Regulation of Actin Dynamics by Protein Kinase R Control of Gelsolin Enforces Basal Innate Immune Defense

SummaryPrimary resistance to pathogens is reliant on both basal and inducible immune defenses. To date, research has focused upon inducible innate immune responses. In contrast to resistance via cytokine induction, basal defense mechanisms are less evident. Here we showed that the antiviral protein kinase R (PKR) inhibited the key actin-modifying protein gelsolin to regulate actin dynamics and control cytoskeletal cellular functions under homeostatic conditions. Through this mechanism, PKR controlled fundamental innate immune, actin-dependent processes that included membrane ruffling and particle engulfment. Accordingly, PKR counteracted viral entry into the cell. These findings identify a layer of host resistance, showing that the regulation of actin-modifying proteins during the innate immune response bolsters first-line defense against intracellular pathogens and has a sustained effect on virus production. Moreover, these data provide proof of principle for a concept in which the cell cytoskeleton could be targeted to elicit broad antiviral protection.

Graphical AbstractFigure optionsDownload high-quality image (153 K)Download as PowerPoint slideHighlights
► Basal resistance to pathogens is instigated by regulation of the cell cytoskeleton
► The antiviral PKR controls the actin-modulator gelsolin to instigate this immunity
► PKR affects actin dynamics and fundamental actin-dependent processes
► Gelsolin is a critical factor in resistance to infection