Novel Interplay of KILN and MKL1 in Vascular Pathophysiology

血管平滑肌细胞(VSMCs)表现出显著的表型可塑性，从而分化 在病理条件下，收缩的VSMCs转换为合成状态。合成的VSMC被证明 由于它们对炎症的激活和收缩能力的丧失高度敏感，在很大程度上导致了各种 血管疾病，如血管成形术后的再狭窄和动脉瘤。靶向VSMC的早期激活 炎症可能是一种有吸引力的阻断血管病变的策略。然而，分子 涉及关键调控因子(S)驱动炎症前血管平滑肌细胞表型的机制尚不完全 明白了。一种尚未探索的可能性是普遍存在的一类长的非编码RNA (LncRNAs)。通过一项无偏见的rna-seq研究，我们发现了一种新的人类特异的lncRNA，kirn，它 富含促炎血管平滑肌细胞和患病的人体血管(动脉瘤)。RNA-seq透露了这一损失 体外培养的VSMC中的窑灰抑制多种炎症基因的表达。值得注意的是，窑炉是高度 人源化细菌人工染色体转基因小鼠对炎性侮辱的反应 携带窑(BAC-KORN)或同时携带窑及其邻近基因IL8(BAC-KIRN/IL8)。都是转基因的 线条显示血管损伤引发的炎症反应加剧。这些结果支持 窑炉在促进VSMC炎症和血管疾病中的关键作用。从机械上讲，窑炉之间的相互作用 MKL1是一种有效的转录辅助因子，在反式激活VSMC收缩基因方面具有公认的作用。 有趣的是，MKL1基因缺失的小鼠在培养的VSMCs中可以防止动脉瘤的形成和MKL1的耗尽 损害促炎基因程序。这些结果表明，MKL1和窑炉之间存在潜在的联系 VSMC炎症和血管疾病。事实上，失去窑炉会降低MKL1蛋白水平和MKL1/P65 物理相互作用，后者对于促炎基因的反式激活至关重要。这些令人兴奋的东西 初步发现支持一个中心假设，即KILN与MKL1相互作用以稳定MKL1蛋白， 它加强了MKL1/P65激活的VSMC炎症和血管病理。我们提出了两个具体的 旨在探索这一假说。目的1阐明窑炉在病理过程中的调节和作用 利用BAC转基因小鼠进行血管重塑，并评估KINN在血管和血浆中的表达 动脉瘤患者的外周小体。目的2阐明窑介导血管形成的分子机制 炎症和疾病涉及窑炉破坏MKL1泛素化以增强MKL1/p65 促炎基因程序的反式激活。成功完成拟议的研究将确定 一种新的分子开关，它包含一个新的富含VSMC的lncRNA(Kirn)，它与MKL1结合，用于 VSMC炎症与病理性血管重塑。这些研究将增进我们对 LncRNA和MKL1血管病理生理学，有可能为治疗策略提供新的见解 各种炎症性血管疾病。

Vascular smooth muscle cells (VSMCs) exhibit remarkable phenotypic plasticity, whereby differentiated contractile VSMCs switch to a synthetic state under pathological conditions. Synthetic VSMCs are manifested by their high susceptibility to inflammatory activation and loss of contractility, contributing largely to various vascular disorders such as post-angioplasty restenosis and aneurysm. Targeting early activation of VSMC inflammation may represent an attractive strategy to block vascular pathologies. However, molecular mechanisms involving key regulator(s) that drive the proinflammatory VSMC phenotype are incompletely understood. One possibility that has yet to be explored is the pervasive class of long noncoding RNAs (lncRNAs). Through an unbiased RNA-seq study, we discovered a novel human-specific lncRNA, KILN, which is enriched in proinflammatory VSMCs and diseased human vessels (aneurysm). RNA-seq revealed that loss of KILN in cultured VSMCs suppresses expression of multiple inflammatory genes. Notably, KILN is highly responsive to inflammatory insults in humanized Bacterial Artificial Chromosome (BAC) transgenic mice carrying either KILN (BAC-KILN) or both KILN and its neighboring gene IL8 (BAC-KILN/IL8). Both transgenic lines display an exacerbated inflammatory response triggered by vascular injury. These results support a critical role of KILN in promoting VSMC inflammation and vascular disease. Mechanistically, KILN interacts with MKL1, a potent transcriptional cofactor with a recognized role in transactivating VSMC contractile genes. Intriguingly, Mkl1 null mice are protected from aneurysm formation and depletion of MKL1 in cultured VSMCs impairs the proinflammatory gene program. These results suggest a potential link between MKL1 and KILN in VSMC inflammation and vascular disease. Indeed, loss of KILN decreases MKL1 protein levels and MKL1/p65 physical interaction, the latter being critical for transactivation of proinflammatory genes. These exciting preliminary findings support a central hypothesis that KILN interacts with MKL1 to stabilize MKL1 protein, which potentiates MKL1/p65-activated VSMC inflammation and vascular pathologies. We propose two specific aims to probe this hypothesis. Aim 1 will elucidate the regulation and function of KILN during pathological vascular remodeling using BAC transgenic mice, and evaluate KILN expression in vessels and plasma exosomes from aneurysm patients. Aim 2 will elucidate the molecular mechanism of KILN-mediated vascular inflammation and disease involving KILN disruption of MKL1 ubiquitination to potentiate MKL1/p65 transactivation of the proinflammatory gene program. Successful completion of the proposed studies will define a new molecular switch comprising a novel VSMC-enriched lncRNA (KILN) that associates with MKL1 for VSMC inflammation and pathological vascular remodeling. These studies will advance our knowledge of lncRNA and MKL1 vascular pathophysiology, potentially providing novel insights into therapeutic strategies for various inflammatory vascular diseases.