Splice factor polypyrimidine tract-binding protein 1 (Ptbp1) primes endothelial inflammation in atherogenic disturbed flow conditions.
Splice factor polypyrimidine tract-binding protein 1 (Ptbp1) primes endothelial inflammation in atherogenic disturbed flow conditions.
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DOI：
10.1073/pnas.2122227119
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发表时间：
2022-07-26
影响因子：
11.1
通讯作者：
Murphy PA
中科院分区：
文献类型：
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作者：
Hensel JA;Nicholas SE;Kimble AL;Nagpal AS;Omar OMF;Tyburski JD;Jellison ER;Ménoret A;Ozawa M;Rodriguez-Oquendo A;Vella AT;Murphy PA
斑块形成于脉管系统的低流动区域和扰动流动区域，其中血小板粘附并且内皮细胞被“启动”以响应细胞因子（例如，肿瘤坏死因子-α）与通过NF-κB信号通路的细胞粘附分子水平升高。我们发现，剪接因子聚嘧啶道结合蛋白（Ptbp 1;紫色）介导的启动。ptbp 1通过血小板募集在内皮细胞中被诱导，促进引发和随后髓样细胞浸润到斑块中。从机制上讲，Ptbp 1调节基因的剪接（例如，Ripk 1）参与NF-κB信号通路，是内皮细胞NF-κB有效核转位所必需的。这提供了新的见解的分子机制，加强血管炎症的内皮启动过程。NF-κ B介导的内皮活化部分通过粘附分子Icam 1和Vcam 1驱动白细胞募集和动脉粥样硬化。内皮细胞通过暴露于低血流和血流紊乱（LDF）而被激活NF-κB的细胞因子激活，但其分子基础尚未完全了解。在LDF的实验性体内模型中，血小板是几种RNA结合剪接因子（包括聚嘧啶束结合蛋白（Ptbp 1））表达增加所必需的。这与引发细胞中NF-κB通路中RNA剪接的变化相协调，导致我们检查剪接因子作为引发介质。使用肿瘤坏死因子（TNF）-α刺激的Icam 1和Vcam 1诱导作为读数，我们进行了CRISPR Cas9敲除筛选，并确定了引发中对Ptbp 1的需求。Ptbp 1的缺失对细胞生长或对凋亡刺激的反应没有影响，但逆转了LDF剪接模式，抑制了NF-κB核转位和下游靶点（包括Icam 1和Vcam 1）的转录激活。在人冠状动脉中，PTBP 1升高与TNF途径基因的表达和斑块相关。在体内，Ptbp 1的内皮特异性缺失减少了动脉粥样硬化小鼠LDF区域的Icam 1表达和髓样细胞浸润，限制了动脉粥样硬化。这可能是介导的，在一定程度上，通过允许包含一个保守的选择性外显子在Ripk 1导致Ripk 1蛋白的减少。我们的数据表明，Ptbp 1，这是诱导在内皮细胞的一个子集的血小板募集在LDF的区域，是必要的启动内皮细胞随后的NF-κB活化，髓样细胞募集和动脉粥样硬化。
Plaque forms in low and disturbed flow regions of the vasculature, where platelets adhere and endothelial cells are “primed” to respond to cytokines (e.g., tumor necrosis factor-α) with elevated levels of cell adhesion molecules via the NF-κB signaling pathway. We show that the splice factor polypyrimidine tract binding protein (Ptbp1; purple) mediates priming. Ptbp1 is induced in endothelial cells by platelet recruitment, promoting priming and subsequent myeloid cell infiltration into plaque. Mechanistically, Ptbp1 regulates splicing of genes (e.g., Ripk1) involved in the NF-κB signaling pathway and is required for efficient nuclear translocation of NF-κB in endothelial cells. This provides new insight into the molecular mechanisms underlying an endothelial priming process that reinforces vascular inflammation. NF-κB–mediated endothelial activation drives leukocyte recruitment and atherosclerosis, in part through adhesion molecules Icam1 and Vcam1. The endothelium is primed for cytokine activation of NF-κB by exposure to low and disturbed blood flow (LDF)but the molecular underpinnings are not fully understood. In an experimental in vivo model of LDF, platelets were required for the increased expression of several RNA-binding splice factors, including polypyrimidine tract binding protein (Ptbp1). This was coordinated with changes in RNA splicing in the NF-κB pathway in primed cells, leading us to examine splice factors as mediators of priming. Using Icam1 and Vcam1 induction by tumor necrosis factor (TNF)-α stimulation as a readout, we performed a CRISPR Cas9 knockout screen and identified a requirement for Ptbp1 in priming. Deletion of Ptbp1 had no effect on cell growth or response to apoptotic stimuli, but reversed LDF splicing patterns and inhibited NF-κB nuclear translocation and transcriptional activation of downstream targets, including Icam1 and Vcam1. In human coronary arteries, elevated PTBP1 correlates with expression of TNF pathway genes and plaque. In vivo, endothelial-specific deletion of Ptbp1 reduced Icam1 expression and myeloid cell infiltration at regions of LDF in atherosclerotic mice, limiting atherosclerosis. This may be mediated, in part, by allowing inclusion of a conserved alternative exon in Ripk1 leading to a reduction in Ripk1 protein. Our data show that Ptbp1, which is induced in a subset of the endothelium by platelet recruitment at regions of LDF, is required for priming of the endothelium for subsequent NF-κB activation, myeloid cell recruitment and atherosclerosis.