Fsp27通过抑制HSL的脂滴定位调控脂肪水解

Fsp27是CIDE蛋白家族的一员,其特异性地在脂肪组织中表达并定位于脂滴表面,促进脂滴融合增大和脂肪积累.Fsp27敲除小鼠表现出胰岛素敏感性增强,有较高的能量消耗,并且可以抵抗高脂食物引起的肥胖,但Fsp27是否直接参与脂肪水解的调控过程并不清楚.本研究发现,在3T3-L1脂肪细胞中基因沉默Fsp27导致脂肪水解速率上升,并且这种上升是由激素敏感型脂肪酶(HSL)所介导.进一步在3T3-L1前脂肪细胞中过表达Fsp27以及HSL,对其定位的观察结果显示,Fsp27可以显著地抑制HSL在脂滴表面的定位.本研究表明,在脂肪组织中,Fsp27能够直接影响HSL在脂滴表面的定位,进而抑制脂肪水解速率,导致脂类积累.     

PPARα信号通路激活抵抗高脂和Leptin缺失诱导的肥胖和脂肪肝

脂肪酰基辅酶A氧化酶1(acyl-coenzyme A oxidase 1,Acox1)缺失可通过内源性配体激活过氧化物酶体增殖物激活受体α(peroxisome proliferator-activated receptor-α,PPARα)及其调控的信号通路,从而减轻肥胖基因leptin突变型(ob/ob)小鼠的肥胖和脂肪肝症状,但提高了其肝癌发生率.为进一步研究PPARα信号通路在高脂日粮和leptin缺失诱导的脂肪肝形成过程中的作用,本研究以野生型、Acox1-/-、ob/ob和Acox1Δob/ob小鼠为模型,用正常日粮或60%高脂日粮饲喂10个月.结果显示,正常日粮或高脂日粮饲喂情况下,Acox1-/-和Acox1Δob/ob小鼠的体重、白色脂肪细胞体积、棕色脂肪组织含量及肝脏脂肪含量均分别显著低于WT和ob/ob小鼠.溴化脱氧尿嘧啶核苷(Brdurd)及烯酰辅酶A水合酶(L-PBE)免疫组化染色结果显示Acox1-/-和Acox1Δob/ob小鼠肝脏内肝细胞增殖及L-PBE活性、肝脏重量及其占体重的百分比均显著高于WT和ob/ob小鼠.正常日粮饲喂的WT、Acox1-/-、ob/ob和Acox1Δob/ob小鼠肝癌发生率分别为0%、100%、0%和4%,高脂日粮饲喂后,其肝癌发生率分别为0%、100%、2.9%和100%.Q-PCR结果显示Acox1-/-和Acox1Δob/ob小鼠肝脏内L-PBE、Cyp4a3、Akr1b10、ap2等基因的表达水平显著高于WT和ob/ob小鼠.综上所述,PPARα信号通路激活可以抵抗高脂日粮和leptin缺失诱导的肥胖和脂肪肝,但脂质过氧化反应可能通过Nrf2-Akr1b10信号通路促进了肝癌发生.     

冷刺激对小鼠脂肪组织褐色化和脂代谢的影响

目的:探讨4摄氏度冷刺激对小鼠脂肪组织褐色化的影响。方法:野生型小鼠在4摄氏度环境下饲养一周,称取小鼠重量并取不同的脂肪组织固定,进行HE染色;对血液中甘油三酯、脂肪酸的水平进行检测;检测不同脂肪组织中脂肪含量和相关蛋白的表达水平。结果:野生型小鼠在4℃环境下饲养一周后体重明显降低。血液中甘油三酯、脂肪酸和甘油的水平明显下降。皮下白色脂肪组织(subcutaneous white adipose tissue, SWAT),腹腔生殖腺旁白色脂肪(gonadal visceral white adipose tissue, GWAT)和褐色脂肪(brown adipose tissue, BAT)中的脂肪含量明显降低,其中SWAT和BAT中脂肪含量降低近50%。SWAT发生明显的褐色化现象,组织中出现含有多个脂滴的脂肪细胞,同时褐色化的标志蛋白UCP1(uncoupling protein 1)和Cidea明显增加。GWAT中脂滴仍呈现单室大脂滴,脂肪细胞变小,脂肪积累降低约14%,低于SWAT和BAT中的相应变化。BAT组织中脂滴明显变小,UCP1的表达明显增加。同时我们在三种脂肪组织中都观察到线粒体相关蛋白CPT1 (Carnitine palmitoyltransferase I)的明显增加。结论:冷刺激能明显改变小鼠的脂代谢状态,全身的脂肪积累明显降低。SWAT发生明显的褐色化现象,Cidea和UCP1的表达明显增加。SWAT, GWAT和BAT脂肪组织中有明显的线粒体活性的增加。     

