5-Aminolevulinic acid with sodium ferrous citrate induces autophagy and protects cardiomyocytes from hypoxia-induced cellular injury through MAPK-Nrf-2-HO-1 signaling cascade.
BACKGROUND
Hypoxia causes cardiac disease via oxidative stress and mitochondrial dysfunction. 5-Aminolevulinic acid in combination with sodium ferrous citrate (ALA/SFC) has been shown to up-regulate heme oxygenase-1 (HO-1) and decrease macrophage infiltration and renal cell apoptosis in renal ischemia injury mice. However, its underlying mechanism remains largely unknown. The aim of this study was to investigate whether ALA/SFC could protect cardiomyocytes from hypoxia-induced apoptosis by autophagy via HO-1 signaling.


METHODS
Murine atrial cardiomyocyte HL-1 cells were pretreated with ALA/SFC and then exposed to hypoxia.


RESULTS
ALA/SFC pretreatment significantly attenuated hypoxia-induced cardiomyocyte apoptosis, reactive oxygen species production, and mitochondrial injury, while it increased cell viability and autophagy levels. HO-1 expression by ALA/SFC was associated with up-regulation and nuclear translocation of Nrf-2, whereas Nrf-2 siRNA dramatically reduced HO-1 expression. ERK1/2, p38, and SAPK/JNK pathways were activated by ALA/SFC and their specific inhibitors significantly reduced ALA/SFC-mediated HO-1 upregulation. Silencing of either Nrf-2 or HO-1and LY294002, inhibitor of autophagy, abolished the protective ability of ALA/AFC against hypoxia-induced injury and reduced ALA/SFC-induced autophagy.


CONCLUSIONS
Taken together, our data suggest that ALA/SFC induces autophagy via activation of MAPK/Nrf-2/HO-1 signaling pathway to protect cardiomyocytes from hypoxia-induced apoptosis.
Division of Transplantation Immunology, National Research Institute for Child Health and Development, Tokyo, Japan; Guangdong Cardiovascular Institute, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, China; Department of Pediatrics, The Third Xiangya Hospital, Central South University, Changsha, China.
Mingyi
M
Zhao
Division of Transplantation Immunology, National Research Institute for Child Health and Development, Tokyo, Japan; Guangdong Cardiovascular Institute, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, China.
Ping
P
Zhu
Division of Transplantation Immunology, National Research Institute for Child Health and Development, Tokyo, Japan; AIDS Research Center, National Institute of Infectious Diseases, Tokyo, Japan.
Masayuki
M
Fujino
Division of Transplantation Immunology, National Research Institute for Child Health and Development, Tokyo, Japan.
Yoshiaki
Y
Nishio
Guangdong Cardiovascular Institute, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, China.
Jimei
J
Chen
SBI Pharmaceuticals Co., Ltd., Tokyo, Japan.
Hidenori
H
Ito
SBI Pharmaceuticals Co., Ltd., Tokyo, Japan.
Kiwamu
K
Takahashi
SBI Pharmaceuticals Co., Ltd., Tokyo, Japan.
Motowo
M
Nakajima
SBI Pharmaceuticals Co., Ltd., Tokyo, Japan.
Tohru
T
Tanaka
Department of Pediatrics, The Third Xiangya Hospital, Central South University, Changsha, China.
Lingling
L
Zhao
Guangdong Cardiovascular Institute, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, China. Electronic address: zhuangjianzggd@aliyun.com.
Jian
J
Zhuang
Division of Transplantation Immunology, National Research Institute for Child Health and Development, Tokyo, Japan. Electronic address: ri-k@ncchd.go.jp.
Xiao-Kang
XK
Li
D000622:Aminolevulinic Acid / Q000494:pharmacology*; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001343:Autophagy / Q000187:drug effects*; D015687:Cell Hypoxia / Q000187:drug effects*; D002867:Chromones / Q000494:pharmacology; D019343:Citric Acid; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005296:Ferrous Compounds / Q000494:pharmacology*; D051547:Heme Oxygenase-1 / Q000378:metabolism; D007511:Ischemia / Q000517:prevention & control; D007668:Kidney / Q000098:blood supply; D020935:MAP Kinase Signaling System / Q000187:drug effects; D008264:Macrophages / Q000187:drug effects; D051379:Mice; D020928:Mitogen-Activated Protein Kinases; D009025:Morpholines / Q000494:pharmacology; D032383:Myocytes, Cardiac / Q000187:drug effects* / Q000201:enzymology; D018384:Oxidative Stress / Q000187:drug effects; D020011:Protective Agents / Q000494:pharmacology; D034741:RNA, Small Interfering / Q000235:genetics; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D015854:Up-Regulation
D002867:Chromones; D004791:Enzyme Inhibitors; D005296:Ferrous Compounds; D009025:Morpholines; D020011:Protective Agents; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; D019343:Citric Acid; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C016600:ferrous citrate; D000622:Aminolevulinic Acid; D051547:Heme Oxygenase-1; D020928:Mitogen-Activated Protein Kinases
ALA; Apoptosis; Autophagy; Cardioprotection; HO-1; Hypoxia; MAPK; Nrf-2