Gray, R. | Search bioRxiv

bioRxiv2018

Nanoscale Polarization of the Vaccinia Virus Entry Fusion Complex Drives Efficient Fusion

The spatial distribution of binding and fusion proteins on most viruses and the functional relevance of this organization remains largely unexplored. Employing super-resolution microscopy we define the nanoscale membrane architecture of the prototypic poxvirus, vaccinia. We show that binding and entry fusion complex (EFC) proteins are organized into distinct functional domains with fusion proteins polarized to the tips of virions. Repression of individual EFC components disrupted fusion protein polarization, correlating with a loss of fusion activity. Repression of vaccinia A27, a non-EFC protein implicated in fusion, revealed that disruption of EFC localization impacts virus fusion pore formation. We propose that the polarized distribution of EFCs is essential for poxvirus fusion efficiency.

microbiology↗

bioRxiv2018

Mutations in Kinesin Family Member 6 Reveal Specific Role in Ependymal Cell Function and Human Neuro-Cranial Development

Cerebrospinal fluid flow is crucial for neurodevelopment and homeostasis of the ventricular system of the brain, with localized flow being established by the polarized beating of the ependymal cell (EC) cilia. Here, we report a homozygous one base-pair deletion, c.1193delT (p.Leu398Glnfs*2), in the Kinesin Family Member 6 (KIF6) gene in a child displaying neurocranial defects and intellectual disability. To test the pathogenicity of this novel human KIF6 mutation we engineered an analogous C-terminal truncating mutation in mouse. These mutant mice display severe, postnatal-onset hydrocephalus. We generated a Kif6-LacZ transgenic mouse strain and report expression specifically and uniquely within the ependymal cell (EC) layer of the brain, without labeling other multiciliated mouse tissues. Analysis of Kif6 mutant mice with scanning electron microscopy (SEM) and immunofluorescence (IF) revealed a reduction in EC cilia, without effect on other multiciliated tissues. Consistent with our findings in mice, defects of the ventricular system and EC cilia were observed in kif6 mutant zebrafish. Overall, this work describes the first clinically-defined KIF6 homozygous null mutation in human and defines KIF6 as a conserved mediator of neuro-cranial morphogenesis with a specific role in the maintenance of EC cilia in vertebrates.\n\nAUTHOR SUMMARYCerebrospinal fluid flow is crucial for neurodevelopment and homeostasis of the ventricular system of the brain. Localized flows of cerebrospinal fluid throughout the ventricular system of the brain are established from the polarized beating of the ependymal cell (EC) cilia. Here, we identified a homozygous truncating mutation in KIF6 in a child displaying neuro-cranial defects and intellectual disability. To test the function of KIF6 in vivo, we engineered mutations of Kif6 in mouse. These Kif6 mutant mice display severe hydrocephalus, coupled with a loss of EC cilia. Similarly, we observed hydrocephalus and a reduction in EC cilia in kif6 mutant zebrafish. Overall, this work describes the first clinically-defined KIF6 mutation in human, while our animal studies demonstrate the pathogenicity of mutations in KIF6 and establish KIF6 as a conserved mediator of neuro-cranial development and EC cilia maintenance in vertebrates.\n\n\n\nO_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=183 SRC=\"FIGDIR/small/350140_ufig1.gif\" ALT=\"Figure 1\">\nView larger version (58K):\norg.highwire.dtl.DTLVardef@d36bc6org.highwire.dtl.DTLVardef@48cbfborg.highwire.dtl.DTLVardef@147e273org.highwire.dtl.DTLVardef@641ce3_HPS_FORMAT_FIGEXP M_FIG C_FIG

genetics↗