基于Cre/LoxP系统建立睾丸Occludin基因敲除小鼠模型

目的:基于Cre/LoxP系统建立睾丸Occludin基因敲除小鼠模型,并进一步观察其表型变化差异。方法:使用Cre-LoxP系统构建Occludin-floxed(基因型Floxp/-)小鼠,与AQP2-cre(基因型Cre/-)小鼠进行杂交,得到睾丸内Occludin条件性敲除小鼠(基因型Floxp/Floxp Cre/-。利用PCR及Southern印迹技术鉴定F1代敲除小鼠基因型,利用qPCR,Western印迹以及免疫组化鉴定Occludin敲除小鼠中Occludin蛋白表达来验证Occludin敲除小鼠获得成功。比较实验鼠与正常鼠的精子数量,分析其生育能力。结果:Southern印迹和PCR结果我们成功地获得了Occludin基因敲除的目标小鼠。Occludin基因敲除小鼠较正常小鼠Occludin蛋白表达减少,精子数量减少,生育能力降低。差异显著(P0.05)。结论:采用Cre-LoxP技术可成功构建Occludin基因敲除小鼠,并且Occludin的缺乏会对小鼠的生殖功能产生影响。     

特异性敲除β-连环蛋白基因对小鼠肝缺血再灌注损伤的影响

目的 通过构建特异性敲除小鼠模型观察β-连环蛋白(β-catenin)基因在小鼠肝缺血再灌注损伤中的作用.方法 应用Cre-lox系统构建肝细胞特异性敲除β-catenin基因小鼠模型,90 min半肝血流阻断制造肝脏缺血再灌注小鼠模型,分为β-catenin基因敲除组及对照组,再灌注后0、3、6、20 h测血清谷丙转氨酶(ALT)、谷草转氨酶(AST)及其肝脏组织学改变.结果 肝细胞特异性敲除β-catenin基因小鼠基因表型为:ctnnb纯合(loxP/loxP)并且Alb-Cre阳性表达,Western blot 方法证实其β-catenin蛋白表达丰度明显低于对照组.再灌注3、6、20 h敲除组小鼠血清ALT水平分别为282、405及128 U/ml;对照组分别为221、295及101 U/ml.敲除组AST水平分别为603、805及396 U/ml;对照组分别为421、398及336 U/ml,各时间点两组间差异均有统计学意义(P＜0.05).其肝细胞坏死、窦状隙充血以及炎细胞浸润程度明显重于对照组.结论 β-catenin对肝脏缺血再灌注引起的肝损伤起保护作用.

Abstract：

Objective To study the role of β-catenin in liver ischemia-reperfusion injury used a conditional knockout approach to delete p-catenin in the liver. Methods We adapted the Cre-lox recombination system to create the p-catenin conditional knockout (KO) mice and liver ischemia-reperfusion injury were made by 90min hemiliver blood supply block. Experimental animal were randomized into two groups:p-catenin conditional knockout group (KO group) and control group (C group). 0,3,6,20 h after reperfusion,serum samples were used for measurement of serum alanine transaminase ( ALT) and aspartate aminotransferase (AST) ,liver sections were subjected to hematoxylin-eosin staining. Results Genotyping identified that β-catenin KO mice showed ctnnb homozygosis ( - / - ) and Alb-Cre positive. Western blotting analysis showed an obviously lower expression of p-catenin in KO group. Three,6,20 h after reperfusion,KO group ALT level were 282,405 and 128 U/ml. C group were 221,295 and 101 U/ml. KO group AST level were 603,805 and 396 U/ml,C group were 421,398 and 336 U/ml. Hematoxylin and Eosin (HE)staining showed significant sinusoid inflation and congestion, extensive acidophilic necrosis, focal hemorrhages , hepatic lobula structure disorder and slightly lymphocyte inflammatory cells infiltration in KO group. In C group, HE staining show slightly sinusoid inflation and congestion, limited acidophilic necrosis and focal hemorrhages, hepatic lobula structure nearly integrity, slightly lymphocyte inflammatory cells infiltration.Conclusion β-catenin may play a protect role in liver ischemia-reperfusion injury.     

