Department of Biology, University of Maryland, College Park, MD, USA.
Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile.
FEBS J. 2021 Jun;288(12):3799-3812. doi: 10.1111/febs.15620. Epub 2020 Dec 28.
Cells possess a variety of organelles with characteristic structure and subcellular localization intimately linked to their specific function. While most are intracellular and found in virtually all eukaryotic cells, there is a small group of organelles of elongated cylindrical shapes in highly specialized cells that protrude into the extracellular space, such as cilia, flagella, and microvilli. The ATP required by intracellular organelles is amply available in the cytosol, largely generated by mitochondria. However, such is not the case for cilia and flagella, whose slender structures cannot accommodate mitochondria. These organelles consume massive amounts of ATP to carry out high energy-demanding functions, such as sensory transduction or motility. ATP from the nearest mitochondria or other reactions within the cell body is severely limited by diffusion and generally insufficient to fuel the entire length of cilia and flagella. These organelles overcome this fuel restriction by local generation of ATP, using mechanisms that vary depending on the nutrients that are available in their particular external environment. Here, we review, with emphasis in mammals, the remarkable adaptations that cilia and flagella use to fuel their metabolic needs. Additionally, we discuss how a decrease in nutrients surrounding olfactory cilia might impair olfaction in COVID-19 patients.
细胞拥有多种具有特征结构和亚细胞定位的细胞器，这些结构和定位与其特定功能密切相关。虽然大多数细胞器都是细胞内的，存在于几乎所有真核细胞中，但有一小部分呈长圆柱形的细胞器存在于高度特化的细胞中，它们突出到细胞外空间，如纤毛、鞭毛和微绒毛。细胞内细胞器所需的 ATP 在细胞质中大量存在，主要由线粒体产生。然而，纤毛和鞭毛的情况并非如此，它们细长的结构无法容纳线粒体。这些细胞器需要大量的 ATP 来执行高能量需求的功能，如感觉转导或运动。由于扩散的限制，来自最近的线粒体或细胞体内部其他反应的 ATP 通常不足以为整个纤毛和鞭毛提供燃料，因此这些细胞器通过利用局部产生 ATP 的机制来克服这种燃料限制，这些机制取决于它们特定的外部环境中可用的营养物质而有所不同。在这里，我们重点讨论了哺乳动物中的纤毛和鞭毛，以强调它们用于满足代谢需求的显著适应性。此外，我们还讨论了周围嗅纤毛的营养物质减少如何可能损害 COVID-19 患者的嗅觉。
