A functional role for the 'fibroblast-like cells' in gastrointestinal smooth muscles
A functional role for the 'fibroblast-like cells' in gastrointestinal smooth muscles
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DOI：
10.1113/jphysiol.2010.201129
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发表时间：
2011-02-01
影响因子：
5.5
通讯作者：
Sanders, Kenton M.
中科院分区：
文献类型：
--
作者：
Kurahashi, Masaaki;Zheng, Haifeng;Sanders, Kenton M.
非技术概述平滑肌，如胃肠道中的平滑肌，由几种类型的细胞组成。胃肠肌含有平滑肌细胞、肠神经元、神经胶质细胞、免疫细胞和各种类型的间质细胞。一种类型的间质细胞，被形态学家称为“成纤维细胞样细胞”，是常见的，但其功能尚不清楚。这些细胞位于肠道运动神经元的末端附近，这表明它们可能在产生帮助控制胃肠运动的神经反应中发挥作用。我们使用了一种新的小鼠，其明亮的绿色荧光蛋白在成纤维细胞样细胞中特异性表达，以帮助我们在用酶分散整个肌肉时获得的细胞混合物中识别这些细胞。我们分离出这些细胞，发现它们对一种主要的抑制性神经递质--嘌呤有反应。我们描述了这些反应，我们的结果提供了一个新的假设，平滑肌组织中的成纤维细胞样细胞的作用。形态学家描述了平滑肌中的成纤维细胞样细胞（FLC）。在胃肠道中，FLC分布于肠运动神经元的沿着突起以及环行肌层和纵行肌层之间。它们靠近神经静脉曲张并与平滑肌细胞形成缝隙连接。它们用血小板衍生生长因子受体α（PDGFR α）和小电导Ca 2+激活K+（SK 3）通道的抗体标记。我们使用在PDGFR α +细胞中组成型表达增强型绿色荧光蛋白（eGFP）的转基因小鼠，以分离和研究PDGFR α +细胞作为嘌呤能神经传递的可能介质的功能。PDGFR α +细胞大量表达嘌呤受体（P2 Y1）和SK 3通道。在全细胞电压钳下，一些PDGFR α +细胞产生大幅度自发瞬时外向电流，其被蜂毒肽（300 nm）阻断。透析的细胞与Ca 2+（500 nm）激活大振幅K+电流，也被阻断的蜂毒肽。应用三磷酸腺苷（ATP）、腺嘌呤二磷酸（ADP）或β-烟酰胺腺嘌呤二核苷酸（β-NAD）（1-1000 μ m）激活PDGFR α +细胞中的大幅度、apamin敏感性K+电流，该电流被P2 Y1拮抗剂MRS 2500（1 μ m）阻断。在同等条件下，平滑肌细胞对嘌呤的反应没有引起，在优化条件下（例如透化贴片和高浓度ATP; 1 mm）仅引起非常小的外向电流。这些数据表明，PDGFR α +细胞是一类新的可兴奋细胞，具有大电流密度，可归因于SK通道以及介导胃肠道肌肉中对嘌呤的肠道抑制反应的分子和离子装置。
Non-technical summarySmooth muscles, as in the gastrointestinal tract, are composed of several types of cells. Gastrointestinal muscles contain smooth muscle cells, enteric neurons, glial cells, immune cells, and various classes of interstitial cells. One type of interstitial cell, referred to as 'fibroblast-like cells' by morphologists, are common, but their function is unknown. These cells are found near the terminals of enteric motor neurons, suggesting they could have a role in generating neural responses that help control gastrointestinal movements. We used a novel mouse with bright green fluorescent protein expressed specifically in the fibroblast-like cells to help us identify these cells in the mixture of cells obtained when whole muscles are dispersed with enzymes. We isolated these cells and found they respond to a major class of inhibitory neurotransmitters - purines. We characterized these responses, and our results provide a new hypothesis about the role of fibroblast-like cells in smooth muscle tissues.Morphologists have described 'fibroblast-like cells' (FLCs) in smooth muscles. In the gastrointestinal tract, FLCs are distributed along processes of enteric motor neurons and between the circular and longitudinal muscle layers. They are close to nerve varicosities and make gap junctions with smooth muscle cells. They are labelled with antibodies for platelet derived growth factor receptor alpha (PDGFR alpha) and small conductance Ca2+-activated K+ (SK3) channels. We used transgenic mice with constitutive expression of enhanced green fluorescent protein (eGFP) in PDGFR alpha+ cells to isolate and study the function of PDGFR alpha+ cells as possible mediators of purinergic neurotransmission. PDGFR alpha+ cells expressed purine receptors (P2Y1) and SK3 channels abundantly. Under whole cell voltage clamp some PDGFR alpha+ cells generated large amplitude spontaneous transient outward currents that were blocked by apamin (300 nm). Dialysis of cells with Ca2+ (500 nm) activated large amplitude K+ currents that were also blocked by apamin. Application of adenosine triphosphate (ATP), adenine diphosphate (ADP) or beta-nicotinamide adenine dinucleotide (beta-NAD) (1-1000 mu m) activated large amplitude, apamin-sensitive K+ currents in PDGFR alpha+ cells that were blocked by the P2Y1 antagonist MRS2500 (1 mu m). Responses to purines were not elicited in smooth muscle cells under equivalent conditions, and only very small outward currents were elicited under optimized conditions (e.g. permeabilized patches and high concentrations of ATP; 1 mm). These data show that PDGFR alpha+ cells are a novel class of excitable cells with large current densities attributable to SK channels and the molecular and ionic apparatus to mediate enteric inhibitory responses to purines in GI muscles.