Actin-Propelled Invasive Membrane Protrusions Promote Fusogenic Protein Engagement During Cell-Cell Fusion

Shilagardi, Khurts; Li, Shuo; Luo, Fengbao; Faiz, Marikar; Duan, Rui; Jin, Peng; Kim, Ji Hoon; Murnen, Katherine; Chen, Elizabeth H.

doi:10.1126/science.1234781

Cited by 127 publications

(152 citation statements)

References 36 publications

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“…The dynamic nature of Arp3 around the pillars indicates rapid actin nucleation through the Arp2/3 complex during self-contact-induced membrane fusion. This is similar to how membrane protrusions generated by actin polymerization are required for fusogen engagement (24,25). Whether finger-like membrane protrusions or pillar obstacles, these high curvature membrane structures may be selectively inducing actin polymerization until fusion is completed.…”

Section: Discussionmentioning

confidence: 59%

“…Actin rearrangement during myoblast fusion depends on nucleation-promoting factors (23,24) to assist the Arp2/3 complex branching of the actin network. To highlight the importance of actin dynamics during fusion, reconstitution of fusion in a non-fusing cell line, even with the expression of a fusogen, still required actin-driven membrane protrusions to engage the fusogens on opposing membranes (25). The suppression of selfcontact-induced membrane fusion with the Rac1 inhibitor was more robust than with the Cdc42 inhibitor (Fig.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Rho GTPases and the Downstream Effectors Actin-related Protein 2/3 (Arp2/3) Complex and Myosin II Induce Membrane Fusion at Self-contacts

Sumida

Yamada

2015

Journal of Biological Chemistry

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Section: Discussionmentioning

confidence: 59%

Section: Discussionmentioning

confidence: 99%

Rho GTPases and the Downstream Effectors Actin-related Protein 2/3 (Arp2/3) Complex and Myosin II Induce Membrane Fusion at Self-contacts

Sumida

Yamada

2015

Journal of Biological Chemistry

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“…Please note that cell viability after Iressa treatment was measured at 10 and 25 M for Vero, HeLaS3, and HEp-2 cells and at 1, 5, and 10 M for PtK 2 cells. the cell interior, where they can proceed with microtubule transport toward the nuclear pores (24,84,(87)(88)(89).…”

Section: Discussionmentioning

confidence: 99%

Herpes Simplex Virus Internalization into Epithelial Cells Requires Na ⁺ /H ⁺ Exchangers and p21-Activated Kinases but neither Clathrin- nor Caveolin-Mediated Endocytosis

Devadas

Koithan

Diestel

et al. 2014

J Virol

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Herpes simplex virus 1 (HSV-1) is an alphaherpesvirus that has been reported to infect some epithelial cell types by fusion at the plasma membrane but others by endocytosis. To determine the molecular mechanisms of productive HSV-1 cell entry, we perturbed key endocytosis host factors using specific inhibitors, RNA interference (RNAi), or overexpression of dominant negative proteins and investigated their effects on HSV-1 infection in the permissive epithelial cell lines Vero, HeLa, HEp-2, and PtK 2 . HSV-1 internalization required neither endosomal acidification nor clathrin-or caveolin-mediated endocytosis. In contrast, HSV-1 gene expression and internalization were significantly reduced after treatment with 5-(N-ethyl-N-isopropyl)amiloride (EIPA). EIPA blocks the activity of Na ؉ /H ؉ exchangers, which are plasma membrane proteins implicated in all forms of macropinocytosis. HSV-1 internalization furthermore required the function of p21-activated kinases that contribute to macropinosome formation. However, in contrast to some forms of macropinocytosis, HSV-1 did not enlist the activities of protein kinase C (PKC), tyrosine kinases, C-terminal binding protein 1, or dynamin to activate its internalization. These data suggest that HSV-1 depends on Na ؉ /H ؉ exchangers and p21-activated kinases either for macropinocytosis or for local actin rearrangements required for fusion at the plasma membrane or subsequent passage through the actin cortex underneath the plasma membrane. IMPORTANCE After initial replication in epithelial cells, herpes simplex viruses (HSVs) establish latent infections in neurons innervating these regions.Upon primary infection and reactivation from latency, HSVs cause many human skin and neurological diseases, particularly in immunocompromised hosts, despite the availability of effective antiviral drugs. Many viruses use macropinocytosis for virus internalization, and many host factors mediating this entry route have been identified, although the specific perturbation profiles vary for different host and viral cargo. In addition to an established entry pathway via acidic endosomes, we show here that HSV-1 internalization depended on sodium-proton exchangers at the plasma membrane and p21-activated kinases. These results suggest that HSV-1 requires a reorganization of the cortical actin cytoskeleton, either for productive cell entry via pHindependent fusion from macropinosomes or for fusion at the plasma membrane, and subsequent cytosolic passage to microtubules that mediate capsid transport to the nucleus for genome uncoating and replication.

