Bioactivity of the putative apelin proprotein expands the repertoire of apelin receptor ligands
Bioactivity of the putative apelin proprotein expands the repertoire of apelin receptor ligands
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DOI：
10.1016/j.bbagen.2017.05.017
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发表时间：
2017-08-01
影响因子：
3
通讯作者：
Rainey, Jan K.
中科院分区：
文献类型：
--
作者：
Shin, Kyungsoo;Chapman, Nigel A.;Rainey, Jan K.
背景资料：爱帕琳是A类G蛋白偶联受体的肽配体，称为爱帕琳受体（AR或APJ），其调节血管生成、脂肪细胞轴和心血管功能。已显示爱帕琳作为13、17和36个氨基酸的同种型、嘌呤失活的55个残基前蛋白（爱帕琳原或爱帕琳-55）的C-末端片段具有生物活性。虽然已经提出了细胞内蛋白质前体加工，从初乳和牛奶中分离的爱帕琳-55证明了潜在的分泌前处理和爱帕琳原-AR interaction.Methods的可能性：爱帕琳同种型的活性和效力进行了比较，通过细胞内Western（TM）测定ERK磷酸化使用一个稳定的AR转染的HEK 293 A细胞系。通过圆二色性和异色性溶液状态核磁共振spectroscopy.Results：Apelin-55显示激活AR，具有类似的最大ERK磷酸化反应和效力，除了apelin-13，表现出更大的效力，较短的亚型的构象比较。与此共享的活动，高度相似的构象表现出在所有爱帕琳亚型的共享的C-末端区域负责receptor binding and activation.Conclusions：AR激活所有爱帕琳亚型可能铰链上共享的构象和动力学的C-末端，爱帕琳-55提供了一种替代的生物活性亚型，尽管增加了19个N-末端残基相对于爱帕琳-36。
Background: Apelin is a peptide ligand for a class A G-protein coupled receptor called the apelin receptor (AR or APJ) that regulates angiogenesis, the adipoinsular axis, and cardiovascular functions. Apelin has been shown to be bioactive as 13, 17, and 36 amino acid isoforms, C-terminal fragments of the putatively inactive 55-residue proprotein (proapelin or apelin-55). Although intracellular proprotein processing has been proposed, isolation of apelin-55 from colostrum and milk demonstrates potential for secretion prior to processing and the possibility of proapelin-AR interaction.Methods: Apelin isoform activity and potency were compared by an In-Cell Western (TM) assay for ERK phosphorylation using a stably AR-transfected HEK293A cell line. Conformational comparison of apelin isoforms was carried out by circular dichroism and heteronuclear solution-state nuclear magnetic resonance spectroscopy.Results: Apelin-55 is shown to activate the AR, with similar maximum ERK phophorylation response and potency to the shorter isoforms except for apelin-13, which exhibited a greater potency. Correlating to this shared activity, highly similar conformations are exhibited in all apelin isoforms for the shared C-terminal region responsible for receptor binding and activation.Conclusions: AR activation by all apelin isoforms likely hinges upon shared conformation and dynamics in the C-terminus, with apelin-55 providing an alternative bioactive isoform despite the addition of 19 N-terminal residues relative to apelin-36.