Department of Gastroenterology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China.
Neurogastroenterol Motil. 2021 May;33(5):e14052. doi: 10.1111/nmo.14052. Epub 2021 Jan 16.
Age-associated changes alter calcium-activated potassium channel (BK ) expression of colon. Sphingolipids (SLs) are important cell membrane structural components; altered composition of SLs may affect BK expression. This study investigated the mechanism by which sphingosine-1-phosphate (S1P) contributes to age-associated contractile dysfunction.
Fifty male Sprague Dawley rats of different ages were randomly assigned to five age-groups, namely 3, 6, 12, 18, and 24 months. BK expression, S1P levels, and phosphorylated myosin light chain (p-MLC) levels were tested in colonic tissues. In the absence and presence of S1P treatment, BK expression, p-MLC levels, and intracellular calcium mobilization were tested in vitro. BK small interfering RNA (siRNA) was used to investigate whether p-MLC expression and calcium mobilization were affected by BK in colonic smooth muscle cells (SMCs). The expressions of phosphorylated protein kinase B, c-Jun N-terminal kinases (JNKs), extracellular-regulated protein kinases, nuclear factor kappa-B (NF-κB), and protein kinase C (PKC ) were examined to investigate the correlation between S1P and BK .
Sphingosine-1-phosphate levels and sphingosine-1-phosphate receptor 2 (S1PR2) and BK expressions were upregulated and p-MLC expression was downregulated in the colonic tissues, age dependently. In the cultured SMCs, S1P treatment increased BK expression and reduced calcium concentration and p-MLC was observed. BK siRNA increased calcium concentration, and p-MLC levels significantly compared with control. We also showed that S1P upregulated BK through PKC , JNK, and NF-κB pathways.
In conclusion, S1P and S1PR2 participate in age-associated contractile dysfunction via BK upregulation through PKC , JNK, and NF-κB pathways.
年龄相关的变化改变了结肠钙激活钾通道（BK）的表达。神经鞘脂（SLs）是重要的细胞膜结构成分；SLs 组成的改变可能会影响 BK 的表达。本研究探讨了 1-磷酸鞘氨醇（S1P）如何导致与年龄相关的收缩功能障碍。
50 只雄性 Sprague Dawley 大鼠随机分为 5 个年龄组，分别为 3、6、12、18 和 24 个月。检测结肠组织中的 BK 表达、S1P 水平和磷酸化肌球蛋白轻链（p-MLC）水平。在无 S1P 处理和有 S1P 处理的情况下，检测 BK 表达、p-MLC 水平和细胞内钙动员情况。使用 BK 小干扰 RNA（siRNA）研究 p-MLC 表达和钙动员是否受结肠平滑肌细胞（SMCs）中 BK 的影响。检测磷酸化蛋白激酶 B、c-Jun N 端激酶（JNKs）、细胞外调节蛋白激酶、核因子 kappa-B（NF-κB）和蛋白激酶 C（PKC）的表达，以研究 S1P 与 BK 之间的相关性。
S1P 水平及其受体 2（S1PR2）和 BK 表达随年龄增长而上调，而 p-MLC 表达则呈下降趋势。在培养的 SMCs 中，S1P 处理增加了 BK 表达，降低了钙浓度和 p-MLC。与对照组相比，BK siRNA 显著增加了钙浓度和 p-MLC 水平。我们还表明，S1P 通过 PKC、JNK 和 NF-κB 途径上调 BK。
总之，S1P 和 S1PR2 通过 PKC、JNK 和 NF-κB 途径上调 BK，参与与年龄相关的收缩功能障碍。
