2. Academic Validation
  3. RhoA/Cdc42 signaling drives cytoplasmic maturation but not endomitosis in megakaryocytes

RhoA/Cdc42 signaling drives cytoplasmic maturation but not endomitosis in megakaryocytes

  • Cell Rep. 2021 May 11;35(6):109102. doi: 10.1016/j.celrep.2021.109102.
Tobias Heib 1,  Heike M Hermanns 2,  Georgi Manukjan 1,  Maximilian Englert 1,  Charly Kusch 1,  Isabelle Carlotta Becker 1,  Annika Gerber 1,  Lou Martha Wackerbarth 1,  Philipp Burkard 1,  Thomas Dandekar 3,  Johannes Balkenhol 4,  Daniel Jahn 2,  Sarah Beck 1,  Mara Meub 5,  Sebastian Dütting 1,  Christian Stigloher 6,  Markus Sauer 5,  Deya Cherpokova 1,  Harald Schulze 1,  Cord Brakebusch 7,  Bernhard Nieswandt 8,  Zoltan Nagy 1,  Irina Pleines 9
Affiliations

Affiliations

  • 1 Institute of Experimental Biomedicine, University Hospital, University of Würzburg, 97080 Würzburg, Germany; Rudolf Virchow Center, University of Würzburg, 97080 Würzburg, Germany.
  • 2 Department of Internal Medicine II, Hepatology Research Laboratory, University Hospital Würzburg, 97080 Würzburg, Germany.
  • 3 Department of Bioinformatics, Biocenter, University of Würzburg, 97074 Würzburg, Germany.
  • 4 Department of Internal Medicine II, Hepatology Research Laboratory, University Hospital Würzburg, 97080 Würzburg, Germany; Department of Bioinformatics, Biocenter, University of Würzburg, 97074 Würzburg, Germany.
  • 5 Department of Biotechnology and Biophysics, Biocenter, University of Würzburg, 97074 Würzburg, Germany.
  • 6 Imaging Core Facility, Biocenter, University of Würzburg, 97074 Würzburg, Germany.
  • 7 Biotech Research and Innovation Centre (BRIC), University of Copenhagen, 2200 Copenhagen, Denmark.
  • 8 Institute of Experimental Biomedicine, University Hospital, University of Würzburg, 97080 Würzburg, Germany; Rudolf Virchow Center, University of Würzburg, 97080 Würzburg, Germany. Electronic address: bernhard.nieswandt@virchow.uni-wuerzburg.de.
  • 9 Institute of Experimental Biomedicine, University Hospital, University of Würzburg, 97080 Würzburg, Germany; Rudolf Virchow Center, University of Würzburg, 97080 Würzburg, Germany. Electronic address: pleines_i@ukw.de.
PMID: 33979620 DOI: 10.1016/j.celrep.2021.109102
Abstract

Megakaryocytes (MKs), the precursors of blood platelets, are large, polyploid cells residing mainly in the bone marrow. We have previously shown that balanced signaling of the Rho GTPases RhoA and Cdc42 is critical for correct MK localization at bone marrow sinusoids in vivo. Using conditional RhoA/Cdc42 double-knockout (DKO) mice, we reveal here that RhoA/Cdc42 signaling is dispensable for the process of polyploidization in MKs but essential for cytoplasmic MK maturation. Proplatelet formation is virtually abrogated in the absence of RhoA/Cdc42 and leads to severe macrothrombocytopenia in DKO Animals. The MK maturation defect is associated with downregulation of Myosin light chain 2 (MLC2) and β1-tubulin, as well as an upregulation of LIM kinase 1 and cofilin-1 at both the mRNA and protein level and can be linked to impaired MKL1/SRF signaling. Our findings demonstrate that MK endomitosis and cytoplasmic maturation are separately regulated processes, and the latter is critically controlled by RhoA/Cdc42.

Keywords

Cdc42; Rho GTPase; RhoA; cytoskeleton; endomitosis; megakaryocyte; platelet; proplatelet formation; transcription.

Figures
Products