KDEL Receptors Assist Dengue Virus Exit from the Endoplasmic Reticulum

Abstract

Membrane receptors at the surface of target cells are key host factors for virion entry; however, it is unknown whether trafficking and secretion of progeny virus requires host intracellular receptors. In this study, we demonstrate that dengue virus (DENV) interacts with KDEL receptors (KDELR), which cycle between the ER and Golgi apparatus, for vesicular transport from ER to Golgi. Depletion of KDELR by siRNA reduced egress of both DENV progeny and recombinant subviral particles (RSPs). Coimmunoprecipitation of KDELR with dengue structural protein prM required three positively charged residues at the N terminus, whose mutation disrupted protein interaction and inhibited RSP transport from the ER to the Golgi. Finally, siRNA depletion of class II Arfs, which results in KDELR accumulation in the Golgi, phenocopied results obtained with mutagenized prME and KDELR knockdown. Our results have uncovered a function for KDELR as an internal receptor involved in DENV trafficking.

New tricks for KDEL receptors

“…Using RSPs, we demonstrated that sequestering KDELR in Golgi apparatus by depletion of the small GTPases Arf4 and Arf5 accumulated RSPs in the ER [7]. We have now found that KDELR knockdown by siRNA reduced egress of RSPs and DENV and have identified three positive charged amino acid residues at the N-terminus of prM that mediate interaction with KDELR in vitro [5]. Only KDELR1 and 2 were involved, similarly to what observed for ECM degradation [4].…”

“…These findings place KDLER at the center of a complex system of signals, which originate at the Golgi but exert their effects at multiple levels. Two recent papers have shed new light on the role of KDELR by implicating them in as diverse functions as cell invasion [4] and virus infection [5]. …”

“…This is an ideal situation to be exploited by professional parasites, such as viruses, which led us to consider the involvement of KDELR in assisting Dengue virus (DENV) secretion [5]. DENV is responsible for 50-100 million infections annually in over 100 endemic countries [6].…”

Activation of Src-family kinases orchestrate secretion of flaviviruses by targeting mature progeny virions to secretory autophagosomes

“…To address mechanisms of virus release, we previously established a cell-line that stably expresses the Dengue structural proteins pre-membrane (prM) and envelope (E), and constitutively secretes non-infectious recombinant virus like particles (VLPs) 13,14 . Transport of these VLPs mimic the intracellular trafficking characteristics of infectious Dengue particles -thus providing a convenient method to identify the molecular determinants of Dengue secretion without confounding effects from viral entry and replication.…”

“…Transport of these VLPs mimic the intracellular trafficking characteristics of infectious Dengue particles -thus providing a convenient method to identify the molecular determinants of Dengue secretion without confounding effects from viral entry and replication. Using this tool, we determined that interaction between Dengue prM and cellular KDEL receptors (KDELRs) facilitated ER-to-Golgi transport of newly formed Dengue particles 13 .…”