# Drug Phosphorylation and Aging

> **NIH NIH R01** · JOHNS HOPKINS UNIVERSITY · 2022 · $210,412

## Abstract

Adenylate kinase 2 (AK2) is a key regulator of cellular homeostasis via the interconversion of adenine nucleotides
ATP, ADP, and AMP. We recently demonstrated that AK2 plays a crucial role in the activation of the antiretroviral
drug tenofovir (TFV) in cells and tissues that are putative sites of HIV infection. TFV is a nucleotide reverse
transcriptase inhibitor that is prescribed as a tenofovir disoproxil prodrug in combination with other drugs for the
treatment of HIV. TFV requires two sequential phosphorylation steps in order to become pharmacologically
active. Tenofovir disoproxil is also a component of the only FDA approved HIV pre-exposure prophylaxis (PrEP)
regimen. The identification of AK2 as a TFV-activating kinase spurred us to sequence the human genomic DNA
of ~1200 individuals and identify AK2 genetic variants that could impact TFV activation. Thus far, in vitro studies
have revealed that several of these variants do indeed impact AK2 activity towards TFV. In moving forward, an
effect of aging on AK2 expression and activity will be tested specifically. Determining whether the activity of TFV-
activating kinases, particularly AK2, could exhibit differential activity in older versus younger adults is of
importance since older adults (≥50 years of age) account for an approximate 17% of new HIV infections annually.
The aims of this proposal are to: 1) measure the levels of TFV and phosphorylated metabolites of TFV in single
circulating CD4+ T cells that are key targets for HIV infection, and determine whether the drug/metabolite levels
differ between older adults (ages 65-80) and younger adults (ages 18-30); 2) test the hypothesis that the patterns
of expression of kinases that activate TFV are divergent in older adults (ages 65-80) versus younger adults (ages
18-30) in circulating CD4+ T cells using single cell proteomics.

## Key facts

- **NIH application ID:** 10613052
- **Project number:** 3R01AG064908-03S1
- **Recipient organization:** JOHNS HOPKINS UNIVERSITY
- **Principal Investigator:** Benjamin Carl Orsburn
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $210,412
- **Award type:** 3
- **Project period:** 2020-04-01 → 2024-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10613052

## Citation

> US National Institutes of Health, RePORTER application 10613052, Drug Phosphorylation and Aging (3R01AG064908-03S1). Retrieved via AI Analytics 2026-05-27 from https://api.ai-analytics.org/grant/nih/10613052. Licensed CC0.

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