title: Hyperglycemia induces apoptosis via CB1 activation through the decrease of FAAH 1 in retinal pigment epithelial cells.
abstract: Fatty acid amide hydrolase (FAAH), the enzyme responsible for the degradation of the main endocannabinoid, anandamide, and related fatty acid amides, has emerged as a regulator of endocannabinoid signaling. Retinal pigment epithelial (RPE) cells are believed to be important cells in the pathogenesis of diabetic retinopathy. However, the pathophysiology of FAAH in diabetic retinopathy has not been determined. Thus, we examined the effect of high glucose (HG) on the expression of FAAH and CB(1)R in the ARPE-19 human RPE cells. We found that HG downregulated the expression of FAAH 1 mRNA and protein in ARPE-19 cells. In contrast, it upregulated the expression of CB(1)R mRNA and protein. HG-induced internalization of CB(1)R in HEK 293 cells and ARPE-19 cells was blocked by overexpression of FAAH 1 and treatment with the CB(1)R blocker, AM 251. HG-induced generation of reactive oxygen species and lipid peroxide formation were blocked by the overexpression of FAAH 1. FAAH 1 overexpression also blocked HG-induced expression of CB(1)R in the cytosolic fraction. We also investigated whether the overexpression of FAAH 1 protected against HG-induced apoptosis. High glucose increased the Bax/Bcl-2 ratio and levels of cleaved PARP, cleaved caspase-9 and caspase-3, and reduced cell viability. HG-induced apoptotic effects were reduced by the overexpression of FAAH 1, treatment with the CB(1)R-specific antagonist AM 251 and CB(1)R siRNA transfection. In conclusion, HG-induced apoptosis in ARPE-19 cells by inducing CB(1)R expression through the downregulation of FAAH 1 expression. Our results provide evidence that CB(1)R blockade through the recovery of FAAH 1 expression may be a potential anti-diabetic therapy for the treatment of diabetic retinopathy.
authors: Bio-Therapy Human Resources Center, College of Veterinary Medicine, Chonnam National University, Gwangju, Korea.
authors: Seul Ki
authors: SK
authors: Lim
authors: Min Jung
authors: MJ
authors: Park
authors: Jae Cheong
authors: JC
authors: Lim
authors: Jong Choon
authors: JC
authors: Kim
authors: Ho Jae
authors: HJ
authors: Han
authors: Gye-Yeop
authors: GY
authors: Kim
authors: Benjamin F
authors: BF
authors: Cravatt
authors: Chang Hoon
authors: CH
authors: Woo
authors: Seung Jin
authors: SJ
authors: Ma
authors: Kyung Cheol
authors: KC
authors: Yoon
authors: Soo Hyun
authors: SH
authors: Park
mesh_terms: D000581:Amidohydrolases / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology; D005947:Glucose / Q000633:toxicity*; D006801:Humans; D006943:Hyperglycemia / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species; D043884:Receptor, Cannabinoid, CB1 / Q000235:genetics / Q000378:metabolism*; D055213:Retinal Pigment Epithelium / Q000166:cytology*; D000099252:Fatty Acid Amide Hydrolases
chemical_list: D000581:Amidohydrolases; D005947:Glucose; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D043884:Receptor, Cannabinoid, CB1; D000099252:Fatty Acid Amide Hydrolases