Post-injury stress signals alter epigenetic profile of cytosine methylation in the proviral genome of endogenous retroviruses

Enrichment of H3S28p and H3K9me2 Epigenetic Marks on Inflammatory-Associated Gene Promoters in Response to Severe Burn Injury

BACKGROUND

Severe burns activate systemic inflammation and lead to an increase in cytokine levels. Epigenetic elements are key regulators of inflammation; however, their involvement in severe burns has not been studied. In this work, we aimed to unveil the histone H3 posttranslational modifications (PTM) profile and their enrichment in promoters of inflammatory genes in response to severe burns.

METHODS

The levels of H3 PTMs were analyzed by ELISA assays in circulating cells from burn patients. ChIP assays were conducted to evaluate the enrichment of H3K9me2 and H3S28p at the promoter of CXCL8, IL-17, TNFA, IL-6, FOS, and IL-1B genes.

RESULTS

We found that eight H3 PTMs decreased at 5 days post-burn. Burn patients showed a decreased enrichment of H3K9me2 in CXCL8, IL-17, and TNFA promoters, whereas IL-6, FOS, and IL-1B promoters displayed an H3S28p enrichment diminution during the first 10 days post-burn. Interestingly, burn-injured septic patients exhibited an increased enrichment of H3K9me2 in TNFA, IL-1B, CXCL8, and IL-17 promoters, whereas H3S28p was increased in promoters of TNFA and IL-1B at 1 dpb.

CONCLUSION

Severe burns trigger epigenetic changes and differential H3 PTM enrichment at inflammation gene promoters. Epigenetic misregulation of H3 may be involved in sepsis occurrence after severe burn injury.

Specific and Stable Suppression of HIV Provirus Expression In Vitro by Chimeric Zinc Finger DNA Methyltransferase 1

HIV-1 inserts its proviral DNA into the infected host cells, by which HIV proviral DNA can then be duplicated along with each cell division. Thus, provirus cannot be eradicated completely by current antiretroviral therapy. We have developed an innovative strategy to silence the HIV provirus by targeted DNA methylation on the HIV promoter region. We genetically engineered a chimeric DNA methyltransferase 1 composed of designed zinc-finger proteins to become ZF2 DNMT1. After transient transfection of the molecular clone encoding this chimeric protein into HIV-1 infected or latently infected cells, efficient suppression of HIV-1 expression by the methylation of CpG islands in 5′-LTR was observed and quantified. The effective suppression of HIV in latently infected cells by ZF2-DNMT1 is stable and can last through about 40 cell passages. Cytotoxic caused by ZF2-DNMT1 was only observed during cellular proliferation. Taken together, our results demonstrate the potential of this novel approach for anti-HIV-1 therapy.

Divergent and dynamic activity of endogenous retroviruses in burn patients and their inflammatory potential

Genes constitute ~3% of the human genome, whereas human endogenous retroviruses (HERVs) represent ~8%. We examined post-burn HERV expression in patients' blood cells, and the inflammatory potentials of the burn-associated HERVs were evaluated. Buffy coat cells, collected at various time points from 11 patients, were screened for the expression of eight HERV families, and we identified their divergent expression profiles depending on patient, HERV, and time point. The population of expressed HERV sequences was patient-specific, suggesting HERVs' inherent genomic polymorphisms and/or differential expression potentials depending on characteristics of patients and courses of injury response. Some HERVs were shared among the patients, while the others were divergent. Interestingly, one burn-associated HERV gag gene from a patient's genome induced IL-6, IL-1β, Ptgs-2, and iNOS. These findings demonstrate that injury stressors initiate divergent HERV responses depending on patient, HERV, and disease course and implicate HERVs as genetic elements contributing to polymorphic injury pathophysiology.