Selective targeting of ITK blocks multiple steps of HIV replication

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 105; no. 18; pp. 6684 - 6689
• Main Authors: Readinger, Julie A, Schiralli, Gillian M, Jiang, Jian-Kang, Thomas, Craig J, August, Avery, Henderson, Andrew J, Schwartzberg, Pamela L
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 06.05.2008; National Acad Sciences
• Subjects: actin; Actins; Actins - metabolism; Antiretroviral agents; Biochemistry; Biological Sciences; calcium; Cell lines; CXCR4 receptor; DNA, Viral - metabolism; gene overexpression; HIV; HIV Envelope Protein gp120 - metabolism; HIV infections; HIV Infections - enzymology; HIV-1 - genetics; HIV-1 - physiology; Human immunodeficiency virus; Humans; Infections; Jurkat Cells; Kinases; mutants; Mutation; Protein-Tyrosine Kinases - antagonists & inhibitors; Proviruses - genetics; Reverse Transcription - genetics; Small interfering RNA; T cell receptors; T lymphocytes; Terminal Repeat Sequences - genetics; transcription factors; Transfection; tyrosine; Virion - enzymology; Virions; Virus Integration; Virus Internalization; Virus Replication; Viruses
• ISSN: 0027-8424; 1091-6490; 1091-6490
• DOI: 10.1073/pnas.0709659105

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 PLCγ-1, Ca²⁺ 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.