Ntimbane Thierry, Mailhot Geneviève, Spahis Schohraya, Rabasa-Lhoret Remi, Kleme Marie-Laure, Melloul Danielle, Brochiero Emmanuelle, Berthiaume Yves, Levy Emile
Research Centre, Centre Hospitalier Universitaire Sainte-Justine, Université de Montréal, Montreal, Quebec, Canada;
Research Centre, Centre Hospitalier Universitaire Sainte-Justine, Université de Montréal, Montreal, Quebec, Canada; Department of Nutrition, Université de Montréal, Montreal, Quebec, Canada;
Am J Physiol Endocrinol Metab. 2016 Feb 1;310(3):E200-12. doi: 10.1152/ajpendo.00333.2015. Epub 2015 Dec 1.
Cystic fibrosis (CF)-related diabetes (CFRD) has become a critical complication that seriously affects the clinical outcomes of CF patients. Although CFRD has emerged as the most common nonpulmonary complication of CF, little is known about its etiopathogenesis. Additionally, whether oxidative stress (OxS), a common feature of CF and diabetes, influences CFRD pathophysiology requires clarification. The main objective of this study was to shed light on the role of the cystic fibrosis transmembrane conductance regulator (CFTR) in combination with OxS in insulin secretion from pancreatic β-cells. CFTR silencing was accomplished in MIN6 cells by stable expression of small hairpin RNAs (shRNA), and glucose-induced insulin secretion was evaluated in the presence and absence of the valuable prooxidant system iron/ascorbate (Fe/Asc; 0.075/0.75 mM) along with or without the antioxidant Trolox (1 mM). Insulin output from CFTR-silenced MIN6 cells was significantly reduced (∼ 70%) at basal and at different glucose concentrations compared with control Mock cells. Furthermore, CFTR silencing rendered MIN6 cells more sensitive to OxS as evidenced by both increased lipid peroxides and weakened antioxidant defense, especially following incubation with Fe/Asc. The decreased insulin secretion in CFTR-silenced MIN6 cells was associated with high levels of NF-κB (the major participant in inflammatory responses), raised apoptosis, and diminished ATP production in response to the Fe/Asc challenge. However, these defects were alleviated by the addition of Trolox, thereby pointing out the role of OxS in aggravating the effects of CFTR deficiency. Our findings indicate that CFTR deficiency in combination with OxS may contribute to endocrine cell dysfunction and insulin secretion, which at least in part may explain the development of CFRD.
囊性纤维化（CF）相关糖尿病（CFRD）已成为一种严重影响CF患者临床结局的关键并发症。尽管CFRD已成为CF最常见的非肺部并发症，但其发病机制却鲜为人知。此外，氧化应激（OxS）作为CF和糖尿病的共同特征，是否影响CFRD的病理生理学仍有待阐明。本研究的主要目的是阐明囊性纤维化跨膜传导调节因子（CFTR）与OxS在胰腺β细胞胰岛素分泌中的作用。通过稳定表达小发夹RNA（shRNA）在MIN6细胞中实现CFTR沉默，并在有或没有有价值的促氧化系统铁/抗坏血酸（Fe/Asc；0.075/0.75 mM）以及有或没有抗氧化剂托可索仑（1 mM）的情况下评估葡萄糖诱导的胰岛素分泌。与对照Mock细胞相比，CFTR沉默的MIN6细胞在基础状态和不同葡萄糖浓度下的胰岛素分泌均显著降低（约70%）。此外，CFTR沉默使MIN6细胞对OxS更敏感，脂质过氧化物增加和抗氧化防御减弱均证明了这一点，尤其是在与Fe/Asc孵育后。CFTR沉默的MIN6细胞中胰岛素分泌减少与高水平的NF-κB（炎症反应的主要参与者）、细胞凋亡增加以及对Fe/Asc刺激的ATP产生减少有关。然而，添加托可索仑可缓解这些缺陷，从而指出OxS在加重CFTR缺乏影响方面的作用。我们的研究结果表明，CFTR缺乏与OxS相结合可能导致内分泌细胞功能障碍和胰岛素分泌，这至少部分可以解释CFRD的发生。
