NSF-BSF: The role of protein phosphorylation in the mitochondrial matrix in determining mitophagic selectivity

线粒体通常被称为“细胞的动力库”，是几乎存在于人体每一个细胞和大多数真核生物中的细胞器。由于它们参与了高能化合物的产生，许多虚假的副反应可能会产生有毒的自由基，从而破坏细胞器。为了减轻这些毒性影响，细胞已经进化出各种策略来维持细胞健康。其中一种策略被称为有丝分裂，它促进了整个线粒体的周转。由于这种更替发生在细胞器水平，因此人们认为大多数线粒体蛋白质在有丝分裂过程中的周转率相似，因为它们共同存在于单个细胞器中。然而，最近的数据显示，在有丝分裂过程中，特定线粒体蛋白质的周转率之间存在显著的偏差。这就引出了一个自然的问题：这种选择性是如何实现的？这个项目将通过研究一种众所周知的细胞修饰--蛋白质磷酸化及其与选择性线粒体蛋白质周转的联系来解决这个问题。这项工作的更广泛的影响包括它的内在价值，因为所有含有这些细胞器的细胞都可能使用类似的机制，并且已知当吞噬核功能受损时会出现几种疾病。其他活动包括扩大未被充分代表的群体在科学领域的参与，特别是在生物化学领域的妇女和少数群体。我们的初步研究表明，干扰参与蛋白质磷酸化的酶的表达大大改变了选定线粒体蛋白质的周转率。这个项目试图提供对这种反应如何发生的机械性理解，并确定从酵母到哺乳动物系统这种反应的潜在调节因素。我们将使用同位素标记和质谱学来跟踪线粒体蛋白质的周转率，以绘制丝裂原选择性的图谱，并确定它是如何被失调的磷酸化改变的。同时，我们将测试更有针对性的假设，以确定参与有丝分裂选择性的蛋白质，以及在酵母、培养细胞和小鼠中发生这一过程的分子机制。了解这些机制将增强我们解决线粒体功能生理失衡的能力，线粒体功能失衡广泛导致发病率和疾病。这一美国/以色列合作项目得到了美国国家科学基金会和以色列双国科学基金会的支持，该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Mitochondria, commonly known as ‘the powerhouses of the cell,’ are organelles found in virtually every cell in the human body and in most eukaryotes. Because of their involvement in the production of high energy compounds, many spurious side reactions can produce toxic radicals that can damage the organelle. To mitigate these toxic effects, cells have evolved various strategies to maintain cellular health. One such strategy is termed mitophagy, which promotes the turnover of whole mitochondria. As this turnover occurs at the organellar level, it has been assumed that most mitochondrial proteins undergoing mitophagy would have similar turnover rates, as they are collectively housed within a single organelle. However, recent data demonstrate significant deviation between turnover rates of specific mitochondrial proteins during mitophagy. This leads to a natural question: how is such selectivity achieved? This project will address this question by studying a well-known cellular modification, protein phosphorylation, and its ties to selective mitochondrial protein turnover. The Broader Impacts of the work include its intrinsic merit because all cells harboring these organelles likely use similar mechanisms and several diseases are known to arise when mitophagy is impaired. Additional activities include the broadening participation of underrepresented groups in science, particularly women and minorities in the field of biochemistry.Our preliminary studies suggest that disrupting the expression of enzymes involved in protein phosphorylation substantially alters the turnover rates of select mitochondrial proteins. This project seeks to provide a mechanistic understanding of how this occurs and to identify potential regulators of this response from yeast to mammalian systems. We will use isotopic labeling and mass spectrometry to track the turnover rates of mitochondrial proteins to map the mitophagic selectivity and determine how it is altered by dysregulated phosphorylation. In parallel, we will test more focused hypotheses to determine the proteins involved in mitophagic selectivity and the molecular mechanisms by which this process occurs in yeast, cultured cells, and mice. Understanding these mechanisms will bolster our ability to address physiological imbalances in mitochondrial function, which broadly lead to morbidity and disease. This collaborative US/Israel project is supported by the US National Science Foundation and the Israeli Binational Science FoundationThis award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.