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Authors: Kumm, Elena J.
Pagel, Oliver
Gambaryan, Stepan
Walter, Ulrich
Zahedi, René P.
Smolenski, Albert
Jurk, Kerstin
Title: The cell cycle checkpoint system MAST(L)-ENSA/ARPP19-PP2A is targeted by cAMP/PKA and cGMP/PKG in anucleate human platelets
Online publication date: 10-Jun-2020
Year of first publication: 2020
Language: english
Abstract: The cell cycle is controlled by microtubule-associated serine/threonine kinase-like (MASTL), which phosphorylates the cAMP-regulated phosphoproteins 19 (ARPP19) at S62 and 19e/α-endosulfine (ENSA) at S67and converts them into protein phosphatase 2A (PP2A) inhibitors. Based on initial proteomic data, we hypothesized that the MASTL-ENSA/ARPP19-PP2A pathway, unknown until now in platelets, is regulated and functional in these anucleate cells. We detected ENSA, ARPP19 and various PP2A subunits (including seven different PP2A B-subunits) in proteomic studies of human platelets. ENSA-S109/ARPP19–S104 were efficiently phosphorylated in platelets treated with cAMP- (iloprost) and cGMP-elevating (NO donors/riociguat) agents. ENSA-S67/ARPP19-S62 phosphorylations increased following PP2A inhibition by okadaic acid (OA) in intact and lysed platelets indicating the presence of MASTL or a related protein kinase in human platelets. These data were validated with recombinant ENSA/ARPP19 and phospho-mutants using recombinant MASTL, protein kinase A and G. Both ARPP19 phosphorylation sites S62/S104 were dephosphorylated by platelet PP2A, but only S62-phosphorylated ARPP19 acted as PP2A inhibitor. Low-dose OA treatment of platelets caused PP2A inhibition, diminished thrombin-stimulated platelet aggregation and increased phosphorylation of distinct sites of VASP, Akt, p38 and ERK1/2 MAP kinases. In summary, our data establish the entire MASTL(like)–ENSA/ARPP19–PP2A pathway in human platelets and important interactions with the PKA, MAPK and PI3K/Akt systems. Keywords: platelets; serine/threonine protein phosphatases; cyclic AMP; cyclic GMP; ENSA; ARPP19; MAP kinase
DDC: 610 Medizin
610 Medical sciences
Institution: Johannes Gutenberg-Universität Mainz
Department: FB 04 Medizin
Place: Mainz
URN: urn:nbn:de:hebis:77-publ-598652
Version: Published version
Publication type: Zeitschriftenaufsatz
License: CC BY
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Journal: Cells
Pages or article number: Art. 472
Publisher: MDPI
Publisher place: Basel
Issue date: 2020
ISSN: 2073-4409
Publisher URL:
Publisher DOI: 10.3390/cells9020472
Appears in collections:JGU-Publikationen

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