Activating transcription factor 4 （ATF4） has been shown to play key roles in many physiological processes. There are no reports, however, demonstrating a direct link between ATF4 and lipid metabolism. We noticed tha...Activating transcription factor 4 （ATF4） has been shown to play key roles in many physiological processes. There are no reports, however, demonstrating a direct link between ATF4 and lipid metabolism. We noticed that Atf4- deficient mice are lean, suggesting a possible role for ATF4 in regulating lipid metabolism. The goal of our current study is to investigate the involvement of ATF4 in lipid metabolism and elucidate the underlying mechanisms. Studies using Atf4-deficient mice revealed increased energy expenditure, as measured by oxygen consumption. These mice also showed increases in lipolysis, expression of uncoupling protein 2 （UCP2） and p-oxidation genes and decreases in expression of lipogenic genes in white adipose tissue （WAT）, suggesting increased utilization and decreased synthesis of fatty acids, respectively. Expression of UCP1, 2 and 3 was also increased in brown adipose tissue （BAT）, suggesting increased thermogenesis. The effect of ATF4 deletion on expression of UCPs in BAT suggests that increased thermogenesis may underlie increased energy expenditure. Thus, our study identifies a possible new function for ATF4 in regulating lipid metabolism and thermogenesis.展开更多
目的研究乳源五肽脯氨酸-甘氨酸-脯氨酸-异亮氨酸-脯氨酸(PGPIP)缓解小鼠慢性酒精性肝损伤及其相关的分子机制。方法40只C57BL/6小鼠,随机均分为对照组、模型组、谷胱甘肽(GSH)组、PGPIP组。采用10 d Lieber-Decarli酒精饲料喂养加1次...目的研究乳源五肽脯氨酸-甘氨酸-脯氨酸-异亮氨酸-脯氨酸(PGPIP)缓解小鼠慢性酒精性肝损伤及其相关的分子机制。方法40只C57BL/6小鼠,随机均分为对照组、模型组、谷胱甘肽(GSH)组、PGPIP组。采用10 d Lieber-Decarli酒精饲料喂养加1次急性酒精灌胃的方法建立小鼠慢性酒精性脂肪肝模型,造模的同时给予药物干预。根据已有的基因表达综合(GEO)数据库中RNA测序数据,采用聚类热图对肝脏内质网应激相关基因差异表达分析。肝脏苏木素-伊红(HE)染色分析各处理组对小鼠酒精性肝损伤的病理学影响,油红O染色分析各处理组对小鼠肝脏脂滴积累的影响。透射电子显微镜分析酒精代谢引起的脂滴积累对肝细胞显微结构的影响并验证PGPIP的作用效果。蛋白质免疫印迹法(Western blot)检测内质网应激相关信号转导蛋白表达变化。结果PGPIP组病理学检查类似正常对照组,小鼠肝脏损伤明显减轻。模型组小鼠肝脏中有明显的脂滴积累,表现为大小不同程度的混合型脂滴,PGPIP处理后明显减少酒精诱导的肝脏脂滴积累。PGPIP对PERK-eIF2α-ATF4通路有较大影响,且对转录激活因子6(ATF6)和Cleaved Caspase 3蛋白的表达有显著性的效果。结论五肽PGPIP能缓解小鼠慢性酒精性脂肪肝和肝损伤,其机制可能是通过减少肝细胞中的脂滴积累,并且减少内质网应激和肝细胞凋亡从而发挥作用。展开更多
目的探讨栝楼桂枝汤对脑缺血再灌注损伤模型大鼠皮质内质网应激相关因子m RNA表达的影响。方法将大鼠随机分为假手术组和造模组,造模组采用线栓法制备大鼠大脑中动脉阻塞(MCAO)模型,假手术组除不插入线栓外其余操作相同。将造模成功的...目的探讨栝楼桂枝汤对脑缺血再灌注损伤模型大鼠皮质内质网应激相关因子m RNA表达的影响。方法将大鼠随机分为假手术组和造模组,造模组采用线栓法制备大鼠大脑中动脉阻塞(MCAO)模型,假手术组除不插入线栓外其余操作相同。将造模成功的大鼠随机分为模型组、阳性对照组、低剂量组、中剂量组和高剂量组。低、中、高剂量组分别予不同剂量的栝楼桂枝汤灌胃,阳性对照组给予尼莫地平混悬液灌胃,假手术组和模型组予等量生理盐水灌胃,每日1次,连续干预7 d。采用Longa神经学评分法评定大鼠神经功能损伤程度,RTq PCR法检测大鼠缺血侧皮质组织中葡萄糖调节蛋白78(GRP78)、转录活化因子4(ATF4)、C/EBP同源蛋白(CHOP)及其B淋巴细胞瘤-2基因(Bcl-2)、半胱氨酸天冬氨酸蛋白-3(Caspase-3)m RNA的表达。结果与假手术组比较,模型组神经功能损伤评分及大鼠皮质组织中GRP78、ATF4、CHOP、Caspase-3 m RNA表达明显提高(P<0.01,P<0.05),Bcl-2 m RNA表达降低(P<0.05);与模型组比较,阳性对照组和低、中、高剂量组神经功能损伤评分及大鼠皮质组织中GRP78、ATF4、CHOP、Caspase-3 m RNA表达明显下降(P<0.01,P<0.05),Bcl-2m RNA表达提高(P<0.05)。结论栝楼桂枝汤对MCAO模型大鼠具有较好的治疗作用,其作用机制可能与调控内质网应激相关因子的表达,降低内质网应激水平有关。展开更多
Toll-like receptors （TLRs） are sentinels of the host defense system, which recognize a large number of microbial pathogens. The host defense system may be inefficient or inflammatory diseases may develop if microbia...Toll-like receptors （TLRs） are sentinels of the host defense system, which recognize a large number of microbial pathogens. The host defense system may be inefficient or inflammatory diseases may develop if microbial recognition by TLRs and subsequent TLR-triggered cytokine production are deregulated. Activating transcription factor 4 （ATF4）, a member of the ATF/CREB transcription factor family, is an important factor that participates in several pathophysiological processes. In this report, we found that ATF4 is also