Human kinome profiling identifies a requirement for AMP-activated protein kinase during human cytomegalovirus infection

Abstract

Human cytomegalovirus (HCMV) modulates numerous cellular signaling pathways. Alterations in signaling are evident from the broad changes in cellular phosphorylation that occur during HCMV infection and from the altered activity of multiple kinases. Here we report a comprehensive RNAi screen, which predicts that 106 cellular kinases influence growth of the virus, most of which were not previously linked to HCMV replication. Multiple elements of the AMP-activated protein kinase (AMPK) pathway scored in the screen. As a regulator of carbon and nucleotide metabolism, AMPK is poised to activate many of the metabolic pathways induced by HCMV infection. An AMPK inhibitor, compound C, blocked a substantial portion of HCMV-induced metabolic changes, inhibited the accumulation of all HCMV proteins tested, and markedly reduced the production of infectious progeny. We propose that HCMV requires AMPK or related activity for viral replication and reprogramming of cellular metabolism.herpesvirus | siRNA V iruses are dependent on host cell signaling pathways for replication and spread. Infection with the prevalent β-herpes virus human cytomegalovirus (HCMV) induces increased levels of protein phosphorylation and markedly alters host cell signal transduction pathways (1). A portion of the phosphorylation changes induced by HCMV infection are attributed to the Ser/ Thr kinase encoded by the viral genome, pUL97 (2), and others may derive from cellular kinase(s) packaged into virions (3) or from cellular kinases known to be activated by HCMV (4).Here we sought to more completely delineate the effects of HCMV infection on kinase signaling by performing an siRNA screen of the entire cellular kinome. The screen identified 106 kinases predicted to influence the production of virus. The hits included the 5′-AMP-activated protein kinase (AMPK), a sensor of cellular energy homeostasis. AMPK is composed of three subunits: a catalytic subunit, AMPKα, and two regulatory subunits, AMPKβ and AMPKγ. Activation of the kinase requires cooperative AMP binding to AMPKγ, which occurs stochastically with shifts in the AMP:ATP ratio, and phosphorylation of AMPKα at Thr172 (5, 6). At least three different kinases are reported to phosphorylate Thr172 of AMPKα: Ca 2+ /calmodulindependent kinase kinase (CaMKK), TGF-β-activated kinase 1 (TAK1), and liver kinase B1 (LKB1) (7). Activated AMPK phosphorylates a number of substrates to effect changes in central carbon metabolism, lipid metabolism, physiological homeostasis, cell growth, apoptosis, and gene expression (5).HCMV induces glycolysis (8-10) and also causes increased levels of the glucose transporter GLUT4 at the plasma membrane increasing glucose uptake (11).AMPK controls GLUT4 relocalization to the plasma membrane (5), and this regulation likely links the kinase to altered metabolism in HCMV-infected cells. However, previous work indicates that pharmacological activation of AMPK during the early phase of HCMV infection can be deleterious to viral replication (12), yet CaMKK activity is required for ...

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“…Kinases that act as metabolic regulators in uninfected cells are co-opted by HCMV to remodeling metabolism. Amp-activated protein kinase (AMPK) and calmodulin-dependent kinase kinase (CAMKK) are important for changes in central carbon metabolism (McArdle et al 2012;McArdle et al 2011;Terry et al 2012). Viral changes to fatty acid metabolism involve mTOR signaling (Spencer et al 2011;Purdy et al 2015).…”