Abstract
Purpose: :
To identify the cochlin interacting proteins in the glaucomatous trabecular meshwork (TM) and to demonstrate potential differences in the transcriptional regulation machinery for cochlin expression in the glaucomatous TM compared to controls.
Methods: :
Normal human and POAG donor eyes (n=20 for each group) were obtained from NDRI in accordance with the declaration of Helsinki. Dissected TM tissues were subjected to protein extraction, Western analysis and overlay assays. Electrophoretic mobility shift assays (EMSA) were performed using biotin labeled oligonucleotides (bearing transcription factor binding sites in the cochlin promoter region identified by bioinformatics) and TM nuclear extracts (glaucomatous and control).
Results: :
Annexin A2 was identified as cochlin interacting protein in the glaucomatous TM by mass spectrometry and confirmed by reciprocal immunoprecipitation. Expression of cochlin in HEK cells, but not annexin, led to secretion of annexin. Glaucomatous TM in contrast to normal TM showed elevated levels of transcription factors including Brn-3 by EMSA and Western analysis.
Conclusions: :
Annexin A2 interacts with cochlin in glaucomatous TM. Protein expression studies (in mammalian cells) and elevated levels of select transcription factors in glaucomatous TM compared to control further supports transcriptional control of cochlin-interacting proteins in the glaucomatous TM.
Keywords: trabecular meshwork • extracellular matrix • transcription factors