Epigenetic basis for aberrant upregulation of autoantigen genes in humans with ANCA vasculitis
Dominic J. Ciavatta, JiaJin Yang, Gloria A. Preston, Anshul K. Badhwar, Hong Xiao, Peter Hewins, Carla M. Nester, William F. Pendergraft III, Terry R. Magnuson, J. Charles Jennette, Ronald J. Falk
Dominic J. Ciavatta, JiaJin Yang, Gloria A. Preston, Anshul K. Badhwar, Hong Xiao, Peter Hewins, Carla M. Nester, William F. Pendergraft III, Terry R. Magnuson, J. Charles Jennette, Ronald J. Falk
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Research Article Autoimmunity

Epigenetic basis for aberrant upregulation of autoantigen genes in humans with ANCA vasculitis

Abstract

Antineutrophil cytoplasmic autoantibody (ANCA) causes vascular injury that leads to small-vessel vasculitis. Patients with ANCA aberrantly express neutrophil granule–encoding genes, including 2 that encode autoantigens: proteinase 3 (PR3) and myeloperoxidase (MPO). To uncover a potential transcriptional regulatory mechanism for PR3 and MPO disrupted in patients with ANCA vasculitis, we examined the PR3 and MPO loci in neutrophils from ANCA patients and healthy control individuals for epigenetic modifications associated with gene silencing. We found that levels of the chromatin modification H3K27me3, which is associated with gene silencing, were depleted at PR3 and MPO loci in ANCA patients compared with healthy controls. Interestingly, in both patients and controls, DNA was unmethylated at a CpG island in PR3, whereas in healthy controls, DNA was methylated at a CpG island in MPO. Consistent with decreased levels of H3K27me3, JMJD3, the demethylase specific for H3K27me3, was preferentially expressed in ANCA patients versus healthy controls. In addition, we describe a mechanism for recruiting the H3K27 methyltransferase enhancer of zeste homolog 2 (EZH2) to PR3 and MPO loci mediated by RUNX3. RUNX3 message was decreased in patients compared with healthy controls, and may also be under epigenetic control. DNA methylation was increased at the RUNX3 promoter in ANCA patients. These data indicate that epigenetic modifications associated with gene silencing are perturbed at ANCA autoantigen–encoding genes, potentially contributing to inappropriate expression of PR3 and MPO in ANCA patients.

Authors

Dominic J. Ciavatta, JiaJin Yang, Gloria A. Preston, Anshul K. Badhwar, Hong Xiao, Peter Hewins, Carla M. Nester, William F. Pendergraft III, Terry R. Magnuson, J. Charles Jennette, Ronald J. Falk

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Figure 5

Overexpression of RUNX3 in U937 myeloid cells silences PR3 expression.

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Overexpression of RUNX3 in U937 myeloid cells silences PR3 expression. ...
(A) Relative RUNX3 and PR3 mRNA levels in undifferentiated U937 cells and undifferentiated U937/P44 cells were determined by quantitative real-time RT-PCR with SYBR green (RUNX3) and Taqman (PR3). (B and C) Western blot analysis was performed to detect RUNX3 (B) and PR3 (C) protein in undifferentiated U937 and U937/P44 cells and in PMA-differentiated U937 cells as indicated. Lanes in B were run on the same gel but were noncontiguous (white line). (D) H3K27me3 levels at PR3 were determined by quantitative ChIP analysis in undifferentiated U937 and U937/P44 cells. Data show percent DNA input for 3 separate experiments, with exact values shown above bars.