TY - JOUR A1 - Rosa, Annabelle A1 - Butt, Elke A1 - Hopper, Christopher P. A1 - Loroch, Stefan A1 - Bender, Markus A1 - Schulze, Harald A1 - Sickmann, Albert A1 - Vorlova, Sandra A1 - Seizer, Peter A1 - Heinzmann, David A1 - Zernecke, Alma T1 - Cyclophilin a is not acetylated at lysine-82 and lysine-125 in resting and stimulated platelets JF - International Journal of Molecular Sciences N2 - Cyclophilin A (CyPA) is widely expressed by all prokaryotic and eukaryotic cells. Upon activation, CyPA can be released into the extracellular space to engage in a variety of functions, such as interaction with the CD147 receptor, that contribute to the pathogenesis of cardiovascular diseases. CyPA was recently found to undergo acetylation at K82 and K125, two lysine residues conserved in most species, and these modifications are required for secretion of CyPA in response to cell activation in vascular smooth muscle cells. Herein we addressed whether acetylation at these sites is also required for the release of CyPA from platelets based on the potential for local delivery of CyPA that may exacerbate cardiovascular disease events. Western blot analyses confirmed the presence of CyPA in human and mouse platelets. Thrombin stimulation resulted in CyPA release from platelets; however, no acetylation was observed—neither in cell lysates nor in supernatants of both untreated and activated platelets, nor after immunoprecipitation of CyPA from platelets. Shotgun proteomics detected two CyPA peptide precursors in the recombinant protein, acetylated at K28, but again, no acetylation was found in CyPA derived from resting or stimulated platelets. Our findings suggest that acetylation of CyPA is not a major protein modification in platelets and that CyPA acetylation is not required for its secretion from platelets. KW - Cyclophilin A KW - acetylation KW - platelets KW - CD147 KW - EMMPRIN Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-284011 SN - 1422-0067 VL - 23 IS - 3 ER - TY - JOUR A1 - Wang, Chenglong A1 - Stöckl, Sabine A1 - Li, Shushan A1 - Herrmann, Marietta A1 - Lukas, Christoph A1 - Reinders, Yvonne A1 - Sickmann, Albert A1 - Grässel, Susanne T1 - Effects of extracellular vesicles from osteogenic differentiated human BMSCs on osteogenic and adipogenic differentiation capacity of naïve human BMSCs JF - Cells N2 - Osteoporosis, or steroid-induced osteonecrosis of the hip, is accompanied by increased bone marrow adipogenesis. Such a disorder of adipogenic/osteogenic differentiation, affecting bone-marrow-derived mesenchymal stem cells (BMSCs), contributes to bone loss during aging. Here, we investigated the effects of extracellular vesicles (EVs) isolated from human (h)BMSCs during different stages of osteogenic differentiation on the osteogenic and adipogenic differentiation capacity of naïve (undifferentiated) hBMSCs. We observed that all EV groups increased viability and proliferation capacity and suppressed the apoptosis of naïve hBMSCs. In particular, EVs derived from hBMSCs at late-stage osteogenic differentiation promoted the osteogenic potential of naïve hBMSCs more effectively than EVs derived from naïve hBMSCs (naïve EVs), as indicated by the increased gene expression of COL1A1 and OPN. In contrast, the adipogenic differentiation capacity of naïve hBMSCs was inhibited by treatment with EVs from osteogenic differentiated hBMSCs. Proteomic analysis revealed that osteogenic EVs and naïve EVs contained distinct protein profiles, with pro-osteogenic and anti-adipogenic proteins encapsulated in osteogenic EVs. We speculate that osteogenic EVs could serve as an intercellular communication system between bone- and bone-marrow adipose tissue, for transporting osteogenic factors and thus favoring pro-osteogenic processes. Our data may support the theory of an endocrine circuit with the skeleton functioning as a ductless gland. KW - extracellular vesicles KW - mesenchymal stem cells KW - osteogenic potential KW - osteogenic differentiation KW - adipogenic differentiation KW - ECM remodeling KW - bone regeneration Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-286112 SN - 2073-4409 VL - 11 IS - 16 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 -