Vajna R, Schramm M, Pereverzev A, Arnhold S, Grabsch H, Klöckner U, Perez-Reyes E, Hescheler J, Schneider T
Institute of Neurophysiology, University of Cologne, Germany.
Eur J Biochem. 1998 Oct 1;257(1):274-85. doi: 10.1046/j.1432-1327.1998.2570274.x.
The expression of Ca2+ channel alpha1E isoforms has been analyzed in different cell lines, embryoid bodies and tissues. The comparison of the different cloned alpha1E cDNA sequences led to the prediction of alpha1E splice variants. Transcripts of two cloned alpha1E isoforms, which are discriminated by a carboxy terminal 129-bp sequence, have been detected in different cell lines and tissues. Transcripts of the shorter alpha1E isoform have been assigned to the rat cerebrum and to neuron-like cells from in vitro, differentiated embryonic stem cells. The shorter isoform is the major transcript amplified from total RNA by reverse transcription (RT)-PCR and visualized on the protein level by Western blotting with common and isoform-specific antibodies. Transcripts of the longer alpha1E isoform have been identified in mouse, rat and human cerebellum, in in vitro, differentiated embryoid bodies, in the insulinoma cell lines INS-1 (rat) and betaTC-3 (mouse), in the pituitary cell line AtT-20 (mouse) when grown in 5 mM glucose, and in islets of Langerhans (rat) and kidney (rat and human). The detection of different isoforms of alpha1E in cell lines and tissues shows that the wide expression of alpha1E has to be specified by identifying the corresponding isoforms in each tissue. In islets of Langerhans and in kidney, a distinct isoform called alpha1Ee has been determined by RT-PCR, while in cerebellum a set of different alpha1E structures has been detected, which might reflect the functional heterogeneity of cerebellar neurons. The tissue-specific expression of different isoforms might be related to specific functions, which are not yet known, but the expression of the new isoform alpha1Ee in islets of Langerhans and kidney leads to the suggestion that alpha1E might be involved in the modulation of the Ca2+-mediated hormone secretion.
已在不同细胞系、胚状体和组织中分析了Ca2+通道α1E亚型的表达。对不同克隆的α1E cDNA序列进行比较，预测出了α1E剪接变体。在不同细胞系和组织中检测到了两种克隆的α1E亚型的转录本，这两种亚型通过羧基末端129 bp的序列来区分。较短的α1E亚型的转录本已在大鼠大脑以及体外分化的胚胎干细胞来源的神经元样细胞中发现。较短的亚型是通过逆转录（RT）-PCR从总RNA中扩增出的主要转录本，并通过使用通用抗体和亚型特异性抗体的蛋白质印迹在蛋白质水平上得以显现。较长的α1E亚型的转录本已在小鼠、大鼠和人类的小脑中、体外分化的胚状体中、胰岛素瘤细胞系INS-1（大鼠）和βTC-3（小鼠）中、在5 mM葡萄糖条件下培养的垂体细胞系AtT-20（小鼠）中、大鼠的胰岛和肾脏（大鼠和人类）中被鉴定出来。在细胞系和组织中检测到α1E的不同亚型表明，α1E的广泛表达必须通过鉴定每个组织中的相应亚型来明确。在胰岛和肾脏中，通过RT-PCR确定了一种名为α1Ee的独特亚型，而在小脑中检测到了一组不同的α1E结构，这可能反映了小脑神经元的功能异质性。不同亚型的组织特异性表达可能与尚未明确的特定功能有关，但新亚型α1Ee在胰岛和肾脏中的表达提示α1E可能参与Ca2+介导的激素分泌的调节。
