Encapsidation of Staufen-2 Enhances Infectivity of HIV-1

Abstract

Staufen, the RNA-binding family of proteins, affects various steps in the Human Immuno-Deficiency Virus (HIV-1) replication cycle. While our previous study established Staufen-2–HIV-1 Rev interaction and its role in augmenting nucleocytoplasmic export of RRE-containing viral RNA, viral incorporation of Staufen-2 and its effect on viral propagation were unknown. Here, we report that Staufen-2 interacts with HIV-1 Gag and is incorporated into virions and that encapsidated Staufen-2 boosted viral infectivity. Further, Staufen-2 gets co-packaged into virions, possibly by interacting with host factors Staufen-1 or antiviral protein APOBEC3G, which resulted in different outcomes on the infectivity of Staufen-2-encapsidated virions. These observations suggest that encapsidated host factors influence viral population dynamics and infectivity. With the explicit identification of the incorporation of Staufen proteins into HIV-1 and other retroviruses, such as Simian Immunodeficiency Virus (SIV), we propose that packaging of RNA binding proteins, such as Staufen, in budding virions of retroviruses is probably a general phenomenon that can drive or impact the viral population dynamics, infectivity, and evolution.

Staufen‐2 functions as a cofactor for enhanced Rev‐mediated nucleocytoplasmic trafficking of HIV‐1 genomic RNA via the CRM1 pathway

“…The nature of these interacting proteins could influence the fate of the viral life cycle. For instance, in our recent study, we demonstrated that Staufen‐2 is incorporated into virions that influence both viral production and infectivity [35]. These observations open new avenues of investigation and are also a part of the ongoing research in our lab.…”

“…For the construction of Staufen‐2 knockout HEK293T cells, CRISPR‐Cas9 techniques were used as described earlier [35], and Western blotting was carried out to confirm the Staufen‐2 knockout marked by its absence as compared to wildtype vector control.…”

“…Contrary to its canonical role in RNA localization, Staufen‐1 impacts HIV replication at various stages, such as affecting Gag multimerization, viral‐RNA incorporation and viral assembly [31‐34]. Our recent studies elucidated the molecular role of encapsidated Staufen‐2 in viral infectivity [35]. These studies point to the complex mechanisms employed by HIV to sustain propagation.…”

The nuclear pore protein NUP98 impedes LTR-driven basal gene expression of HIV-1, viral propagation, and infectivity

“…The plasmids expressing different domains of NUP98 cloned in pEGFPC1 and full-length Myc-NUP98 cloned in pcDNA were a kind gift from Dr. Maureen Powers (Emory University, Atlanta, USA) ( 53 ). pSIV AGM -Luc-R − E − Δvif was a kind gift from Carsten Munk (Heinrich-Heine-University, Düsseldorf, Germany) ( 54 ). pNLC4.3GFP was a kind gift from Prof. Barbara Muller (University of Heidelberg, Germany) ( 55 ).…”

“…The efficiency of the knockdown of NUP98 by shRNA was determined by Western blotting using anti-NUP98 antibody. The lentivirus used for the knockdown of NUP98 in SupT1 cells was prepared by transfecting HEK293T cells with packaging and transfer vectors as previously described ( 54 ). Briefly, HEK293T cells in a six-well plate were co-transfected with VSV-G encoding pMD2.G (250 ng), Gag-Pol encoding psPAX2 (1,000 ng), and pLKO.1-Puro (1,000 ng) harboring NUP98-specific shRNA sequences by the calcium phosphate method.…”