苹果MLP家族基因鉴定及非生物胁迫响应分析

在苹果中鉴定了13个Major Latex Protein(MLP)家族基因Md MLP。序列比对及构建蛋白同源模型发现,Md MLP蛋白含有Bet_v1典型的Gly-rich loop区域结构,且为MLP家族特有的Gxxxxx G结构。经多物种MLP系统发育及共线性比较分析,Md MLP与其他蔷薇科物种MLP具有相似基因结构和蛋白质保守结构域。q RT-PCR分析表明,Md MLP在‘新疆1号’苹果14个器官组织中均有不同程度的表达,对ABA、Na Cl、PEG、低温(4℃)和高温(40℃)有一定响应,且同一亚族基因表达情况呈现相似趋势。String构建蛋白互作网络发现,Md MLP可能通过与PRSP、SNRK1/2、b HLH等应激、ABA相关转录蛋白互作,参与苹果对非生物胁迫的防御。

PLIN2 promotes lipid accumulation in RAW264.7 macrophages by regulating SREBP2

AIM To investigate whether perilipin 2 （PLIN2） promotes lipid accumulation by regulating the expression of sterol regulatory element binding protein 2 （SREBP2） in mouse RAW264.7 macrophages. METHODS Oxidized low-density lipoprotein （ox-LDL） was used to treat RAW264.7 macrophages for different time （0， 6， 12， 24 and 48 h）， and Western blot was used to detect the protein levels of PLIN2 and SREBP2. The expression levels of SREBP2， 3-hydroxy-3-methylglutaryl-coenzyme A reductase （HMGCR） and glucose-regulated protein 78 （GRP78） were detected by RT-qPCR and Western blot in RAW264.7 macrophages with PLIN2 over-expression or knock-down， and lipid accumulation in the cells was observed by oil red O staining. The effects of PLIN2 on SREBP2 nuclear translocation and intracellular free cholesterol （FC） were detected by immunofluorescence and oxidase methods， respectively. The RAW264.7 cells were treated with endoplasmic reticulum stress （ERS） inhibitor 4-phenylbutyric acid （4-PBA） for 2 h， and the expression levels of GRP78， SREBP2 and HMGCR were detected by RT-qPCR and Western blot. RESULTS Pretreatment with ox-LDL at 50 mg/L for 24 h significantly increased the protein levels of PLIN2 and SREBP2. Over-expression of PLIN2 up-regulated the expression of SREBP2 and HMGCR， and increased the FC content and lipid accumulation in the cells， while knock-down of PLIN2 had an opposite result. In addition， the protein level of GRP78 was decreased， and the nuclear translocation of SREBP2 was increased in the cells with PLIN2 over-expression. Treatment with ERS inhibitor 4-PBA for 2 h significantly decreased the protein levels of SREBP2 and HMGCR in the cells. CONCLUSION PLIN2 promotes lipid accumulation in RAW264.7 macrophages by up-regulating SREBP2 signaling.