischer, Klaus-Dieter; Dudeck, Jan; Dudeck, Anne; Lipka, Daniel B.; Schraven, Burkhart; Green, Anthony R.; Müller, Andreas J. ... & Fischer, Thomas
