Reciprocal regulation of ARPP-16 by PKA and MAST3 kinases provides a cAMP-regulated switch in protein phosphatase 2A inhibition

• DOI: 10.7554/elife.24998
• Publication Date: 2017-06-14T12:00:18Z
• Authors: Veronica Musante; Lu Li; Jean Kanyo; Tukiet T Lam; Christopher M Col...; Shuk Kei Cheng; A Harrison Brody; Paul Greengard; Nicolas Le Novère; Angus C Nairn
• Keywords: 0303 health sciences; phosphatase PP2A; QH301-705.5; Science; Q; R; neurons; Protein Serine-Threonine Kinases; Phosphoproteins; Cyclic AMP-Dependent Protein Kinases; purified proteins; computational model; 03 medical and health sciences; HEK293 Cells; Gene Expression Regulation; hek293 cell line; Cyclic AMP; Medicine; Humans; Protein Phosphatase 2; Biology (General); Microtubule-Associated Proteins; Computational and Systems Biology

ARPP-16, ARPP-19, and ENSA are inhibitors of protein phosphatase PP2A. ARPP-19 and ENSA phosphorylated by Greatwall kinase inhibit PP2A during mitosis. ARPP-16 is expressed in striatal neurons where basal phosphorylation by MAST3 kinase inhibits PP2A and regulates key components of striatal signaling. The ARPP-16/19 proteins were discovered as substrates for PKA, but the function of PKA phosphorylation is unknown. We find that phosphorylation by PKA or MAST3 mutually suppresses the ability of the other kinase to act on ARPP-16. Phosphorylation by PKA also acts to prevent inhibition of PP2A by ARPP-16 phosphorylated by MAST3. Moreover, PKA phosphorylates MAST3 at multiple sites resulting in its inhibition. Mathematical modeling highlights the role of these three regulatory interactions to create a switch-like response to cAMP. Together, the results suggest a complex antagonistic interplay between the control of ARPP-16 by MAST3 and PKA that creates a mechanism whereby cAMP mediates PP2A disinhibition.