Section of Human Anatomy and Histology, Department of Biomedical and Biotechnological Sciences, University of Catania, Italy.
San Raffaele Open University of Rome, Department of Human Science and Promotion of quality of Life, Italy.
Peptides. 2019 Sep;119:170108. doi: 10.1016/j.peptides.2019.170108. Epub 2019 Jun 24.
Diabetic retinopathy (DR) is one of the most common microvascular complications of diabetes. In the last years, several in vivo studies have demonstrated the protective role of pituitary adenylate cyclase-activating peptide (PACAP-38) to counteract several alterations occurring during DR. Recently, different studies have demonstrated that some PACAP-38 effects are mediated by EGFR trans-activation, although no data exist regarding the link between this peptide and EGFR in DR. The aim of the present study has been to investigate whether retinal effect of PACAP-38 against high glucose damage is mediated by EGFR phosphorylation. Diabetes was induced by a single injection of streptozotocin (STZ) in rats. After 1 week, a group of animals was treated with a single intravitreal injection of 100 μM PACAP-38 or saline solution. Immunohistochemistry and western blot analysis have demonstrated that intravitreal injection of PACAP-38 induced p-EGFR over-expression in retina of diabetic rats. Several pathogenic mechanisms may contribute to diabetic retinopathy including BRB alteration. To better clarify the relationship between PACAP-38 and EGFR, we have also carried out a study on ARPE-19 cells, representing a model in vitro of outer BRB. Our results have shown that PACAP-38 treatment improved cell viability in ARPE-19 cells exposed to hyperglycemic/hypoxic insult mimicking tissue microenvironment occurring in DR. Binding to PAC1R, peptide induces EGFR phosphorylation via PKA-signaling cascade stimulation. EGFR trans-activation triggers MAPK/ERK signaling pathway involved in cell survival and proliferation. In conclusion, data have suggested that PACAP-38 acts through EGFR phosphorylation in DR and this effect particularly occurs on RPE layer.
糖尿病性视网膜病变（DR）是糖尿病最常见的微血管并发症之一。在过去的几年中，几项体内研究已经证明了垂体腺苷酸环化酶激活肽（PACAP-38）在对抗 DR 过程中发生的几种改变的保护作用。最近，不同的研究已经证明，PACAP-38 的一些作用是通过表皮生长因子受体（EGFR）的转激活来介导的，尽管关于这种肽与 DR 中的 EGFR 之间的联系还没有数据。本研究的目的是研究 PACAP-38 对高葡萄糖损伤的视网膜作用是否通过 EGFR 磷酸化来介导。糖尿病通过链脲佐菌素（STZ）单次注射诱导。1 周后，一组动物接受单次玻璃体腔内注射 100μM PACAP-38 或生理盐水溶液。免疫组织化学和 Western blot 分析表明，玻璃体腔内注射 PACAP-38 诱导糖尿病大鼠视网膜中 p-EGFR 的过度表达。几种发病机制可能导致糖尿病性视网膜病变，包括 BRB 改变。为了更好地阐明 PACAP-38 与 EGFR 之间的关系，我们还对 ARPE-19 细胞进行了研究，该细胞代表了 DR 中发生的组织微环境的体外外 BRB 模型。我们的结果表明，PACAP-38 处理改善了暴露于高血糖/缺氧刺激的 ARPE-19 细胞的细胞活力，模拟了 DR 中发生的组织微环境。通过与 PAC1R 结合，肽通过 PKA 信号级联刺激诱导 EGFR 磷酸化。EGFR 的转激活触发了参与细胞存活和增殖的 MAPK/ERK 信号通路。总之，数据表明 PACAP-38 在 DR 中通过 EGFR 磷酸化起作用，这种作用特别发生在 RPE 层上。
