A conserved pressure-driven mechanism for regulating cytosolic osmolarity
A conserved pressure-driven mechanism for regulating cytosolic osmolarity
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DOI：
10.1016/j.cub.2023.06.061
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发表时间：
2023-08-21
期刊：
影响因子：
9.2
通讯作者：
Fritz-Laylin，Lillian K.
中科院分区：
文献类型：
--
作者：
Velle，Katrina B.;Garner，Rikki M.;Fritz-Laylin，Lillian K.
控制细胞内渗透压对所有细胞的生命都是至关重要的。生活在低渗透环境中的细胞，如淡水，必须不断地与水流入作斗争，以避免肿胀，直到它们破裂。许多真核细胞使用可收缩的液泡从胞浆中收集多余的水，并将其泵出细胞。尽管可收缩的空泡对包括重要病原体在内的许多物种都是必不可少的，但控制其动态的机制仍不清楚。为了确定控制收缩液泡功能的基本原理，我们在这里研究了来自不同真核生物谱系的两个具有不同空泡形态的物种的分子机制：圆盘形藻和变形虫粘液霉菌盘基网柄菌。利用定量细胞生物学，我们发现，尽管这两个物种对渗透压挑战的反应不同，但它们都使用空泡型质子泵来填充可收缩的空泡，并使用肌动蛋白来进行渗透调节，但不是用来驱动水的排出。我们还使用分析模型显示，细胞质压力足以将水从这些物种的收缩空泡中驱逐出去，这与来自泡状草履虫多微核的发现类似。这些分析表明，细胞质压力足以驱动各种细胞压力和空泡几何形状的收缩液泡排空。由于液泡型质子泵依赖的收缩空泡充盈和压力依赖的空泡排空在10亿多年前的三个真核生物谱系中被证实，我们认为这代表了一种古老的真核渗透调节机制。
Controlling intracellular osmolarity is essential to all cellular life. Cells that live in hypo-osmotic environments, such as freshwater, must constantly battle water influx to avoid swelling until they burst. Many eukaryotic cells use contractile vacuoles to collect excess water from the cytosol and pump it out of the cell. Although contractile vacuoles are essential to many species, including important pathogens, the mechanisms that control their dynamics remain unclear. To identify the basic principles governing contractile vacuole function, we investigate here the molecular mechanisms of two species with distinct vacuolar morphologies from different eukaryotic lineages: the discobanNaegleria gruberiand the amoebozoan slime moldDictyostelium discoideum. Using quantitative cell biology, we find that although these species respond differently to osmotic challenges, they both use vacuolar-type proton pumps for filling contractile vacuoles and actin for osmoregulation, but not to power water expulsion. We also use analytical modeling to show that cytoplasmic pressure is sufficient to drive water out of contractile vacuoles in these species, similar to findings from the alveolateParamecium multimicronucleatum. These analyses show that cytoplasmic pressure is sufficient to drive contractile vacuole emptying for a wide range of cellular pressures and vacuolar geometries. Because vacuolar-type proton-pump-dependent contractile vacuole filling and pressure-dependent emptying have now been validated in three eukaryotic lineages that diverged well over a billion years ago, we propose that this represents an ancient eukaryotic mechanism of osmoregulation.