Disruption of the Coxsackievirus and Adenovirus Receptor-Homodimeric Interaction Triggers Lipid Microdomain- and Dynamin-dependent Endocytosis and Lysosomal Targeting

Sara Salinas,Charleine Zussy,Fabien Loustalot,Daniel Henaff,Guillermo Menendez,Penny E Morton,Maddy Parsons,Giampietro Schiavo,Eric J Kremer

doi:10.1074/jbc.m113.518365

Abstract

The coxsackievirus and adenovirus receptor (CAR) serves as a docking factor for some adenovirus (AdV) types and group B coxsackieviruses. Its role in AdV internalization is unclear as studies suggest that its intracellular domain is dispensable for some AdV infection. We previously showed that in motor neurons, AdV induced CAR internalization and co-transport in axons, suggesting that CAR was linked to endocytic and long-range transport machineries. Here, we characterized the mechanisms of CAR endocytosis in neurons and neuronal cells. We found that CAR internalization was lipid microdomain-, actin-, and dynamin-dependent, and subsequently followed by CAR degradation in lysosomes. Moreover, ligands that disrupted the homodimeric CAR interactions in its D1 domains triggered an internalization cascade involving sequences in its intracellular tail.

Highlights

The coxsackievirus and adenovirus receptor (CAR) acts as a docking factor during infection
Multiple Ligands Induced CAR Internalization in Primary Neurons and Neu2A Cells—Receptor engagement by viruses or viral proteins is often linked with conformational changes that can lead to endocytosis of the receptor-pathogen complex
CAV-2 and FKCAV led to CAR internalization in puncta that were positive for Tf, which label endocytic structures (as observed in motor neurons [8]) (Fig. 1, A, B, and E)

Summary

Background

The coxsackievirus and adenovirus receptor (CAR) acts as a docking factor during infection. Our current understanding of its role in AdV entry is that it serves as “docking platform,” but does not significantly participate in internalization This is based primary on the finding that when the entire intracellular tail of CAR is deleted AdV infection still progressed efficiently [6]. Others have showed that CAR may regulate intracellular signaling pathways through engagement with co-receptors such as junctional adhesion molecule type L [10], or after human AdV type 5 (HAdV5) binding [11]. HAdV5 FK was efficiently internalized in lacrimal acinar cells and may stimulate endocytic pathways such as macropinocytosis to regulate HAdV5 entry [12] Whether this effect was CAR-dependent was, not addressed. We demonstrated that CAR was targeted to lysosomes for degradation in primary rodent neuron cultures and in the rodent brain

EXPERIMENTAL PROCEDURES

RESULTS

DISCUSSION