Grantcharova Evelina, Reusch H Peter, Beyermann Michael, Rosenthal Walter, Oksche Alexander
Institut für Pharmakologie, Charité Campus Benjamin Franklin, Thielallee 67-73, 14195 Berlin, Germany.
Exp Biol Med (Maywood). 2006 Jun;231(6):757-60.
Endothelin-1 (ET-1) acts on two different G protein-coupled receptors, namely the endothelin A (ET(A)) and the endothelin B (ET(B)) receptors. Both receptor subtypes show differences in their tissue expression and signal transduction. In the present study, we compared the ability of ET(A) and ET(B) receptors to stimulate extracellular signal-regulated kinase 1/2 (ERK1/2). In addition, we analyzed the role of the extracellular N terminus for ERK1/2 activation, because the ET(B) receptor undergoes an agonist-dependent N-terminal proteolysis. ET-1 stimulation of HEK293 cells stably expressing the ET(A) receptor induced a monophasic, but sustained ERK1/2 activation, whereas the ET(B) receptor showed a biphasic ERK1/2 activation. A truncated mutant ET(B) receptor, lacking the proteolytically cleaved N terminus (delta2-64 ET(B)) revealed only a monophasic and transient ERK1/2 activation. Treatment of HEK293 delta2-64 ET(B) cell clones with ET-1 and a synthetic NT27-64 peptide, corresponding to the N-terminally cleaved fragment of the ET(B) receptor and ET-1, did not restore the biphasic activation of ERK1/2. A chimeric ET(B) receptor in which the N terminus was replaced by the N terminus of the ET(A) receptor elicited biphasic ERK1/2 activation. The presented data suggest that an intact N terminus of the ET(B) receptor is necessary for the second phase of ERK1/2 activation. However, it appears that the length of the N terminus rather than a specific sequence motif is required for biphasic ERK1/2 activation.
内皮素-1（ET-1）作用于两种不同的G蛋白偶联受体，即内皮素A（ET(A)）受体和内皮素B（ET(B)）受体。两种受体亚型在组织表达和信号转导方面存在差异。在本研究中，我们比较了ET(A)和ET(B)受体刺激细胞外信号调节激酶1/2（ERK1/2）的能力。此外，我们分析了细胞外N末端在ERK1/2激活中的作用，因为ET(B)受体经历激动剂依赖性的N末端蛋白水解。稳定表达ET(A)受体的HEK293细胞经ET-1刺激后诱导出单相但持续的ERK1/2激活，而ET(B)受体则表现出双相ERK1/2激活。一种缺失经蛋白水解切割的N末端的截短突变ET(B)受体（δ2-64 ET(B)）仅显示单相和短暂的ERK1/2激活。用ET-1和一种合成的NT27-64肽（对应于ET(B)受体和ET-1的N末端切割片段）处理HEK293 δ2-64 ET(B)细胞克隆，并未恢复ERK1/2的双相激活。一种N末端被ET(A)受体的N末端取代的嵌合ET(B)受体引发了双相ERK1/2激活。所呈现的数据表明，ET(B)受体完整的N末端是ERK1/2激活第二阶段所必需的。然而，似乎双相ERK1/2激活需要的是N末端的长度而非特定的序列基序。
