Modulation of Mitofusin Activity to Treat Heart Disease

调节丝裂霉素活性治疗心脏病

• 批准号: 10280485
• 负责人: Richard N Kitsis
• 金额: $ 68.91万
• 依托单位: ALBERT EINSTEIN COLLEGE OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-08-01 至 2025-07-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10280485
• 关键词: Adult; Apoptotic; Attenuated; Binding; Brain Ischemia; Cardiac Myocytes; Cell Death; Cells; Cellular Metabolic Process; Cessation of life; Collaborations; Data; Event; Family; Goals; Guanosine Triphosphate Phosphohydrolases; Heart Diseases; Heart failure; Individual; Infarction; Ischemia; Knockout Mice; Mediating; Membrane; Metabolism; Mitochondria; Modeling; Molecular Conformation; Mus; Myocardial Infarction; Myocardial Ischemia; Necrosis; Organelles; Outer Mitochondrial Membrane; Peptides; Phenocopy; Play; Proteins; Reperfusion Therapy; Reporting; Respiratory Chain; Role; Sarcoplasmic Reticulum; Shapes; Structure; Testing; Therapeutic; experimental study; genetic approach; heart function; heart metabolism; in vivo; inhibitor/antagonist; mitochondrial metabolism; mouse model; myocardial infarct sizing; new therapeutic target; novel therapeutic intervention; overexpression; small molecule

Mitochondrial “connectivity” and mitochondrial-endoplasmic/sarcoplasmic reticulum (ER/SR) “proximity” each potentiate mitochondrial-mediated metabolism and necrosis through a variety of mechanisms. Mitofusins (MFN) 1 and 2 are large GTPases that play critical roles in mitochondrial connectivity and mitochondrial-ER/SR proximity. MFN1 and MFN2 reside in the outer mitochondrial membrane where they mediate mitochondrial fusion. MFN2, but not MFN1, also resides in the ER/SR membrane, where it tethers ER/SR to mitochondria through interactions with mitochondrial-localized MFN1 or MFN2. Deletion of MFN1 or MFN2 reduces myocardial infarct (MI) size during ischemia/reperfusion (I/R). Conversely, MFN1 and MFN2 overexpression augment metabolism. Given this information, therapeutic inhibition of MFNs would be expected to reduce infarct size during MI, while therapeutic activation of MFNs might attenuate heart failure (HF) by augmenting metabolism. The challenge has been to find a means to manipulate the activities of endogenous MFNs. In collaboration with others, we created the first peptides and small molecules that modulate conformations of MFN1 and MFN2 and delineated the underlying structural basis for these effects. We reported previously that MFN activators increase, while MFN inhibitors decrease, mitochondrial fusion. These are direct effects that require binding of these agents to either MFN1 or MFN2. We present here new data showing that MFN activators increase, while MFN inhibitors decrease, mitochondrial-ER/SR proximity and Ca2+ transfer to mitochondria. Moreover, we observed that MFN activators exacerbate infarct size during myocardial I/R, while MFN inhibitors reduce infarct size in both heart and brain I/R models. Interestingly, these effects of the activators are dependent on MFN2, but not MFN1, suggesting the importance of mitochondrial-ER/SR proximity but not excluding the possibility that MFN2- dependent changes in mitochondrial connectivity and shape also contribute. Additionally, MFN activators promote cardiomyocyte metabolism. The goals of this project are to understand the mechanisms by which MFN modulators impact cardiomyocyte death and metabolism and to test whether these agents might provide novel therapeutic strategies for MI and HF. We propose: 1. To correlate changes in MFN activation/inhibition with mitochondrial connectivity, mitochondrial-ER/SR proximity, Ca2+ transfer, cell death, and metabolism in adult cardiomyocytes. 2. To delineate the individual contributions of mitochondrial connectivity and mitochondrial- ER/SR proximity to cell death and metabolism in cardiomyocytes in vivo. 3. To assess whether mitofusin modulators provide novel therapeutic strategies for MI and HF. This project breaks new ground in defining the mechanisms by which MFN modulators impact cardiomyocyte death and metabolism and whether MFNs provide an actionable target for novel therapies directed against MI and HF.

线粒体“连通性”和线粒体内质/肌浆网(ER/SR)“邻近” 通过多种机制增强线粒体介导的新陈代谢和坏死。最惠国集团(MFN) 1和2是大的GTP酶，在线粒体连接和线粒体ER/SR中起关键作用 接近。Mfn1和Mfn2驻留在线粒体膜外，在那里它们调节线粒体 核聚变。Mfn2，而不是Mfn1，也存在于ER/SR膜上，在那里它将ER/SR拴在线粒体上 通过与线粒体定位的Mfn1或Mfn2相互作用。Mfn1或Mfn2基因缺失可降低心肌 缺血/再灌流(I/R)时心肌梗死(MI)范围。相反，Mfn1和Mfn2的过表达增加 新陈代谢。根据这一信息，治疗抑制MFN有望减少梗塞面积。 在MI期间，MFN的治疗性激活可能通过增强代谢来减轻心力衰竭(HF)。 挑战一直是找到一种手段来操纵内源性最惠国集团的活动。与 其他人，我们创造了第一个调节Mfn1和Mfn2构象的多肽和小分子，以及 勾勒出了这些影响的根本结构基础。我们之前报道过最惠国待遇激活剂增加， 当MFN抑制剂减少时，线粒体融合。这些都是直接的影响，需要这些试剂的结合 设置为Mfn1或Mfn2。我们在此提供的新数据表明，最惠国待遇激活剂增加，而最惠国待遇抑制剂 减少，线粒体-ER/SR接近，钙离子向线粒体转移。此外，我们观察到最惠国待遇 激动剂在心肌I/R期间加重心肌梗死范围，而MFN抑制剂则减少两个心脏的梗死范围 和脑I/R模型。有趣的是，激活剂的这些作用依赖于MFN1，而不是MFN1， 提示线粒体-ER/SR邻近的重要性，但不排除Mfn2- 线粒体连接性和形状的依赖变化也起到了作用。此外，最惠国待遇促进剂 促进心肌细胞代谢。这一项目的目标是了解最惠国待遇 调节剂影响心肌细胞死亡和新陈代谢，并测试这些调节剂是否可以提供新的 心肌梗塞和心力衰竭的治疗策略。我们建议：1.将最惠国待遇激活/抑制的变化与 成人线粒体连通性、线粒体-ER/SR近似性、钙离子转运、细胞死亡和代谢 心肌细胞。2.描绘线粒体连接性和线粒体-的个体贡献 ER/SR与在体心肌细胞死亡和代谢的关系3.评估丝裂原纤维蛋白是否 调节剂为心肌梗塞和心力衰竭提供了新的治疗策略。该项目在定义 MFN调节剂影响心肌细胞死亡和代谢的机制以及MFN是否提供 针对心肌梗塞和心力衰竭的新疗法的一个可操作的靶点。