Baculovirus actin-rearrangement-inducing factor ARIF-1 induces the formation of dynamic invadosome clusters

Abstract

The baculovirus Autographa californica multiple nucleopolyhedrovirus (AcMNPV), a pathogen of lepidopteran insects, has a striking dependence on the host cell actin cytoskeleton. During the delayed-early stage of infection, AcMNPV was shown to induce the accumulation of actin at the cortex of infected cells. However, the dynamics and molecular mechanism of cortical actin assembly remained unknown. Here, we show that AcMNPV induces dynamic cortical clusters of dot-like actin structures that mediate degradation of underlying extracellular matrix and therefore function similarly to clusters of invadosomes in mammalian cells. Furthermore, we find that the AcMNPV protein actin-rearrangement-inducing factor-1 (ARIF-1), which was previously shown to be necessary and sufficient for cortical actin assembly and efficient viral infection in insect hosts, is both necessary and sufficient for invadosome formation. We mapped the sequences within the C-terminal cytoplasmic region of ARIF-1 that are required for invadosome formation and identified individual tyrosine and proline residues that are required for organizing these structures. Additionally, we found that ARIF-1 and the invadosome-associated proteins cortactin and the Arp2/3 complex localize to invadosomes, and Arp2/3 complex is required for their formation. These ARIF-1-induced invadosomes may be important for the function of ARIF-1 in systemic virus spread. [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text]

Baculovirus Actin Rearrangement-Inducing Factor 1 Can Remodel the Mammalian Actin Cytoskeleton

“…1e ). Our results were consistent with the finding that invadosome formation also requires the membrane-targeted C terminus of Arif-1 ( 16 ).…”

“…A functional role of the C-terminal 200 amino acids for the Arif-1-induced actin changes was initially shown by infection studies with mutant AcMNPV lacking this domain ( 11 ). Recent expression studies of C-terminal truncations of Arif-1 have indicated that the transmembrane domains are also required for Arif-1 function and that the C terminus between residues 303 and 417 is at least necessary for the formation of invadosome clusters in S. frugiperda cells ( 16 ). Here, we expressed either the N- or C-terminal domain of Arif-1 in TN368 cells ( Fig.…”

“…Indeed, studies in larvae infected with genetically modified Bombyx mori nucleopolyhedrovirus (BmNPV) lacking Arif-1 indicated that Arif-1 slows down systemic infection ( 15 ). Moreover, recent findings in cultured Spodoptera frugiperda cells showed that Arif-1 induces the formation of invadosome-like structures which can accelerate infection in larvae by penetrating the basal lamina and thereby assisting passage of the virus from the midgut to the tracheal system ( 16 ). In the mammalian system, invadosomes are known as actin-based structures that are involved in the proteolytic invasion of cells ( 17 ).…”

Quantitative proteomic analysis of extracellular vesicles in response to baculovirus infection of a Trichoplusia ni cell line

“…Lauko et al . showed that baculovirus infection induces the formation of invadosome clusters potentially triggering an active degradation of ECM and Means and Passarelli reported a signalling cascade ultimately leading to rearrangement of the basal lamina upon baculovirus infection [ 48 , 49 ]. It is therefore tempting to speculate that baculoviruses actively downregulate the packaging of ECM components into EVs and thereby counteract the assembly and renewal of ECM layers, which might otherwise hamper systemic infection.…”

Cross Talk between Viruses and Insect Cells Cytoskeleton

“…Arif-1 is expressed at the early stage of baculovirus infection and co-localizes with F-actin at the plasma membrane until late gene expression. It has been suggested that ARIF-1 induces the formation of invadosomelike structures, leading to the formation of organized structures to enable systemic viral spread [40]. The fast and early translocation of the nucleocapsids to the nucleus is critical for baculovirus replication.…”