Critical role of TXNIP in oxidative stress, DNA damage and retinal pericyte apoptosis under high glucose: implications for diabetic retinopathy.
Diabetic retinopathy (DR) is characterized by early loss of retinal capillary pericytes and microvascular dysfunction. We recently showed that pro-oxidative stress and pro-apoptotic thioredoxin interacting protein (TXNIP) is significantly up-regulated in rat retinas in experimental diabetes and mediates inflammation and apoptosis. Therefore, we hypothesize here that TXNIP up-regulation in pericyte plays a causative role in oxidative stress and apoptosis under sustained high glucose exposure in culture. We maintained a rat retinal capillary pericyte cell line (TR-rPCT1) for 5 days under low glucose (LG, 5.5mM) or high glucose (HG, 25 mM) with or without anti-oxidant N-acetylcysteine (5mM, NAC), Azaseine (2 μM, AzaS), an inhibitor of TXNIP, and TXNIP siRNA (siTXNIP3, 20 nM). The results show that HG increases TXNIP expression in TR-rPCT1, which correlates positively with ROS generation, protein S-nitrosylation, and pro-apoptotic caspase-3 activation. Furthermore, pericyte apoptosis is demonstrated by DNA fragmentation (alkaline comet assay) and a reduction in MTT survival assay. Treatment of TR-rPCT1 with NAC or an inhibition of TXNIP by AzaS or siTXNIP3 each reduces HG-induced ROS, caspase-3 activation and DNA damage demonstrating that TXNIP up-regulation under chronic hyperglycemia is critically involved in cellular oxidative stress, DNA damage and retinal pericyte apoptosis. Thus, TXNIP represents a novel gene and drug target to prevent pericyte loss and progression of DR.
Department of Anatomy and Cell Biology, Wayne State University School of Medicine, Detroit, MI, USA.
Takhellambam S
TS
Devi
Ken-Ichi
K
Hosoya
Tetsuya
T
Terasaki
Lalit P
LP
Singh
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002352:Carrier Proteins / Q000378:metabolism*; D018797:Cell Cycle Proteins; D002478:Cells, Cultured; D004249:DNA Damage / Q000502:physiology; D003930:Diabetic Retinopathy / Q000378:metabolism*; D005947:Glucose / Q000494:pharmacology*; D006943:Hyperglycemia / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects*; D020286:Pericytes / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D012160:Retina / Q000166:cytology / Q000378:metabolism*; D013879:Thioredoxins / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects
D002352:Carrier Proteins; D018797:Cell Cycle Proteins; C493796:TXNIP protein, rat; D013879:Thioredoxins; D005947:Glucose