肝脏类器官构建及其对小鼠部分肝切除术后肝再生的作用#br#

目的 观察肝脏类器官对小鼠部分肝切除术后肝再生的作用。方法 体外构建肝脏类器官，通过形态学、PCR和免疫荧光对类器官进行初步鉴定。C57BL/6小鼠随机等分为对照组和治疗组，每组18只。对照组进行肝左叶、中叶切除术+肝包膜注射200 μL PBS；治疗组进行肝左叶、中叶切除术+肝包膜移植200 μL类器官悬液。建模成功后分别于术后第1、4、7天收集标本。通过血清生化检测、免疫组化和Western blotting评估肝脏类器官对小鼠肝部分切除术后肝再生的作用。结果 类器官体外培养3 d，从直径20 μm的囊性结构扩增到约125 μm的细胞团（P＜0.05），直径扩增近6 倍。肝脏干细胞标志基因EPCAM、SOX9和CK19明显上调（P＜0.05），传代前后基因保持稳定。免疫荧光显示CK8、Desmin、AFP和PCNA呈阳性。HE显示术后第4天，治疗组肝细胞形态大小基本恢复正常，形态较清晰，无炎症细胞浸润，无脂肪或气球样变。对照组小鼠肝细胞核仁染色加深，仍有炎性细胞浸润，部分区域存在肝细胞坏死区。免疫组化Ki67和Western blotting对增殖水平进行检测，结果显示治疗组增殖能力是对照组的3 倍。肝功能检测发现治疗组在术后第4天ALT、AST、TBIL和DBIL明显下降，ALB合成增加（P＜0.05）。结论 具有肝脏干细胞属性和增殖能力的肝脏类器官，能通过保护肝细胞、改善部分肝切除术后小鼠肝功能，发挥促进肝再生作用。     

外源性IL-6促进IL-6基因敲除小鼠移植肝再生的研究

目的 观察外源性重组白细胞介素6(rIL-6)对白细胞介素6(IL-6)基因敲除小鼠原位肝移植后存活时间和移植肝再生过程的影响.方法 动物为C57BL/6野生型小鼠和IL-6基因敲除小鼠,分为4组进行实验:基因敲除对照组,肝移植供、受者均为IL-6基因敲除小鼠；野生型对照组,以IL-6基因敲除小鼠为供者,野生型C57BL/6小鼠为受者；基因敲除rIL-6组,供、受者均为IL-6基因敲除小鼠,肝移植前1h于受者皮下注射rIL-6,1 mg/kg;野生型rIL-6组,以IL-6基因敲除小鼠为供者,野生型C57BL/6小鼠为受者,受者应用rIL-6,用法和用量同前组.观察受鼠的存活情况.获取移植肝,进行组织学和免疫组织化学检查.结果 供肝冷缺血时间约为50 min.基因敲除对照组受鼠平均存活2.2d,野生型对照组受鼠平均存活1.9 d,基因敲除rIL-6组受鼠平均存活＞17.6 d,野生型rIL-6组受鼠平均存活＞20.4 d.各组间存活时间的差异均有统计学意义(P＜0.01).基因敲除对照组和野生型对照组受鼠移植肝有片状坏死和肝细胞气球样变,有极少数溴脱氧尿核苷染色阳性的细胞存在.基因敲除rIL-6组和野生型rIL-6组受鼠的移植肝无细胞坏死等改变,有散在的肝细胞溴脱氧尿核苷染色阳性.结论 外源性的IL-6能够延长IL-6基因敲除小鼠肝移植后的存活时间,促进其移植肝细胞再生.     

