Enteric Neuroscience Program and Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota; Gastroenterology Research Unit, Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, Minnesota.
Enteric Neuroscience Program and Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota; Gastroenterology Research Unit, Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, Minnesota.
Cell Mol Gastroenterol Hepatol. 2021;11(1):117-145. doi: 10.1016/j.jcmgh.2020.07.011. Epub 2020 Aug 7.
BACKGROUND & AIMS: Gastric dysfunction in the elderly may cause reduced food intake, frailty, and increased mortality. The pacemaker and neuromodulator cells interstitial cells of Cajal (ICC) decline with age in humans, and their loss contributes to gastric dysfunction in progeric klotho mice hypomorphic for the anti-aging Klotho protein. The mechanisms of ICC depletion remain unclear. Klotho attenuates Wnt (wingless-type MMTV integration site) signaling. Here, we examined whether unopposed Wnt signaling could underlie aging-associated ICC loss by up-regulating transformation related protein TRP53 in ICC stem cells (ICC-SC).
Mice aged 1-107 weeks, klotho mice, APC mice with overactive Wnt signaling, mouse ICC-SC, and human gastric smooth muscles were studied by RNA sequencing, reverse transcription-polymerase chain reaction, immunoblots, immunofluorescence, histochemistry, flow cytometry, and methyltetrazolium, ethynyl/bromodeoxyuridine incorporation, and ex-vivo gastric compliance assays. Cells were manipulated pharmacologically and by gene overexpression and RNA interference.
The klotho and aged mice showed similar ICC loss and impaired gastric compliance. ICC-SC decline preceded ICC depletion. Canonical Wnt signaling and TRP53 increased in gastric muscles of klotho and aged mice and middle-aged humans. Overstimulated canonical Wnt signaling increased DNA damage response and TRP53 and reduced ICC-SC self-renewal and gastric ICC. TRP53 induction persistently inhibited G/S and G/M cell cycle phase transitions without activating apoptosis, autophagy, cellular quiescence, or canonical markers/mediators of senescence. G/S block reflected increased cyclin-dependent kinase inhibitor 1B and reduced cyclin D1 from reduced extracellular signal-regulated kinase activity.
Increased Wnt signaling causes age-related ICC loss by up-regulating TRP53, which induces persistent ICC-SC cell cycle arrest without up-regulating canonical senescence markers.
老年人的胃功能障碍可能导致食物摄入减少、虚弱和死亡率增加。在人类中，起搏细胞和神经调节细胞 Cajal 间质细胞（ICC）随着年龄的增长而减少，其损失导致抗老化 Klotho 蛋白低表达的 progeric klotho 小鼠胃功能障碍。ICC 耗竭的机制仍不清楚。Klotho 可减弱 Wnt（无翅型 MMTV 整合位点）信号。在这里，我们通过在 ICC 干细胞（ICC-SC）中上调转化相关蛋白 TRP53，研究了未受抑制的 Wnt 信号是否会导致与衰老相关的 ICC 丢失。
研究了年龄为 1-107 周的小鼠、klotho 小鼠、Wnt 信号过度激活的 APC 小鼠、小鼠 ICC-SC 和人胃平滑肌细胞，采用 RNA 测序、逆转录聚合酶链反应、免疫印迹、免疫荧光、组织化学、流式细胞术、甲基四唑盐、乙炔基/溴脱氧尿苷掺入和离体胃顺应性测定。通过药理学和基因过表达和 RNA 干扰对细胞进行操作。
klotho 小鼠和老年小鼠表现出相似的 ICC 丢失和胃顺应性受损。ICC-SC 下降先于 ICC 耗竭。klotho 小鼠和老年小鼠以及中年人类的胃肌中，经典 Wnt 信号和 TRP53 增加。过度刺激的经典 Wnt 信号增加了 DNA 损伤反应和 TRP53，减少了 ICC-SC 的自我更新和胃 ICC。TRP53 诱导持续抑制 G1/S 和 G2/M 细胞周期阶段过渡，而不激活细胞凋亡、自噬、细胞静止或衰老的经典标志物/介质。G1/S 阻滞反映了细胞外信号调节激酶活性降低导致细胞周期蛋白依赖性激酶抑制剂 1B 增加和细胞周期蛋白 D1 减少。
增加的 Wnt 信号通过上调 TRP53 导致与年龄相关的 ICC 丢失，TRP53 诱导持续的 ICC-SC 细胞周期阻滞，而不上调经典的衰老标志物。
Zotero 插件
