Molecular and Histopathological Changes Associated with Keratoconus

Table 1

List of proteins with expression change in cornea samples affected with keratoconus.

Protein name	Functions	Corneal layer	Method of detection	Expression change	Reference
Superoxide dismutase	Antioxidant enzyme that can metabolize superoxide radicle	Central portion of the cornea	ELISA	Decreased	[188]
Annexin A2	Involved in cellular growth regulation and in signal transduction pathways	Epithelium	2D-DIGE	Decreased	[155]
Annexin A8				Increased
Carbonic anhydrase I	Playing a role in the barrier function of corneal endothelium	Stroma	Nano-ESI-LC-MS (MS)^2	Decreased	[152]
Collagen I α1, Collagen I α2	Structural protein	Epithelium	Nano-ESI-LC-MS (MS)^2	Decreased	[152]
Cathepsin B	Member of corneal epithelial lysosomal proteases	Epithelium and stroma; tears	IM; MF10-LTQ-FT MS	Increased	[159, 162]
Vimentin	A type of intermediate filament	Stroma; epithelium	Nano-ESI-LC-MS (MS)^2	Increased	[152, 155]
Keratocan	Proteoglycan protein, unique for cornea	Stroma	IM, Nano-ESI-LC-MS (MS)^2	Increased	[154, 155]
Serotransferrin	Iron binding transport proteins	Stroma	Nano-ESI-LC-MS (MS)^2	Decreased	[155]
Transketolase	Enzyme in the nonoxidative branch of the pentose-phosphate pathway	Epithelium	Nano-ESI-LC-MS (MS)^2	Decreased	[155]
Phosphoglycerate kinase 1	ATP-generating glycolytic enzyme	Epithelium	Nano-ESI-LC-MS (MS)^2	Decreased	[155]
NADPH oxidase	Alarm system for cellular stress response	Epithelium	Nano-ESI-LC-MS (MS)^2	Decreased	[155]
NADPH menadione oxidoreductase 1	Reducing menadione into a stable hydroquinone that can be readily conjugated and excreted	Epithelium	Nano-ESI-LC-MS (MS)^2	Decreased	[155]
Heat shock B1	Involved in stress resistance and actin organization	Epithelium	2D-DIGE	Decreased	[155]
S100-A4	Binding to several components of the cytoskeleton	Epithelium	WB and IM; 2D-DIGE; Nano-ESI-LC-MS (MS)^2	Increased	[145, 152, 155]
Keratin 1	Structural protein	Epithelium	Nano-ESI-LC-MS (MS)^2	Increased	[155]
Keratin 6A	Structural protein	Epithelium	Nano-ESI-LC-MS (MS)^2	Increased	[152]
Keratin 16	Structural protein	Epithelium	Nano-ESI-LC-MS (MS)^2	Increased	[152]
Desmoglein 3	Cell adhesion molecule	Epithelium	WB and IM	Increased	[145]
Decorin	Proteoglycan core protein	Stroma	IM; Nano-ESI-LC-MS (MS)^2	Increased	[154, 155]
Collagen VI α1, Collagen VI α2, and Collagen VI α3	Structural protein	Epithelium	Nano-ESI-LC-MS (MS)^2	Decreased	[152]
Collagen VII α1	Structural protein	Epithelium	Nano-ESI-LC-MS (MS)^2	Decreased	[152]
Lactoferrin	Iron binding transport proteins	Tears; epithelium	2D-DIGE; Nano-ESI-LC-MS (MS)^2	Decreased	[152, 208, 209]
Lipocalin 1	Major lipid-binding protein in tears	Stroma	Nano-ESI-LC-MS (MS)^2	Decreased	[152]
Hepatocyte growth factor	Regulating cell growth and motility	Epithelium	IM	Increased	[186]

Nano-ESI-LC-MS (MS)²: Nano-Electrospray Ionization Liquid Chromatography Tandem Mass Spectrometry; 2D-DIGE: two-dimensional-difference gel electrophoresis coupled with mass spectrometric methods; IM: immunostaining; WB: Western blot; MF10-LTQ-FT MS: prefractionating and enriching the proteins followed by linear ion trap quadrupole Fourier transform mass spectrometer.