Division of Surgical Sciences, Department of Surgery, School of Medicine, University of Virginia, Charlottesville, VA 22908, USA.
Division of Surgical Sciences, Department of Surgery, School of Medicine, University of Virginia, Charlottesville, VA 22908, USA; Department of Ophthalmology, University of Virginia, Charlottesville, VA 22908, USA; Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22908, USA.
Cell Signal. 2024 Apr;116:111069. doi: 10.1016/j.cellsig.2024.111069. Epub 2024 Jan 28.
Pro-inflammatory cytokine production by the retinal pigment epithelium (RPE) is a key etiology in retinal degenerative diseases, yet the underlying mechanisms are not well understood. TMEM97 is a scarcely studied transmembrane protein recently implicated in retinal degeneration. BAH domain coiled coil 1 (BAHCC1) is a newly discovered histone code reader involved in oncogenesis. A role for TMEM97 and BAHCC1 in RPE inflammation was not known. Here we found that they constitute a novel axis regulating pro-inflammatory cytokine expression in RPE cells. Transcriptomic analysis using a TMEM97-/- ARPE19 human cell line and the validation via TMEM97 loss- and gain-of-function revealed a profound role of TMEM97 in promoting the expression of pro-inflammatory cytokines, notably IL1β and CCL2, and unexpectedly BAHCC1 as well. Moreover, co-immunoprecipitation indicated an association between the TMEM97 and BAHCC1 proteins. While TMEM97 ablation decreased and its overexpression increased NFκB (p50, p52, p65), the master transcription factor for pro-inflammatory cytokines, silencing BAHCC1 down-regulated NFκB and downstream pro-inflammatory cytokines. Furthermore, in an RPE-damage retinal degeneration mouse model, immunofluorescence illustrated down-regulation of IL1β and CCL2 total proteins and suppression of glial activation in the retina of Tmem97-/- mice compared to Tmem97+/+ mice. Thus, TMEM97 is a novel determinant of pro-inflammatory cytokine expression acting via a previously unknown TMEM97- > BAHCC1- > NFκB cascade. SYNOPSIS: Retinal pigment epithelium (RPE) inflammation can lead to blindness. We identify here a previously uncharacterized cascade that underlies RPE cell production of pro-inflammatory cytokines. Specifically, transmembrane protein TMEM97 positively regulates the recently discovered histone code reader BAHCC1, which in turn enhances pro-inflammatory cytokine expression via the transcription factor NFκB.
视网膜色素上皮 (RPE) 的促炎细胞因子产生是视网膜退行性疾病的一个关键病因，但潜在机制尚不清楚。TMEM97 是一种研究甚少的跨膜蛋白，最近与视网膜变性有关。BAH 结构域卷曲螺旋 1 (BAHCC1) 是一种新发现的参与致癌作用的组蛋白编码读取器。TMEM97 和 BAHCC1 在 RPE 炎症中的作用尚不清楚。在这里，我们发现它们构成了一个调节 RPE 细胞促炎细胞因子表达的新轴。使用 TMEM97-/-ARPE19 人细胞系进行转录组分析，并通过 TMEM97 缺失和功能获得进行验证，发现 TMEM97 在促进促炎细胞因子（特别是 IL1β 和 CCL2）的表达中起着深远的作用，出乎意料的是 BAHCC1 也是如此。此外，免疫共沉淀表明 TMEM97 和 BAHCC1 蛋白之间存在关联。虽然 TMEM97 缺失减少，而过表达增加 NFκB（p50、p52、p65），即促炎细胞因子的主要转录因子，但沉默 BAHCC1 可下调 NFκB 和下游促炎细胞因子。此外，在 RPE 损伤性视网膜变性小鼠模型中，与 Tmem97+/+ 小鼠相比，免疫荧光表明 Tmem97-/- 小鼠的视网膜中 IL1β 和 CCL2 总蛋白下调，并且胶质细胞激活受到抑制。因此，TMEM97 是一种通过以前未知的 TMEM97->BAHCC1->NFκB 级联起作用的新型促炎细胞因子表达决定因素。摘要：视网膜色素上皮 (RPE) 炎症可导致失明。我们在这里确定了一个以前未被描述的级联，它是 RPE 细胞产生促炎细胞因子的基础。具体而言，跨膜蛋白 TMEM97 正向调节最近发现的组蛋白编码读取器 BAHCC1，后者通过转录因子 NFκB 增强促炎细胞因子的表达。