ADAM10对小鼠颅颌面膜内成骨的影响

目的探索解聚素样金属蛋白酶10(ADAM10)对小鼠颅颌面骨骼膜内成骨的影响。方法应用组织免疫荧光染色及蛋白免疫印迹研究ADAM10在小鼠颅颌面骨中的不同时间点、不同部位的表达水平。通过cre-loxp技术在胚胎小鼠颅颌面骨骼中特异性敲除ADAM10基因,应用体视显微镜观察基因敲除小鼠的颅颌面畸形,X线检查、von Kossa染色检测基因敲除小鼠骨钙化情况,双标免疫荧光观察基因敲除小鼠骨组织细胞增殖、分化、凋亡能力的改变。结果组织免疫荧光染色显示小鼠上、下颌骨成骨活跃区ADAM10表达明显,同时蛋白免疫印迹结果证实,ADAM10在小鼠出生前后表达高,成年后表达明显降低。大体观察基因敲除小鼠身体体型较小,颅颌面畸形表现为面中部发育不足,上下颌骨发育不足,颅顶塌陷。X线片检测及von Kosaa染色显示基因敲除小鼠全身骨骼密度减低,骨组织形成较弱。免疫荧光检测发现ADAM10基因敲除小鼠下颌骨细胞增殖、成骨分化能力减低、凋亡增加。结论 ADAM10广泛表达于小鼠膜内成骨区域,可能通过影响骨组织细胞增殖、分化及凋亡来调控小鼠颅面部膜内成骨过程。     

利用Cre/loxP系统构建胰岛α细胞特异性敲除血管紧张素转换酶2基因的小鼠模型

目的构建α细胞特异性血管紧张素转换酶2(ACE2)敲除小鼠模型, 为研究胰岛α细胞ACE2功能提供基础。方法利用Cre/loxP系统, 将雌性ACE2loxP/WT与雄性Gcg-cre+/-小鼠进行交配, 取鼠尾组织, 通过PCR法鉴定子代基因型。选取基因型为ACE2loxP/y Gcg-cre+/-的雄性小鼠为实验所需要构建的模型小鼠(αACE2KO小鼠)。采用免疫荧光和免疫组织化学法检测ACE2表达。采用独立样本t检验。结果免疫荧光分析提示, 在Gcg-Cre小鼠胰岛中, (55.14±25.33)%的α细胞表达ACE2, 然而αACE2KO小鼠胰岛α细胞中未检测到ACE2表达(t=14.202, P<0.01), 同时αACE2KO小鼠的肝、肾、肺、心和骨骼肌中仍然表达ACE2。结论成功利用Cre/loxP原理特异性敲除α细胞ACE2, 为研究胰岛局部α细胞ACE2功能提供动物模型和基础。     

肝脏类器官构建及其对小鼠部分肝切除术后肝再生的作用

目的观察肝脏类器官对小鼠部分肝切除术后肝再生的作用。方法体外构建肝脏类器官,通过形态学、PCR和免疫荧光对类器官进行初步鉴定。C57BL/6小鼠随机等分为对照组和治疗组,每组18只。对照组进行肝左叶、中叶切除术+肝包膜注射200 μL PBS;治疗组进行肝左叶、中叶切除术+肝包膜移植200 μL类器官悬液。建模成功后分别于术后第1、4、7天收集标本。通过血清生化检测、免疫组化和Westernblotting评估肝脏类器官对小鼠肝部分切除术后肝再生的作用。结果类器官体外培养3 d,从直径20 μm的囊性结构扩增到约125 μm的细胞团(P0.05),直径扩增近6倍。肝脏干细胞标志基因EPCAM、SOX9和CK19明显上调(P0.05),传代前后基因保持稳定。免疫荧光显示CK8、Desmin、AFP和PCNA呈阳性。HE显示术后第4天,治疗组肝细胞形态大小基本恢复正常,形态较清晰,无炎症细胞浸润,无脂肪或气球样变。对照组小鼠肝细胞核仁染色加深,仍有炎性细胞浸润,部分区域存在肝细胞坏死区。免疫组化Ki67和Western blotting对增殖水平进行检测,结果显示治疗组增殖能力是对照组的3倍。肝功能检测发现治疗组在术后第4天ALT、AST、TBIL和DBIL明显下降,ALB合成增加(P0.05)。结论具有肝脏干细胞属性和增殖能力的肝脏类器官,能通过保护肝细胞、改善部分肝切除术后小鼠肝功能,发挥促进肝再生作用。     

