Microtubule affinity-regulating kinase 2 potentiates host antiviral defenses by phosphorylating GEF-H1 at serine 645

Abstract The innate immune system is essential for defending against pathogen invasions, effectively controlling infections, and triggering adaptive immune responses to eliminate infectious agents. This study unveils the pivotal role of Microtubule Affinity-Regulating Kinase 2 (MARK2) as a regulator of broad-spectrum antiviral immunity, specifically through its interaction with Guanine nucleotide exchange factor H1 (GEF-H1) and association with TANK-binding kinase 1 (TBK1). Crucially, the antiviral efficacy of MARK2 is dependent on its kinase activity, particularly its capability to phosphorylate GEF-H1 at serine 645. This phosphorylation event is a critical trigger for activating TBK1, leading to the induction of type I interferon (IFN-I) and interferon-stimulated genes (ISGs). Our results demonstrate that GEF-H1 is an ISG, and promoted by MARK2. These findings not only establish MARK2 as a kinase for GEF-H1 but also reveal a previously unrecognized mechanism by which MARK2 potentiates host antiviral defenses. By enhancing IFN-I signaling through strategic phosphorylation of GEF-H1, MARK2 significantly bolsters the antiviral immune response, offering new insights into the molecular orchestration of cellular defense mechanisms.