Serum albumin in mammalian cornea: implications for clinical application.
OBJECTIVE
To compare the abundance and spatial distribution of serum albumin in the mouse and bovine cornea.


METHODS
Serum albumin from cornea was separated from transketolase by SDS-PAGE (+/-dithiothreitol [DTT]) and identified by peptide sequencing and immunoblot analyses. The fractional content of serum albumin was determined in water-soluble extracts of cornea by imaging analyses after SDS-PAGE. Serum albumin was localized in cornea by immunohistochemistry and by SDS-PAGE analyses of samples from separated epithelium and stroma.


RESULTS
SDS-PAGE (-DTT) resolved mouse serum albumin and transketolase and indicated that serum albumin was 13% of the water-soluble protein in whole mouse corneas. By contrast, corneal epithelial fractions contained little (<1%) serum albumin. Immunohistochemistry indicated that mouse serum albumin was present throughout the stroma between collagen lamellae. Immunohistochemical analyses of bovine cornea yielded similar results. In addition, immunohistochemistry for serum albumin revealed positive staining in a small number of basal epithelial cells next to Bowman's membrane, and greater staining in the anterior-peripheral stroma as well as immediately adjacent to Descemet's membrane.


CONCLUSIONS
Mouse and bovine cornea have a similar content and spatial distribution of serum albumin. The appreciable serum albumin in the cornea documented here and elsewhere raise the possibility that it contributes to the physiological or optical functions of the cornea. Moreover, serum albumin's ability to bind drugs suggests that mice corneas could be exploited to study drug-serum albumin interactions in vivo and to test the usefulness of serum albumin as a drug carrier for corneal disorders.
Nees
David W
DW
Laboratory of Molecular and Developmental Biology, National Eye Institute, Bethesda, Maryland, USA.
Fariss
Robert N
RN
Piatigorsky
Joram
J
D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D003315:Cornea / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D005455:Fluorescent Antibody Technique; D015151:Immunoblotting; D051379:Mice; D018613:Microscopy, Confocal; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid; D012709:Serum Albumin / Q000737:chemistry / Q000378:metabolism*; D012710:Serum Albumin, Bovine / Q000737:chemistry / Q000378:metabolism; D014174:Transketolase / Q000378:metabolism
D012709:Serum Albumin; D012710:Serum Albumin, Bovine; D014174:Transketolase