Kinesin-1 Proteins KIF5A, -5B, and -5C Promote Anterograde Transport of Herpes Simplex Virus Enveloped Virions in Axons

Abstract

Herpes simplex virus (HSV) and other alphaherpesviruses must spread from sites of viral latency in sensory ganglia to peripheral tissues, where the viruses can replicate to higher titers before spreading to other hosts. These viruses move in neuronal axons from ganglia to the periphery propelled by kinesin motors moving along microtubules. Two forms of HSV particles undergo this anterograde transport in axons: (i) unenveloped capsids that become enveloped after reaching axon tips and (ii) enveloped virions that are transported within membrane vesicles in axons. Fundamental to understanding this axonal transport is the question of which of many different axonal kinesins convey HSV particles. Knowing which kinesins promote axonal transport would provide clues to the identity of HSV proteins that tether onto kinesins. Prominent among axonal kinesins are the kinesin-1 (KIF5A, -5B, and -5C) and kinesin-3 (e.g., KIF1A and -1B) families. We characterized fluorescent forms of cellular cargo molecules to determine if enveloped HSV particles were present in the vesicles containing these cargos. Kinesin-1 cargo proteins were present in vesicles containing HSV particles, but not kinesin-3 cargos. Fluorescent kinesin-1 protein KIF5C extensively colocalized with HSV particles, while fluorescent kinesin-1 KIF1A did not. Silencing of kinesin-1 proteins KIF5A, -5B, and -5C or light chains KLC1 and KLC2 inhibited the majority of HSV anterograde transport, while silencing of KIF1A had little effect on HSV transport in axons. We concluded that kinesin-1 proteins are important in the anterograde transport of the majority of HSV enveloped virions in neuronal axons and kinesin-3 proteins are less important. Herpes simplex virus (HSV) and other alphaherpesviruses, such as varicella-zoster virus, depend upon the capacity to navigate in neuronal axons. To do this, virus particles tether onto dyneins and kinesins that motor along microtubules from axon tips to neuronal cell bodies (retrograde) or from cell bodies to axon tips (anterograde). Following reactivation from latency, alphaherpesviruses absolutely depend upon anterograde transport of virus particles in axons in order to reinfect peripheral tissues and spread to other hosts. Which of the many axonal kinesins transport HSV in axons is not clear. We characterized fluorescent cellular cargo molecules and kinesins to provide evidence that HSV enveloped particles are ferried by kinesin-1 proteins KIF5A, -5B, and -5C and their light chains, KLC1 and KLC2, in axons. Moreover, we obtained evidence that kinesin-1 proteins are functionally important in anterograde transport of HSV virions by silencing these proteins.

Atxn2-CAG100-KnockIn mouse spinal cord shows progressive TDP43 pathology associated with cholesterol biosynthesis suppression

“…A known correlate of this cascade in SCA2 pathology is probably the accumulation of Staufen1 as a marker of neuronal RNA granules, which is also recruited into ATXN2 aggregates [144]. Given that KIF5 is crucial for anterograde transport of virus particles [42], the progressive expression downregulation of all three KIF5 subunits in the KIN spinal cord might constitute a protective antiviral response within neurons. The progressive downregulation of Hecw1 expression is known to modulate the vulnerability of motor neurons by reduced degradation of misfolded SOD1, which was shown to affect stress granule dynamics via interaction with G3BP1 [54].…”

Microtubule-Dependent Trafficking of Alphaherpesviruses in the Nervous System: The Ins and Outs

“…If US9p-KIF1A mediates transport of PRV and HSV-1 alphaherpesvirus particles within the cell body and are responsible for delivery of virions into the axon, are other motors and motor-receptors utilized for subsequent axonal trafficking? In cultured differentiated mouse CAD cells anterograde-trafficking HSV-1 particles in the axon frequently colocalized with GAP43 and SNAP25, cargo commonly transported by kinesin-1/KIF5 [197] (these same cellular proteins were found to be associated with the envelopment organelles utilized by HSV-1 capsids at nerve terminals in human fetal DRGs, Section 6.2 [152]). Similarly, a fluorescently tagged allele of KIF5C showed substantial colocalization with axonal HSV-1 particles, whereas a fluorescent KIF1A did not [197].…”

“…In cultured differentiated mouse CAD cells anterograde-trafficking HSV-1 particles in the axon frequently colocalized with GAP43 and SNAP25, cargo commonly transported by kinesin-1/KIF5 [197] (these same cellular proteins were found to be associated with the envelopment organelles utilized by HSV-1 capsids at nerve terminals in human fetal DRGs, Section 6.2 [152]). Similarly, a fluorescently tagged allele of KIF5C showed substantial colocalization with axonal HSV-1 particles, whereas a fluorescent KIF1A did not [197]. Furthermore, silencing of the three kinesin-1 subtypes KIF5A, -5B, and -5C, or KLC1 and KLC2 (kinesin light chains-1 and -2) [140] inhibited most HSV-1 transport in axons, while silencing of KIF1A had little effect [197].…”

A Kinesin-3 Recruitment Complex Facilitates Axonal Sorting of Enveloped Alpha Herpesvirus Capsids

“…We compared the presence of Kif5 (kinesin-1) and Kif1a (kinesin-3) in DRM fractions of mock, PRV wild-type, or ΔUs9-infected SCG neurons. Kif1a and Kif5 motors drive anterograde transport of cellular axonal cargoes, and have both have been reported to be involved in PRV and HSV-1 anterograde transport (17,35,36). In wild-type infected samples, we detected an increase in Kif1a in the DRM fractions compared to mock and ΔUs9-infected conditions, but no enrichment of Kif5.…”

“…(Figure 3C). Other studies have implicated other kinesin motors using more indirect methods, including truncated motor proteins or motor knock-down experiments (36). For PRV, motor recruitment alone appears to be necessary and sufficient to guide progeny capsids in enveloped structures into the axon process and subsequently along microtubules past the axon initial segment to distal egress sites.…”