Divergent roles of β- and γ-actin isoforms during spread of vaccinia virus.

N Bishara Marzook, Sharissa L Latham, Helena Lynn, Christopher Mckenzie, Christine Chaponnier, Georges E Grau, Timothy P Newsome

Cytoskeleton (Hoboken, N.J.) 2017 Mar 17

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Actin is a major component of the cytoskeleton and is present as two isoforms in non-muscle cells: β- and γ-cytoplasmic actin. These isoforms are strikingly conserved, differing by only four N-terminal amino acids. During spread from infected cells, vaccinia virus (VACV) particles induce localized actin nucleation that propel virus to surrounding cells and facilitate cell-to-cell spread of infection. Here we show that virus-tipped actin comets are composed of β- and γ-actin. We employed isoform-specific siRNA knockdown to examine the role of the two isoforms in VACV-induced actin comets. Despite the high level of similarity between the actin isoforms, and their colocalization, VACV-induced actin nucleation was dependent exclusively on β-actin. Knockdown of β-actin led to a reduction in the release of virus from infected cells, a phenotype dependent on virus-induced Arp2/3 complex activity. We suggest that local concentrations of actin isoforms may regulate the activity of cellular actin nucleator complexes. © 2017 Wiley Periodicals, Inc.

Citation

N Bishara Marzook, Sharissa L Latham, Helena Lynn, Christopher Mckenzie, Christine Chaponnier, Georges E Grau, Timothy P Newsome. Divergent roles of β- and γ-actin isoforms during spread of vaccinia virus. Cytoskeleton (Hoboken, N.J.). 2017 Mar 17;74(4):170-183