条件性敲除Osterix基因获得先天性脊柱侧凸小鼠动物模型及表型分析

目的 通过Osterix基因敲除获得先天性脊柱侧凸动物模型及表型分析.方法 应用Cre-LoxP系统繁育成骨细胞特异性敲除Osterix基因小鼠.取4、12周龄的敲除小鼠各10只,以同龄同系野生型小鼠各10只为对照,行全身及脊柱X线摄像观察;收集脊柱标本行苏木素-伊红(HE)染色及抗酒石酸酸性磷酸酶(TRAP)染色观察并检测.结果 成功获得成骨细胞特异性敲除Osterix基因小鼠,X线显示敲除小鼠中75％出现严重的脊柱侧凸,Cobb角平均值为35..HE染色显示敲除小鼠椎体生长板增宽,椎体骨量增加,TRAP染色显示腰椎中破骨细胞数量显著减少(P＜0.05).结论 小鼠成骨细胞中条件性敲除Osterix基因后成功获得先天性脊柱侧凸模型,提示Osterix在先天性脊柱侧凸的发病中有重要作用.     

PDZK1敲除对小鼠肝脏胆固醇代谢和胆囊结石形成影响的实验研究

目的探讨敲除PDZK1(Postsynaptic density-95,disks-large,ZO-1-domain K1,PDZK1)基因对小鼠肝脏胆固醇代谢调节和胆囊结石形成的影响。方法雄性成年PDZK1基因敲除小鼠(PDZK1 knockout,KO组)和野生型小鼠(wild type,WT组),每组各10只,以成石饲料分别喂养4周,观察胆囊成石情况,并收集肝脏和胆囊组织。采用蛋白印迹法测定肝脏PDZK1和清道夫受体B族1型(scavenger receptor B type 1,SRB1)表达。采用胆总管插管收集肝胆汁,测定胆汁分泌率和胆汁胆固醇含量。采用试剂盒酶法测定胆囊胆汁成分并计算胆汁胆固醇饱和指数(cholesterol saturation index,CSI)。以实时定量PCR检测肝脏脂质代谢相关基因的mRNA表达。结果成石饲料喂养4周后,WT组小鼠全部成石(10/10),KO组小鼠则为40%(4/10)成石。两组小鼠肝胆汁分泌率差异无统计学意义,但KO组小鼠肝胆汁胆固醇含量显著降低(P0.05),胆汁酸含量增加(P0.05),且CSI降低(P0.05)。KO组小鼠肝脏SRB1蛋白表达降低(P0.05),甾醇氧-酰基转移酶基因1/2mRNA表达降低(P0.05),而肝型脂肪酸结合蛋白1和胆汁酸转运相关蛋白(ATP结合盒b11)表达则显著增加(P0.05)。结论 PDZK1影响SRB1在小鼠肝脏中表达,降低对高密度脂蛋白胆固醇摄取,减少胆汁胆固醇分泌,继而降低胆囊结石形成。     

