PACS1 is an HIV-1 cofactor that functions in Rev-mediated nuclear export of viral RNA.

HIV-1 is dependent upon cellular proteins to mediate the many processes required for viral replication. One such protein, PACS1, functions to localize Furin to the trans-Golgi network where Furin cleaves HIV-1 gp160 Envelope into gp41 and gp120. We show here that PACS1 also shuttles between the nucleus and cytoplasm, associates with the viral Rev protein and its cofactor CRM1, and contributes to nuclear export of viral transcripts.

Regulation of cyclin T1 during HIV replication and latency establishment in human memory CD4 T cells.

Background: The regulatory cyclin, Cyclin T1 (CycT1), is a host factor essential for HIV-1 replication in CD4 T cells and macrophages. The importance of CycT1 and the Positive Transcription Elongation Factor b (P-TEFb) complex for HIV replication is well-established, but regulation of CycT1 expression and protein levels during HIV replication and latency establishment in CD4 T cells is less characterized.

Methods: To better define the regulation of CycT1 levels during HIV replication in CD4 T cells, multiparameter flow cytometry was utilized to study the interaction between HIV replication (intracellular p24) and CycT1 of human peripheral blood memory CD4 T cells infected with HIV in vitro.

Mining the human complexome database identifies RBM14 as an XPO1-associated protein involved in HIV-1 Rev function.

Unlabelled: By recruiting the host protein XPO1 (CRM1), the HIV-1 Rev protein mediates the nuclear export of incompletely spliced viral transcripts. We mined data from the recently described human nuclear complexome to identify a host protein, RBM14, which associates with XPO1 and Rev and is involved in Rev function. Using a Rev-dependent p24 reporter plasmid, we found that RBM14 depletion decreased Rev activity and Rev-mediated enhancement of the cytoplasmic levels of unspliced viral transcripts.

Reactivation of latent HIV: do all roads go through P-TEFb?

The HIV/AIDS field is gaining momentum in the goal of finding a functional cure for HIV infection by utilizing strategies that specifically reactivate the latent viral reservoir in combination with the HAART regimen to prevent further viral spread. Small-molecule inhibitors such as histone deacetylase (HDAC) and bromodomain and extraterminal (BET) inhibitors can successfully activate HIV transcription and reverse viral latency in clonal cell lines. However, in resting CD4 T cells, thought to be the principal physiological reservoir of latent HIV, their effect in reactivating the viral reservoir is more variable.

Cyclin T1 and CDK9 T-loop phosphorylation are downregulated during establishment of HIV-1 latency in primary resting memory CD4+ T cells.

P-TEFb, a cellular kinase composed of Cyclin T1 and CDK9, is essential for processive HIV-1 transcription. P-TEFb activity is dependent on phosphorylation of Thr186 in the CDK9 T loop. In resting CD4(+) T cells which are nonpermissive for HIV-1 replication, the levels of Cyclin T1 and T-loop-phosphorylated CDK9 are very low but increase significantly upon cellular activation.

Phosphatase PPM1A negatively regulates P-TEFb function in resting CD4(+) T cells and inhibits HIV-1 gene expression.

Background: Processive elongation of the integrated HIV-1 provirus is dependent on recruitment of P-TEFb by the viral Tat protein to the viral TAR RNA element. P-TEFb kinase activity requires phosphorylation of Thr186 in the T-loop of the CDK9 subunit. In resting CD4+T cells, low levels of T-loop phosphorylated CDK9 are found, which increase significantly upon activation.

Making a Short Story Long: Regulation of P-TEFb and HIV-1 Transcriptional Elongation in CD4+ T Lymphocytes and Macrophages.

Productive transcription of the integrated HIV-1 provirus is restricted by cellular factors that inhibit RNA polymerase II elongation. The viral Tat protein overcomes this by recruiting a general elongation factor, P-TEFb, to the TAR RNA element that forms at the 5' end of nascent viral transcripts. P-TEFb exists in multiple complexes in cells, and its core consists of a kinase, Cdk9, and a regulatory subunit, either Cyclin T1 or Cyclin T2.

Evaluation of two real-time PCR chemistries for the detection of Chlamydophila pneumoniae in clinical specimens.

Chlamydophila pneumoniae is an atypical bacterial respiratory pathogen that is responsible for approximately 3-10% of community-acquired pneumonia cases. We report the evaluation of two distinct real-time PCR assays for rapid and specific detection of C. pneumoniae.