Glutamine as an alternative fuel source for photoreceptors

摘要：在许多视网膜疾病中，光感受器细胞死亡是导致视力丧失的最终原因，有 对神经保护性治疗以提高存活率的未得到满足的需求。对生物能量的要求 光感受器与肿瘤组织的感光器相媲美。为了满足这种需求，光感受器具有独特的新陈代谢 调整预算以满足他们的生物能量需求。一种这样的适应是有氧糖酵解的利用，所以 葡萄糖代谢一直是光感受器生理学研究的中心。即便如此，其他燃料 葡萄糖可以用来满足光感受器的需要，特别是在生物能量应激的时候。 考虑到它们拥挤、营养有限的环境，光感受器可能已经进化到可以去除任何僵硬的 对燃料来源的限制。这一建议将提供对潜在客户的贡献的基本见解 光感受器新陈代谢、功能和存活的替代燃料来源，同时为 职业发展方面的关键技能。这项工作的长期目标是发展所需的技能 作为一名独立的临床科学家，防止光感受器退化中视力丧失的新疗法。 K08提案的科学目标是验证谷氨酰胺是一种关键燃料的假设 维持光感受器生物量，调节氧化还原平衡，并提高光感受器存活 营养缺乏期。我们建议使用以下方法评估谷氨酰胺在体外和体内的代谢命运 稳定同位素代谢通量分析及其对感光细胞氧化还原平衡、功能和 光感受器特异性谷氨酰胺酶(GLS)条件性基因敲除中谷氨酰胺分解代谢的干扰存活 老鼠。我们将利用两个特定的目标来研究我们的假设：1)确定谷氨酰胺是如何 有助于光感受器生物量的成分，并调节氧化还原动态平衡；2)确定如何 光感受器利用谷氨酰胺作为替代燃料来源，以促进在视网膜外部应激期间的存活。 职业发展的目标是培养发展所需的技能和指导。 在代谢组学数据的应用、获取和分析方面的专业知识，并实现科学 独立。课程作业、研讨会和指导将是研究的补充。多种多样- 学科导师团队，每个人都有互补的技能集，深深地致力于校长 调查员的成功。眼科和视觉科学系和密歇根大学 拥有世界一流的师资和设施，建议的研究与国际接轨得格外好 在密歇根大学和导师的指导下，在代谢和代谢组学方面获得公认的专业知识 一队。机构环境、指导和职业发展计划最大限度地提高了 研究目标和首席研究员成为独立的临床医生-科学家研究的能力 光感受器新陈代谢和生存的接口，以开发新的治疗范例，以防止 视网膜疾病中的视力丧失。

SUMMARY: Photoreceptor cell death is the ultimate cause of vision loss in many retinal disorders, and there is an unmet need for neuroprotective therapies to improve their survival. The bioenergetic requirements of photoreceptors rival that of neoplastic tissue. To meet this demand, photoreceptors have unique metabolic adaptations to budget their bioenergetic needs. One such adaptation is the utilization of aerobic glycolysis, so glucose metabolism has been central in the study of photoreceptor physiology. Even so, fuels other than glucose may be used to meet the needs of photoreceptors, especially during times of bioenergetic stress. Given their crowded, nutrient-limited environment, photoreceptors may have evolved to remove any rigid constraints on fuel sources. This proposal will provide fundamental insight into the contribution of a potential alternative fuel source to photoreceptor metabolism, function, and survival, while providing the substrate for critical skills in career development. The long-term goal of this work is to develop the skills needed to pursue novel therapies that prevent vision loss in photoreceptor degenerations as an independent clinician-scientist. The scientific objective of this K08 proposal is to test the hypothesis that glutamine is a key fuel source to maintain photoreceptor biomass, regulate redox balance, and boost photoreceptor survival during periods of nutrient deprivation. We propose to assess the metabolic fate of glutamine in vitro and in vivo using stable-isotope metabolic flux analysis and its contribution to photoreceptor redox balance, function, and survival by disrupting glutamine catabolism in a photoreceptor-specific, glutaminase (Gls) conditional knockout mouse. Two focused specific aims will be utilized to investigate our hypothesis: 1) Determine how glutamine contributes to components of photoreceptor biomass and regulates redox homeostasis.; 2) Determine how photoreceptors utilize glutamine as an alternative fuel source to promote survival during outer retinal stress. The career development objective is to cultivate the skills and mentorship required to develop expertise in the application, acquisition, and analysis of metabolomics data, and to achieve scientific independence. The coursework, seminars, and mentorship will complement the research. The multi- disciplinary team of mentors, each with a complementary skill set, is deeply committed to the principal investigator’s success. The Department of Ophthalmology and Visual Sciences and the University of Michigan has world-class faculty and facilities, and the research proposed fits exceptionally well with the internationally recognized expertise in metabolism and metabolomics at the University of Michigan and within the mentoring team. The institutional environment, mentoring, and career development plan maximize the success of the research aims and the ability of the principal investigator to become an independent clinician-scientist studying the interface of photoreceptor metabolism and survival to develop novel therapeutic paradigms that prevent vision loss in retinal disorders.