AMPK与脂肪细胞分化的关系研究及其在人脂肪源性肿瘤组织中的表达特点

目的:探讨AMPK在脂肪细胞分化过程中的作用以及与脂滴相关表面蛋白Cidec的表达关系,为肥胖发生及其防治肥胖及肥胖相关性疾病提供重要的理论依据。方法:通过免疫组织化学、Real-time PCR和Western blot等方法分析AMPK和Cidec在脂肪细胞分化中的作用,明确二者的相关性。结果:在不同分化程度的脂肪源性肿瘤组织中,AMPK表达随着脂肪细胞分化程度的升高而表达降低,而Cidec的表达是逐渐增高的;在不同发育阶段的胎儿脂肪组织中,AMPK随着胎龄的增加表达逐渐降低(P0.01),而Cidec的表达则呈逐渐增高的趋势(P0.01);以上AMPKα的表达均与Cidec的表达水平呈负相关。结论:AMPK可能在脂肪细胞分化过程中扮演重要角色,研究其与Cidec的表达与作用关系可能为脂肪细胞发育及分化提供重要线索及依据。     

Cidec基因敲除小鼠肠道菌群的特征

目的:探究Cidec敲除(CIDEC-KO)小鼠肠道菌群的结构。方法:随机分别挑选体重相近、2月龄5只野生型和5只Cidec敲除的雄性小鼠,收集两种基因型小鼠经高脂饲料16周喂养前后的新鲜粪便。提取粪便中的细菌基因组,对菌群基因组16S r RNA基因V4高变区进行测序,对数据进行PCoA分析、Alpha多样性分析及LEf Se分析。结果:属水平下的LEf Se分析显示,在普通饲料喂养条件下,Cidec缺失小鼠对比野生型小鼠粪便中PrevotellaceaUCG001属丰度显著上升,Blautia属、Streptococcus属、LachnospiraceaeUCG006属丰度显著下降。与同月龄同高脂喂养的野生型小鼠比,Cidec敲除小鼠粪便中RuminococcaceaeUCG014属丰度显著下降。进一步比较同一种基因型下饮食对肠道菌群的改变,发现在喂养高脂饲料后,某些属的丰度仅在Cidec缺失小鼠中发生显著变化,但是在野生型小鼠中未发现有显著变化,这些属包括:Alistipes属、Bacteroides属、Paraprevotella属、Streptococcus属、LachnospiraceaeUCG006属丰度显著上升。而喂养高脂后,仅在野生型小鼠中发现Peptococcus属和Ruminococcustorquesgroup属丰度的显著上升,以及Tyzzerella3属、Ruminiclostidium6属和A2属丰度的显著下降,在Cidec缺失小鼠粪便中并未发现这些属的丰度有显著变化。结论:高脂诱导下,对比野生型小鼠,某些同代谢综合征正相关的属只在Cidec缺失小鼠肠道菌群中丰度显著上升。     

小鼠Cidea蛋白N端缺失异构体的鉴定和研究

Cidea蛋白调节脂肪代谢,在机体能量平衡过程中起重要作用,在转录和翻译后水平受到严格调控,但在翻译水平的调节还不清楚．通过对CIDEA基因敲除小鼠模型研究,鉴定了小鼠棕色脂肪组织内源性表达Cidea蛋白N端缺失异构体mCidea-22．定点突变等研究表明其产生机制为选择性起始翻译．并且,在异位表达时,N端缺失异构体和全长异构体的比例呈现细胞系特异性．此外,蛋白质稳定性实验表明mCidea-22半衰期很短．亚细胞定位研究显示mCidea-22是内质网和脂滴定位蛋白．为深入理解Cidea蛋白的功能和精细调节提供了新的思路和方向．     

