Zika virus (ZIKV) is a teratogenic human pathogen that causes congenital eye and brain diseases. Affected babies exhibit vision impairment and associated ocular pathology, including loss of foveal reflex and macular pigment mottling, chorioretinal scarring, and macular atrophy. ZIKV has become endemic and local transmissions in the USA have been reported previously. The long-term effects of structural damage on vision, as well as the pathogenic processes of congenital ZIKV eye diseases are beginning to be understood. The signaling pathways governing normal eye development, which are dysregulated during ZIKV infection, are not well characterized. We recently carried out a series of experiments by establishing a ZIKV infectious ocular cell culture system and mouse models to understand the structural and molecular perturbations. For successful replication, viruses have evolved various strategies to evade innate immune response as well as to enhance the availability of cellular metabolites required to meet the heightened energy demand for viral genome synthesis. We found that the AMPK?, a cellular master energy sensor, is activated in the ZIKV-infected retinal cells. Moreover, pharmacological activation of AMPK resulted in attenuated ZIKV replication. Another interesting finding is that the YAP/TAZ factors in the tumor suppressor Hippo/SWH signaling pathway were induced early on, but degraded at later stage of ZIKV infection in RPE cells. Silencing YAP/TAZ resulted in reduced ZIKV replication. Since the energy sensor AMPK and Hippo signaling pathways control key cellular processes, including host antiviral responses, it is critical to understand the fundamental mechanism of these two pathways deregulation. We hypothesize that ZIKV modulates AMPK and Hippo signaling pathways in ocular cells to 1) increase intracellular metabolic resources, and 2) inhibit TBK1 to antagonize antiviral defense. These molecular changes can be orchestrated through viral coded factors resulting in the pathogenesis of ocular cell injury. The following specific aims will be investigated.
Aim 1 focuses on systematically evaluating the role of AMPK- Hippo signaling on regulating antiviral response to ZIKV infection in RPE cells. The cross talk between these pathways will be investigated at the YAP/TAZ level. Pharmacological activation/inhibition, and gene knockout approaches in RPE cells will be carried out.
Aim 2 is designed to elucidate the effect of ZIKV on Hippo and AMPK signaling pathways during retinal development. Human iPSC-derived 3D-retinal cup organoids will be used to investigate the link between retinal development and ZIKV-mediated deregulation of these key pathways. The ZIKV-encoded virulence factors regulating these pathways will be characterized.
Aim 3 is to determine the effect of RPE-specific ablation of AMPK, TBK1, and Hippo signaling on the pathogenesis of ZIKV-induced chorioretinal atrophy in mice. This proposed study would yield novel insights into the pathogenesis of ZIKV in ocular diseases and identification of potential therapeutic targets.
Zika virus (ZIKV), an emerging human pathogen, causes congenital eye and neurological diseases, and we observed that ZIKV modulates the components of developmental Hippo signaling and energy sensor AMPK pathways in infected ocular cells. The molecular mechanisms of AMPK and Hippo pathway deregulation and the role of Zika viral virulence factors in ocular injury and development is poorly understood. We propose to elucidate the basic mechanisms of ZIKV mediated- deregulation of AMPK and Hippo pathways and cellular antiviral response using human ocular cell culture systems, retinal cup organoids, and mice models, which could yield novel insights into the pathogenesis of ZIKV ocular disease.