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

Tobias Heib; Heike M Hermanns; Georgi Manukjan; Maximilian Englert; Charly Kusch; Isabelle Carlotta Becker; Annika Gerber; Lou Martha Wackerbarth; Philipp Burkard; Thomas Dandekar; Johannes Balkenhol; Daniel Jahn; Sarah Beck; Mara Meub; Sebastian Dütting; Christian Stigloher; Markus Sauer; Deya Cherpokova; Harald Schulze; Cord Brakebusch; Bernhard Nieswandt; Zoltan Nagy; Irina Pleines

doi:10.1016/j.celrep.2021.109102

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.

Authors

Tobias Heib¹, Heike M Hermanns², Georgi Manukjan¹, Maximilian Englert¹, Charly Kusch¹, Isabelle Carlotta Becker¹, Annika Gerber¹, Lou Martha Wackerbarth¹, Philipp Burkard¹, Thomas Dandekar³, Johannes Balkenhol⁴, Daniel Jahn², Sarah Beck¹, Mara Meub⁵, Sebastian Dütting¹, Christian Stigloher⁶, Markus Sauer⁵, Deya Cherpokova¹, Harald Schulze¹, Cord Brakebusch⁷, Bernhard Nieswandt⁸, Zoltan Nagy¹, Irina Pleines⁹

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.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
Cytoplasm / metabolism*
Humans
Megakaryocytes / metabolism*
Mice
Signal Transduction
cdc42 GTP-Binding Protein / metabolism*
rhoA GTP-Binding Protein / metabolism*

Substances

Cdc42 protein, mouse
RhoA protein, mouse
cdc42 GTP-Binding Protein
rhoA GTP-Binding Protein