Brown D, Breton S
Renal Unit, Massachusetts General Hospital, Boston 02129, USA.
J Exp Biol. 1996 Nov;199(Pt 11):2345-58. doi: 10.1242/jeb.199.11.2345.
Several transporting epithelia in vertebrates and invertebrates contain cells that are specialized for proton or bicarbonate secretion. These characteristic 'mitochondria-rich' (MR) cells have several typical features, the most important of which is an extremely high expression of a vacuolar-type proton-pumping ATPase (H+V-ATPase) both on intracellular vesicles and on specific domains of their plasma membrane. Physiological modulation of proton secretion is achieved by recycling the H+V-ATPase between the plasma membrane and the cytoplasm in a novel type of nonclathrin-coated vesicle. In the kidney, these cells are involved in urinary acidification, while in the epididymis and vas deferens they acidify the luminal environment to allow normal sperm development. Osteoclasts are non-epithelial MR cells that use H+V-ATPase activity for bone remodeling. In some insects, similar cells in the midgut energize K+ secretion by means of a plasma membrane H+V-ATPase. This review emphasizes important structural and functional features of proton-secreting cells, describes the tissue distribution of these cells and discusses the known functions of these cells in their respective epithelia.
脊椎动物和无脊椎动物的几种转运上皮中含有专门用于质子或碳酸氢盐分泌的细胞。这些具有特征性的“富含线粒体”（MR）细胞有几个典型特征，其中最重要的是液泡型质子泵ATP酶（H⁺V-ATP酶）在细胞内囊泡及其质膜的特定区域均有极高表达。质子分泌的生理调节是通过在一种新型的非网格蛋白包被囊泡中，使H⁺V-ATP酶在质膜和细胞质之间循环来实现的。在肾脏中，这些细胞参与尿液酸化，而在附睾和输精管中，它们使管腔环境酸化以确保精子正常发育。破骨细胞是利用H⁺V-ATP酶活性进行骨重塑的非上皮MR细胞。在一些昆虫中，中肠中的类似细胞通过质膜H⁺V-ATP酶为钾离子分泌提供能量。本综述强调了质子分泌细胞重要的结构和功能特征，描述了这些细胞的组织分布，并讨论了这些细胞在各自上皮中的已知功能。
