Cysteamine Prevents Vascular Leakage Through Inhibiting Transglutaminase in Diabetic Retina
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235 1 Y-J LEE and others Cysteamine prevention of 235:1 39–48 Research vascular leakage Cysteamine prevents vascular leakage through inhibiting transglutaminase in diabetic retina Yeon-Ju Lee1, Se-Hui Jung1, JongYun Hwang2, Sohee Jeon3, Eun-Taek Han4, Won Sun Park5, Seok-Ho Hong6, Young-Myeong Kim1 and Kwon-Soo Ha1 1Department of Molecular and Cellular Biochemistry, Kangwon National University School of Medicine, Chuncheon, Kangwon-do, Korea 2Department of Obstetrics and Gynecology, Kangwon National University School of Medicine, Chuncheon, Kangwon-do, Korea 3Department of Ophthalmology, Seoul St. Mary’s Hospital, Catholic University, Seoul, Korea 4Department of Medical Environmental Biology and Tropical Medicine, Kangwon National University School of Medicine, Chuncheon, Kangwon-do, Korea Correspondence 5Department of Physiology, Kangwon National University School of Medicine, Chuncheon, Kangwon-do, Korea should be addressed 6Department of Internal Medicine, Kangwon National University School of Medicine, Chuncheon, to K-S Ha Kangwon-do, Korea Email [email protected] Abstract Cysteamine (an aminothiol), which is derived from coenzyme A degradation and Key Words Endocrinology of metabolized into taurine, has beneficial effects against cystinosis and neurodegenerative f cysteamine diseases; however, its role in diabetic complications is unknown. Thus, we sought to f diabetic retinopathy determine the preventive effect of cysteamine against hyperglycemia-induced vascular f transglutaminase Journal leakage in the retinas of diabetic mice. Cysteamine and ethanolamine, the sulfhydryl f vascular endothelial group-free cysteamine analogue, inhibited vascular endothelial growth factor (VEGF)- growth factor induced stress fiber formation and vascular endothelial (VE)-cadherin disruption in f vascular leakage endothelial cells, which play a critical role in modulating endothelial permeability. Intravitreal injection of the amine compounds prevented hyperglycemia-induced vascular leakage in the retinas of streptozotocin-induced diabetic mice. We then investigated the potential roles of reactive oxygen species (ROS) and transglutaminase (TGase) in the cysteamine prevention of VEGF-induced vascular leakage. Cysteamine, but not ethanolamine, inhibited VEGF-induced ROS generation in endothelial cells and diabetic retinas. In contrast, VEGF-induced TGase activation was prevented by both cysteamine and ethanolamine. Our findings suggest that cysteamine protects against vascular leakage through inhibiting VEGF-induced TGase activation rather than ROS Journal of Endocrinology generation in diabetic retinas. (2017) 235, 39–48 Introduction Cysteamine (β-mercaptoethylamine), an aminothiol with depletes cystine through reacting with its disulfide bridge, a primary amine group and a sulfhydryl group, is derived changes the enzymatic activity of several proteins as a from coenzyme A degradation and metabolized into result of binding to their thiol groups and enhances brain- taurine (Pinto et al. 2005, Besouw et al. 2013). Cysteamine derived neurotrophic factor secretion (Besouw et al. 2013). http://joe.endocrinology-journals.org © 2017 Society for Endocrinology Published by Bioscientifica Ltd. DOI: 10.1530/JOE-17-0109 Printed in Great Britain Downloaded from Bioscientifica.com at 10/11/2021 12:11:13PM via free access 10.1530/JOE-17-0109 Research Y-J LEE and others Cysteamine prevention of 235:1 40 vascular leakage Due to cysteamine’s varied effects, it has been proposed that cysteamine prevents vascular leakage by inhibiting as a treatment for many diseases, including cystinosis hyperglycemia-induced TGase activation rather than ROS and neurodegenerative and neuropsychiatric disorders generation in the diabetic retinas. We found that the (Besouw et al. 2013). Cysteamine was initially utilized primary amine group of cysteamine was implicated in the to protect against X-rays and as a therapy for radiation prevention of VEGF-induced endothelial cell permeability sickness (Bacq et al. 1953). This compound was introduced and hyperglycemia-induced vascular leakage in the retinas as a potential treatment for cystinosis and is currently of streptozotocin-induced diabetic mice. The primary used to treat corneal cystine crystal accumulation in amine was also involved in hyperglycemia-induced TGase patients with cystinosis (Kaiser-Kupfer et al. 1987, Tsilou activation in diabetic retinas. However, the sulfhydryl et al. 2003). Cysteamine has been evaluated as a treatment group of cyateamine was required for inhibition of for neurodegenerative diseases, including Huntington’s ROS generation, but not essential for preventing TGase disease (Gibrat & Cicchetti 2011, Shannon & Fraint 