AIM: Macrophage apoptosis is a vital event in advanced atherosclerosis, and oxidized low-density lipoprotein (ox-LDL) is a major contributor to this process. Acid sphingomyelinase (ASM) and ceramide are also involved in the induction of apoptosis, particularly in macrophages. Our current study focuses on ASM and investigates its role in ox-LDL-induced macrophage apoptosis. METHODS: Human THP-1 and mouse peritoneal macrophages were cultured in vitro and treated with ox-LDL. ASM activity and ceramide levels were quantified using ultra performance liquid chromatography. Protein and mRNA levels were analyzed using Western blot analysis and quantitative real-time PCR, respectively. Cell apoptosis was determined using Hoechst staining and flow cytometry. RESULTS: Ox-LDL-induced macrophage apoptosis was triggered by profound endoplasmic reticulum (ER) stress, leading to an upregulation of ASM activity and ceramide levels at an early stage. ASM was inhibited by siRNA or desipramine (DES), and/or ceramide was degraded by recombinant acid ceramidase (AC). These events attenuated the effect of ox-LDL on ER stress. In contrast, recombinant ASM upregulated ceramide and ER stress. ASM siRNA, DES, recombinant AC, and ER stress inhibitor 4-phenylbutyric acid were blocked by elevated levels of C/EBP homologous protein (CHOP); ox-LDL induced elevated levels of CHOP. These events attenuated macrophage apoptosis. CONCLUSION: These results indicate that ASM/ceramide signaling pathway is involved in ox-LDL-induced macrophage apoptosis via ER stress pathway.
AIM: Macrophage apoptosis is a vital event in advanced atherosclerosis, and oxidized low-density lipoprotein (ox-LDL) is a major contributor to this process. Acid sphingomyelinase (ASM) and ceramide are also involved in the induction of apoptosis, particularly in macrophages. Our current study focuses on ASM and investigates its role in ox-LDL-induced macrophage apoptosis. METHODS:HumanTHP-1 and mouse peritoneal macrophages were cultured in vitro and treated with ox-LDL. ASM activity and ceramide levels were quantified using ultra performance liquid chromatography. Protein and mRNA levels were analyzed using Western blot analysis and quantitative real-time PCR, respectively. Cell apoptosis was determined using Hoechst staining and flow cytometry. RESULTS:Ox-LDL-induced macrophage apoptosis was triggered by profound endoplasmic reticulum (ER) stress, leading to an upregulation of ASM activity and ceramide levels at an early stage. ASM was inhibited by siRNA or desipramine (DES), and/or ceramide was degraded by recombinant acid ceramidase (AC). These events attenuated the effect of ox-LDL on ER stress. In contrast, recombinant ASM upregulated ceramide and ER stress. ASM siRNA, DES, recombinant AC, and ER stress inhibitor 4-phenylbutyric acid were blocked by elevated levels of C/EBP homologous protein (CHOP); ox-LDL induced elevated levels of CHOP. These events attenuated macrophage apoptosis. CONCLUSION: These results indicate that ASM/ceramide signaling pathway is involved in ox-LDL-induced macrophage apoptosis via ER stress pathway.
Authors: Umut Ozcan; Erkan Yilmaz; Lale Ozcan; Masato Furuhashi; Eric Vaillancourt; Ross O Smith; Cem Z Görgün; Gökhan S Hotamisligil Journal: Science Date: 2006-08-25 Impact factor: 47.728
Authors: Anna Fernandez; Núria Matias; Raquel Fucho; Vicente Ribas; Claudia Von Montfort; Natalia Nuño; Anna Baulies; Laura Martinez; Núria Tarrats; Montserrat Mari; Anna Colell; Albert Morales; Laurent Dubuquoy; Philippe Mathurin; Ramón Bataller; Joan Caballeria; Montserrat Elena; Jesus Balsinde; Neil Kaplowitz; Carmen Garcia-Ruiz; Jose C Fernandez-Checa Journal: J Hepatol Date: 2013-05-23 Impact factor: 25.083
Authors: Luca Scorrano; Scott A Oakes; Joseph T Opferman; Emily H Cheng; Mia D Sorcinelli; Tullio Pozzan; Stanley J Korsmeyer Journal: Science Date: 2003-03-06 Impact factor: 47.728