Song Ni-Na, Huang Xu, Lu Hong-Li, Lu Chen, Chen Jie, Xu Wen-Xie
Department of Anatomy and Physiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
Department of Physiology, Xuzhou Medical University, Xuzhou, China.
J Neurogastroenterol Motil. 2023 Apr 30;29(2):250-261. doi: 10.5056/jnm22052.
BACKGROUND/AIMS: The gastrointestinal symptom of diabetes mellitus, chronic constipation, seriously affects patients' life. Whereas, the mechanism of chronic constipation is still ambiguous, resulting in a lack of effective therapies for this symptom. As a part of the smooth muscle cells, interstitial cells of Cajal, and platelet-derived growth factor receptor alpha-positive (PDGFRα) cells syncytium (SIP syncytium), PDGFRα cells play an important role in regulating colonic motility. According to our previous study, in PDGFRα cells in colons of diabetic mice, the function of the P2Y1 purinergic receptor/type 3 small-conductance calcium-activated potassium (SK3) channel signaling pathway is strengthened, which may lead to colonic dysmotility. The purpose of this study is to investigate the changes in SK3 channel properties of PDGFRα cells in diabetic mice.
Whole-cell patch clamp, Western blotting, superoxide dismutase activity measurement, and malondialdehyde measurement were main methods in the present study.
The present study revealed that when dialysed with low calcium ion (Ca) solution, the SK3 current density was significantly decreased in PDGFRα cells from diabetic mice. However, the SK3 current density in PDGFRα cells was enhanced from diabetic mice when dialysed with high Ca solution. Moreover, hydrogen peroxide-treatment mimicked this phenomenon in SK3 transgenic HEK293 cells. The subunit of SK3 channels, protein kinase CK2, was up-regulated in colonic muscle layers and hydrogen peroxide-treated HEK293 cells. Additionally, protein phosphatase 2A, the subunit of SK3 channels, was not changed in streptozotocin-treated mouse colons or hydrogen peroxide-treated HEK293 cells.
The diabetic oxidative stress-induced upregulation of CK2 contributed to modulating SK3 channel sensitivity to Ca in colonic PDGFRα cells, which may result in colonic dysmotility in diabetic mice.
背景/目的：糖尿病的胃肠道症状——慢性便秘，严重影响患者生活。然而，慢性便秘的机制仍不明确，导致针对该症状缺乏有效的治疗方法。作为平滑肌细胞、Cajal间质细胞和血小板衍生生长因子受体α阳性（PDGFRα）细胞合胞体（SIP合胞体）的一部分，PDGFRα细胞在调节结肠动力中起重要作用。根据我们之前的研究，在糖尿病小鼠结肠的PDGFRα细胞中，P2Y1嘌呤能受体/3型小电导钙激活钾（SK3）通道信号通路的功能增强，这可能导致结肠动力障碍。本研究的目的是探讨糖尿病小鼠PDGFRα细胞中SK3通道特性的变化。
全细胞膜片钳、蛋白质印迹法、超氧化物歧化酶活性测定和丙二醛测定是本研究的主要方法。
本研究表明，用低钙离子（Ca）溶液透析时，糖尿病小鼠PDGFRα细胞中的SK3电流密度显著降低。然而，用高Ca溶液透析时，糖尿病小鼠PDGFRα细胞中的SK3电流密度增强。此外，过氧化氢处理在SK3转基因HEK293细胞中模拟了这一现象。SK3通道亚基蛋白激酶CK2在结肠肌层和过氧化氢处理的HEK293细胞中上调。此外，SK3通道亚基蛋白磷酸酶2A在链脲佐菌素处理的小鼠结肠或过氧化氢处理的HEK293细胞中未发生变化。
糖尿病氧化应激诱导的CK2上调有助于调节结肠PDGFRα细胞中SK3通道对Ca的敏感性，这可能导致糖尿病小鼠结肠动力障碍。