Daxx基因在小鼠睾丸精子发生过程中的表达特征

目的:研究死亡结构域相关蛋白(Daxx)基因在小鼠睾丸精子发生过程中的表达特征,初步探讨其在生精过程中的作用。方法:通过实时荧光定量PCR(q PCR)、Western印迹及免疫荧光等方法检测Daxx在不同周龄野生型小鼠睾丸组织以及成年睾丸支持细胞雄激素受体特异性敲除(SCARKO)和雄激素受体敲除(ARKO)小鼠睾丸中的表达特征。结果:q PCR、Western印迹和免疫荧光结果表明,Daxx基因在出生4周后小鼠睾丸中高表达,且主要定位于细胞核;与野生型小鼠相比,SCARKO小鼠睾丸中DAXX的表达差异不显著(0.853±0.058 vs1.000±0.015),但在生精细胞细胞核中呈极性分布;DAXX在ARKO小鼠睾丸表达显著降低(0.299±0.026 vs1.000±0.015,P0.01)。结论 :Daxx基因在小鼠睾丸发育中期时表达最高。ARKO小鼠中DAXX的表达与野生型相比显著降低,睾丸支持细胞中AR基因特异性敲除影响DAXX定位。DAXX可能参与调控小鼠的精子发生过程。     

p27Kip1 inactivation provides a proliferative advantage to transplanted hepatocytes in DPPIV/Rag2 double knockout mice after repeated host liver injury

Studies were conducted to develop a new DPPIV(-/-)/Rag2(-/-) mouse model for hepatocyte transplantation by allogeneic and xenogeneic cells and to compare the proliferative capacity of p27 null hepatocytes versus normal hepatocytes in this system. Dipeptidyl peptidase IV (DPPIV) gene knockout mice, in which wild-type (wt) DPPIV+ donor hepatocytes can be readily identified by enzyme histochemistry, were bred with Rag2 null mice to prepare immunotolerant DPPIV(-/-)/Rag2(-/-) double knockout mice. DPPIV(-/-)/Rag(-/-) mice were transplanted with wt hepatocytes or p27 null mouse hepatocytes, which show enhanced cell cycle activity due to disruption of the Kip1 cyclin kinase inhibitor gene, and liver repopulation was assessed under nonproliferative versus proliferative experimental conditions. After their initial engraftment, transplanted wt hepatocytes did not proliferate in untreated livers or increase significantly in response to an acute liver regenerative stimulus. p27 null hepatocytes engrafted with the same efficiency as wt hepatocytes, but showed a noticeable, although not statistically significant, increase in proliferation in response to partial hepatectomy or acute CCl4 administration. Repeated treatments with CCl4 substantially increased proliferation and liver repopulation by p27 null hepatocytes but not by wt hepatocytes. These results suggest that p27 gene inactivation does not overcome proliferative restrictions imposed on hepatocytes by the normal liver, but that after repeated episodes of toxic liver injury, the augmented proliferative capacity of p27 null hepatocytes leads to significant liver repopulation compared with wt hepatocytes. These properties of p27-deficient hepatocytes could prove useful as a target for liver repopulation in patients with intermittent or a low level of chronic liver injury.     

IKKε增加血管平滑肌细胞自噬促进小鼠腹主动脉瘤形成作用研究

目的:探讨IKKε对小鼠腹主动脉瘤形成过程中血管平滑肌细胞自噬的影响。方法:将载脂蛋白E敲除(ApoE -/-)的小鼠与载脂蛋白E和IKKε双敲(ApoE -/-IKKε -/-)的小鼠用生理盐水(saline)和血管紧张素Ⅱ(AngⅡ)分别刺激28天,检测小鼠的代谢水平以及用超声心...     

不同能量平衡状态下瘦素及瘦素受体在小鼠肝细胞损伤中的作用机制

目的 探讨在不同能量平衡状态下瘦素(leptin)及瘦素受体(leptin receptor,LEPR)参与肝细胞损伤的作用机制研究.方法 选取4周龄FVB/N雌性小鼠18只,分为3组:Mex3c+/-突变组(文中简称Mex3c+/-组,n=6),HFD组(给予高脂饮食,n=6)和Control组(给予普通饲料,n=6...     

