Human immunodeficiency virus Tat associates with a specific set of cellular RNAs

Abstract

BackgroundHuman Immunodeficiency Virus 1 (HIV-1) exhibits a wide range of interactions with the host cell but whether viral proteins interact with cellular RNA is not clear. A candidate interacting factor is the trans-activator of transcription (Tat) protein. Tat is required for expression of virus genes but activates transcription through an unusual mechanism; binding to an RNA stem-loop, the transactivation response element (TAR), with the host elongation factor P-TEFb. HIV-1 Tat has also been shown to alter the expression of host genes during infection, contributing to viral pathogenesis but, whether Tat also interacts with cellular RNAs is unknown.ResultsUsing RNA immunoprecipitation coupled with microarray analysis, we have discovered that HIV-1 Tat is associated with a specific set of human mRNAs in T cells. mRNAs bound by Tat share a stem-loop structural element and encode proteins with common biological roles. In contrast, we do not find evidence that Tat associates with microRNAs or the RNA-induced silencing complex (RISC). The interaction of Tat with cellular RNA requires an intact RNA binding domain and Tat RNA binding is linked to an increase in RNA abundance in cell lines and during infection of primary CD4+ T cells by HIV.ConclusionsWe conclude that Tat interacts with a specific set of human mRNAs in T cells, many of which show changes in abundance in response to Tat and HIV infection. This work uncovers a previously unrecognised interaction between HIV and its host that may contribute to viral alteration of the host cellular environment.

HIV-1-Tat Protein Inhibits SC35-mediated Tau Exon 10 Inclusion through Up-regulation of DYRK1A Kinase

“…6E. The amount of RNA extracted from samples immunoprecipitated with antiTat or IgG was about 25 and 1 ng/l, respectively, confirming that Tat can associate with cellular RNAs, as recently reported (55). Semiquantitative RT-PCR revealed the presence of both E10 included (top band) and E10 excluded (lower band) in the samples in which Tat and TAU were present (Fig.…”

“…In addition, recent reports indicating that cellular factors such as SC35 can function in a manner similar to Tat (53,54) further support the possibility that Tat itself may compete with cellular proteins or with host RNA species to affect RNA metabolism. This possibility was confirmed by RNA immunoprecipitation coupled with microarray analysis, which demonstrated that Tat can interact with cellular RNAs in T cells (55). Although in that report TAU RNA was not detected, likely due to the low abundance of TAU in T cells, there is a surprising similarity between Tau exon 10 and TAR LTR stem-loop structures, suggesting the possibility of a Tat-TAU RNA interaction.…”

Tat basic domain: A “Swiss army knife” of HIV‐1 Tat?

“…In another experiment, K50 interacted with G34 of TAR RNA loop, indicating that the protein‐RNA cross‐link occurred at K50 position whereas mutation at G34 to U34 significantly reduced Tat‐Cyclin T1 binding capacity . Mutations of the first two lysines at 50 and 51 positions to serine and glycine (K50S and K51G), respectively, showed a decrease in Tat activity by 50% in vivo . Interesting results assessing transactivation of HIV LTR came from molecular dynamics simulations combined with in vitro experiments by the Carloni group.…”

“…In addition to viral RNA, Tat is believed to interact with cellular RNAs. The ability of Tat basic domain to associate with human RNAs was examined via immunoprecipitation analysis of the wild‐type Tat and its mutated form, K50S‐K51G . The mutant form showed a significant decrease in interaction with RNA, in particular Tat‐bound FADD and TNFRSF8 RNAs, leading to speculations that, in addition to TAR RNA, Tat was able to associate with the specific set of human RNAs for which an intact basic domain was required .…”

“…The ability of Tat basic domain to associate with human RNAs was examined via immunoprecipitation analysis of the wild‐type Tat and its mutated form, K50S‐K51G . The mutant form showed a significant decrease in interaction with RNA, in particular Tat‐bound FADD and TNFRSF8 RNAs, leading to speculations that, in addition to TAR RNA, Tat was able to associate with the specific set of human RNAs for which an intact basic domain was required . Moreover, Tat basic domain was proposed to specifically target Dicer‐dependent RNAi, the innate immune response against the viral infection .…”