双硫仑治疗小鼠肥胖的安全性和有效性评价

摘要 目的：观察双硫仑治疗小鼠肥胖的安全性和有效性。方法：取6周龄C57BL/6J雄性小鼠10只,高脂饲料诱导肥胖后,随机分为双硫仑组（双硫仑玉米油溶液,300 mg/(kg?d）和对照组（等量玉米油）,每组5只小鼠。每日灌胃给药1次,连续2周,期间仍给与高脂饲料。监测小鼠食物消耗量和体重。给药结束后取小鼠血清、附睾白色脂肪垫、肩胛间区棕色脂肪和肝脏。白色、棕色脂肪和肝脏进行HE染色,观察细胞形态。电镜下观察棕色脂肪细胞内的脂滴和线粒体。Realtime-qPCR法检测棕色脂肪组织中Ucp1、Fabp4、Prdml6和Cidea的mRNA相对表达量,Western blot法检测Ucp1的蛋白表达量。检测血清中转氨酶ALT和AST含量。取8周龄C57BL/6J雄性小鼠10只,随机分为双硫仑组（双硫仑300 mg/(kg?d）和对照组（等量玉米油）,每日灌胃1次,连续2周。给药结束后进行棕色脂肪和肝脏HE染色并检测血清中ALT和AST含量。取8周龄C57BL/6J雄性小鼠10只,随机分为双硫仑组（双硫仑300 mg/(kg?d）和对照组（等量玉米油）,每日灌胃1次,连续4周,进行肝脏HE染色并检测血清中ALT和AST含量。取孕13.5天的C57BL/6J胚胎小鼠,进行成纤维细胞原代培养,分为双硫仑组（双硫仑5 mg/L）和对照组（等量DMSO）并诱导分化为棕色脂肪细胞。分化8天后进行油红O染色,观察脂滴形成情况,检测Ucp1、Fabp4、Prdml6和Cidea的mRNA相对表达量和Ucp1的蛋白表达量。结果：肥胖小鼠给药过程中,双硫仑组和对照组的进食量及体重变化并无明显差别（P＞0.05）。给药结束后,两组白色脂肪细胞大小无明显差别。双硫仑组小鼠棕色脂肪细胞直径和细胞内脂滴明显增大（P＜0.05）,脂滴数量、线粒体形态及数量无明显差别（P＞0.05）。双硫仑组小鼠棕色脂肪中Cidea和Prdm16的mRNA表达减少（P＜0.05）。正常体重小鼠双硫仑给药2周后棕色脂肪细胞脂滴也增大。细胞实验结果显示,双硫仑组脂滴形成明显减少,Ucp1、Cidea、Prdm16的mRNA表达明显减少（P<0.05）;Ucp1的蛋白表达明显减少（P<0.05）。肥胖与正常小鼠双硫仑给药2周后均出现明显的肝细胞水肿,血清中ALT和AST升高（P<0.05）,正常小鼠给药4周后仍有明显肝细胞水肿,ALT和AST升高（P<0.05）。结论：短期使用双硫仑对饮食诱导的肥胖小鼠无明显减肥作用;双硫仑在体内、外均可抑制小鼠棕色脂肪细胞的分化。短期使用双硫仑可引起肝损害。双硫仑用于减肥治疗的安全性及有效性尚不够理想。     

HMGB1/SREBP-1参与IFN-γ介导的小鼠肾小球系膜细胞内的脂质沉积

目的:探讨γ-干扰素(IFN-γ)诱导小鼠系膜细胞内脂质沉积的可能机制。方法:常规培养的小鼠系膜细胞(MMC)分为正常对照组、刺激组、刺激+空质粒组(sh-HMGB1)和刺激+质粒组(sh-SREBP-1);油红O染色观察细胞内脂质沉积;RT-PCR检测HMGB1、SREBP-1和脂肪酸合成酶(FAS)mRNA表达;Wesern blot检测蛋白表达。结果:油红O检测显示IFN-γ刺激组MMC细胞中出现明显脂滴;IFN-γ刺激能够上调HMGB、SREBP-1和FASmRNA及蛋白表达;沉默HMGB1能够降低IFN-γ诱导的SREBP-1和FAS上调,并减少细胞内脂质沉积;沉默SREBP-1能够减少HMGB诱导的MMC细胞内脂质沉积。结论:IFN-γ可能通过上调HMGB/SREBP-1/FAS的表达促进小鼠系膜细胞内脂滴沉积。     

