Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Houston, Texas, USA.
PLoS One. 2012;7(8):e44426. doi: 10.1371/journal.pone.0044426. Epub 2012 Aug 31.
Ca(2+)/calmodulin-dependent protein kinases (CaMKs) are major downstream mediators of neuronal calcium signaling that regulate multiple neuronal functions. CaMKII, one of the key CaMKs, plays a significant role in mediating cellular responses to external signaling molecules. Although calcium signaling plays an essential role in the enteric nervous system (ENS), the role of CaMKII in neurogenic intestinal function has not been determined. In this study, we investigated the function and expression pattern of CaMKII in the ENS across several mammalian species.
METHODOLOGY/PRINCIPAL FINDINGS: CaMKII expression was characterized by immunofluorescence analyses and Western Blot. CaMKII function was examined by intracellular recordings and by assays of colonic contractile activity. Immunoreactivity for CaMKII was detected in the ENS of guinea pig, mouse, rat and human preparations. In guinea pig ENS, CaMKII immunoreactivity was enriched in both nitric oxide synthase (NOS)- and calretinin-containing myenteric plexus neurons and non-cholinergic secretomotor/vasodilator neurons in the submucosal plexus. CaMKII immunoreactivity was also expressed in both cholinergic and non-cholinergic neurons in the ENS of mouse, rat and human. The selective CaMKII inhibitor, KN-62, suppressed stimulus-evoked purinergic slow EPSPs and ATP-induced slow EPSP-like response in guinea pig submucosal plexus, suggesting that CaMKII activity is required for some metabotropic synaptic transmissions in the ENS. More importantly, KN-62 significantly suppressed tetrodotoxin-induced contractile response in mouse colon, which suggests that CaMKII activity is a major determinant of the tonic neurogenic inhibition of this tissue.
ENS neurons across multiple mammalian species express CaMKII. CaMKII signaling constitutes an important molecular mechanism for controlling intestinal motility and secretion by regulating the excitability of musculomotor and secretomotor neurons. These findings revealed a fundamental role of CaMKII in the ENS and provide clues for the treatment of intestinal dysfunctions.
钙/钙调蛋白依赖性蛋白激酶（CaMKs）是神经元钙信号的主要下游介质，调节多种神经元功能。CaMKII 是关键的 CaMK 之一，在介导细胞对外界信号分子的反应中起着重要作用。尽管钙信号在肠神经系统（ENS）中起着至关重要的作用，但 CaMKII 在神经源性肠道功能中的作用尚未确定。在这项研究中，我们研究了 CaMKII 在几种哺乳动物 ENS 中的功能和表达模式。
方法/主要发现：通过免疫荧光分析和 Western Blot 来描述 CaMKII 的表达。通过细胞内记录和结肠收缩活性测定来检查 CaMKII 的功能。在豚鼠、小鼠、大鼠和人肠道标本中检测到 CaMKII 的免疫反应性。在豚鼠 ENS 中，CaMKII 免疫反应性富集于一氧化氮合酶（NOS）和钙调蛋白阳性的肌间神经丛神经元和黏膜下神经丛中的非胆碱能 secretomotor/vasodilator 神经元中。在小鼠、大鼠和人 ENS 中的胆碱能和非胆碱能神经元中也表达了 CaMKII。选择性 CaMKII 抑制剂 KN-62 抑制了刺激诱导的嘌呤能慢 EPSP 和 ATP 诱导的慢 EPSP 样反应，表明 CaMKII 活性是 ENS 中某些代谢型突触传递所必需的。更重要的是，KN-62 显著抑制了小鼠结肠中河豚毒素诱导的收缩反应，这表明 CaMKII 活性是该组织中紧张性神经源性抑制的主要决定因素。
多种哺乳动物的 ENS 神经元表达 CaMKII。CaMKII 信号构成了调节肌运动神经元和 secretomotor 神经元兴奋性的控制肠道运动和分泌的重要分子机制。这些发现揭示了 CaMKII 在 ENS 中的基本作用，并为肠道功能障碍的治疗提供了线索。
