Cytosolic sulfotransferase 1A1 regulates HIV-1 minus-strand DNA elongation in primary human monocyte-derived macrophages.

Background: The cellular sulfonation pathway modulates key steps of virus replication. This pathway comprises two main families of sulfonate-conjugating enzymes: Golgi sulfotransferases, which sulfonate proteins, glycoproteins, glycolipids and proteoglycans; and cytosolic sulfotransferases (SULTs), which sulfonate various small molecules including hormones, neurotransmitters, and xenobiotics. Sulfonation controls the functions of numerous cellular factors such as those involved in cell-cell interactions, cell signaling, and small molecule detoxification. We previously showed that the cellular sulfonation pathway regulates HIV-1 gene expression and reactivation from latency. Here we show that a specific cellular sulfotransferase can regulate HIV-1 replication in primary human monocyte-derived macrophages (MDMs) by yet another mechanism, namely reverse transcription.

Methods: MDMs were derived from monocytes isolated from donor peripheral blood mononuclear cells (PBMCs) obtained from the San Diego Blood Bank. After one week in vitro cell culture under macrophage-polarizing conditions, MDMs were transfected with sulfotranserase-specific or control siRNAs and infected with HIV-1 or SIV constructs expressing a luciferase reporter. Infection levels were subsequently monitored by luminescence. Western blotting was used to assay siRNA knockdown and viral protein levels, and qPCR was used to measure viral RNA and DNA products.

Results: We demonstrate that the cytosolic sulfotransferase SULT1A1 is highly expressed in primary human MDMs, and through siRNA knockdown experiments, we show that this enzyme promotes infection of MDMs by single cycle VSV-G pseudotyped human HIV-1 and simian immunodeficiency virus vectors and by replication-competent HIV-1. Quantitative PCR analysis revealed that SULT1A1 affects HIV-1 replication in MDMs by modulating the kinetics of minus-strand DNA elongation during reverse transcription.

Conclusions: These studies have identified SULT1A1 as a cellular regulator of HIV-1 reverse transcription in primary human MDMs. The normal substrates of this enzyme are small phenolic-like molecules, raising the possibility that one or more of these substrates may be involved. Targeting SULT1A1 and/or its substrate(s) may offer a novel host-directed strategy to improve HIV-1 therapeutics.