engleski

Remodeling of the endosomal system during Murine Cytomegalovirus infection

INTRODUCTION: Mouse cytomegalovirus (MCMV) is a large DNA virus, part of the Herpesviridae family, with a number of genes that manipulate cellular functions. Among many other modifications, MCMV reorganizes endosomal system of the host cell in order to establish environment for virion envelopment. The endosomal reorganization starts early in the infection and continues throughout the entire replication cycle until the assembly compartment is established at the beginning of the late phase of infection. In our study, we focused on the early phase of the viral infection. MATERIALS AND METHODS: We infected Balb 3T3 fibroblasts with recombinant murine cytomegalovirus ΔMC95.15 with deleted m138 gene that encodes a protein with immunoglobulin binding capacity (viral FcR). Selected markers of endocytic pathways were followed by immunofluorescence and confocal microscopy using corresponding antibodies or fluorescently labelled ligands. The intracellular routes were determined by functional assays. Western-blot analysis was used to elucidate intracellular expression of endosome regulating proteins of Rab and Arf family. RESULTS: The endosomal remodeling was apparent at 6 hours post infection as juxtanuclear vacuole-tubular compartment(s) that retained early endosomal cargo molecules (i.e. TfR, MHC- I) and markers (i.e. EEA1, Rab5). This compartment was characterized using a set of early endosomal as well as “early” (i.e. MLN64) and “late” (i.e. NPC1) late endosomal markers. The endosomal system reshaping was associated with rapid downregulation of Rab proteins that regulate endosomal recycling (Rab4, Rab22a, Rab11, Arf1), early-to-late endosome transit (Rab7 and Rab9) or late endosomal recycling (Rab27a). CONCLUSIONs: Observed perturbations indicate that MCMV uses a mechanism of rapid Rab or Arf protein degradation in order to reshape endosomal system.

MCMV; intracellular membrane system; Balb 3T3 fibroblasts

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