involved in the TLR-mediated innate immune response, which participates in TLR4 signal transduction and mediates the secretion of a variety of cytokines. We observed that ATF4 is activated and translocates to the nucleus following l ipopolysaccharide （LPS） stimulation via the TLR4-MyD88-dependent pathway. Additionally, a cytokine array assay showed that some key inflammatory cytokines, such as I L-6, I L-8 and RANTES, are positively regulated by ATF4. We also demonstrate that c-Jun directly binds to ATF4, thereby promoting the secretion of inflammatory cytokines. Taken together, these results indicate that ATF4 acts as a positive regulator in TLR4-triggered cytokine production.展开更多
Several studies have shown that activation of unfolded protein response and endoplasmic reticulum(ER)stress plays a crucial role in severe cerebral ischemia/reperfusion injury.Autophagy occurs within hours after cereb...Several studies have shown that activation of unfolded protein response and endoplasmic reticulum(ER)stress plays a crucial role in severe cerebral ischemia/reperfusion injury.Autophagy occurs within hours after cerebral ischemia,but the relationship between ER stress and autophagy remains unclear.In this study,we established experimental models using oxygen-glucose deprivation/reoxygenation in PC12 cells and primary neurons to simulate cerebral ischemia/reperfusion injury.We found that prolongation of oxygen-glucose deprivation activated the ER stress pathway protein kinase-like endoplasmic reticulum kinase(PERK)/eukaryotic translation initiation factor 2 subunit alpha(e IF2α)-activating transcription factor 4(ATF4)-C/EBP homologous protein(CHOP),increased neuronal apoptosis,and induced autophagy.Furthermore,inhibition of ER stress using inhibitors or by si RNA knockdown of the PERK gene significantly attenuated excessive autophagy and neuronal apoptosis,indicating an interaction between autophagy and ER stress and suggesting PERK as an essential target for regulating autophagy.Blocking autophagy with chloroquine exacerbated ER stress-induced apoptosis,indicating that normal levels of autophagy play a protective role in neuronal injury following cerebral ischemia/reperfusion injury.Findings from this study indicate that cerebral ischemia/reperfusion injury can trigger neuronal ER stress and promote autophagy,and suggest that PERK is a possible target for inhibiting excessive autophagy in cerebral ischemia/reperfusion injury.展开更多
文摘Activating transcription factor 4 （ATF4） has been shown to play key roles in many physiological processes. There are no reports, however, demonstrating a direct link between ATF4 and lipid metabolism. We noticed that Atf4- deficient mice are lean, suggesting a possible role for ATF4 in regulating lipid metabolism. The goal of our current study is to investigate the involvement of ATF4 in lipid metabolism and elucidate the underlying mechanisms. Studies using Atf4-deficient mice revealed increased energy expenditure, as measured by oxygen consumption. These mice also showed increases in lipolysis, expression of uncoupling protein 2 （UCP2） and p-oxidation genes and decreases in expression of lipogenic genes in white adipose tissue （WAT）, suggesting increased utilization and decreased synthesis of fatty acids, respectively. Expression of UCP1, 2 and 3 was also increased in brown adipose tissue （BAT）, suggesting increased thermogenesis. The effect of ATF4 deletion on expression of UCPs in BAT suggests that increased thermogenesis may underlie increased energy expenditure. Thus, our study identifies a possible new function for ATF4 in regulating lipid metabolism and thermogenesis.
