Composition and proteolytic processing of corneal deposits associated with mutations in the TGFBI gene

Exp Eye Res. 2012 Mar;96(1):163-70. doi: 10.1016/j.exer.2011.11.014. Epub 2011 Dec 3.


Different types of granular corneal dystrophy (GCD) and lattice corneal dystrophy (LCD) are associated with mutations in the transforming growth factor beta induced gene (TGFBI). These dystrophies are characterized by the formation of non-amyloid granular deposits (GCDs) and amyloid (LCD type 1 and its variants) in the cornea. Typical corneal non-amyloid deposits from GCD type 2 (R124H), amyloid from a variant of LCD type 1 (V624M) and disease-free tissue controls were procured by laser capture microdissection and analyzed by tandem mass spectrometry. Label-free quantitative comparisons of deposits and controls suggested that the non-amyloid sample (R124H) specifically accumulated transforming growth factor beta induced protein (TGFBIp/keratoepithelin/βig-h3), serum amyloid P-component, clusterin, type III collagen, keratin 3, and histone H3-like protein. The amyloid (V624M) similarly accumulated serum amyloid P-component and clusterin but also a C-terminal fragment of TGFBIp containing residues Y571-R588 derived from the fourth fasciclin-1 domain (FAS1-4), apolipoprotein E and apolipoprotein A-IV. Significantly, analyses of the amyloid sample also revealed the presence of the serine protease Htr (High-temperature requirement) A1 and a number of proteolytic cleavage sites in the FAS1-4 domain of TGFBIp. These cleavage sites were consistent with the ligand binding and proteolytic activity of HtrA1 suggesting that it plays a role in the proteolytic processing of the amyloidogenic FAS1-4 domain. Taken together, the data suggest that the amyloidogenic-prone region of the fourth FAS1 domain of TGFBIp encompasses the Y571-R588 peptide and that HtrA1 is involved in the proteolytic processing of TGFBIp-derived amyloid in vivo.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amyloidosis, Familial / genetics
  • Amyloidosis, Familial / metabolism*
  • Apolipoproteins / metabolism
  • Chromatography, Liquid
  • Clusterin / metabolism
  • Collagen Type III / metabolism
  • Corneal Dystrophies, Hereditary / genetics
  • Corneal Dystrophies, Hereditary / metabolism*
  • Corneal Stroma / metabolism*
  • Extracellular Matrix Proteins / genetics*
  • Humans
  • Keratin-3 / metabolism
  • Laser Capture Microdissection
  • Mutation*
  • Plaque, Amyloid / metabolism*
  • Proteolysis
  • Proteomics
  • Serum Amyloid P-Component / metabolism
  • Tandem Mass Spectrometry
  • Transforming Growth Factor beta / genetics*


  • Apolipoproteins
  • CLU protein, human
  • Clusterin
  • Collagen Type III
  • Extracellular Matrix Proteins
  • KRT3 protein, human
  • Keratin-3
  • Serum Amyloid P-Component
  • Transforming Growth Factor beta
  • betaIG-H3 protein

Supplementary concepts

  • Corneal dystrophy, gelatinous drop-like
  • Groenouw type I corneal dystrophy