title: Effects of phlorizin on diabetic retinopathy according to isobaric tags for relative and absolute quantification-based proteomics in db/db mice.
abstract: OBJECTIVE
  Diabetic retinopathy (DR) is a leading cause of vision loss in working-age people. To retard the development and progression of retina lesions, effective therapeutic strategies directed toward key molecular targets are desired. Phlorizin is effective in treating diabetic complications, but little is known about functional protein changes that may mediate its actions. The aim of this study was to identify retinal proteomic alterations in db/db mice treated with phlorizin.
  
  
  METHODS
  We used C57BLKS/J db/db mice as a type 2 diabetic animal model, while C57BLKS/J db/m mice were selected as the control. Phlorizin (20 mg/kg bodyweight /d) was administrated to db/db mice for ten weeks. Serum fasting blood glucose and advanced glycation end products were determined. Meanwhile, retina cell apoptosis was determined with terminal transferase dUTP nick end labeling. Isobaric tags for relative and absolute quantification and subsequent liquid chromatography-tandem mass spectrometry (LC-MS/MS) were used to identify and profile retinal proteins among control, untreated diabetic, and phlorizin-treated db/db mice. The expression of glial fibrillary acidic protein was measured in retinas using western blotting analysis.
  
  
  RESULTS
  Phlorizin treatment significantly reduced fasting blood glucose and levels of advanced glycation end products (p<0.05) and remarkably inhibited retina cell apoptosis and the expression of glial fibrillary acidic protein in the retinas of db/db mice. In addition, we identified 1,636 proteins from retina tissue in total, of which 348 proteins were differentially expressed in db/db mice compared with the controls. Only 60 proteins in the retinas of the db/db mice were found to be differentially changed following phlorizin treatment, including 33 proteins that were downregulated and 27 proteins that were upregulated. Most of these differentially changed proteins were involved in oxidative stress, apoptosis, energy metabolism, and signaling transduction.
  
  
  CONCLUSIONS
  Our study revealed the expression of proteins differentially changed after phlorizin therapy. These proteins are most likely to participate in the development and recovery of DR. Our findings help expand understanding of the mechanism underlying the onset and progression of DR, and provide novel targets for evaluating the effects of phlorizin therapy.
authors.affiliation: Key Laboratory of Cardiovascular Proteomics of Shandong Province, Department of Geriatrics, Qi-Lu Hospital of Shandong University, Jinan, Shandong Province, China.
authors.forename: Shi-yang
authors.initials: SY
authors.lastname: Zhang
authors.forename: Bao-ying
authors.initials: BY
authors.lastname: Li
authors.forename: Xiao-li
authors.initials: XL
authors.lastname: Li
authors.forename: Mei
authors.initials: M
authors.lastname: Cheng
authors.forename: Qian
authors.initials: Q
authors.lastname: Cai
authors.forename: Fei
authors.initials: F
authors.lastname: Yu
authors.forename: Wei-dong
authors.initials: WD
authors.lastname: Wang
authors.forename: Min
authors.initials: M
authors.lastname: Tan
authors.forename: Guang
authors.initials: G
authors.lastname: Yan
authors.forename: Shi-lian
authors.initials: SL
authors.lastname: Hu
authors.forename: Hai-qing
authors.initials: HQ
authors.lastname: Gao
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001786:Blood Glucose / Q000187:drug effects / Q000378:metabolism; D015153:Blotting, Western; D001835:Body Weight / Q000187:drug effects; D019295:Computational Biology; D003921:Diabetes Mellitus, Experimental / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D003930:Diabetic Retinopathy / Q000188:drug therapy* / Q000378:metabolism* / Q000473:pathology; D005136:Eye Proteins / Q000378:metabolism; D005215:Fasting / Q000097:blood; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D017127:Glycation End Products, Advanced / Q000378:metabolism; D020287:In Situ Nick-End Labeling; D007553:Isotope Labeling / Q000379:methods*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009457:Neuroglia / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D010695:Phlorhizin / Q000494:pharmacology / Q000627:therapeutic use*; D040901:Proteomics / Q000379:methods*; D012162:Retinal Degeneration / Q000097:blood / Q000473:pathology; D013347:Subcellular Fractions / Q000187:drug effects / Q000378:metabolism
chemical_list: D001786:Blood Glucose; D005136:Eye Proteins; D005904:Glial Fibrillary Acidic Protein; D017127:Glycation End Products, Advanced; D010695:Phlorhizin