文摘目的探讨栝楼桂枝汤对脑缺血再灌注损伤模型大鼠皮质内质网应激相关因子m RNA表达的影响。方法将大鼠随机分为假手术组和造模组,造模组采用线栓法制备大鼠大脑中动脉阻塞(MCAO)模型,假手术组除不插入线栓外其余操作相同。将造模成功的大鼠随机分为模型组、阳性对照组、低剂量组、中剂量组和高剂量组。低、中、高剂量组分别予不同剂量的栝楼桂枝汤灌胃,阳性对照组给予尼莫地平混悬液灌胃,假手术组和模型组予等量生理盐水灌胃,每日1次,连续干预7 d。采用Longa神经学评分法评定大鼠神经功能损伤程度,RTq PCR法检测大鼠缺血侧皮质组织中葡萄糖调节蛋白78(GRP78)、转录活化因子4(ATF4)、C/EBP同源蛋白(CHOP)及其B淋巴细胞瘤-2基因(Bcl-2)、半胱氨酸天冬氨酸蛋白-3(Caspase-3)m RNA的表达。结果与假手术组比较,模型组神经功能损伤评分及大鼠皮质组织中GRP78、ATF4、CHOP、Caspase-3 m RNA表达明显提高(P<0.01,P<0.05),Bcl-2 m RNA表达降低(P<0.05);与模型组比较,阳性对照组和低、中、高剂量组神经功能损伤评分及大鼠皮质组织中GRP78、ATF4、CHOP、Caspase-3 m RNA表达明显下降(P<0.01,P<0.05),Bcl-2m RNA表达提高(P<0.05)。结论栝楼桂枝汤对MCAO模型大鼠具有较好的治疗作用,其作用机制可能与调控内质网应激相关因子的表达,降低内质网应激水平有关。
文摘Toll-like receptors （TLRs） are sentinels of the host defense system, which recognize a large number of microbial pathogens. The host defense system may be inefficient or inflammatory diseases may develop if microbial recognition by TLRs and subsequent TLR-triggered cytokine production are deregulated. Activating transcription factor 4 （ATF4）, a member of the ATF/CREB transcription factor family, is an important factor that participates in several pathophysiological processes. In this report, we found that ATF4 is also involved in the TLR-mediated innate immune response, which participates in TLR4 signal transduction and mediates the secretion of a variety of cytokines. We observed that ATF4 is activated and translocates to the nucleus following l ipopolysaccharide （LPS） stimulation via the TLR4-MyD88-dependent pathway. Additionally, a cytokine array assay showed that some key inflammatory cytokines, such as I L-6, I L-8 and RANTES, are positively regulated by ATF4. We also demonstrate that c-Jun directly binds to ATF4, thereby promoting the secretion of inflammatory cytokines. Taken together, these results indicate that ATF4 acts as a positive regulator in TLR4-triggered cytokine production.
基金supported by the National Natural Science Foundation of China,Nos.82260245(to YX),81660207(to YX),81960253(to YL),82160268(to YL),U1812403(to ZG)Science and Technology Projects of Guizhou Province,Nos.[2019]1440(to YX),[2020]1Z067(to WH)+1 种基金Cultivation Foundation of Guizhou Medical University,No.[20NSP069](to YX)Excellent Young Talents Plan of Guizhou Medical University,No.(2022)101(to WH)。
文摘Several studies have shown that activation of unfolded protein response and endoplasmic reticulum(ER)stress plays a crucial role in severe cerebral ischemia/reperfusion injury.Autophagy occurs within hours after cerebral ischemia,but the relationship between ER stress and autophagy remains unclear.In this study,we established experimental models using oxygen-glucose deprivation/reoxygenation in PC12 cells and primary neurons to simulate cerebral ischemia/reperfusion injury.We found that prolongation of oxygen-glucose deprivation activated the ER stress pathway protein kinase-like endoplasmic reticulum kinase(PERK)/eukaryotic translation initiation factor 2 subunit alpha(e IF2α)-activating transcription factor 4(ATF4)-C/EBP homologous protein(CHOP),increased neuronal apoptosis,and induced autophagy.Furthermore,inhibition of ER stress using inhibitors or by si RNA knockdown of the PERK gene significantly attenuated excessive autophagy and neuronal apoptosis,indicating an interaction between autophagy and ER stress and suggesting PERK as an essential target for regulating autophagy.Blocking autophagy with chloroquine exacerbated ER stress-induced apoptosis,indicating that normal levels of autophagy play a protective role in neuronal injury following cerebral ischemia/reperfusion injury.Findings from this study indicate that cerebral ischemia/reperfusion injury can trigger neuronal ER stress and promote autophagy,and suggest that PERK is a possible target for inhibiting excessive autophagy in cerebral ischemia/reperfusion injury.