Targeted Disruption of G0/G1 Switch Gene 2 Enhances Adipose Lipolysis,Alters Hepatic Energy Balance,and Alleviates High-Fat Diet–Induced Liver Steatosis

Recent biochemical and cell-based studies identified G₀/G₁ switch gene 2 (G0S2) as an inhibitor of adipose triglyceride lipase (ATGL), a key mediator of intracellular triacylglycerol (TG) mobilization. Here, we show that upon fasting, G0S2 protein expression exhibits an increase in liver and a decrease in adipose tissue. Global knockout of G0S2 in mice enhanced adipose lipolysis and attenuated gain of body weight and adiposity. More strikingly, G0S2 knockout mice displayed a drastic decrease in hepatic TG content and were resistant to high-fat diet (HFD)-induced liver steatosis, both of which were reproduced by liver-specific G0S2 knockdown. Mice with hepatic G0S2 knockdown also showed increased ketogenesis, accelerated gluconeogenesis, and decelerated glycogenolysis. Conversely, overexpression of G0S2 inhibited fatty acid oxidation in mouse primary hepatocytes and caused sustained steatosis in liver accompanied by deficient TG clearance during the fasting-refeeding transition. In response to HFD, there was a profound increase in hepatic G0S2 expression in the fed state. Global and hepatic ablation of G0S2 both led to improved insulin sensitivity in HFD-fed mice. Our findings implicate a physiological role for G0S2 in the control of adaptive energy response to fasting and as a contributor to obesity-associated liver steatosis.     

Hepatic TRAF2 regulates glucose metabolism through enhancing glucagon responses

Obesity is associated with intrahepatic inflammation that promotes insulin resistance and type 2 diabetes. Tumor necrosis factor receptor-associated factor (TRAF)2 is a key adaptor molecule that is known to mediate proinflammatory cytokine signaling in immune cells; however, its metabolic function remains unclear. We examined the role of hepatic TRAF2 in the regulation of insulin sensitivity and glucose metabolism. TRAF2 was deleted specifically in hepatocytes using the Cre/loxP system. The mutant mice were fed a high-fat diet (HFD) to induce insulin resistance and hyperglycemia. Hepatic glucose production (HGP) was examined using pyruvate tolerance tests, (2)H nuclear magnetic resonance spectroscopy, and in vitro HGP assays. The expression of gluconeogenic genes was measured by quantitative real-time PCR. Insulin sensitivity was analyzed using insulin tolerance tests and insulin-stimulated phosphorylation of insulin receptors and Akt. Glucagon action was examined using glucagon tolerance tests and glucagon-stimulated HGP, cAMP-responsive element-binding (CREB) phosphorylation, and expression of gluconeogenic genes in the liver and primary hepatocytes. Hepatocyte-specific TRAF2 knockout (HKO) mice exhibited normal body weight, blood glucose levels, and insulin sensitivity. Under HFD conditions, blood glucose levels were significantly lower (by >30%) in HKO than in control mice. Both insulin signaling and the hypoglycemic response to insulin were similar between HKO and control mice. In contrast, glucagon signaling and the hyperglycemic response to glucagon were severely impaired in HKO mice. In addition, TRAF2 overexpression significantly increased the ability of glucagon or a cAMP analog to stimulate CREB phosphorylation, gluconeogenic gene expression, and HGP in primary hepatocytes. These results suggest that the hepatic TRAF2 cell autonomously promotes hepatic gluconeogenesis by enhancing the hyperglycemic response to glucagon and other factors that increase cAMP levels, thus contributing to hyperglycemia in obesity.     

