title: PKA phosphorylation of p62/SQSTM1 regulates PB1 domain interaction partner binding.
abstract: p62, also known as SQSTM1, is a multi-domain signalling scaffold protein involved in numerous critical cellular functions such as autophagy, apoptosis and inflammation. Crucial interactions relevant to these functions are mediated by the N-terminal Phox and Bem1p (PB1) domain, which is divided into two interaction surfaces, one of predominantly acidic and one of basic character. Most known interaction partners, including atypical protein kinase C (aPKC), bind to the basic surface, and acidic-basic interactions at this interface also allow for p62 homopolymerisation. We identify here that the coupling of p62 to the cAMP signalling system is conferred by both the direct binding of cAMP degrading phosphodiesterase-4 (PDE4) to the acidic surface of the p62 PB1 domain and the phosphorylation of the basic surface of this domain by cAMP-dependent protein kinase (PKA). Such phosphorylation is a previously unknown means of regulating PB1 domain interaction partnerships by disrupting the interaction of p62 with basic surface binding partners, such as aPKCs, as well as p62 homopolymerisation. Thus, we uncover a new regulatory mechanism that connects cAMP signalling with the p62 multi-domain signalling scaffold and autophagy cargo receptor protein.
authors.affiliation: Institute of Cardiovascular and Medical Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, UK.
authors.forename: Frank
authors.initials: F
authors.lastname: Christian
authors.affiliation: Leibniz-Institut für Molekulare Pharmakologie (FMP), Campus Berlin-Buch, Robert-Roessle-Str. 10, 13125 Berlin, Germany.
authors.forename: Eberhard
authors.initials: E
authors.lastname: Krause
authors.affiliation: Institute of Pharmaceutical Sciences, King's College London, London SE1 9NH, UK.
authors.forename: Miles D
authors.initials: MD
authors.lastname: Houslay
authors.affiliation: Institute of Cardiovascular and Medical Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, UK. Electronic address: george.baillie@glasgow.ac.uk.
authors.forename: George S
authors.initials: GS
authors.lastname: Baillie
keywords: Autophagy; Phosphodiesterase; Protein kinase A; Protein–protein interaction; cAMP signalling; p62