Identifying and characterizing pathways of amino acid signaling and metabolism

氨基酸，特别是支链氨基酸(BCAA)，如亮氨酸、异亮氨酸和缬氨酸，主要用于制造生长所需的蛋白质，但也用于在细胞的动力室(线粒体)内产生能量。一旦进入细胞，支链氨基酸被转化为支链阿尔法酮酸(BCKA)，然后能够进入线粒体用于能量产生过程。在之前的NSERC资助期间，使用已建立的分析支链氨基酸分解产物的方法，我们发现BCKA干扰了胰岛素的作用，从而劫持和重塑了细胞的新陈代谢和功能。尽管BCKA存在于全身和细胞内，但它们对细胞新陈代谢、生长和功能的影响仍未被研究。在下一个NSERC资助期，使用细胞生物学、遗传学和全身方法，我们将解决两个总体问题。1)细胞内BCKA是否/如何调控胰岛素作用和重塑代谢。2)BCKA是否/如何与细胞沟通，以决定细胞合成蛋白质和调节生长和生存的能力。我们将研究BCKA进出细胞的调节，BCKA如何干扰胰岛素的作用，BCKA如何针对线粒体的健康，BCKA是否与其他营养物质竞争能量供细胞消耗，以及哪些途径调节这一营养竞争过程。我们将研究BCKA是否在化学或结构上改变线粒体以控制新陈代谢、呼吸和生存。我们将识别和鉴定由BCKA触发的基因和蛋白质，并确定BCKA信号是否/如何在细胞内调节蛋白质周转和合成途径。这项研究将为我实验室的本科生和研究生提供细胞和分子生物学方法学方面的培训，以及检测和定位参与氨基酸代谢的分子成员的技术。弄清细胞BCKA信号、代谢和生理的分子网络将直接有助于扩大我们对氨基酸生物学的知识，并在能量代谢、食品科学和人类营养领域产生长期影响，有利于加拿大的发现科学、教育和创新。

Amino acids, particularly branched-chain amino acids (BCAA) such as leucine, isoleucine, and valine, are mostly used for manufacturing proteins for growth but are also used for generating energy within the powerhouse of the cells (mitochondria). Once inside the cell, BCAA is converted to branch chain alpha ketoacids (BCKA), which are then able to enter the mitochondria for use in the energy generation process. In the previous NSERC funding period, using established methods for analyzing BCAA breakdown products we discovered that BCKA disrupts insulin action thereby hijacking and remodeling cellular metabolism and function. Despite systemic and intracellular presence of BCKA their impact on cellular metabolism, growth and function remains unexplored. In the next NSERC funding period using cell biology, genetics and whole-body approaches we will address two over-arching questions. 1) If/how cellular BCKA exerts control on insulin action and remodel metabolism. 2) If/how BCKA communicates to the cell to dictate cell's ability to synthesize proteins and regulate growth and survival. We will investigate regulation of BCKA entry and exit from cells, how BCKA perturb insulin action, how BCKA targets mitochondrial well being, if BCKA competes with other nutrients for consumption by the cell for energy and which pathways regulate this process of nutrient competition. We will examine whether BCKA chemically or structurally modifies mitochondria to govern metabolism, respiration and survival. We will identify and characterize genes and proteins that are triggered by BCKA and ascertain if/how BCKA signals within the cell to modulate protein turnover and synthesis pathways. This research will provide undergraduate and graduate HQP in my laboratory with training in cell and molecular biology methodologies and in technologies for detection and targeting of molecular players involved in amino acid metabolism. Clarifying molecular networks of cellular BCKA signaling, metabolism and physiology will directly contribute to expanding our knowledge of amino acid biology with long-lasting impacts in the field of energy metabolism, food science and human nutrition benefitting Canadian discovery science, education and innovation.