Ferri Gianmarco, Tesi Marta, Pesce Luca, Bugliani Marco, Grano Francesca, Occhipinti Margherita, Suleiman Mara, De Luca Carmela, Marselli Lorella, Marchetti Piero, Cardarelli Francesco
Laboratorio NEST-Scuola Normale Superiore, Piazza San Silvestro 12, 56127 Pisa, Italy.
Department of Clinical and Experimental Medicine, Islet Cell Laboratory, University of Pisa, 56127 Pisa, Italy.
Pharmaceutics. 2021 Sep 3;13(9):1403. doi: 10.3390/pharmaceutics13091403.
Glucagon-like peptide-1 receptor (GLP-1R) agonists are being used for the treatment of type 2 diabetes (T2D) and may have beneficial effects on the pancreatic β-cells. Here, we evaluated the effects of GLP-1R agonism on insulin secretory granule (ISG) dynamics in primary β-cells isolated from human islets exposed to palmitate-induced lipotoxic stress. Islets cells were exposed for 48 h to 0.5 mM palmitate (hereafter, 'Palm') with or without the addition of a GLP-1 agonist, namely 10 nM exendin-4 (hereafter, 'Ex-4'). Dissociated cells were first transfected with syncollin-EGFP in order to fluorescently mark the ISGs. Then, by applying a recently established spatiotemporal correlation spectroscopy technique, the average structural (i.e., size) and dynamic (i.e., the local diffusivity and mode of motion) properties of ISGs are extracted from a calculated imaging-derived Mean Square Displacement (MSD) trace. Besides defining the structural/dynamic fingerprint of ISGs in human cells for the first time, MSD analysis allowed to probe fingerprint variations under selected conditions: namely, it was shown that Palm affects ISGs dynamics in response to acute glucose stimulation by abolishing the ISGs mobilization typically imparted by glucose and, concomitantly, by reducing the extent of ISGs active/directed intracellular movement. By contrast, co-treatment with Ex-4 normalizes ISG dynamics, i.e., re-establish ISG mobilization and ability to perform active transport in response to glucose stimulation. These observations were correlated with standard glucose-stimulated insulin secretion (GSIS), which resulted in being reduced in cells exposed to Palm but preserved in cells concomitantly exposed to 10 nM Ex-4. Our data support the idea that GLP-1R agonism may exert its beneficial effect on human β-cells under metabolic stress by maintaining ISGs' proper intracellular dynamics.
胰高血糖素样肽-1受体（GLP-1R）激动剂正用于治疗2型糖尿病（T2D），并且可能对胰腺β细胞具有有益作用。在此，我们评估了GLP-1R激动作用对从暴露于棕榈酸酯诱导的脂毒性应激的人胰岛中分离的原代β细胞中胰岛素分泌颗粒（ISG）动力学的影响。胰岛细胞在有或没有添加GLP-1激动剂（即10 nM艾塞那肽-4，以下简称“Ex-4”）的情况下，暴露于0.5 mM棕榈酸酯（以下简称“Palm”）48小时。首先用同步素-EGFP转染解离的细胞，以便对ISG进行荧光标记。然后，通过应用最近建立的时空相关光谱技术，从计算得出的成像衍生均方位移（MSD）轨迹中提取ISG的平均结构（即大小）和动态（即局部扩散率和运动模式）特性。除了首次定义人类细胞中ISG的结构/动态指纹外，MSD分析还允许在选定条件下探测指纹变化：即，结果表明，Palm通过消除通常由葡萄糖赋予的ISG动员，并同时减少ISG活跃/定向细胞内运动的程度，来影响急性葡萄糖刺激下的ISG动力学。相比之下，与Ex-4共同处理可使ISG动力学正常化，即重新建立ISG动员以及响应葡萄糖刺激进行主动运输的能力。这些观察结果与标准葡萄糖刺激的胰岛素分泌（GSIS）相关，GSIS在暴露于Palm的细胞中降低，但在同时暴露于10 nM Ex-4的细胞中得以保留。我们的数据支持这样一种观点，即GLP-1R激动作用可能通过维持ISG适当的细胞内动力学，在代谢应激下对人类β细胞发挥有益作用。
