title: Survival or death: a dual role for autophagy in stress-induced pericyte loss in diabetic retinopathy.
abstract: Intra-retinal extravasation and modification of LDL have been implicated in diabetic retinopathy: autophagy may mediate these effects.
  
  
  
  Immunohistochemistry was used to detect autophagy marker LC3B in human and murine diabetic and non-diabetic retinas. Cultured human retinal capillary pericytes (HRCPs) were treated with in vitro-modified heavily-oxidised glycated LDL (HOG-LDL) vs native LDL (N-LDL) with or without autophagy modulators: green fluorescent protein-LC3 transfection; small interfering RNAs against Beclin-1, c-Jun NH(2)-terminal kinase (JNK) and C/EBP-homologous protein (CHOP); autophagy inhibitor 3-MA (5 mmol/l) and/or caspase inhibitor Z-VAD-fmk (100 μmol/l). Autophagy, cell viability, oxidative stress, endoplasmic reticulum stress, JNK activation, apoptosis and CHOP expression were assessed by western blots, CCK-8 assay and TUNEL assay. Finally, HOG-LDL vs N-LDL were injected intravitreally to STZ-induced diabetic vs control rats (yielding 50 and 200 mg protein/l intravitreal concentration) and, after 7 days, retinas were analysed for ER stress, autophagy and apoptosis.
  
  
  
  Intra-retinal autophagy (LC3B staining) was increased in diabetic vs non-diabetic humans and mice. In HRCPs, 50 mg/l HOG-LDL elicited autophagy without altering cell viability, and inhibition of autophagy decreased survival. At 100-200 mg/l, HOG-LDL caused significant cell death, and inhibition of either autophagy or apoptosis improved survival. Further, 25-200 mg/l HOG-LDL dose-dependently induced oxidative and ER stress. JNK activation was implicated in autophagy but not in apoptosis. In diabetic rat retina, 50 mg/l intravitreal HOG-LDL elicited autophagy and ER stress but not apoptosis; 200 mg/l elicited greater ER stress and apoptosis.
  
  
  
  Autophagy has a dual role in diabetic retinopathy: under mild stress (50 mg/l HOG-LDL) it is protective; under more severe stress (200 mg/l HOG-LDL) it promotes cell death.
authors.affiliation: Centre for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, 97 Lisburn Road, Belfast, BT9 7BL, UK.|Department of Immunology, Harbin Medical University, Harbin, People's Republic of China.
authors.forename: Dongxu
authors.initials: D
authors.lastname: Fu
authors.affiliation: Centre for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, 97 Lisburn Road, Belfast, BT9 7BL, UK.
authors.forename: Jeremy Y
authors.initials: JY
authors.lastname: Yu
authors.affiliation: Section of Endocrinology and Diabetes, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA.
authors.forename: Shihe
authors.initials: S
authors.lastname: Yang
authors.affiliation: Section of Endocrinology and Diabetes, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA.
authors.forename: Mingyuan
authors.initials: M
authors.lastname: Wu
authors.affiliation: Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, SC, USA.
authors.forename: Samar M
authors.initials: SM
authors.lastname: Hammad
authors.affiliation: Centre for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, 97 Lisburn Road, Belfast, BT9 7BL, UK.
authors.forename: Anna R
authors.initials: AR
authors.lastname: Connell
authors.affiliation: Section of Endocrinology and Diabetes, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA.
authors.forename: Mei
authors.initials: M
authors.lastname: Du
authors.affiliation: Section of Endocrinology and Diabetes, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA.
authors.forename: Junping
authors.initials: J
authors.lastname: Chen
authors.affiliation: Centre for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, 97 Lisburn Road, Belfast, BT9 7BL, UK. t.lyons@qub.ac.uk.
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Lyons
mesh_terms: D000225:Adenine / Q000031:analogs & derivatives / Q000494:pharmacology; D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D001343:Autophagy / Q000187:drug effects / Q000502:physiology*; D000071186:Beclin-1 / Q000235:genetics / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects / Q000235:genetics; D003930:Diabetic Retinopathy / Q000378:metabolism* / Q000473:pathology*; D059865:Endoplasmic Reticulum Stress / Q000187:drug effects / Q000235:genetics; D017127:Glycation End Products, Advanced; D006801:Humans; D007150:Immunohistochemistry; D008077:Lipoproteins, LDL / Q000494:pharmacology; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000235:genetics; D051379:Mice; D010084:Oxidation-Reduction / Q000187:drug effects; D018384:Oxidative Stress / Q000187:drug effects / Q000235:genetics; D020286:Pericytes / Q000378:metabolism* / Q000473:pathology*; D012160:Retina / Q000378:metabolism / Q000473:pathology; D051742:Transcription Factor CHOP / Q000378:metabolism; D000093844:Glycated Proteins
chemical_list: D000225:Adenine; D000590:Amino Acid Chloromethyl Ketones; D000071186:Beclin-1; D017127:Glycation End Products, Advanced; D008077:Lipoproteins, LDL; D051742:Transcription Factor CHOP; C497250:Ddit3 protein, mouse; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; C031797:glycated lipoproteins, LDL; D000093844:Glycated Proteins; C025946:3-methyladenine
keywords: Apoptosis; Autophagy; Diabetic retinopathy; ER stress; LC3B; Modified LDL; Oxidative stress; Pericytes