有氧运动对高脂饮食小鼠肝脏中CLK2蛋白表达的影响

目的: 探讨有氧运动对高脂饮食小鼠肝脏中Cdc2 激酶(CLK2)蛋白表达及肝脏脂肪含量的影响。方法: 雄性C57/BL6小鼠经正常饮食或高脂饮食16周后,分为正常饮食组、高脂饮食组和高脂饮食+运动组(8周有氧运动),每组10只小鼠。采用免疫印迹方法比较各组小鼠肝脏CLK2蛋白表达;采用油红O染色法比较各组小鼠肝脏脂肪含量;采用实时定量PCR方法比较各组小鼠脂肪代谢相关基因。结果:与正常饮食组小鼠相比,高脂饮食小鼠表现出胰岛素抵抗,肝脏CLK2蛋白含量增加,以及肝脏脂肪积累增加。然而有氧运动可改善高脂饮食小鼠胰岛素抵抗状态,并抑制肝脏中CLK2蛋白增加。结论:有氧运动可降低高脂饮食小鼠肝脏中CLK2蛋白表达,而改善肥胖小鼠肝脏脂肪堆积及代谢紊乱。     

KLF9通过上调CD36调节肝脏脂代谢

非酒精性脂肪性肝病(nonalcoholic fatty liver disease, NAFLD)的发生和发展与脂肪酸的摄取密切相关。本研究旨在探索Krüppel样转录因子9 (Krüppel-like factor 9, KLF9)对脂肪酸转位酶CD36、肝细胞的脂代谢以及非酒精性脂肪肝的发生和发展所产生的影响。采用高脂饮食构建的高脂模型C57BL/6J小鼠和db/db糖尿病小鼠,检测其肝脏内Klf9和Cd36基因和蛋白表达水平的变化。分离C57BL/6J小鼠原代肝细胞进行体外培养,分别给予Ad-GFP、Ad-Klf9、Ad-shCtrl或Ad-shKlf9处理,然后利用油酸和棕榈酸进行24 h的诱导;同时构建肝脏特异性Klf9基因敲除小鼠,采用Western blot检测KLF9蛋白表达水平的变化,real-time PCR检测Klf9和Cd36 mRNA表达水平的变化,试剂盒测定甘油三酯含量的变化,油红O染色检测脂质含量的变化。结果显示:(1)与对照组相比,高脂饮食诱导的肥胖小鼠或db/db糖尿病小鼠肝脏Klf9的表达显著增加;(2)在小鼠原代肝脏细胞中过量表达Klf9会增加Cd36表达水平,导致细胞脂肪含量增加;(3)相反,在小鼠原代肝脏细胞中敲低Klf9的表达则降低Cd36表达水平,从而减少肝细胞脂肪含量;(4)小鼠肝脏Klf9敲除能降低肝脏Cd36表达,改善高脂饮食诱导的脂肪肝表型。上述结果表明,肝脏KLF9通过促进CD36的表达影响肝脏的脂代谢。     

Differential Roles of Cell Death-inducing DNA Fragmentation Factor-α-like Effector (CIDE) Proteins in Promoting Lipid Droplet Fusion and Growth in Subpopulations of Hepatocytes

Lipid droplets (LDs) are dynamic subcellular organelles whose growth is closely linked to obesity and hepatic steatosis. Cell death-inducing DNA fragmentation factor-α-like effector (CIDE) proteins, including Cidea, Cideb, and Cidec (also called Fsp27), play important roles in lipid metabolism. Cidea and Cidec are LD-associated proteins that promote atypical LD fusion in adipocytes. Here, we find that CIDE proteins are all localized to LD-LD contact sites (LDCSs) and promote lipid transfer, LD fusion, and growth in hepatocytes. We have identified two types of hepatocytes, one with small LDs (small LD-containing hepatocytes, SLHs) and one with large LDs (large LD-containing hepatocytes, LLHs) in the liver. Cideb is localized to LDCSs and promotes lipid exchange and LD fusion in both SLHs and LLHs, whereas Cidea and Cidec are specifically localized to the LDCSs and promote lipid exchange and LD fusion in LLHs. Cideb-deficient SLHs have reduced LD sizes and lower lipid exchange activities. Fasting dramatically induces the expression of Cidea/Cidec and increases the percentage of LLHs in the liver. The majority of the hepatocytes from the liver of obese mice are Cidea/Cidec-positive LLHs. Knocking down Cidea or Cidec significantly reduced lipid storage in the livers of obese animals. Our data reveal that CIDE proteins play differential roles in promoting LD fusion and lipid storage; Cideb promotes lipid storage under normal diet conditions, whereas Cidea and Cidec are responsible for liver steatosis under fasting and obese conditions.     

