Discovery and Characterization of Nonpeptidyl Agonists of the Tissue-Protective Erythropoietin Receptor
作者:James L. Miller、Timothy J. Church、Dmitri Leonoudakis、Karen Lariosa-Willingham、Normand L. Frigon、Connie S. Tettenborn、Jeffrey R. Spencer、Juha Punnonen
DOI:10.1124/mol.115.098400
日期:2015.8
Erythropoietin (EPO) and its receptor are expressed in a wide variety of tissues, including the central nervous system. Local expression of both EPO and its receptor is upregulated upon injury or stress and plays a role in tissue homeostasis and cytoprotection. High-dose systemic administration or local injection of recombinant human EPO has demonstrated encouraging results in several models of tissue protection and organ injury, while poor tissue availability of the protein limits its efficacy. Here, we describe the discovery and characterization of the nonpeptidyl compound STS-E412 (2-[2-(4-chlorophenoxy)ethoxy]-5,7-dimethyl-[1,2,4]triazolo[1,5- a ]pyrimidine), which selectively activates the tissue-protective EPO receptor, comprising an EPO receptor subunit (EPOR) and the common β -chain (CD131). STS-E412 triggered EPO receptor phosphorylation in human neuronal cells. STS-E412 also increased phosphorylation of EPOR, CD131, and the EPO-associated signaling molecules JAK2 and AKT in HEK293 transfectants expressing EPOR and CD131. At low nanomolar concentrations, STS-E412 provided EPO-like cytoprotective effects in primary neuronal cells and renal proximal tubular epithelial cells. The receptor selectivity of STS-E412 was confirmed by a lack of phosphorylation of the EPOR/EPOR homodimer, lack of activity in off-target selectivity screening, and lack of functional effects in erythroleukemia cell line TF-1 and CD34+ progenitor cells. Permeability through artificial membranes and Caco-2 cell monolayers in vitro and penetrance across the blood-brain barrier in vivo suggest potential for central nervous system availability of the compound. To our knowledge, STS-E412 is the first nonpeptidyl, selective activator of the tissue-protective EPOR/CD131 receptor. Further evaluation of the potential of STS-E412 in central nervous system diseases and organ protection is warranted.
红细胞生成素(EPO)及其受体在多种组织中表达,包括中枢神经系统。在受伤或压力情况下,EPO及其受体的局部表达上调,在组织稳态和细胞保护中发挥作用。高剂量全身给药或局部注射重组人EPO在多个组织保护和器官损伤模型中显示出令人鼓舞的结果,但该蛋白在组织中的可用性差限制了其疗效。在此,我们描述了一种非肽类化合物STS-E412(2-[2-(4-氯苯氧基)乙氧基]-5,7-二甲基-[1,2,4]三唑[1,5-a] 嘧啶)的发现及特征,该化合物选择性地激活组织保护性EPO受体,包含EPO受体亚单位(EPOR)和共同β链(CD131)。STS-E412在人体神经细胞中诱导EPO受体磷酸化。STS-E412还增加了在表达EPOR和CD131的HEK293转染细胞中EPOR、CD131以及与EPO相关的信号分子JAK2和AKT的磷酸化。在低纳摩尔浓度下,STS-E412在初级神经元细胞和肾小管上皮细胞中提供了类似EPO的细胞保护效应。STS-E412的受体选择性通过以下方式得到验证:EPOR/EPOR同二聚体的磷酸化缺失、在非靶标选择性筛选中的活性缺失,以及在红细胞白血病细胞系TF-1和CD34+前体细胞中的功能效应缺失。通过人工膜和Caco-2细胞单层的渗透性,及其在体内穿越血脑屏障的能力,提示该化合物在中枢神经系统中的可用性潜力。据我们所知,STS-E412是首个非肽类的组织保护性EPOR/CD131受体选择性激活剂。进一步评估STS-E412在中枢神经系统疾病和器官保护中的潜力是必要的。