Biosynthesis and Function of Phosphoinositides during Enteroviral Infection

Host cells infected with positive-strand RNA viruses undergo dramatic remodeling of their intracellular membranes into so-called replication organelles (RO). Enterovirus71 (EV71), a member of the Enterovirus genus in the Picornavirus family, replicates its genome in association with membranes. In fact, the RNA virus creates its own genome-replication organelle (RO) with a unique lipid composition, including an abundance of the phosphoinositide (PIP), phosphatidylinositol-4-phosphate (PI4P). During the past five years, many laboratories have been in search of the mechanism by which PI4P biosynthesis is induced by various picornaviruses, including enterovirus 71 (EV71) and poliovirus (PV). In general, these studies tested the hypothesis that a single viral protein hijacks a single cellular PI4 kinase (PI4K), leading to kinase relocalization and synthesis of PI4P. Because of the long-established connection between the enteroviral 3A(B) protein and the guanine nucleotide exchange factor, GBF1, most of the early studies focused on 3A(B) and concluded that this viral protein is responsible for hijacking a PI4K, often by an indirect mechanism. However, this once-held consensus opinion has now returned to uncertainty. Many years ago, our laboratory, in collaboration with Dr. Craig Cameron (the Penn State University, PA, USA) obtained genetic evidence for a possible role of 3CD in the biogenesis of poliovirus (PV) RO. EV-3CD is a PIP-binding protein and a regulator of multiple PIP biosynthetic pathways. Our proposed studies aim to address the questions: Aim 1 – Define the structure-function relationships of the PIP-binding domains of 3C and 3D alone and in the context of 3CD. Aim 2 – Elucidate the mechanism of induction of PI4P biosynthesis by 3CD alone and in the context of infection. Aim 3 – Elucidate the mechanism of induction of PIP2 biosynthesis by 3CD alone and in the context of infection. Aim 4 – Investigate the PIs biosynthesis after enterovirus infection in mice. Completion of these goals will permit us to reduce or eliminate PIP2 production during viral infection, a circumstance that will facilitate discovery of the role of PIP2, if any, during the EV life cycle. Finally, we have the privilege of substantial cross-disciplinary synergy because of the team of collaborators with whom we interact that have been essential to maintaining a vibrant, productive research program. Collectively, the statements above attest to a proposal rife with conceptual, technical and intellectual innovation.

Project ID:PC10708-1222
External Project ID:MOST107-2320-B182-029