Selective targeting of ITK blocks multiple steps of HIV replication.
Treatment for HIV has relied on the use of antiretroviral agents that can be subject to the development of resistant viruses. The study of inhibitors directed against cellular proteins required for HIV replication is therefore of growing interest. Inducible T cell kinase (ITK) is a Tec family tyrosine kinase that regulates T cell receptor (TCR)-induced activation of PLCgamma-1, Ca(2+) mobilization and transcription factor activation, and actin rearrangement downstream of both TCR and chemokine receptors. Because productive infection of T cells with HIV requires T cell activation, chemokine receptors and actin reorganization, we asked whether ITK affects HIV infection using ITK-specific siRNA, a kinase-inactive ITK mutant or an ITK inhibitor. We demonstrate that loss of ITK function resulted in marked reductions in intracellular p24 levels upon HIV infection. Loss of ITK function after establishment of HIV infection also decreased virus spread within the culture. Inhibition of ITK did not affect expression of the HIV coreceptors CD4 or CXCR4 but partially blocked HIV viral entry, an effect that correlated with decreased actin polarization to gp120. Additionally, ITK was required for efficient HIV transcription, and overexpression of ITK increased both viral transcription and virus-like particle formation. Our data suggest that inhibition of ITK blocks HIV infection by affecting multiple steps of HIV replication.
Readinger
Julie A
JA
Genetic Disease Research Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892, USA.
Schiralli
Gillian M
GM
Jiang
Jian-Kang
JK
Thomas
Craig J
CJ
August
Avery
A
Henderson
Andrew J
AJ
Schwartzberg
Pamela L
PL
D000199:Actins / Q000378:metabolism; D004279:DNA, Viral / Q000378:metabolism; D015699:HIV Envelope Protein gp120 / Q000378:metabolism; D015658:HIV Infections / Q000201:enzymology; D015497:HIV-1 / Q000235:genetics / Q000502:physiology*; D006801:Humans; D019169:Jurkat Cells; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors*; D011533:Proviruses / Q000235:genetics; D048348:Reverse Transcription / Q000235:genetics; D020079:Terminal Repeat Sequences / Q000235:genetics; D014771:Virion / Q000201:enzymology; D016662:Virus Integration; D053586:Virus Internalization; D014779:Virus Replication
D000199:Actins; D004279:DNA, Viral; D015699:HIV Envelope Protein gp120; D011505:Protein-Tyrosine Kinases; C080813:emt protein-tyrosine kinase