Department of Cardiovascular Science, Fondazione Policlinico Universitario A. Gemelli, IRCCS, Rome, Italy.
Policlinico Umberto I Hospital, Sapienza University of Rome, Viale Regina Elena 324, 00161, Rome, Italy.
Atherosclerosis. 2021 Jun;327:68-75. doi: 10.1016/j.atherosclerosis.2021.04.016. Epub 2021 May 9.
Perilipin 2 (PLIN2) regulates intracellular lipid metabolism in macrophages, and thus, plays a role in atherosclerosis. Aim of the study was to evaluate whether PLIN2 dysregulation is involved in the onset of preclinical atherosclerosis in children with overweight/obesity and to explore dysregulation mechanisms.
Sixty-three children with overweight/obesity and 21 normal weight children (controls) of the same age and sex were enrolled. Carotid intima media thickness (cIMT) was evaluated; mRNA expression of PLIN2 and proteasome subunits (PSMD3, PSMC4) was determined by Real Time PCR, and protein expression of PLIN2, LAMP2A and Hsc70 by Western blot analysis; fluorimetric assay was used to measure proteasome chymotrypsin like activity. We performed transient LAMP2A downregulation by siRNA and quantified intracellular lipids in monocytes by Nile Red staining and flow cytometry analysis.
PLIN2 protein levels were significantly higher in children with overweight/obesity and correlated with cIMT after adjusting for confounders. Accordingly, monocytes of children with overweight/obesity showed a higher intracellular amount of lipids compared with controls. mRNA expression of the regulatory subunits PSMC4 and PSMD3 and proteasome activity were lower in children with overweight/obesity, while expression of LAMP2A and Hsc70 proteins, which belong to the chaperone-mediated autophagy (CMA) pathway, was not different, suggesting that PLIN2 dysregulation in monocytes was due to an impairment of proteasome efficiency and was not CMA related.
PLIN2 was overexpressed in monocytes of children with overweight/obesity and could contribute to the onset of arteropathy. Our data suggest that proteasome impairment could contribute to PLIN2 overexpression.
脂滴包被蛋白 2（PLIN2）调节巨噬细胞内的脂质代谢，因此在动脉粥样硬化中发挥作用。本研究旨在评估肥胖儿童的临床前动脉粥样硬化发病过程中是否存在 PLIN2 失调，并探讨其失调机制。
本研究共纳入 63 名超重/肥胖儿童和 21 名年龄和性别相匹配的正常体重儿童（对照组）。评估颈动脉内膜中层厚度（cIMT）；通过实时 PCR 测定 PLIN2 和蛋白酶体亚基（PSMD3、PSMC4）的 mRNA 表达，通过 Western blot 分析测定 PLIN2、LAMP2A 和 Hsc70 的蛋白表达；荧光法测定蛋白酶体糜蛋白酶样活性。通过 siRNA 瞬时下调 LAMP2A，并通过尼罗红染色和流式细胞术分析定量单核细胞内的脂质。
超重/肥胖儿童的 PLIN2 蛋白水平显著升高，且在校正混杂因素后与 cIMT 相关。相应地，与对照组相比，超重/肥胖儿童的单核细胞内脂质含量更高。超重/肥胖儿童的调节亚基 PSMC4 和 PSMD3 的 mRNA 表达以及蛋白酶体活性降低，而 LAMP2A 和 Hsc70 蛋白的表达（属于伴侣介导的自噬（CMA）途径）没有差异，这表明单核细胞中 PLIN2 的失调是由于蛋白酶体效率受损，与 CMA 无关。
超重/肥胖儿童的单核细胞中 PLIN2 过度表达，可能导致动脉病变的发生。我们的数据表明，蛋白酶体受损可能导致 PLIN2 过表达。
