Interferon-γ increases expression of the long non-Coding RNA BANCR in retinal pigment epithelial cells by activating JAK/STAT signaling pathway

Abstract

Purpose : Long non-coding RNAs (lncRNAs), non-protein coding transcripts with a minimum length of 200 nucleotides, are known to regulate many pathophysiological processes. We have reported earlier that the decrease in retinal pigment epithelial (RPE) characteristics and the increase in epithelial-mesenchymal transition (EMT)-like changes in ARPE-19 cells in response to treatment with a proinflammatory cytokine mixture (IFN-γ + TNF-α + IL-1β) were accompanied by highly increased expression of the lncRNA BANCR. The purpose of the present study was to investigate the mechanism by which these proinflammatory cytokines regulate the expression of BANCR in RPE cells.

Methods : ARPE-19 cells, cultured until they expressed visual cycle genes and exhibited epithelial morphology, were treated with IFN-γ, TNF-α and/or IL-1β in the presence of serum. Additionally, the cells were also treated with IFN-γ in the presence of JAK Inhibitor I. The expression of BANCR and other transcripts was analyzed by real-time PCR. Activation of STAT1 was detected by Western blot analysis using anti-phospho-STAT1 antibody.

Results : Differentiated ARPE-19 cells responded to a combination of IFN-γ, TNF-α and IL-1β by increasing the expression of BANCR while simultaneously decreasing the expression of RPE-characteristic genes. IFN-γ by itself increased the expression of BANCR while the other two cytokines did not show any noticeable effect. The increase in BANCR expression by IFN-γ was associated with the activation of STAT1, as indicated by the generation of phospho-STAT1. JAK Inhibitor I, a known blocker of the JAK/STAT signaling pathway, effectively suppressed both the induction of BANCR and STAT1 activation.

Conclusions : Loss of RPE characteristics in ARPE-19 cells exposed to proinflammatory cytokines is associated with an increase in the expression of lncRNA BANCR, a known regulator of EMT. The BANCR expression appears to be regulated by the IFN-γ via JAK/STAT1 signaling pathway. Thus, BANCR could potentially act as a link between RPE dysfunction and inflammatory response and, therefore, may play a role in the pathology of age-related macular degeneration (AMD).

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.