A role for the SNARE protein syntaxin 3 in human cytomegalovirus morphogenesis

• Published in: Cellular microbiology Vol. 13; no. 6; pp. 846 - 858
• Main Authors: Cepeda, Victoria, Fraile‐Ramos, Alberto
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.06.2011; Hindawi Limited
• Subjects: Cell Line; Cell Membrane - chemistry; Cytomegalovirus - physiology; Cytomegalovirus - ultrastructure; endosomes; Herpes simplex virus 1; Herpesvirus 1, Human - physiology; Host-Pathogen Interactions; Human cytomegalovirus; Humans; Immunohistochemistry; Infection; Lysosomes; Membrane fusion; Membrane glycoproteins; Microscopy, Electron; Morphogenesis; N-Ethylmaleimide-sensitive protein; Plasma membranes; Qa-SNARE Proteins - metabolism; Replication; RNA-mediated interference; SNAP receptors; Staining and Labeling; Syntaxin; Virions; Virus Assembly
• ISSN: 1462-5814; 1462-5822
• DOI: 10.1111/j.1462-5822.2011.01583.x

Summary As an enveloped virus, replication of human cytomegalovirus (HCMV) is dependent on interaction with cellular membrane systems. Its final envelopment occurs into intracellular membranes prior to its secretion. However the mechanisms underlying these processes are poorly understood. Here, we show that HCMV infection induces expression of the soluble N‐ethylmaleimide‐sensitive factor attachment protein receptor (SNARE) syntaxin 3 (STX3), a component of the cellular machinery for membrane fusion. STX3 was located at the plasma membrane and at the assembly site where it was found associated with virus wrapping membranes by immunogold labelling. Depletion of STX3 using RNA interference reduced HCMV production, while expression of a STX3 construct resistant to RNAi inhibition enhanced virus production. Ultrastructural examination of the assembly site in HCMV‐infected STX3‐depleted cells showed fewer mature virions and more viruses undergoing final envelopment. In contrast, silencing of STX3 did not affect herpes simplex virus type 1 production. The mechanism through which STX3 affected HCMV morphogenesis likely involved late endosomes/lysosomes since STX3 depletion reduced the expression of lysosomal membrane glycoproteins. Our results demonstrate a function for STX3 in HCMV morphogenesis, and unravel a new role for this SNARE protein in late endosomes/lysosomes compartments.