Department of Cell Biology and Molecular Medicine, University of Szeged, 6720 Szeged, Hungary.
ELKH-SZTE Stereochemistry Research Group, Institute of Pharmaceutical Chemistry, University of Szeged, 6720 Szeged, Hungary.
Int J Mol Sci. 2022 Jan 19;23(3):1079. doi: 10.3390/ijms23031079.
Kynurenic acid (KYNA) is implicated in antiinflammatory processes in the brain through several cellular and molecular targets, among which microglia-related mechanisms are of paramount importance. In this study, we describe the effects of KYNA and one of its analogs, the brain-penetrable SZR104 (N-(2-(dimethylamino)ethyl)-3-(morpholinomethyl)-4-hydroxyquinoline-2-carboxamide), on the intracellular distribution and methylation patterns of histone H3 in immunochallenged microglia cultures. Microglia-enriched secondary cultures made from newborn rat forebrains were immunochallenged with lipopolysaccharide (LPS). The protein levels of selected inflammatory markers C-X-C motif chemokine ligand 10 (CXCL10) and C-C motif chemokine receptor 1 (CCR1), histone H3, and posttranslational modifications of histone H3 lys methylation sites (H3K9me3 and H3K36me2, marks typically associated with opposite effects on gene expression) were analyzed using quantitative fluorescent immunocytochemistry and western blots in control or LPS-treated cultures with or without KYNA or SZR104. KYNA and SZR104 reduced levels of the inflammatory marker proteins CXCL10 and CCR1 after LPS-treatment. Moreover, KYNA and SZR104 favorably affected histone methylation patterns as H3K9me3 and H3K36me2 immunoreactivities, and histone H3 protein levels returned toward control values after LPS treatment. The cytoplasmic translocation of H3K9me3 from the nucleus indicated inflammatory distress, a process that could be inhibited by KYNA and SZR104. Thus, KYNA signaling and metabolism, and especially brain-penetrable KYNA analogs such as SZR104, could be key targets in the pathway that connects chromatin structure and epigenetic mechanisms with functional consequences that affect neuroinflammation and perhaps neurodegeneration.
犬尿酸(KYNA)通过多种细胞和分子靶点参与大脑中的抗炎过程,其中小胶质细胞相关机制至关重要。在这项研究中,我们描述了 KYNA 及其类似物 SZR104(N-(2-(二甲氨基)乙基)-3-(吗啉代甲基)-4-羟基喹啉-2-甲酰胺)对免疫挑战的小胶质细胞培养物中组蛋白 H3 的细胞内分布和甲基化模式的影响。从小鼠前脑分离的富含小胶质细胞的二级培养物用脂多糖(LPS)进行免疫挑战。使用定量荧光免疫细胞化学和 Western blot 分析对照或 LPS 处理的培养物中选定的炎症标志物 C-X-C 基序趋化因子配体 10(CXCL10)和 C-C 基序趋化因子受体 1(CCR1)、组蛋白 H3 以及组蛋白 H3 赖氨酸甲基化位点(H3K9me3 和 H3K36me2)的蛋白水平,这些修饰通常与基因表达的相反效果相关)在 LPS 处理的培养物中,有无 KYNA 或 SZR104。KYNA 和 SZR104 降低了 LPS 处理后炎症标志物蛋白 CXCL10 和 CCR1 的水平。此外,KYNA 和 SZR104 还对组蛋白甲基化模式产生有利影响,如 H3K9me3 和 H3K36me2 免疫反应性,并且 LPS 处理后组蛋白 H3 蛋白水平恢复到对照值。H3K9me3 从细胞核向细胞质的易位表明存在炎症应激,这一过程可被 KYNA 和 SZR104 抑制。因此,KYNA 信号转导和代谢,尤其是可穿透血脑屏障的 KYNA 类似物如 SZR104,可能是连接染色质结构和表观遗传机制与影响神经炎症和神经退行性变的功能后果的途径中的关键靶点。
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