TY  - JOUR
A1  - Dütting, Sebastian
A1  - Gaits-Iacovoni, Frederique
A1  - Stegner, David
A1  - Popp, Michael
A1  - Antkowiak, Adrien
A1  - van Eeuwijk, Judith M.M.
A1  - Nurden, Paquita
A1  - Stritt, Simon
A1  - Heib, Tobias
A1  - Aurbach, Katja
A1  - Angay, Oguzhan
A1  - Cherpokova, Deya
A1  - Heinz, Niels
A1  - Baig, Ayesha A.
A1  - Gorelashvili, Maximilian G.
A1  - Gerner, Frank
A1  - Heinze, Katrin G.
A1  - Ware, Jerry
A1  - Krohne, Georg
A1  - Ruggeri, Zaverio M.
A1  - Nurden, Alan T.
A1  - Schulze, Harald
A1  - Modlich, Ute
A1  - Pleines, Irina
A1  - Brakebusch, Cord
A1  - Nieswandt, Bernhard
T1  - A Cdc42/RhoA regulatory circuit downstream of glycoprotein Ib guides transendothelial platelet biogenesis
JF  - Nature Communications
N2  - Blood platelets are produced by large bone marrow (BM) precursor cells, megakaryocytes (MKs), which extend cytoplasmic protrusions (proplatelets) into BM sinusoids. The molecular cues that control MK polarization towards sinusoids and limit transendothelial crossing to proplatelets remain unknown. Here, we show that the small GTPases Cdc42 and RhoA act as a regulatory circuit downstream of the MK-specific mechanoreceptor GPIb to coordinate polarized transendothelial platelet biogenesis. Functional deficiency of either GPIb or Cdc42 impairs transendothelial proplatelet formation. In the absence of RhoA, increased Cdc42 activity and MK hyperpolarization triggers GPIb-dependent transmigration of entire MKs into BM sinusoids. These findings position Cdc42 (go-signal) and RhoA (stop-signal) at the centre of a molecular checkpoint downstream of GPIb that controls transendothelial platelet biogenesis. Our results may open new avenues for the treatment of platelet production disorders and help to explain the thrombocytopenia in patients with Bernard–Soulier syndrome, a bleeding disorder caused by defects in GPIb-IX-V.
KW  - megakaryocytes
KW  - blood platelets
KW  - regulatory circuit downstream
KW  - glycoprotein Ib
Y1  - 2017
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-170797
VL  - 8
IS  - 15838
ER  - 
TY  - JOUR
A1  - Schanbacher, Constanze
A1  - Bieber, Michael
A1  - Reinders, Yvonne
A1  - Cherpokova, Deya
A1  - Teichert, Christina
A1  - Nieswandt, Bernhard
A1  - Sickmann, Albert
A1  - Kleinschnitz, Christoph
A1  - Langhauser, Friederike
A1  - Lorenz, Kristina
T1  - ERK1/2 activity is critical for the outcome of ischemic stroke
JF  - International Journal of Molecular Sciences
N2  - Ischemic disorders are the leading cause of death worldwide. The extracellular signal-regulated kinases 1 and 2 (ERK1/2) are thought to affect the outcome of ischemic stroke. However, it is under debate whether activation or inhibition of ERK1/2 is beneficial. In this study, we report that the ubiquitous overexpression of wild-type ERK2 in mice (ERK2\(^{wt}\)) is detrimental after transient occlusion of the middle cerebral artery (tMCAO), as it led to a massive increase in infarct volume and neurological deficits by increasing blood–brain barrier (BBB) leakiness, inflammation, and the number of apoptotic neurons. To compare ERK1/2 activation and inhibition side-by-side, we also used mice with ubiquitous overexpression of the Raf-kinase inhibitor protein (RKIP\(^{wt}\)) and its phosphorylation-deficient mutant RKIP\(^{S153A}\), known inhibitors of the ERK1/2 signaling cascade. RKIP\(^{wt}\) and RKIP\(^{S153A}\) attenuated ischemia-induced damages, in particular via anti-inflammatory signaling. Taken together, our data suggest that stimulation of the Raf/MEK/ERK1/2-cascade is severely detrimental and its inhibition is rather protective. Thus, a tight control of the ERK1/2 signaling is essential for the outcome in response to ischemic stroke.
KW  - ERK1/2
KW  - tMCAO
KW  - ischemic stroke
KW  - RKIP
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-283991
SN  - 1422-0067
VL  - 23
IS  - 2
ER  -