Cidea Control of Lipid Storage and Secretion in Mouse and Human Sebaceous Glands

Sebaceous glands are skin appendages that secrete sebum onto hair follicles to lubricate the hair and maintain skin homeostasis. In this study, we demonstrated that Cidea is expressed at high levels in lipid-laden mature sebocytes and that Cidea deficiency led to dry hair and hair loss in aged mice. In addition, Cidea-deficient mice had markedly reduced levels of skin surface lipids, including triacylglycerides (TAGs) and wax diesters (WDEs), and these mice were defective in water repulsion and thermoregulation. Furthermore, we observed that Cidea-deficient sebocytes accumulated a large number of smaller-sized lipid droplets (LDs), whereas overexpression of Cidea in human SZ95 sebocytes resulted in increased lipid storage and the accumulation of large LDs. Importantly, Cidea was highly expressed in human sebaceous glands, and its expression levels were positively correlated with human sebum secretion. Our data revealed that Cidea is a crucial regulator of sebaceous gland lipid storage and sebum lipid secretion in mammals and humans.     

Identification of the lipid droplet targeting domain of the Cidea protein

Cidea, the cell death-inducing DNA fragmentation factor-α-like effector (CIDE) domain-containing protein, is targeted to lipid droplets in mouse adipocytes, where it inhibits triglyceride hydrolysis and promotes lipid storage. In mice, Cidea may prevent lipolysis by binding and shielding lipid droplets from lipase association. Here we demonstrate that human Cidea localizes with lipid droplets in both adipocyte and nonadipocyte cell lines, and we ascribe specific functions to its protein domains. Expression of full-length Cidea in undifferentiated 3T3-L1 cells or COS-1 cells increases total cellular triglyceride and strikingly alters the morphology of lipid droplets by enhancing their size and reducing their number. Remarkably, both lipid droplet binding and increased triglyceride accumulation are also elicited by expression of only the carboxy-terminal 104 amino acids, indicating this small domain directs lipid droplet targeting and triglyceride shielding. However, unlike the full-length protein, expression of the carboxy-terminus causes clustering of small lipid droplets but not the formation of large droplets, identifying a novel function of the N terminus. Furthermore, human Cidea promotes lipid storage via lipolysis inhibition, as the expression of human Cidea in fully differentiated 3T3-L1 adipocytes causes a significant decrease in basal glycerol release. Taken together, these data indicate that the carboxy-terminal domain of Cidea directs lipid droplet targeting, lipid droplet clustering, and triglyceride accumulation, whereas the amino terminal domain is required for Cidea-mediated development of enlarged lipid droplets.     

Cidea controls lipid droplet fusion and lipid storage in brown and white adipose tissue

Excess lipid storage in adipose tissue results in the development of obesity and other metabolic disorders including diabetes,fatty liver and cardiovascular diseases.The lipid droplet(LD)is an important subcellular organelle responsible for lipid storage.We previously observed that Fsp27,a member of the CIDE family proteins,is localized to LD-contact sites and promotes atypical LD fusion and growth.Cidea,a close homolog of Fsp27,is expressed at high levels in brown adipose tissue.However,the exact role of Cidea in promoting LD fusion and lipid storage in adipose tissue remains unknown.Here,we expressed Cidea in Fsp27-knockdown adipocytes and observed that Cidea has similar activity to Fsp27 in promoting lipid storage and LD fusion and growth.Next,we generated Cidea and Fsp27 double-deficient mice and observed that these animals had drastically reduced adipose tissue mass and a strong lean phenotype.In addition,Cidea/Fsp27 double-deficient mice had improved insulin sensitivity and were intolerant to cold.Furthermore,we observed that the brown and white adipose tissues of Cidea/Fsp27double-deficient mice had significantly reduced lipid storage and contained smaller LDs compared to those of Cidea or Fsp27single deficient mice.Overall,these data reveal an important role of Cidea in controlling lipid droplet fusion,lipid storage in brown and white adipose tissue,and the development of obesity.     

Molecular evolution of Cide family proteins: Novel domain formation in early vertebrates and the subsequent divergence

Background  

Cide family proteins including Cidea, Cideb and Cidec/Fsp27, contain an N-terminal CIDE-N domain that shares sequence similarity to the N-terminal CAD domain (NCD) of DNA fragmentation factors Dffa/Dff45/ICAD and Dffb/Dff40/CAD, and a unique C-terminal CIDE-C domain. We have previously shown that Cide proteins are newly emerged regulators closely associated with the development of metabolic diseases such as obesity, diabetes and liver steatosis. They modulate many metabolic processes such as lipolysis, thermogenesis and TAG storage in brown adipose tissue (BAT) and white adipose tissue (WAT), as well as fatty acid oxidation and lipogenesis in the liver.     

