OC 48.5 - Crucial role of casein kinase 1α in megakaryocyte cytoskeletal rearrangements and thrombopoiesis

Monday, June 24, 2024

15:45 – 16:00 ICT

Room: 211 A-D

Presenting Author(s)

Ferdinand Kollotzek, M. Sc.

PhD Student
Department of Cardiology and Angiology, University of Tuebingen
Tübingen, Baden-Wurttemberg, Germany

Co-Author(s)

Melina Fischer, MSc

PhD Student
Department of Cardiology and Angiology, University of Tuebingen
Tübingen, Baden-Wurttemberg, Germany
PM

Patrick Münzer

Post-Doc
Department of Cardiology and Angiology, University of Tuebingen
Tübingen, Baden-Wurttemberg, Germany
MM

Mailin-Christin Manke

PhD Student
Department of Cardiology and Angiology, University of Tuebingen
Tübingen, Baden-Wurttemberg, Germany
Vanessa Göb

Postdoc
5Institute for Experimental Biomedicine, University Hospital Würzburg
Würzburg, Bayern, Germany
KM

Kristina Mott

Postdoc
University Hospital Würzburg, Department of Experimental Biomedicine I, Würzburg, Germany
Würzburg, Bayern, Germany
IG

Irene Gonzalez Menendez

Postdoc
Institute of Pathology, University of Tübingen, Germany
Tübingen, Baden-Wurttemberg, Germany
LQ

Leticia Quintanilla de Fend

PI
Institute of Pathology, University of Tübingen, Germany
Tübingen, Baden-Wurttemberg, Germany
AM

Andreas Mack

PI
Institute of Anatomy, University of Tübingen, Germany
Tübingen, Baden-Wurttemberg, Germany
HS

Harald Schulze

Professor
University Hospital Würzburg, Department of Experimental Biomedicine I, Würzburg, Germany
Würzburg, Bayern, Germany
DS

David Stegner

PI
Institute for Experimental Biomedicine, University Hospital Würzburg
Würzburg, Bayern, Germany
Robert Ahrends

PI
Department of Analytical Chemistry, University of Vienna, Austria
Wien, Wien, Austria
OB

Oliver Borst

PI
Department of Cardiology and Angiology, University of Tuebingen
Tübingen, Baden-Wurttemberg, Germany

Background: During thrombopoiesis megakaryocytes (MKs) form proplatelets within the bone marrow (BM) and release platelets into BM sinusoids. Casein kinase 1α (CK1α) is involved in phosphorylating several proteins regulating cytoskeleton dynamics and reorganization, cell survival, apoptosis and cell adhesion, but its role in megakaryocytes pathophysiology is mostly unknown.

Aims: In this project we investigate the role of CK1α-dependent signalling pathways involved in MK development including regulation of MK cytoskeleton and pro-platelet formation, which are all elemental for thrombopoiesis. We dissect underlying mechanisms by identification of intracellular interaction partners of CK1α, modification of cytoskeletal structure and membrane composition in proplatelet producing MKs.

Methods: We examine the role of CK1α in the organization of the MK actin and tubulin cytoskeleton during MK maturation, polyploidization, polarization and proplatelet formation. To this end, immunofluorescence staining of femora cryosections, confocal microscopy and transmission electron microscopy (TEM) are being employed, in particular the formation of the demarcation membrane system (DMS) and the microtubule assembly during proplatelet forming as well as the elongation of Csnk1αPf4Δ/Pf4Δ MKs using directed MK spreading. Further, we employ two-photon intravital microscopy (2P-IVM) to investigate the generation of intravascular protrusions with consecutive proplatelet formation in vivo.

Results: As demonstrated by blood counts, CK1α deficiency resulted in a macro-thrombocytopenia. Csnk1αPf4Δ/Pf4Δ mice display a substantial bone marrow hyperplasia and pivotal changes in nuclear lobulation and less contact to BM sinusoids. Investigations of the cytoskeletal organization revealed a decreased amount of polymerized F-Actin and drastically reduced podosome formation of Csnk1αPf4Δ/Pf4Δ MKs. Further, this comes along with a pronounced defect in DMS polarization and decreased formation of proplatelets of Csnk1αPf4Δ/Pf4Δ MKs indicating that CK1α is highly required for proplatelet formation.

Conclusion(s): The present observations unraveled CK1α as an important signaling molecule in MK cytoskeletal dynamics and polarization, proplatelet formation and polyploidization and our results highlight the crucial impact on platelet biogenesis.