Du Guangwei, Huang Ping, Liang Bruce T, Frohman Michael A
Department of Pharmacology and the Center for Developmental Genetics, University Medical Center at Stony Brook, Stony Brook, New York 11794-5140, USA.
Mol Biol Cell. 2004 Mar;15(3):1024-30. doi: 10.1091/mbc.e03-09-0673. Epub 2004 Jan 12.
Phospholipase D (PLD) is a key facilitator of multiple types of membrane vesicle trafficking events. Two PLD isoforms, PLD1 and PLD2, exist in mammals. Initial studies based on overexpression studies suggested that in resting cells, human PLD1 localized primarily to the Golgi and perinuclear vesicles in multiple cell types. In contrast, overexpressed mouse PLD2 was observed to localize primarily to the plasma membrane, although internalization on membrane vesicles was observed subsequent to serum stimulation. A recent report has suggested that the assignment of PLD2 to the plasma membrane is in error, because the endogenous isoform in rat secretory cells was imaged and found to be present primarily in the Golgi apparatus. We have reexamined this issue by using a monoclonal antibody specific for mouse PLD2, and find, as reported initially using overexpression studies, that endogenous mouse PLD2 is detected most readily at the plasma membrane in multiple cell types. In addition, we report that mouse, rat, and human PLD2 when overexpressed all similarly localize to the plasma membrane in cell lines from all three species. Finally, studies conducted using overexpression of wild-type active or dominant-negative isoforms of PLD2 and RNA interference-mediated targeting of PLD2 suggest that PLD2 functions at the plasma membrane to facilitate endocytosis of the angiotensin II type 1 receptor.
磷脂酶D（PLD）是多种类型膜泡运输事件的关键促进因子。在哺乳动物中存在两种PLD亚型，即PLD1和PLD2。基于过表达研究的初步研究表明，在静息细胞中，人PLD1在多种细胞类型中主要定位于高尔基体和核周囊泡。相比之下，过表达的小鼠PLD2主要定位于质膜，不过在血清刺激后可观察到其在膜泡上的内化。最近的一份报告表明，将PLD2定位于质膜是错误的，因为对大鼠分泌细胞中的内源性亚型进行成像后发现其主要存在于高尔基体中。我们使用针对小鼠PLD2的单克隆抗体重新审视了这个问题，并且发现，正如最初使用过表达研究所报道的那样，在多种细胞类型中，内源性小鼠PLD2最容易在质膜上被检测到。此外，我们报告称，小鼠、大鼠和人的PLD2在过表达时，在来自这三个物种的细胞系中均类似地定位于质膜。最后，使用野生型活性或显性负性PLD2亚型的过表达以及RNA干扰介导的PLD2靶向进行的研究表明，PLD2在质膜上发挥作用，以促进血管紧张素II 1型受体的内吞作用。
