The Cell Cycle Checkpoint System MAST(L)-ENSA/ARPP19-PP2A is Targeted by CAMP/PKA and CGMP/PKG in Anucleate Human Platelets
Overview
Biophysics
Cell Biology
Molecular Biology
Authors
Affiliations
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.
Zhao Y, Liu D, Tan F, Yang W Biology (Basel). 2024; 13(3).
PMID: 38534420 PMC: 10968087. DOI: 10.3390/biology13030149.
Zhang P, Solari F, Heemskerk J, Kuijpers M, Sickmann A, Walter U Int J Mol Sci. 2023; 24(9).
PMID: 37175486 PMC: 10178361. DOI: 10.3390/ijms24097776.
The Role of NO/sGC/cGMP/PKG Signaling Pathway in Regulation of Platelet Function.
Gambaryan S Cells. 2022; 11(22).
PMID: 36429131 PMC: 9688146. DOI: 10.3390/cells11223704.
Woranush W, Moskopp M, Noll T, Dieterich P J Cell Mol Med. 2022; 26(23):5887-5900.
PMID: 36372953 PMC: 9716222. DOI: 10.1111/jcmm.17611.
Jurk K, Adenaeuer A, Sollfrank S, Gross K, Hauser F, Czwalinna A Cells. 2022; 11(19).
PMID: 36231035 PMC: 9564339. DOI: 10.3390/cells11193071.