Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire.
Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire.
J Cell Mol Med. 2019 Feb;23(2):920-933. doi: 10.1111/jcmm.13993. Epub 2018 Nov 5.
Endothelial diaphragms are subcellular structures critical for mammalian survival with poorly understood biogenesis. Plasmalemma vesicle associated protein (PLVAP) is the only known diaphragm component and is necessary for diaphragm formation. Very little is known about PLVAP regulation. Phorbol esters (PMA) are known to induce de novo PLVAP expression and diaphragm formation. We show that this induction relies on the de novo production of soluble factors that will act in an autocrine manner to induce PLVAP transcription and protein expression. We identified vascular endothelial growth factor-A (VEGF-A) signalling through VEGFR2 as a necessary but not sufficient downstream event as VEGF-A inhibition with antibodies and siRNA or pharmacological inhibition of VEGFR2 only partially inhibit PLVAP upregulation. In terms of downstream pathways, inhibition of MEK1/Erk1/2 MAP kinase blocked PLVAP upregulation, whereas inhibition of p38 and JNK MAP kinases or PI3K and Akt had no effect on PMA-induced PLVAP expression. In conclusion, we show that VEGF-A along with other secreted proteins act synergistically to up-regulate PLVAP in MEK1/Erk1/2 dependent manner, bringing us one step further into understanding the genesis of the essential structures that are endothelial diaphragms.
内皮隔膜是哺乳动物生存所必需的亚细胞结构,但它们的生物发生过程仍知之甚少。质膜小泡相关蛋白(PLVAP)是唯一已知的隔膜成分,是隔膜形成所必需的。目前对 PLVAP 的调控知之甚少。佛波酯(PMA)已知可诱导 PLVAP 的新表达和隔膜形成。我们表明,这种诱导依赖于新产生的可溶性因子,这些因子将以自分泌的方式起作用,诱导 PLVAP 转录和蛋白表达。我们确定了血管内皮生长因子-A(VEGF-A)通过 VEGFR2 的信号转导作为一个必要但非充分的下游事件,因为用抗体和 siRNA 抑制 VEGF-A 或仅部分抑制 VEGFR2 的药理学抑制仅部分抑制 PLVAP 的上调。就下游途径而言,MEK1/Erk1/2 MAP 激酶抑制剂阻断了 PLVAP 的上调,而 p38 和 JNK MAP 激酶抑制剂或 PI3K 和 Akt 对 PMA 诱导的 PLVAP 表达没有影响。总之,我们表明 VEGF-A 与其他分泌蛋白一起协同作用,以 MEK1/Erk1/2 依赖性方式上调 PLVAP,使我们在理解内皮隔膜这一必需结构的发生方面又迈进了一步。