Development of gene vectors for pinpoint targeting to human hepatocytes by cationically modified polymer complexes

We developed a vector that might enable gene therapy of metabolic liver disease or hepatoma. Here we demonstrate the use of cationically modified biocompatible phospholipid polymer conjugated with hepatitis B surface (HBs) antigen for the specific transfer of genes into human hepatocytes. Poly(2-methacryloyloxyethyl phosphorylcholine (MPC)- co-N,N-dimethylaminoethyl methacrylate (DMAEMA)-co- p-nitrophenylcarbonyloxyethyl methacrylate(NPMA))(polyMDN) was prepared as a frame of vector. The specific expression of sFlt-1 or GFP by polyMDN conjugated with HBs containing plasmid (plasmid/polyMDN-HBs), polyMDN containing plasmid (plasmid/polyMDN), plasmid only and PBS were assessed in tumor cells (HepG2 or WiDr) in vitro and in vivo. The histological findings, organ weight changes, and degree of liver dysfunction were examined in the mice administered by several reagents. The sFlt-1 and GFP expression was observed only in the HepG2 cells transfected with sFlt-1 or GFP/polyMDN-HBs. None of the side effects mentioned above was observed. In conclusion, these results suggest that polyMDN-HBs is a human hepatocyte-specific gene delivery vector that might not have serious side effects.     

Hepatocyte-specific Ptpn6 deletion protects from obesity-linked hepatic insulin resistance

The protein-tyrosine phosphatase Shp1 negatively regulates insulin action on glucose homeostasis in liver and muscle, but its potential role in obesity-linked insulin resistance has not been examined. To investigate the role of Shp1 in hepatic insulin resistance, we generated hepatocyte-specific Shp1 knockout mice (Ptpn6(H-KO)), which were subjected to extensive metabolic monitoring throughout an 8-week standard chow diet (SD) or high-fat diet (HFD) feeding. We report for the first time that Shp1 expression is upregulated in metabolic tissues of HFD-fed obese mice. When compared with their Shp1-expressing Ptpn6(f/f) littermates, Ptpn6(H-KO) mice exhibited significantly lowered fasting glycemia and heightened hepatic insulin sensitivity. After HFD feeding, Ptpn6(H-KO) mice developed comparable levels of obesity as Ptpn6(f/f) mice, but they were remarkably protected from liver insulin resistance, as revealed by euglycemic clamps and hepatic insulin signaling determinations. Although Ptpn6(H-KO) mice still acquired diet-induced peripheral insulin resistance, they were less hyperinsulinemic during a glucose tolerance test because of reduced insulin secretion. Ptpn6(H-KO) mice also exhibited increased insulin clearance in line with enhanced CC1 tyrosine phosphorylation in liver. These results show that hepatocyte Shp1 plays a critical role in the development of hepatic insulin resistance and represents a novel therapeutic target for obesity-linked diabetes.     

Adiponectin Alleviates Diet-Induced Inflammation in the Liver by Suppressing MCP-1 Expression and Macrophage Infiltration

Adiponectin is an adipokine that exerts insulin-sensitizing and anti-inflammatory roles in insulin target tissues including liver. While the insulin-sensitizing function of adiponectin has been extensively investigated, the precise mechanism by which adiponectin alleviates diet-induced hepatic inflammation remains elusive. Here, we report that hepatocyte-specific knockout (KO) of the adaptor protein APPL2 enhanced adiponectin sensitivity and prevented mice from developing high-fat diet–induced inflammation, insulin resistance, and glucose intolerance, although it caused fatty liver. The improved anti-inflammatory and insulin-sensitizing effects in the APPL2 hepatocyte–specific KO mice were largely reversed by knocking out adiponectin. Mechanistically, hepatocyte APPL2 deficiency enhances adiponectin signaling in the liver, which blocks TNF-α–stimulated MCP-1 expression via inhibiting the mTORC1 signaling pathway, leading to reduced macrophage infiltration and thus reduced inflammation in the liver. With results taken together, our study uncovers a mechanism underlying the anti-inflammatory role of adiponectin in the liver and reveals the hepatic APPL2–mTORC1–MCP-1 axis as a potential target for treating overnutrition-induced inflammation in the liver.