Division of Pulmonary and Critical Care Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, United States of America.
PLoS One. 2010 May 14;5(5):e10656. doi: 10.1371/journal.pone.0010656.
The architectural transcription factor High Mobility Group-A1 (HMGA1) binds to the minor groove of AT-rich DNA and forms transcription factor complexes ("enhanceosomes") that upregulate expression of select genes within the inflammatory cascade during critical illness syndromes such as acute lung injury (ALI). AT-rich regions of DNA surround transcription factor binding sites in genes critical for the inflammatory response. Minor groove binding drugs (MGBs), such as Distamycin A (Dist A), interfere with AT-rich region DNA binding in a sequence and conformation-specific manner, and HMGA1 is one of the few transcription factors whose binding is inhibited by MGBs.
To determine whether MGBs exert beneficial effects during endotoxemia through attenuating tissue inflammation via interfering with HMGA1-DNA binding and modulating expression of adhesion molecules.
METHODOLOGY/PRINCIPAL FINDINGS: Administration of Dist A significantly decreased lung and liver inflammation during murine endotoxemia. In intravital microscopy studies, Dist A attenuated neutrophil-endothelial interactions in vivo following an inflammatory stimulus. Endotoxin induction of P-selectin expression in lung and liver tissue and promoter activity in endothelial cells was significantly reduced by Dist A, while E-selectin induction was not significantly affected. Moreover, Dist A disrupted formation of an inducible complex containing NF-kappaB that binds an AT-rich region of the P-selectin promoter. Transfection studies demonstrated a critical role for HMGA1 in facilitating cytokine and NF-kappaB induction of P-selectin promoter activity, and Dist A inhibited binding of HMGA1 to this AT-rich region of the P-selectin promoter in vivo.
CONCLUSIONS/SIGNIFICANCE: We describe a novel targeted approach in modulating lung and liver inflammation in vivo during murine endotoxemia through decreasing binding of HMGA1 to a distinct AT-rich region of the P-selectin promoter. These studies highlight the ability of MGBs to function as molecular tools for dissecting transcriptional mechanisms in vivo and suggest alternative treatment approaches for critical illness.
高迁移率族蛋白 A1（HMGA1）是一种结构转录因子，可与富含 AT 的 DNA 小沟结合，并形成转录因子复合物（“增强子复合物”），在上皮损伤和急性肺损伤（ALI）等危重病综合征中，上调炎症级联反应中特定基因的表达。富含 AT 的 DNA 区域环绕着对炎症反应至关重要的基因中的转录因子结合位点。小沟结合药物（MGBs），如 Distamycin A（Dist A），以序列和构象特异性的方式干扰富含 AT 的区域 DNA 结合，HMGA1 是少数几种其结合受 MGB 抑制的转录因子之一。
通过干扰 HMGA1-DNA 结合和调节黏附分子的表达，来确定 MGB 在内毒素血症期间是否通过减轻组织炎症发挥有益作用。
方法/主要发现：在小鼠内毒素血症期间，给予 Dist A 可显著降低肺和肝脏的炎症。在活体显微镜研究中，给予 Dist A 后，体内炎症刺激时中性粒细胞-内皮细胞相互作用减弱。内毒素诱导肺和肝组织 P-选择素表达和内皮细胞启动子活性显著降低，而 E-选择素诱导则无明显影响。此外，Dist A 破坏了包含 NF-κB 的诱导复合物的形成，该复合物结合 P-选择素启动子的富含 AT 的区域。转染研究表明，HMGA1 在促进细胞因子和 NF-κB 诱导 P-选择素启动子活性中起关键作用，并且 Dist A 抑制了 HMGA1 与体内 P-选择素启动子富含 AT 的区域的结合。
结论/意义：我们描述了一种新的靶向方法，通过减少 HMGA1 与 P-选择素启动子富含 AT 的特定区域的结合，来调节小鼠内毒素血症期间的肺和肝脏炎症。这些研究强调了 MGB 作为体内转录机制的分子工具的能力，并为危重病提供了替代治疗方法。
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