Up-regulation of ADRP in fatty liver in human and liver steatosis in mice fed with high fat diet

The present study was performed to examine a role of adipose differentiation-related protein (ADRP) in the process of liver steatosis. Immunohistochemical findings indicated that ADRP expression is increased in the hepatocytes in patients with fatty liver when compared with normal liver. ADRP expression is localized in the surface of lipid droplets in the hepatocytes. Increased expression of ADRP mRNA and protein was similarly observed in fatty liver in ob/ob mice and the liver steatosis induced by high fat diet in mice. The up-regulation of ADRP mRNA and protein in the liver by high fat diet was identified in the surface of lipid droplets in a time-dependent manner. Recent studies demonstrated that up-regulation of PPARgamma in the hepatocytes is deeply involved in liver steatosis. To clarify whether ADRP expression is increased by PPARgamma activation in hepatocytes, we examined the effect of a PPARgamma ligand, troglitazone, on ADRP mRNA expression in HepG2 cells. ADRP mRNA expression was increased by troglitazone in dose- and time-dependent manners. All these results suggest that ADRP is up-regulated in liver steatosis in human and mice, and that high fat diet increases expression of ADRP through PPARgamma activation, followed by induction of liver steatosis.     

Hepatic steatosis inhibits autophagic proteolysis via impairment of autophagosomal acidification and cathepsin expression

Autophagy, one of protein degradation system, contributes to maintain cellular homeostasis and cell defense. Recently, some evidences indicated that autophagy and lipid metabolism are interrelated. Here, we demonstrate that hepatic steatosis impairs autophagic proteolysis. Though accumulation of autophagosome is observed in hepatocytes from ob/ob mice, expression of p62 was augmented in liver from ob/ob mice more than control mice. Moreover, degradation of the long-lived protein leucine was significantly suppressed in hepatocytes isolated from ob/ob mice. More than 80% of autophagosomes were stained by LysoTracker Red (LTR) in hepatocytes from control mice; however, rate of LTR-stained autophagosomes in hepatocytes were suppressed in ob/ob mice. On the other hand, clearance of autolysosomes loaded with LTR was blunted in hepatocytes from ob/ob mice. Although fusion of isolated autophagosome and lysosome was not disturbed, proteinase activity of cathepsin B and L in autolysosomes and cathepsin B and L expression of liver were suppressed in ob/ob mice. These results indicate that lipid accumulation blunts autophagic proteolysis via impairment of autophagosomal acidification and cathepsin expression.     

The critical role played by endotoxin-induced liver autophagy in the maintenance of lipid metabolism during sepsis

Macroautophagy/autophagy is a central mechanism by which cells maintain integrity and homeostasis, and endotoxin-induced autophagy plays important roles in innate immunity. Although TLR4 stimulation mediated by lipopolysaccharide (LPS) also upregulates autophagy in hepatocytes and liver, its physiological role remains elusive. The objective of this study was to determine the role of LPS-induced autophagy in the regulation of liver lipid metabolism. LPS treatment (5 mg/kg) increased autophagy, as detected by LC3 conversion and transmission electron microscopy (TEM) analysis in C57BL6 mouse livers. AC2F hepatocytes also showed increased autophagic flux after LPS treatment (1 μg/ml). To investigate the role of LPS-induced autophagy further, liver lipid metabolism changes in LPS-treated mice and fasted controls were compared. Interestingly, LPS-treated mice showed less lipid accumulation in liver than fasted mice despite increased fatty acid uptake and lipid synthesis-associated genes. In vitro analysis using AC2F hepatocytes demonstrated LPS-induced autophagy influenced the degradation of lipid droplets. Inhibition of LPS-induced autophagy using bafilomycin A₁ or Atg7 knockdown significantly increased lipid accumulation in AC2F hepatocytes. In addition, pretreatment with chloroquine aggravated LPS-induced lipid accumulation and inflammation in C57BL6 mouse livers. The physiological importance of autophagy was verified in LPS-treated young and aged rats. Autophagic response was diminished in LPS-treated aged rats and lipid metabolism was impaired during sepsis, indicating autophagy response is important for regulating lipid metabolism after endotoxin challenge. Our findings demonstrate endotoxin-induced autophagy is important for the regulation of lipid metabolism, and suggest that autophagy helps maintain lipid metabolism homeostasis during sepsis.