Regulation of cyclin T1 and HIV-1 Replication by microRNAs in resting CD4+ T lymphocytes.
The replication of integrated human immunodeficiency virus type 1 (HIV-1) is dependent on the cellular cofactor cyclin T1, which binds the viral Tat protein and activates the RNA polymerase II transcription of the integrated provirus. The activation of resting CD4(+) T cells upregulates cyclin T1 protein levels independently of an increase in cyclin T1 mRNA levels, suggesting a translational repression of cyclin T1 in resting CD4(+) T cells. Hypothesizing that microRNAs (miRNAs) repress cyclin T1 translation in resting CD4(+) T cells and that this inhibition is lifted upon cell activation, we used microarray expression analysis to identify miRNAs miR-27b, miR-29b, miR-150, and miR-223 as being significantly downregulated upon CD4(+) T cell activation. The overexpression of these miRNAs decreased endogenous cyclin T1 protein levels, while treatment with the corresponding antagomiRs increased cyclin T1 protein levels. An miR-27b binding site within the cyclin T1 3' untranslated region (3'UTR) was identified and confirmed to be functional after the mutation of key resides abrogated the ability of miR-27b to decrease the expression of a luciferase reporter upstream of the cyclin T1 3'UTR. Ago2 immunoprecipitation revealed an association with cyclin T1 mRNA that was decreased following treatment with miR-27b and miR-29b antagomiRs. Cells overexpressing miR-27b showed decreased viral gene expression levels of the HIV-1 reporter virus and a decreased replication of strain NL4.3; a partial rescue of viral transcription could be seen following the transfection of cyclin T1. These results implicate miR-27b as a novel regulator of cyclin T1 protein levels and HIV-1 replication, while miR-29b, miR-223, and miR-150 may regulate cyclin T1 indirectly.
Department of Molecular Virology and Microbiology, Baylor College of Medicine,Houston, Texas, USA.
Karen
K
Chiang
Tzu-Ling
TL
Sung
Andrew P
AP
Rice
D015496:CD4-Positive T-Lymphocytes / Q000378:metabolism* / Q000821:virology; D002460:Cell Line; D002478:Cells, Cultured; D056906:Cyclin T / Q000235:genetics* / Q000378:metabolism; D015536:Down-Regulation; D015658:HIV Infections / Q000235:genetics* / Q000378:metabolism / Q000821:virology; D015497:HIV-1 / Q000235:genetics / Q000502:physiology*; D006801:Humans; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D014176:Protein Biosynthesis; D015854:Up-Regulation; D014779:Virus Replication
D056906:Cyclin T; D035683:MicroRNAs