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Effects of the inner nuclear membrane proteins SUN1/UNC-84A and SUN2/UNC-84B on the early steps of HIV-1 infection.

Effects of the inner nuclear membrane proteins SUN1/UNC-84A and SUN2/UNC-84B on the early steps of HIV-1 infection.
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Schaller T, Bulli L, Pollpeter D, Betancor G, Kutzner J, Apolonia L, Herold N, Burk R, Malim MH,


Schaller T, Bulli L, Pollpeter D, Betancor G, Kutzner J, Apolonia L, Herold N, Burk R, Malim MH, (click to view)

Schaller T, Bulli L, Pollpeter D, Betancor G, Kutzner J, Apolonia L, Herold N, Burk R, Malim MH,

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Journal of virology 2017 07 26() pii 10.1128/JVI.00463-17

Abstract

Human immunodeficiency virus type 1 (HIV-1) infection of dividing and non-dividing cells involves regulatory interactions with the nuclear pore complex (NPC), followed by translocation to the nucleus and preferential integration into genomic areas in proximity to the inner nuclear membrane (INM). To identify host proteins that may contribute to these processes, we performed an overexpression screen of known membrane-associated NE proteins. We found that the integral transmembrane proteins SUN1/UNC84A and SUN2/UNC84B are potent or modest inhibitors of HIV-1 infection, respectively, and that suppression corresponds to defects in the accumulation of viral cDNA in the nucleus. While laboratory strains (HIV-1NL4.3 and HIV-1IIIB) are sensitive to SUN1-mediated inhibition, the transmitted founder viruses RHPA and ZM247 are largely resistant. Using chimeric viruses, we identified the HIV-1 Capsid (CA) protein as a major determinant of sensitivity to SUN1, and in vitro assembled Capsid-Nucleocapsid (CANC) nanotubes capture SUN1 and SUN2 from cell lysates. Lastly, we generated SUN1-/- or SUN2-/- cells using CRISPR/Cas9 and found that the loss of SUN1 has no effect on HIV-1 infectivity, whereas the loss of SUN2 has a modest suppressive effect. Taken together, these observations suggest that SUN1 and SUN2 may function redundantly to modulate post-entry, nuclear-associated steps of HIV-1 infection.IMPORTANCE HIV-1 causes more than one million deaths per year. The life cycle of HIV-1 has been studied extensively, yet important steps occurring between viral capsid release into the cytoplasm and the expression of viral genes remain elusive. We propose here that the INM components SUN1 and SUN2, two members of the linker of nucleoskeleton and cytoskeleton (LINC) complex, may interact with incoming HIV-1 replication complexes and affect key steps of infection. While overexpression of these proteins reduces HIV-1 infection, disruption of the individual SUN2 and SUN1 genes leads to a mild reduction or no effect on infectivity, respectively. We speculate that SUN1/SUN2 may function redundantly in early HIV-1 infection steps and therefore influence HIV-1 replication and pathogenesis.

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