Bioenergetics of red blood cells regulated by hydrogen sulfide

生物能量学是真核生物通过糖酵解以三磷酸腺苷的形式产生能量的过程。厌氧糖酵解发生在胞浆中，它将葡萄糖转化为乳酸，同时每个葡萄糖分子产生2个三磷酸腺苷。有氧糖酵解是在线粒体中完成的，通过氧化磷酸化(OXPHOS)从每个葡萄糖分子产生30-32个ATP。生物能量学的调控取决于线粒体是否存在、葡萄糖和氧气水平，以及其他内源调节剂的影响。硫化氢(H_2S)是一个重要的内生因素。它的生产和在真核生物中的生物学重要性早在十多年前就已经知道了。由我之前的NSERC Discovery拨款支持的研究已经证明，在哺乳动物细胞的胞浆和线粒体中都产生了硫化氢，并且硫化氢调节线粒体ATP的产生，促进线粒体的生物发生，并影响细胞的存活。*成熟哺乳动物红细胞(RBC)不具有线粒体，其生物能量学依赖于厌氧糖酵解，而鸟类RBC具有功能线粒体，其生物能量学既涉及厌氧糖酵解，也涉及OXPHOS。哺乳动物和禽类红细胞是否使用相同或不同的机制来产生硫化氢尚不清楚。在线粒体存在或不存在的情况下，H_2S对红细胞的生物能量学和活性的调节作用尚未被研究。我们假设H_2S对哺乳动物和鸟类的红细胞的厌氧糖酵解和OXPHOS有不同的调节作用，对这些细胞的功能和存活产生不同的功能影响。本项目的目的是在无线粒体的小鼠红细胞和含线粒体的鸡红细胞中，检测1)内源性H_2S的产生及其调节；2)H_2S对厌氧糖酵解和氧合酶的影响及其机制；3)H_2S调节的生物能量学对细胞存活和功能的影响；以及4)多硫化物对生物能量学和细胞存活率的影响与H_2S的比较。这些短期目标与我研究生涯的长期目标一致，即阐明包括硫化氢在内的气体传递体在真核生物中的新陈代谢和生物学重要性。*拟议的计划可以帮助更好地了解红细胞的生物能量如何受到硫化氢的调节，以维持这些细胞的寿命。新的研究将阐明哺乳动物红细胞线粒体在进化过程中排出与内源性硫化氢代谢有关的意义。所获得的知识还将有助于制定基于硫化氢的战略，以具体调控依赖生物能量学的细胞和身体功能，例如红细胞体外存储的优化条件，氧气供应有限的高原适应，或运动和体力活动。

Bioenergetics is the process whereby energy is generated from glycolysis in eukaryotes in the form of ATP. Anaerobic glycolysis occurs in the cytosol, which converts glucose to lactate while generating 2 ATP per glucose molecule. Aerobic glycolysis is completed in the mitochondrion, producing 30-32 ATP from each molecule of glucose via oxidative phosphorylation (OXPHOS). The regulation of bioenergetics depends on whether mitochondria are present, glucose and oxygen levels, and the effects of other endogenous regulators. ******Hydrogen sulfide (H2S) is one important endogenous factor. Its production and biological importance in eukaryotes have been known for more than a decade. The research supported by my previous NSERC Discovery grants has demonstrated, confirmed by numerous reports from other researchers, that H2S is generated in both the cytosol and mitochondrion in mammalian cells and that H2S regulates mitochondrial ATP production, promotes mitochondrial biogenesis, and affects cell viability. ******Mature mammalian red blood cells (RBCs) do not possess mitochondria and their bioenergetics relies on anaerobic glycolysis whereas avian RBCs have functional mitochondria and their bioenergetics involves both anaerobic glycolysis and OXPHOS. Whether mammalian and avian RBCs use the same or different mechanisms to produce H2S is unknown. The roles of H2S in the regulation of bioenergetics as well as viability of RBCs, in the presence or absence of mitochondria, have not been studied.******We hypothesize that H2S differentially regulates anaerobic glycolysis and OXPHOS in mammalian and avian RBCs, exerting different functional impacts on the function and survival of these cells. The objectives of this program are to examine, in mitochondrion-free mouse RBCs and mitochondrion-containing chicken RBCs, 1) the production of endogenous H2S and its regulation; 2) the effects of H2S on anaerobic glycolysis and OXPHOS and the underlying mechanisms; 3) the impact of H2S-regulated bioenergetics on cellular survival and functions; and 4) the effects of polysulfide on bioenergetics and cell survival in comparison with those of H2S. These short-term objectives align with the long-term objective of my research career, i.e. to elucidate the metabolism and biological importance of gasotransmitters, including H2S, in eukaryotes. ******The proposed program can help better understand how the bioenergetics of RBCs is regulated by H2S to sustain the lifespan of these cells. New light will be shed on the significance of evolutionary extrusion of the mitochondrion from mammalian RBCs in connection to endogenous H2S metabolism. The knowledge gained will also help to devise H2S-based strategies to specifically regulate bioenergetics-dependent cellular and body functions, such as optimized storage conditions for RBCs in vitro, high altitude adaptation where oxygen supply is limited, or exercise and physical activities.