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利用活细胞荧光成像技术解析蛋白激酶 Cδ同工酶与线粒体的特异性相互作用。

Isozyme-specific interaction of protein kinase Cδ with mitochondria dissected using live cell fluorescence imaging.

机构信息

Department of Pharmacology, University of California San Diego, La Jolla, California 92093, USA.

出版信息

J Biol Chem. 2012 Nov 2;287(45):37891-906. doi: 10.1074/jbc.M112.412635. Epub 2012 Sep 17.

Abstract

PKCδ signaling to mitochondria has been implicated in both mitochondrial apoptosis and metabolism. However, the mechanism by which PKCδ interacts with mitochondria is not well understood. Using FRET-based imaging, we show that PKCδ interacts with mitochondria by a novel and isozyme-specific mechanism distinct from its canonical recruitment to other membranes such as the plasma membrane or Golgi. Specifically, we show that PKCδ interacts with mitochondria following stimulation with phorbol esters or, in L6 myocytes, with insulin via a mechanism that requires two steps. In the first step, PKCδ translocates acutely to mitochondria by a mechanism that requires its C1A and C1B domains and a Leu-Asn sequence in its turn motif. In the second step, PKCδ is retained at mitochondria by a mechanism that depends on its C2 domain, a unique Glu residue in its activation loop, intrinsic catalytic activity, and the mitochondrial membrane potential. In contrast, of these determinants, only the C1B domain is required for the phorbol ester-stimulated translocation of PKCδ to other membranes. PKCδ also basally localizes to mitochondria and increases mitochondrial respiration via many of the same determinants that promote its agonist-evoked interaction. PKCδ localized to mitochondria has robust activity, as revealed by a FRET reporter of PKCδ-specific activity (δCKAR). These data support a model in which multiple determinants unique to PKCδ drive a specific interaction with mitochondria that promotes mitochondrial respiration.

摘要

PKCδ 与线粒体的信号转导与线粒体凋亡和代谢有关。然而,PKCδ 与线粒体相互作用的机制尚不清楚。我们使用基于 FRET 的成像技术,展示了 PKCδ 通过一种新颖的、同工型特异性的机制与线粒体相互作用,这种机制与 PKCδ 与其他膜(如质膜或高尔基体)的典型募集机制不同。具体来说,我们展示了 PKCδ 在受到佛波酯或胰岛素刺激后与线粒体相互作用,这一机制需要两步。在第一步中,PKCδ 通过一种需要其 C1A 和 C1B 结构域以及其turn 基序中的亮氨酸-天冬氨酸序列的机制,急性易位到线粒体。在第二步中,PKCδ 通过一种依赖于其 C2 结构域、激活环中的独特谷氨酸残基、内在催化活性和线粒体膜电位的机制,被保留在线粒体上。相比之下,在这些决定因素中,只有 C1B 结构域是 PKCδ 向其他膜转移所需的。PKCδ 还基础定位到线粒体,并通过促进其激动剂诱导相互作用的许多相同决定因素来增加线粒体呼吸。PKCδ 定位到线粒体的活性很强,这一点通过 PKCδ 特异性活性的 FRET 报告器(δCKAR)得到了揭示。这些数据支持了这样一种模型,即 PKCδ 特有的多个决定因素驱动与线粒体的特定相互作用,从而促进线粒体呼吸。

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