AEGiS-15IAC: A DEAD box protein facilitates HIV-1 replication as a critical cellular co-factor of rev.

15th International AIDS Conference

Bangkok, Thailand - July 11-16, 2004

A DEAD box protein facilitates HIV-1 replication as a critical cellular co-factor of rev.

Int Conf AIDS 2004 Jul 11-16; 15:(abstract no. TuOrA1133)

Pomerantz RJ, Kubota S, Yan B, Zhou N, Zhang H, Godbout R, Fang J
Thomas Jefferson University, Philadelphia, PA 19107, United States

Introduction: HIV-1 Rev escorts unspliced viral mRNAs out of the nucleus of infected cells which allows formation of infections HIV-1 virions. We have identified a putative RNA helicase, DDX1, as a novel cellular co-factor which interacts with a specific motif of Rev, entitled nuclear diffusion inhibitory signal (NIS).

METHODS: Yeast and mammalian two-hybrid systems with GST pull-down, and co-immunoprecipitation assays and siRNAs were utilized.

RESULTS: Utilizing the two-hybrid systems, we demonstrated an intracellular binding of DDX1 to the NIS motif of Rev. This was further confirmed using GST pull-down assays and co-immunoprecipitation. Over-expression and down-regulation of DDX1 resulted in marked enhancement and attenuation of Rev function, respectively. Moreover, down-regulation of DDX1 altered the steady state subcellular distribution of Rev, from nuclear/nucleolar to cytoplasmic dominance. Both anti-sense and RNA interference (RNAi) approaches demonstrated the importance of down-regulation of DDX1 on Rev function and viral production.

CONCLUSIONS: As well, as a co-factor of the NIS domain, DDX1 is likely supporting Rev function by acting in a molecular "chaperone" fashion and stabilizing the native structure of the Rev N-terminus required for nuclear dominant Rev localization, to yield proper nucleo cytoplasmic trafficking. Interestingly, the phenotype between down-regulated DDX1 and restricted HIV-1 replication is reminiscent of that found in human astrocytes and certain glial cell-lines. Unfavorable microenvironments for Rev, based on the NIS function and DDX1 expression will contribute to the inefficiency of viral replication during HIV-1 persistence. Restriction of HIV-1 replication occurs in a variety of host cells; which has been shown to be due to several newly described cellular factors. As such, DDX1 is a new critical cellular co-factor for HIV-1. Targeting DDX1 may lead to rationally designed and novel anti-HIV-1 strategies.

Keywords: AEGIS, HIV-1, Virus Replication, Gene Products, rev, Green Fluorescent Proteins, HIV Core Protein p24, Proteins, Cell Nucleus, Cytoplasm, RNA Helicases, Cell Line, Cell Nucleolus, Down-Regulation, RNA-Binding Proteins, Karyopherins, Active Transport, Cell Nucleus, Humans, virology, immunology, genetics, metabolism

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TuOrA1133