SKP2 attenuates autophagy through Beclin1-ubiquitination and its inhibition reduces MERS-Coronavirus infection

Gassen, Nils C.; Niemeyer, Daniela; Muth, Doreen; Corman, Victor M.; Martinelli, Silvia; Gassen, Alwine; Hafner, Kathrin; Papies, Jan; Mösbauer, Kirstin; Zellner, Andreas; Zannas, Anthony S.; Herrmann, Alexander; Holsboer, Florian; Brack-Werner, Ruth; Boshart, Michael; Müller-Myhsok, Bertram; Drosten, Christian; Müller, Marcel A.; Rein, Theo

Autophagy is an essential cellular process affecting virus infections and other diseases and Beclin1 (BECN1) is one of its key regulators. Here, we identified S-phase kinase-associated protein 2 (SKP2) as E3 ligase that executes lysine-48-linked poly-ubiquitination of BECN1, thus promoting its proteasomal degradation. SKP2 activity is regulated by phosphorylation in a hetero-complex involving FKBP51, PHLPP, AKT1, and BECN1. Genetic or pharmacological inhibition of SKP2 decreases BECN1 ubiquitination, decreases BECN1 degradation and enhances autophagic flux. Middle East respiratory syndrome coronavirus (MERS-CoV) multiplication results in reduced BECN1 levels and blocks the fusion of autophagosomes and lysosomes. Inhibitors of SKP2 not only enhance autophagy but also reduce the replication of MERS-CoV up to 28,000-fold. The SKP2-BECN1 link constitutes a promising target for host-directed antiviral drugs and possibly other autophagy-sensitive conditions.