LncRNARP11-34D15.2通过miR-223调控PGC-1a/Irisin通路参与儿童肥胖FFA升高及胰岛素抵抗的机制

The high plasma FFA in obese children has lipotoxicity. Elevated FFA also has a significant role in contributing to insulin resistance and seriously threating children's health.To explore the mechanism of elevated FFA is the key to preventing insulin resistance. We found that RP11-34D15.2 can regulate Irisin expression and affect mitochondrial clearance of FFA. So we propose that LncRNA RP11-34D15.2 contributes to elevated FFA and insulin resistance in obese children through sponging miR-223 and regulating PGC-1a/Irisin pathway. Firstly, we want to clarify the changes of RP11-34D15.2 and Irisin and the relationship between Irisin, FFA and insulin resistance index in obese children. Secondly, we will study the effect of RP11-34D15.2 on miR-223/PGC-1a/Irisin signaling pathway and its role in FFA clearance and insulin resistance. Finally, our study will elucidate the molecular mechanism of RP11-34D15.2 involved in elevated FFA and insulin resistance in obese children through regulating the PGC-1a/Irisin pathway by targeting miR-223 . This study will provide new therapeutic strategies and molecular targets for elevated FFA and insulin resistance in obese children.

肥胖儿童体内高游离脂肪酸（FFA）具有脂毒性，可以引起胰岛素抵抗，严重威胁儿童健康。阐明FFA升高的机制是防治胰岛素抵抗的关键。我们发现RP11-34D15.2可以调控Irisin表达并影响线粒体对FFA清除。在此基础上，提出RP11-34D15.2通过miR-223调控PGC-1a/Irisin通路参与儿童肥胖FFA升高及胰岛素抵抗的假说。本研究首先将明确肥胖儿童 RP11-34D15.2与Irisin的变化及Irisin与FFA及胰岛素抵抗指数间的关系；进而从功能上证实 RP11-34D15.2对靶向miR-223及PGC-1a/Irisin的影响及在FFA清除与胰岛素抵抗中的作用；最后，从机制上探讨RP11-34D15.2通过miR-223调控PGC-1a/Irisin通路，影响FFA清除，促使FFA升高而引起胰岛素抵抗的假说。本研究将为高FFA及胰岛素抵抗的治疗提供新的策略及靶点。

肥胖儿童体内高游离脂肪酸（FFA）具有脂毒性，可以引起胰岛素抵抗，严重威胁儿童健康。阐明FFA升高的机制是防治胰岛素抵抗的关键。我们发现RP11-34D15.2可以调控Irisin表达并影响线粒体对FFA清除。在此基础上，提出RP11-34D15.2通过miR-223调控PGC-1a/Irisin通路参与儿童肥胖FFA升高及胰岛素抵抗的假说。本研究首先以120例肥胖儿童及85例体重正常儿童为研究对象，通过酶联免疫，PCR等方法从临床证实了LncRNA RP11-34D15.2与Irisin基因（FNDC5）表达呈显著正相关，Irisin与胰岛素、HOMA-IR及FFA呈显著负相关；之后以36只C57BL/6J小鼠为研究对象，建立了高脂饲料喂养模型，并进一步尾静脉给予慢病毒lnc- RP11-34D15.2 -shRNA质粒处理，通过PCR及Western等检测发现（1）上调RP11-34D15.2表达，可以显著改善高脂饲料喂养的小鼠体内脂肪蓄积，降低小鼠体重及FFA水平，改善胰岛素抵抗；(2) 上调RP11-34D15.2表达，可以抑制miR-223 mRNA表达，促进PCG-1a、FNDC5/Irisin、CPT-1及UCP-1表达，改善线粒体脂肪酸氧化及产热功能。最后，用油酸诱导SW872细胞分化建立细胞模型，通过免疫共沉淀，双荧光素酶报告基因，小干扰，过表达，PCR及Western等方法进行干预，结果显示：（1）油酸诱导SW872细胞分化72h后，LncRNA RP11-34D15.2及FNDC5、PGC-1a、CPT-1、UCP-1表达显著降低；（2）过表达RP11-34D15.2后miR-223显著降低，而PGC-1a、FNDC5、CPT-1、UCP-1表达均显著升高；（3）下调FNDC5/Irisin表达可以显著降低UCP-1及CPT-1表达，同时，培养基中FFA水平显著增加；（4）过表达FNDC5/Irisin可以促进UCP-1及CPT-1表达；（5）ChIP结果表明PGC-1a与FNDC5/Irisin存在相互作用；（6）双荧光素酶报告基因证实了PCG-1a是miR-223的靶基因，LncRN RP11-34D15.2与miR-223可以直接结合。上述研究为高FFA及胰岛素抵抗的治疗提供了新的治疗策略及治疗靶点。