2015) activation and vascular leakage. Our findings suggest and Parkinson’s disease (Gibrat & Cicchetti 2011, Cisbani that cysteamine prevents vascular leakage by inhibiting et al. 2015) and has been proposed to treat schizophrenia hyperglycemia-induced TGase activation in the retinas (Buckley et al. 2014), cystic fibrosis (De Stefano et al. of diabetic mice, and thus, has therapeutic potential for 2014) and nonalcoholic fatty liver disease (Dohil et al. preventing diabetic retinopathy and vascular leakage- 2011). However, its beneficial effects against diabetic associated diseases. complications, including diabetic retinopathy, remain unknown. Hyperglycemia and the resulting subsequent Materials and methods physiological changes develop into, among others, Cell culture microvascular and macrovascular diabetic complications (Bhatt et al. 2014). One of the major microvascular Human umbilical vein endothelial cells (HUVECs) were complications, diabetic retinopathy, is the leading isolated from the human umbilical cord vein according to the Declaration of Helsinki as previously described (Lim Endocrinology cause of blindness in adults (Wang et al. 2012, Gupta of et al. 2013, Bhatt et al. 2014), which progresses et al. 2014, Lee et al. 2016). Written informed consent from nonproliferative abnormalities, characterized was obtained from all umbilical cord donors. Cells from by vascular leakage, to severe proliferative diabetic several batches were grown at 37°C in a humidified 5% Journal retinopathy (Fong et al. 2004). In nonproliferative CO2 incubator in M199 culture media supplemented diabetic retinopathy, retinal blood vessels are damaged with 20% FBS, 3 ng/mL basic fibroblastic growth factor by pericyte loss, microaneurysm and vascular leakage (Millipore), 5 U/mL heparin (Sigma), 100 U/mL penicillin (Caldwell et al. 2003, Hammes 2005). Retinal vascular and 100 µg/mL streptomycin. Cells in passages three leakage in the early stages of diabetic retinopathy is to six were incubated for 6 h in low-serum medium predominantly caused by vascular endothelial growth supplemented with 1% FBS and antibiotics. This study was factor (VEGF)-mediated stress fiber formation and approved by the Institutional Review Board of Kangwon vascular endothelial (VE)-cadherin disruption (Spindler National University Hospital. et al. 2010, Lim et al. 2014). Recently, we demonstrated that reactive oxygen species (ROS)-mediated activation Measurement of intracellular ROS generation of transglutaminase (TGase) 2 plays a key role in VEGF-induced retinal vascular leakage in diabetic Intracellular ROS generation was determined using mice (Lee et al. 2016). Though various drugs against 2′,7′-dichlorodihydrofluorescein diacetate (H2DCFDA, VEGF, oxidative stress and inflammation have been Invitrogen, Molecular Probes) staining as previously evaluated against VEGF-induced molecular events in described (Bhatt et al. 2016). Cells were treated with the diabetic retina, long-lasting therapies with minimal amine compounds for 30 min and then incubated complications are required to treat diabetic retinopathy with 10 ng/mL VEGF (Millipore) and 10 µM H2DCFDA (Stewart 2016, Tolentino et al. 2016). in low-serum media (phenol red-free) for 10 min. Therefore, we aimed to determine the preventive Labeled cells were immediately analyzed by confocal effect of cysteamine on hyperglycemia-induced vascular microscopy (Fluoview-300; Olympus), and intracellular leakage in the retina of diabetic mice. We hypothesized ROS levels (fold) were determined by measuring http://joe.endocrinology-journals.org © 2017 Society for Endocrinology Published by Bioscientifica Ltd. DOI: 10.1530/JOE-17-0109 Printed in Great Britain Downloaded from Bioscientifica.com at 10/11/2021 12:11:13PM via free access Research Y-J LEE and others Cysteamine prevention of 235:1 41 vascular leakage single-cell fluorescence intensities from ten randomly Cells were acid washed for 30 min using PBS (pH 2.7) selected cells per experiment. containing 25 mM glycine and 3% BSA and then fixed and permeabilized as described previously. Cells were incubated with a FITC-conjugated goat anti-mouse Measurement of in situ TGase activity antibody (1:200, Sigma, Cat. No. F0257) for 2 h and with In situ TGase transamidating activity was determined 1 µg/mL DAPI in PBS for 5 min. VE-cadherin and nuclei by confocal microscopic assay as previously described were visualized using confocal microscopy (K1-Fluo, (Lee et al. 2016). Briefly, cells were incubated with 1 mM Nanoscope Systems, Taejon, Korea). 5-(biotinamido)pentylamine for 1 h at 37°C, fixed with 3.7% formaldehyde in PBS for 30 min and permeabilized Generation of diabetic mouse model with 0.2% Triton X-100 in PBS for 30 min. After incubation with blocking solution (2% BSA in 20 mM Tris (pH 7.6), Six-week-old male C57BL/6 mice were obtained