Defective tubulin organization and proplatelet formation in murine megakaryocytes lacking Rac1 and Cdc42
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Defective tubulin organization and proplatelet formation in murine megakaryocytes lacking Rac1 and Cdc42. / Pleines, Irina; Dütting, Sebastian; Cherpokova, Deya; Eckly, Anita; Meyer, Imke; Morowski, Martina; Krohne, Georg; Schulze, Harald; Gachet, Christian; Debili, Najet; Brakebusch, Cord Herbert; Nieswandt, Bernhard.
I: Blood, Bind 122, Nr. 18, 31.10.2013, s. 3178-87.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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T1 - Defective tubulin organization and proplatelet formation in murine megakaryocytes lacking Rac1 and Cdc42
AU - Pleines, Irina
AU - Dütting, Sebastian
AU - Cherpokova, Deya
AU - Eckly, Anita
AU - Meyer, Imke
AU - Morowski, Martina
AU - Krohne, Georg
AU - Schulze, Harald
AU - Gachet, Christian
AU - Debili, Najet
AU - Brakebusch, Cord Herbert
AU - Nieswandt, Bernhard
PY - 2013/10/31
Y1 - 2013/10/31
N2 - Blood platelets are anuclear cell fragments that are essential for blood clotting. Platelets are produced by bone marrow megakaryocytes (MKs), which extend protrusions, or so-called proplatelets, into bone marrow sinusoids. Proplatelet formation requires a profound reorganization of the MK actin and tubulin cytoskeleton. Rho GTPases, such as RhoA, Rac1, and Cdc42, are important regulators of cytoskeletal rearrangements in platelets; however, the specific roles of these proteins during platelet production have not been established. Using conditional knockout mice, we show here that Rac1 and Cdc42 possess redundant functions in platelet production and function. In contrast to a single-deficiency of either protein, a double-deficiency of Rac1 and Cdc42 in MKs resulted in macrothrombocytopenia, abnormal platelet morphology, and impaired platelet function. Double-deficient bone marrow MKs matured normally in vivo but displayed highly abnormal morphology and uncontrolled fragmentation. Consistently, a lack of Rac1/Cdc42 virtually abrogated proplatelet formation in vitro. Strikingly, this phenotype was associated with severely defective tubulin organization, whereas actin assembly and structure were barely affected. Together, these results suggest that the combined action of Rac1 and Cdc42 is crucial for platelet production, particularly by regulating microtubule dynamics.
AB - Blood platelets are anuclear cell fragments that are essential for blood clotting. Platelets are produced by bone marrow megakaryocytes (MKs), which extend protrusions, or so-called proplatelets, into bone marrow sinusoids. Proplatelet formation requires a profound reorganization of the MK actin and tubulin cytoskeleton. Rho GTPases, such as RhoA, Rac1, and Cdc42, are important regulators of cytoskeletal rearrangements in platelets; however, the specific roles of these proteins during platelet production have not been established. Using conditional knockout mice, we show here that Rac1 and Cdc42 possess redundant functions in platelet production and function. In contrast to a single-deficiency of either protein, a double-deficiency of Rac1 and Cdc42 in MKs resulted in macrothrombocytopenia, abnormal platelet morphology, and impaired platelet function. Double-deficient bone marrow MKs matured normally in vivo but displayed highly abnormal morphology and uncontrolled fragmentation. Consistently, a lack of Rac1/Cdc42 virtually abrogated proplatelet formation in vitro. Strikingly, this phenotype was associated with severely defective tubulin organization, whereas actin assembly and structure were barely affected. Together, these results suggest that the combined action of Rac1 and Cdc42 is crucial for platelet production, particularly by regulating microtubule dynamics.
KW - Animals
KW - Blotting, Western
KW - Cytoskeleton
KW - Hemostasis
KW - Megakaryocyte Progenitor Cells
KW - Megakaryocytes
KW - Mice
KW - Mice, 129 Strain
KW - Mice, Inbred C57BL
KW - Mice, Knockout
KW - Microscopy, Confocal
KW - Microscopy, Electron, Scanning
KW - Microscopy, Electron, Transmission
KW - Microtubules
KW - Pseudopodia
KW - Thrombocytopenia
KW - Thrombosis
KW - Tubulin
KW - cdc42 GTP-Binding Protein
KW - rac1 GTP-Binding Protein
U2 - 10.1182/blood-2013-03-487942
DO - 10.1182/blood-2013-03-487942
M3 - Journal article
C2 - 23861250
VL - 122
SP - 3178
EP - 3187
JO - Blood
JF - Blood
SN - 0006-4971
IS - 18
ER -
ID: 108162595