Activating transcription factor 6-C/EBP homologous protein pathway mediates advanced glycated albumin-induced macrophage apoptosis.
- Author:
Pan-Pan KANG
1
;
Shu-Tong YAO
2
;
Tian-Tian GUO
3
;
Zhi-Chao WANG
2
;
Hua TIAN
2
;
Peng JIAO
2
;
Jian ZHOU
4
;
Shu-Cun QIN
5
Author Information
1. Affiliated Hospital of Chengde Medical University, Chengde 067000, China.
2. Institute of Atherosclerosis, Key Laboratory of Atherosclerosis in Universities of Shandong, Taishan Medical University, Taian 271000, China.
3. School of Dentistry and Oral Health, Taishan Medical University, Taian 271000, China.
4. Affiliated Hospital of Chengde Medical University, Chengde 067000, China. zhoujian0716@sina.com.
5. Institute of Atherosclerosis, Key Laboratory of Atherosclerosis in Universities of Shandong, Taishan Medical University, Taian 271000, China. shucunqin@hotmail.com.
- Publication Type:Journal Article
- From:
Acta Physiologica Sinica
2017;69(6):767-774
- CountryChina
- Language:Chinese
-
Abstract:
The purpose of this study was to investigate whether activating transcription factor 6 (ATF6), a sensor to endoplasmic reticulum stress (ERS), would mediate advanced glycated albumin (AGE-alb)-induced macrophage apoptosis and to elucidate the possible molecular mechanisms. RAW264.7 macrophages were cultured in vitro and treated with AGE-alb (2, 4 and 6 g/L), normal control albumin or tunicamycin (TM, 4 mg/L) for 24 h. ATF6 small interfering RNA (siRNA) was transfected to RAW264.7 cells by Lipofectamine 2000. Cell viability and apoptosis were determined by MTT method and Annexin V-FITC/propidium iodide apoptosis detection kit, respectively. The activities of lactate dehydrogenase (LDH) in medium and caspase-3 in cells were measured by corresponding detection kits. ATF6 nuclear translocation was detected by Western blot and immunofluorescence cytochemistry. Protein and mRNA levels of C/EBP homologous protein (CHOP, a key-signaling component of ERS-induced apoptosis) were detected by Western blot and real-time fluorescence quantitative PCR, respectively. The results showed that similar to TM, AGE-alb increased the expression of CHOP at both the protein and mRNA levels in a concentration dependent manner. ATF6, as a factor that positively regulates CHOP expression, was activated by AGE-alb in a concentration dependent manner. siRNA-mediated knockdown of ATF6 significantly inhibited AGE-alb-induced macrophage injury, as indicated by the increased cell viability and the decreased LDH release, apoptosis and caspase-3 activation. Additionally, ATF6 siRNA attenuated AGE-alb-induced CHOP upregulation at both the protein and mRNA levels. These results suggest that ATF6 and its downstream molecule CHOP are involved in AGE-alb-induced macrophage apoptosis.
