Synaptopodin is upregulated by IL-13 in eosinophilic esophagitis and regulates esophageal epithelial cell motility and barrier integrity
Mark Rochman, Jared Travers, J. Pablo Abonia, Julie M. Caldwell, Marc E. Rothenberg
Mark Rochman, Jared Travers, J. Pablo Abonia, Julie M. Caldwell, Marc E. Rothenberg
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Research Article Gastroenterology Inflammation

Synaptopodin is upregulated by IL-13 in eosinophilic esophagitis and regulates esophageal epithelial cell motility and barrier integrity

Abstract

Eosinophilic esophagitis (EoE) is an allergic inflammatory disease of the esophagus mediated by an IL-13–driven epithelial cell transcriptional program. Herein, we show that the cytoskeletal protein synaptopodin (SYNPO), previously associated with podocytes, is constitutively expressed in esophageal epithelium and induced during allergic inflammation. In addition, we show that the SYNPO gene is transcriptionally and epigenetically regulated by IL-13 in esophageal epithelial cells. SYNPO was expressed in the basal layer of homeostatic esophageal epithelium, colocalized with actin filaments, and expanded into the suprabasal epithelium in EoE patients, where expression was elevated 25-fold compared with control individuals. The expression level of SYNPO in esophageal biopsies correlated with esophageal eosinophil density and was improved following anti–IL-13 treatment in EoE patients. In esophageal epithelial cells, SYNPO gene silencing reduced epithelial motility in a wound healing model, whereas SYNPO overexpression impaired epithelial barrier integrity and reduced esophageal differentiation. Taken together, we demonstrate that SYNPO is induced by IL-13 in vitro and in vivo, is a nonredundant regulator of epithelial cell barrier function and motility, and is likely involved in EoE pathogenesis.

Authors

Mark Rochman, Jared Travers, J. Pablo Abonia, Julie M. Caldwell, Marc E. Rothenberg

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Figure 1

Transcriptional and epigenetic regulation of SYNPO in TE-7 cells.

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Transcriptional and epigenetic regulation of SYNPO in TE-7 cells. (A) Th...
(A) The heatmap shows transcriptional and epigenetic changes in TE-7 cells in response to IL-13 stimulation for 6 hours or eosinophilic esophagitis (EoE) biopsies compared with controls. The yellow color represents log2 fold change in gene expression compared with controls, and the blue color represents M values for the indicated histone mark (note that negative M value indicates increased level of epigenetic marks; see Methods for details). (B) The expression of SYNPO in TE-7 cells stimulated with IL-13 at 100 ng/ml is shown (data are from ref. 15). *P < 0.05, DESeq analysis. RPKM, reads per kilobase per million reads. (C) An image capture from the USCS browser shows the epigenetic landscape for H3K27Ac, H3K9Ac, and H3K4me3 marks in TE-7 cells in the SYNPO gene. The promoter area of SYNPO isoforms 1 and 2 (see Figure 2A for details) is shaded. Arrows point to the histone mark peaks that are significantly increased after 6 hours of IL-13 stimulation. P values comparing IL-13–stimulated cells with untreated cells were calculated by using a MAnorm algorithm. The green rectangle shows the position of the probe used for ChIP-PCR experiments. The read depths of the aligned sequences are of the same scale. (D) The level of the indicated epigenetic marks was assessed in the promoter of SYNPO isoforms 1 and 2 by ChIP-PCR after a 24-hour IL-13 stimulation and subsequent IL-13 withdrawal for 6 hours. One of two independent experiments is shown; the dots represent the mean ± SD for technical replicates. *P < 0.05, compared with untreated cells by ANOVA.