Abstract
Purpose: :
To determine human Bruch’s membrane proteome changes specific to insulin-dependent diabetes mellitus (IDDM).
Methods: :
Human choroid-Bruch’s membrane explants were prepared from young (<55 years-old) and fresh (<24 hours) donor eyes with and without IDDM. Cells were removed with 0.02 N ammonium hydroxide treatment leaving only the extracellular matrices. An excimer laser was then used to trim the choroid leaving only pure human Bruch’s membrane. 6.5 mm circular explants of Bruch’s membrane were further processed for protein extraction and separation using 2-D gel electrophoresis. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and electrospray ionization-quadruple time-of-flight MS/MS (ESI-Q-TOF MS/MS) were used to identify the mapped proteins. Quantitative and qualitative comparison of spots common in >2/3 of the gels were compared between donors with and without IDDM to determine the diabetes-specific differences in the Bruch’s membrane proteome. Results were confirmed with Western blotting analysis.
Results: :
261 proteins were identified in normal young Bruch’s membrane. 132 of these proteins did not reveal any qualitative or quantitative change among normal donors. IDDM was characterized with quantitative alteration of 78 (59.1%) of the common proteins. Among these proteins 53 (40.2%) were over-expressed and 25 (18.9%) were downregulated.
Conclusions: :
IDDM induces specific changes in protein expression in human Bruch’s membrane. It is quite possible that these changes contribute to the cellular pathophysiologic abnormalities in diabetic retinopathy since neighboring cells depend on cell-matrix interactions for survival, proliferation and regulation of their function.
Keywords: Bruch's membrane • diabetes • proteomics