Oshima T, Flores S C, Vaitaitis G, Coe L L, Joh T, Park J H, Zhu Y, Alexander B, Alexander J S
Department of Molecular and Cellular Physiology, Louisiana State University Health Science Center, Shreveport 71130-3932, USA.
AIDS. 2000 Mar 31;14(5):475-82. doi: 10.1097/00002030-200003310-00002.
HIV-1 infection is associated with alterations of several vascular endothelial functions including adhesion molecule expression, growth, and vascular permeability. The bases of these errors are not known, but might involve secretion of the HIV-1 derived transcription factor 'Tat-1'. This study investigated Tat-1 mediated endothelial barrier changes and second message regulation of this phenomenon.
We exposed human umbilical vein endothelial cell monolayers to Tat-1 (0-150 ng/ml) for up to 48 h and measured resulting changes in monolayer permeability. We also investigated the role of tyrosine and mitogen activated protein (MAP) kinases, and protein kinase G using the pharmacological blockers genistein, PD98059 and KT5823 respectively.
Tat-1 significantly reduced monolayer barrier and increased albumin permeability within 24 h. Tat-1 also stimulated tyrosine phosphorylation of multiple endothelial proteins, disorganized junctional phosphotyrosine staining and increased the number of these immunostaining structures. The increased permeability produced by Tat-1 was blocked by genistein and PD98059, but not by KT5823. Genistein and PD98059 pretreatment also prevented the changes in phosphotyrosine immunostaining produced by Tat-1 and blocked phosphorylation of several proteins including MAP kinase.
These results suggest that HIV may dysregulate endothelial barrier through the effects of Tat-1. These blocker experiments suggest that the effects of Tat are transcription/translation-dependent. These data demonstrate that Tat increases endothelial albumin permeability in vitro through tyrosine kinase and MAP kinase, but not protein kinase G pathways.
HIV-1感染与多种血管内皮功能改变有关，包括黏附分子表达、生长及血管通透性。这些异常的原因尚不明确，但可能涉及HIV-1衍生转录因子“Tat-1”的分泌。本研究通过Tat-1介导的内皮屏障变化及该现象的第二信使调控机制作相关调查。
将人脐静脉内皮细胞单层暴露于Tat-1（0-150 ng/ml）长达48小时，并测量单层通透性的变化。我们还分别使用药理阻断剂染料木黄酮、PD98059和KT5823研究了酪氨酸和丝裂原活化蛋白（MAP）激酶以及蛋白激酶G的作用。
Tat-1在24小时内显著降低单层屏障功能并增加白蛋白通透性。Tat-1还刺激多种内皮蛋白的酪氨酸磷酸化，使连接部位的磷酸酪氨酸染色紊乱，并增加这些免疫染色结构的数量。Tat-1引起的通透性增加被染料木黄酮和PD98059阻断，但未被KT5823阻断。染料木黄酮和PD98059预处理还可防止Tat-1引起的磷酸酪氨酸免疫染色变化，并阻断包括MAP激酶在内的多种蛋白质的磷酸化。
这些结果表明，HIV可能通过Tat-1的作用使内皮屏障功能失调。这些阻断剂实验表明，Tat的作用是转录/翻译依赖性的。这些数据表明，Tat在体外通过酪氨酸激酶和MAP激酶而非蛋白激酶G途径增加内皮白蛋白通透性。
