Figure 1.

Transcriptional and Epigenetic Impact of Physiological Hypoxia on the HTLV-1 Provirus

(A) Hypoxia enhances plus-strand HTLV-1 (tax) transcription. PBMCs isolated from HTLV-1-infected individuals (n = 11) were cultured overnight either under atmospheric oxygen conditions (20% oxygen) or under hypoxia (1% or 2% oxygen). RNA was extracted and subjected to qRT-PCR with primers specific for tax mRNA (plus strand), sHBZ mRNA (minus strand), or VEGF mRNA (positive control). Error bars represent the SEM. Statistical significance was calculated using the two-tailed Student's t test (**p < 0.005; ns, not significant).

(B and C) Epigenetic changes at the HTLV-1 provirus upon reactivation under physiological hypoxia or normoxia. HTLV-1-infected PBMCs were either fixed immediately (T₀) or cultured overnight under hypoxia (1% oxygen) or normoxia (20% oxygen) and subsequently fixed and subjected to ChIP-qPCR, using antibodies directed against H3K4me3 (B), H3K36me3 (C), and immunoglobulin G, and primers specific for the 5′-LTR Jn, Gag, Pol, Env, vCTCF, Tax, and 3′-LTR Jn of the HTLV-1 LTR. Enrichment is expressed as percent input DNA and normalized to T₀ at the 5′-LTR junction. Error bars represent the SE of four independent ChIP experiments. Statistical significance was calculated using the two-tailed Student's t test (*p < 0.05, **p < 0.005).