Human uroplakin Ib in ocular surface epithelium.
OBJECTIVE
To investigate the expression and localization of the human gene encoding uroplakin Ib in ocular surface epithelium.


METHODS
The full-length cDNA of human uroplakin Ib was isolated from a cDNA library of human corneal epithelium, and the expression of uroplakin Ib in various tissues was examined by reverse transcription-polymerase chain reaction (RT-PCR). In cornea and conjunctiva, the expressions of uroplakin Ia, II, and III were also examined by RT-PCR. Finally, the localization of uroplakin Ib in the ocular surface was analyzed by immunofluorescence confocal microscopy, by using an antiserum against a synthetic peptide.


RESULTS
Two mRNA isoforms, arising through two polyadenylation sites, were isolated. RT-PCR detected uroplakin Ib in cornea, conjunctiva, bladder, placenta, and kidney. Among other uroplakins, uroplakin II was also faintly detected in cornea and conjunctiva. Immunofluorescence confocal microscopy documented uroplakin Ib protein in the cell membranes of superficial and wing cells in the corneal epithelium. It was not found, however, in the most apical corneal epithelial cells. In limbus and conjunctiva, uroplakin Ib was also localized in the cell membranes of all epithelial layers, apart from the most apical cells.


CONCLUSIONS
Uroplakin Ib is highly expressed in ocular surface epithelia. As in bladder epithelium, uroplakin Ib may protect the ocular surface from bacterial infection.
Adachi
W
W
Department of Ophthalmology, Kyoto Prefectural University of Medicine, Japan. wadachi@ophth.kpu-m.ac.jp
Okubo
K
K
Kinoshita
S
S
D000595:Amino Acid Sequence; D001483:Base Sequence; D015153:Blotting, Western; D003228:Conjunctiva / Q000737:chemistry / Q000378:metabolism; D017931:DNA Primers / Q000737:chemistry; D019573:Epithelium, Corneal / Q000737:chemistry / Q000378:metabolism*; D019084:Fluorescent Antibody Technique, Indirect; D015870:Gene Expression; D006801:Humans; D008562:Membrane Glycoproteins / Q000032:analysis / Q000096:biosynthesis / Q000235:genetics*; D008565:Membrane Proteins / Q000096:biosynthesis / Q000235:genetics; D018613:Microscopy, Confocal; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000096:biosynthesis*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D020539:Sequence Analysis, Protein; D060170:Uroplakin II; D060171:Uroplakin III; D060169:Uroplakin Ib
D017931:DNA Primers; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D012333:RNA, Messenger; C086452:UPK1B protein, human; C554658:UPK2 protein, human; D060170:Uroplakin II; D060171:Uroplakin III; D060169:Uroplakin Ib