FAST-Mediated Pore Expansion: Novel Roles For Annexin A1 and Plasma Membrane Architecture

Abstract

Two approaches investigating the contribution of cellular factors to syncytiogenesis mediated by viral fusogens are reported in this thesis. These include architecture of plasma membrane curvature and the role of annexin A1. I analyzed the effects of membrane shape modifiers on reptilian reovirus p14- and influenza hemagglutinin-mediated pore formation and expansion. By adding lysophosphatidylcholine following pore formation but prior to syncytiogenesis, I was also able to capture a p14- and HA-mediated ‘stalled pore’ phenotype. I also examined the role of annexin A1 during p14- and measles (F)-mediated cell fusion. Knockdown of AX1 and chelation of intracellular calcium impaired p14- and F-mediated pore expansion but not pore formation. Additionally, a calcium-dependent interaction between p14 and F with AX1 was detected. I conclude that intracellular AX1 and calcium play an important role in the resolution of pores generated between fused cells. These lines of evidence suggest a converging mechanism of pore expansion.