Tenofovir (TFV) and other nucleotide reverse transcriptase inhibitors must be activated via phosphorylation by intracellular nucleotide kinases in order to become pharmacologically active. While the kinases that activate TFV in mucosal tissues in adults have been identified, studies have not been performed to determine which enzymes phosphorylate TFV in adolescents. Further, whether hormonal changes during development might impact the expression and activity of the kinases that have thus far been demonstrated to activate TFV hasn't been explored. Gaining a mechanistic understanding of the expression patterns and regulation of these nucleotide kinases across developmental stages in mucosal tissues is of particular importance within the context of using these drugs for HIV pre-exposure prophylaxis since vaginal and colorectal tissues are putative sites of pharmacological activity in this setting. With this in mind, the goals of this proposal are to identify the nucleotide kinases that phosphorylate TFV in adolescent vaginal and colorectal tissue and to probe the effects of hormones that govern developmental maturation on TFV disposition.
The aims are as follows: (1) determine which kinases activate TFV in adolescent tissue; the expression pattern of nucleotide kinases in adolescent vaginal and colorectal tissue will be established using proteomics-based approaches; knockdown of identified kinases will facilitate identification of those that exhibit activity toward TFV in tissue; (2) test whether TFV activation and TFV distribution in tissue are hormonally regulated; nucleotide kinase expression will be measured in response to developmental hormones and mechanisms of hormonal regulation will be probed; MALDI-mass spectrometry imaging will be employed in order to visualize the distribution of TFV as well as phosphorylated metabolites of TFV in adolescents versus adults. It is expected that the completion of the proposed studies will provide a mechanistic foundation for the rational selection and dosing of antiretrovirals for HIV pre-exposure prophylaxis in adolescents.

Public Health Relevance

? Tenofovir is a drug used to treat and prevent HIV infection, that requires activation by proteins inside of cells in order to be efficacious. The goal of this project is to determine whether tenofovir is activated differently in adolescent tissue as compared to adults and to investigate whether hormonal changes during development might impact tenofovir activation. These studies are expected to improve the rational selection and dosing of anti-HIV drugs in adolescents.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Research Project (R01)
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Special Emphasis Panel (ZRG1-AARR-D (51)R)
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Turpin, Jim A
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Johns Hopkins University
Schools of Medicine
United States
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Figueroa, Dominique B; Madeen, Erin P; Tillotson, Joseph et al. (2018) Genetic Variation of the Kinases That Phosphorylate Tenofovir and Emtricitabine in Peripheral Blood Mononuclear Cells. AIDS Res Hum Retroviruses 34:421-429
Seneviratne, Herana Kamal; Hendrix, Craig W; Fuchs, Edward J et al. (2018) MALDI Mass Spectrometry Imaging Reveals Heterogeneous Distribution of Tenofovir and Tenofovir Diphosphate in Colorectal Tissue of Subjects Receiving a Tenofovir-Containing Enema. J Pharmacol Exp Ther 367:40-48