Diabetes and Cardiovascular Research Laboratory, Department of Biomedical Science, Bharathidasan University, Tiruchirappalli, 620 024, Tamilnadu, India.
Diabetes and Cardiovascular Research Laboratory, Department of Biomedical Science, Bharathidasan University, Tiruchirappalli, 620 024, Tamilnadu, India.
Eur J Pharmacol. 2022 Apr 5;920:174683. doi: 10.1016/j.ejphar.2021.174683. Epub 2021 Dec 13.
Altered mRNA metabolism is a feature of many inflammatory diseases. Post transcriptional regulation of interferon-γ-inducible protein (IP)-10 has been uncharacterized in diabetes conditions. RNA-affinity capture method and RNA immuno-precipitation revealed S100b treatment increased the binding of heterogeneous nuclear ribonucleoprotein (hnRNP)K to the IP-10 3'UTR and increased IP-10 mRNA accumulation. Luciferase activity assay using reporter plasmids showed involvement of IP-10 3'UTR. Knocking down of hnRNPK destabilized S100b induced IP-10 mRNA accumulation. S100b promoted the translocation of hnRNPK from nucleus to the cytoplasm and this was confirmed by phosphomimetic S284/353D mutant and non-phosphatable S284/353A hnRNPK mutant. S100b treatment demethylates hnRNPK at Lys219 by Lysine Specific Demethylase (LSD)-1. HnRNPK, a demethylation defective mutant increased IP-10 mRNA stability. Apparently, triple mutant hnRNPK promoted IP-10 mRNA stability. Interestingly, knocking down LSD-1 abolished S100b induced IP-10 mRNA accumulation. These observations show for the first time that IP-10 mRNA stability is dynamically regulated by Lysine demethylation of hnRNPK by LSD-1. These results indicate that hnRNPK plays an important role in IP-10 mRNA stability induced by S100b which could exacerbate monocyte activation, relevant to the pathogenesis of diabetic complications like atherosclerosis.
mRNA 代谢改变是许多炎症性疾病的特征。干扰素-γ诱导蛋白 (IP)-10 的转录后调控在糖尿病条件下尚未确定。RNA 亲和捕获法和 RNA 免疫沉淀显示 S100b 处理增加了异质核核糖核蛋白 (hnRNP)K 与 IP-10 3'UTR 的结合，并增加了 IP-10 mRNA 的积累。使用报告质粒的荧光素酶活性测定表明涉及 IP-10 3'UTR。hnRNPK 的敲低使 S100b 诱导的 IP-10 mRNA 积累不稳定。S100b 促进 hnRNPK 从核转位到细胞质，这通过磷酸模拟 S284/353D 突变体和非磷酸化 S284/353A hnRNPK 突变体得到证实。S100b 处理通过赖氨酸特异性去甲基酶 (LSD)-1 使 hnRNPK 赖氨酸 219 去甲基化。hnRNPK 是一种去甲基化缺陷突变体，增加了 IP-10 mRNA 的稳定性。显然，三重突变体 hnRNPK 促进了 IP-10 mRNA 的稳定性。有趣的是，敲低 LSD-1 消除了 S100b 诱导的 IP-10 mRNA 积累。这些观察结果首次表明，IP-10 mRNA 的稳定性是由 LSD-1 对 hnRNPK 的赖氨酸去甲基化动态调节的。这些结果表明，hnRNPK 在 S100b 诱导的 IP-10 mRNA 稳定性中起重要作用，这可能加剧单核细胞的激活，与动脉粥样硬化等糖尿病并发症的发病机制有关。
