Weiergräber M, Pereverzev A, Vajna R, Henry M, Schramm M, Nastainczyk W, Grabsch H, Schneider T
Institute of Neurophysiology, University of Köln, Köln, Germany.
J Histochem Cytochem. 2000 Jun;48(6):807-19. doi: 10.1177/002215540004800609.
The calcium channel alpha1E subunit was originally cloned from mammalian brain. A new splice variant was recently identified in rat islets of Langerhans and in human kidney by the polymerase chain reaction. The same isoform of alpha1E was detected in rat and guinea pig heart by amplifying indicative cDNA fragments and by immunostaining using peptide-specific antibodies. The apparent molecular size of cardiac alpha1E was determined by SDS-PAGE and immunoblotting (218 +/- 6 kD; n = 3). Compared to alpha1E from stably transfected HEK-293 cells, this is smaller by 28 kD. The distribution of alpha1E in cardiac muscle cells of the conducting system and in the cardiomyoblast cell line H9c2 was compared to the distribution of chromogranin, a marker of neuroendocrine cells, and to the distribution of atrial natriuretic peptide (ANP). In serial sections from atrial and ventricular regions of rat heart, co-localization of alpha1E with ANP was detected in atrium and with chromogranin A/B in Purkinje fibers of the conducting system in both rat atrium and ventricle. The kidney is another organ in which natriuretic peptide hormones are secreted. The detection of alpha1E in the distal tubules of human kidney, where urodilatin is stored and secreted, led to the conclusion that the expression of alpha1E in rat heart and human kidney is linked to regions with endocrine functions and therefore is involved in the Ca(2+)-dependent secretion of peptide hormones such as ANP and urodilatin.
钙通道α1E亚基最初是从哺乳动物大脑中克隆出来的。最近通过聚合酶链反应在大鼠胰岛和人肾脏中鉴定出一种新的剪接变体。通过扩增指示性cDNA片段并使用肽特异性抗体进行免疫染色，在大鼠和豚鼠心脏中检测到相同亚型的α1E。通过SDS-PAGE和免疫印迹法测定心脏α1E的表观分子大小（218±6 kD；n = 3）。与稳定转染的HEK-293细胞中的α1E相比，它小28 kD。将α1E在传导系统心肌细胞和成肌细胞系H9c2中的分布与神经内分泌细胞标志物嗜铬粒蛋白的分布以及心房利钠肽（ANP）的分布进行了比较。在大鼠心脏心房和心室区域的连续切片中，在心房中检测到α1E与ANP共定位，在大鼠心房和心室的传导系统浦肯野纤维中检测到α1E与嗜铬粒蛋白A/B共定位。肾脏是另一个分泌利钠肽激素的器官。在人肾脏远端小管中检测到α1E，尿舒张素在该部位储存和分泌，由此得出结论，α1E在大鼠心脏和人肾脏中的表达与具有内分泌功能的区域相关，因此参与了ANP和尿舒张素等肽激素的钙依赖性分泌。
