Arin R M, Vallejo A I, Rueda Y, Fresnedo O, Ochoa B
Department of Physiology, Faculty of Medicine and Dentistry, University of the Basque Country UPV/EHU, Sarriena s/n, Leioa, 48940, Spain.
Biochemistry (Mosc). 2015 Jan;80(1):120-5. doi: 10.1134/S0006297915010149.
The A2B adenosine receptor (A2BR) mediates biological responses to extracellular adenosine in a wide variety of cell types. Adenosine deaminase (ADA) can degrade adenosine and bind extracellularly to adenosine receptors. Adenosine modulates chloride secretion in gastric glands and gastric mucosa parietal cells. A close functional link between surface A2BR and ADA has been found on cells of the immune system, but whether this occurs in the gastrointestinal tract is unknown. The goal of this study was to determine whether A2BR and ADA are coexpressed at the plasma membrane of the acid-secreting gastric mucosa parietal cells. We used isolated gastric parietal cells after purification by centrifugal elutriation. The membrane fraction was obtained by sucrose gradient centrifugation. A2BR mRNA expression was analyzed by RT-PCR. The surface expression of A2BR and ADA proteins was evaluated by Western blotting, flow cytometry and confocal microscopy. Our findings demonstrate that A2BR and ADA are expressed in cell membranes isolated from gastric parietal cells. They show a high degree of colocalization that is particularly evident in the surface of contact between parietal cells. The confocal microscopy data together with flow cytometry analysis suggest a tight association between A2BR and ADA that might be specifically linked to glandular secretory function.
A2B 腺苷受体（A2BR）介导多种细胞类型对细胞外腺苷的生物学反应。腺苷脱氨酶（ADA）可降解腺苷并在细胞外与腺苷受体结合。腺苷调节胃腺和胃黏膜壁细胞中的氯离子分泌。在免疫系统细胞上已发现表面 A2BR 与 ADA 之间存在密切的功能联系，但在胃肠道中是否如此尚不清楚。本研究的目的是确定 A2BR 和 ADA 是否在分泌酸的胃黏膜壁细胞的质膜上共表达。我们使用通过离心淘析纯化后的分离胃壁细胞。通过蔗糖梯度离心获得膜组分。通过 RT-PCR 分析 A2BR mRNA 表达。通过蛋白质印迹、流式细胞术和共聚焦显微镜评估 A2BR 和 ADA 蛋白的表面表达。我们的研究结果表明，A2BR 和 ADA 在从胃壁细胞分离的细胞膜中表达。它们显示出高度共定位，在壁细胞之间的接触表面尤为明显。共聚焦显微镜数据与流式细胞术分析表明 A2BR 和 ADA 之间存在紧密关联，这可能与腺体分泌功能特别相关。