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“…Actin rearrangement was found to be essential for KSHV entry, but it is not clear whether this process is involved in the fusion step of entry (63). It has also been shown in Drosophila cells that actin-propelled membrane protrusions are necessary and sufficient to promote cell-cell fusion mediated by fusogenic proteins (64). VZV gB/gH-gL might also alter the lipid composition of the cellular membrane via ␣V integrins to enhance fusion, as has been proposed for the interaction of the alphaherpesvirus equine herpesvirus 1 gH with the ␣4␤1 integrin (65).…”

Section: Discussionmentioning

confidence: 99%

Role for the αV Integrin Subunit in Varicella-Zoster Virus-Mediated Fusion and Infection

Yang

Arvin

Oliver

2016

J Virol

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Varicella-zoster virus (VZV) is an alphaherpesvirus that causes varicella and herpes zoster. Membrane fusion is essential for VZV entry and the distinctive syncytium formation in VZV-infected skin and neuronal tissue. Herpesvirus fusion is mediated by a complex of glycoproteins gB and gH-gL, which are necessary and sufficient for VZV to induce membrane fusion. However, the cellular requirements of fusion are poorly understood. Integrins have been implicated to facilitate entry of several human herpesviruses, but their role in VZV entry has not yet been explored. To determine the involvement of integrins in VZV fusion, a quantitative cell-cell fusion assay was developed using a VZV-permissive melanoma cell line. The cells constitutively expressed a reporter protein and short hairpin RNAs (shRNAs) to knock down the expression of integrin subunits shown to be expressed in these cells by RNA sequencing. The ␣V integrin subunit was identified as mediating VZV gB/gH-gL fusion, as its knockdown by shRNAs reduced fusion levels to 60% of that of control cells. A comparable reduction in fusion levels was observed when an anti-␣V antibody specific to its extracellular domain was tested in the fusion assay, confirming that the domain was important for VZV fusion. In addition, reduced spread was observed in ␣V knockdown cells infected with the VZV pOka strain relative to that of the control cells. This was demonstrated by reductions in plaque size, replication kinetics, and virion entry in the ␣V subunit knockdown cells. Thus, the ␣V integrin subunit is important for VZV gB/gH-gL fusion and infection. IMPORTANCE Varicella-zoster virus (VZV) is a highly infectious pathogen that causes chickenpox and shingles. A common complication ofshingles is the excruciating condition called postherpetic neuralgia, which has proven difficult to treat. While a vaccine is now available, it is not recommended for immunocompromised individuals and its efficacy decreases with the recipient's age. These limitations highlight the need for new therapies. This study examines the role of integrins in membrane fusion mediated by VZV glycoproteins gB and gH-gL, a required process for VZV infection. This knowledge will further the understanding of VZV entry and provide insight into the development of better therapies. V aricella-zoster virus (VZV) is an alphaherpesvirus and a hostspecific human pathogen that causes the diseases varicella and herpes zoster, commonly known as chickenpox and shingles (1). Prior to the approval of attenuated vaccines by the Food and Drug Administration, varicella was endemic in the United States population and it was estimated that one in three individuals would develop zoster in their lifetime (1, 2). The program for universal varicella vaccination of children in the United States has proven to be successful in preventing disease by reducing varicella incidence by 57% to 90% (3). The zoster vaccine has been effective in reducing the zoster incidence by 51.3% (4). Individuals afflicted with zoster risk developing p...

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Actin-Propelled Invasive Membrane Protrusions Promote Fusogenic Protein Engagement During Cell-Cell Fusion

Cited by 127 publications

References 36 publications

Rho GTPases and the Downstream Effectors Actin-related Protein 2/3 (Arp2/3) Complex and Myosin II Induce Membrane Fusion at Self-contacts

Rho GTPases and the Downstream Effectors Actin-related Protein 2/3 (Arp2/3) Complex and Myosin II Induce Membrane Fusion at Self-contacts

Herpes Simplex Virus Internalization into Epithelial Cells Requires Na ⁺ /H ⁺ Exchangers and p21-Activated Kinases but neither Clathrin- nor Caveolin-Mediated Endocytosis

Role for the αV Integrin Subunit in Varicella-Zoster Virus-Mediated Fusion and Infection

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Actin-Propelled Invasive Membrane Protrusions Promote Fusogenic Protein Engagement During Cell-Cell Fusion

Cited by 127 publications

References 36 publications

Rho GTPases and the Downstream Effectors Actin-related Protein 2/3 (Arp2/3) Complex and Myosin II Induce Membrane Fusion at Self-contacts

Rho GTPases and the Downstream Effectors Actin-related Protein 2/3 (Arp2/3) Complex and Myosin II Induce Membrane Fusion at Self-contacts

Herpes Simplex Virus Internalization into Epithelial Cells Requires Na + /H + Exchangers and p21-Activated Kinases but neither Clathrin- nor Caveolin-Mediated Endocytosis

Role for the αV Integrin Subunit in Varicella-Zoster Virus-Mediated Fusion and Infection

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Herpes Simplex Virus Internalization into Epithelial Cells Requires Na ⁺ /H ⁺ Exchangers and p21-Activated Kinases but neither Clathrin- nor Caveolin-Mediated Endocytosis