title: Proteomic analysis of human age-related nuclear cataracts and normal lens nuclei.
abstract: OBJECTIVE
  To identify proteomic differences between age-related nuclear cataracts (ARNCs) and normal lens nuclei.
  
  
  METHODS
  Total solubilized proteins from ARNC lens nuclei with different grades were compared with normal controls by 2-D differential in-gel electrophoresis (2-D DIGE). Proteins with different abundances were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and liquid chromatography tandem mass spectrometry (LC-MS/MS) analyses determined the compositions of high molecular weight (HMW; >200 kDa) aggregates found in ARNC lens nuclei. Western blot analysis was used to verify the changes in αA-crystallin and glyceraldehyde 3-phosphate dehydrogenase (GAPDH) levels.
  
  
  RESULTS
  The 2-D differential in-gel electrophoresis results showed that nine proteins were significantly less abundant in lens nuclei from ARNC patients than in control lens nuclei. Six proteins (αA-, βA3-, βA4-, βB1-, and γD-crystallin and putative uncharacterized protein DKFZp434A0627 from the CRYGS family) tended to decrease as the cataract grade increased, while the other three proteins (αB-crystallin, GAPDH, and retinal dehydrogenase 1) did not show such a tendency. SDS-PAGE showed decreased protein levels at ∼20 kDa in ARNC lenses but significantly increased levels at HMW (>200 kDa). Liquid chromatography tandem mass spectrometry analysis showed that the HMW aggregates derived largely from crystallins also contained filensin, phakinin, and carbonyl reductase 1. Of all the components, αA-crystallin accounted for the highest fraction. αA-, αB-, and γD-crystallin and DKFZp434A0627 were more prone to aggregate than other crystallins.
  
  
  CONCLUSIONS
  The results show that crystallins, especially αA-crystallin, aggregate irreversibly during ARNC development. Some enzymes (GAPDH, retinal dehydrogenase 1, and carbonyl reductase 1) may be involved in and/or accelerate this process.
authors: Eye Hospital, the First Affiliated Hospital, Harbin Medical University, Harbin, China.
authors: Sheng
authors: S
authors: Su
authors: Ping
authors: P
authors: Liu
authors: Hong
authors: H
authors: Zhang
authors: Zhijian
authors: Z
authors: Li
authors: Zhen
authors: Z
authors: Song
authors: Lu
authors: L
authors: Zhang
authors: Shuo
authors: S
authors: Chen
mesh_terms: D000375:Aging; D002386:Cataract / Q000378:metabolism*; D002853:Chromatography, Liquid; D003459:Crystallins / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D005136:Eye Proteins / Q000378:metabolism; D006801:Humans; D007907:Lens Nucleus, Crystalline / Q000378:metabolism*; D008875:Middle Aged; D040901:Proteomics; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D053719:Tandem Mass Spectrometry; D057825:Two-Dimensional Difference Gel Electrophoresis
chemical_list: D003459:Crystallins; D005136:Eye Proteins