Sendai virus recruits cellular villin to remodel actin cytoskeleton during fusion with hepatocytes

Abstract

MBoC | ARTICLE Sendai virus recruits cellular villin to remodel actin cytoskeleton during fusion with hepatocytes ABSTRACT Reconstituted Sendai viral envelopes (virosomes) are well recognized for their promising potential in membrane fusion-mediated delivery of bioactive molecules to liver cells. Despite the known function of viral envelope glycoproteins in catalyzing fusion with cellular membrane, the role of host cell proteins remains elusive. Here, we used two-dimensional differential in-gel electrophoresis to analyze hepatic cells in early response to virosomeinduced membrane fusion. Quantitative mass spectrometry together with biochemical analysis revealed that villin, an actin-modifying protein, is differentially up-regulated and phosphorylated at threonine 206-an early molecular event during membrane fusion. We found that villin influences actin dynamics and that this influence, in turn, promotes membrane mixing through active participation of Sendai viral envelope glycoproteins. Modulation of villin in host cells also resulted in a discernible effect on the entry and egress of progeny Sendai virus. Taken together, these results suggest a novel mechanism of regulated viral entry in animal cells mediated by host factor villin.

Site‐specific phosphorylation of villin remodels the actin cytoskeleton to regulate Sendai viral glycoprotein‐mediated membrane fusion

“…These findings provide support to our previous observation that cellular villin plays a crucial role in promoting virus-cell fusion [7]. In addition, this study highlights the importance of phosphorylated villin in fostering an enhancement in membrane fusion, through an intense molecular interplay with cytoskeletal actin.…”

“…Biochemical and microscopic analysis of G/F actin distribution in CHO cells showed a marked increase in G/F actin ratio during early events of fusion, indicating significant actin depolymerization initially, which decreased over time pointing out an active rearrangement of actin during fusion (Fig. This is, however, in contrast to what we found in HepG2 cells which exhibited an initial decrease in G/F actin ratio in fusion samples [7]. This is, however, in contrast to what we found in HepG2 cells which exhibited an initial decrease in G/F actin ratio in fusion samples [7].…”

“…As previously observed in HepG2 cells [7], we found that ectopic expression of wild-type villin in these villin-deficient cells exhibits significant enhancement of fusion via villin-actin interplay. As previously observed in HepG2 cells [7], we found that ectopic expression of wild-type villin in these villin-deficient cells exhibits significant enhancement of fusion via villin-actin interplay.…”

“…However, to address the latter issue, the biggest caveat is a relatively low threshold of villin in influencing fusion, thus demandant of a desirable cellular model that does not inflict any interference from endogenous villin. As described earlier, the fusion assays employed in this study (Figs 1 and 2) ensure that information derived is solely due to complete membrane fusion [7]. The high throughput RNA seq data (Ref GEO GSE75094 for CHO and GSE88089 for HepG2) comparing the read count against villin mRNA in HepG2 and CHO cells clearly shows a negligible expression of villin in CHO cells (Fig.…”

“…To demonstrate whether other ABPs could also affect fusion, we have already shown that downregulation of cofilin an ABP that primarily severs actin filaments, significantly reduces membrane fusion [7]. To demonstrate whether other ABPs could also affect fusion, we have already shown that downregulation of cofilin an ABP that primarily severs actin filaments, significantly reduces membrane fusion [7].…”