Protein composition of TGFBI-R124C and TGFBI-R555W associated aggregates suggests multiple mechanisms leading to Lattice and Granular corneal dystrophy

ABSTRACT: Transforming Growth Factor Beta-induced (TGFBI)-related dystrophies constitute the most common heritable forms of corneal dystrophy worldwide. However, other than the underlying genotypes of these conditions, a limited knowledge exists of the exact pathomechanisms of these disorders. This study expands on our previous research investigating dystrophic stromal aggregates, with the aim of better elucidating the pathomechanism of 2 conditions arising from the most common TGFBI mutations: granular corneal dystrophy (GCD1; R555W), and lattice corneal dystrophy (LCD1; R124C). GCD1 and LCD1 patient corneas were stained with H&E and Congo red to visualise stromal non-amyloid and amyloid deposits, respectively. Laser capture microdissection was used to isolate aggregates and extracted protein was analyzed by mass spectrometry. Proteins were identified and their approximate abundances were determined. Spectra of TGFBIp peptides were also recorded and quantified. In total, 3 proteins were found within GCD1 aggregates that were absent in the healthy control corneal tissue. In comparison an additional 18 and 24 proteins within stromal LCD1 and Bowmanâ??s LCD1 deposits, respectively, were identified. Variances surrounding the endogenous cleavage sites of TGFBIp were also noted. An increase in the number of residues experiencing cleavage was observed in both GCD1 aggregates and LCD1 deposits. The study reveals previously unknown differences 1 between the protein composition of GCD1 and LCD1 aggregates, and confirms the presence of the HtrA1 protease in LCD1-amyloid aggregates. In addition, we find mutation specific differences in the processingof mutant TGFBIp species, which may contribute to the variable phenotypes noted in TGFBI-related dystrophies.

INSTRUMENT(S): TripleTOF 5600

ORGANISM(S): Homo Sapiens (ncbitaxon:9606)

SUBMITTER: Dr Jan J. Enghild 

PROVIDER: MSV000079985 | MassIVE | Fri Jul 22 15:58:00 BST 2016

SECONDARY ACCESSION(S): PXD002236

REPOSITORIES: MassIVE