"Rheostatic" regulation of mitchondrial volume density: evaluating the relative contributions of synthetic and degradative pathways to total organelle content.

线粒体是细胞器，具有许多对细胞内稳态至关重要的功能。为了实现这些不同的功能，线粒体占据总细胞体积的固定百分比，这一参数称为线粒体含量。虽然在高等真核生物的组织中观察到线粒体含量的~2-20倍变化，但建立这些“设定点”的发育程序是未知的。同样不清楚的是，在暴露于给定的生理刺激时，是什么限制了选定组织中细胞器的适应性反应。我的NSERC发现计划将通过测试以下假设来解决这两个基本的生物学问题;总线粒体含量及其适应潜力的组织间差异可以通过合成和降解细胞器的途径对通量的差异调节来解释。一个综合的，多方面的方法将被用来量化总线粒体含量在不同组织的C57 BL/6小鼠，并测量细胞器的生物发生和营业额的相对贡献，在调节这些“设定点”，无论是在基础条件下，在生理过渡。还将研究调节相关合成和降解途径活性的机制，首先在原代培养物中原位研究，然后在整个动物体内研究。最初，这些研究将集中在它们参与调节肝脏中的线粒体含量;然而，从长远来看，它们将扩展到包括C57 BL/6小鼠的其他组织，以及具有细胞器生物发生和周转孤立缺陷的转基因小鼠的组织，以便可以充分解决该假设的组织间性质。在概述的计划中存在许多高素质人员的培训机会，其进步将通过确定调节线粒体含量的分子遗传机制并确定它们是否在组织中保守，为我们对生物学的理解做出根本性贡献。

Mitochondria are organelles that have numerous functions crucial to cellular homeostasis. To fulfill these varied functions, mitochondria occupy a fixed percentage of the total cell volume, a parameter known as mitochondrial content. While ~2-20 fold variations in mitochondrial content are observed across the tissues of higher eukaryotes, the developmental program that establishes these "set points" is unknown. Equally unclear is what limits the adaptive responses of the organelle in select tissues upon exposure to a given physiological stimulus. My NSERC Discovery program will address these two fundamental biological problems by testing the following hypothesis; inter-tissue differences in both total mitochondrial content and its adaptive potential are explained by the differential regulation of flux through pathways that synthesize and degrade the organelle. An integrative, multifaceted approach will be used to quantify total mitochondrial content in different tissues of C57BL/6 mice, and measure the relative contributions of organelle biogenesis and turnover in regulating these "set points", both under basal conditions and during physiological transitions. Mechanisms that regulate the activities of relevant synthetic and degradative pathways will also be investigated, first in situ in primary cultures and then in vivo in the whole animal. Initially, these studies will be focused on the their involvement in regulating mitochondrial content in the liver; however, over the long-term, they will be expanded to include other tissues of C57BL/6 mice, as well as those of transgenic mice with isolated defects in organelle biogenesis and turnover, so that the inter-tissue nature of the hypothesis can be fully addressed. Numerous training opportunities for highly qualified personnel exist within the outlined program, whose advancement will make fundamental contributions to our understanding of biology by identifying the molecular genetic mechanisms that regulate mitochondrial content and determining whether they are conserved across tissues.