Bestrophin-2 is involved in the generation of intraocular pressure.
OBJECTIVE
The bestrophin family of proteins has been demonstrated to generate or regulate Ca2+-activated Cl(-) conductances. Mutations in bestrophin-1 (Best1) cause several blinding eye diseases, but little is known about other bestrophin family members. This study involved disruption of the Best2 gene in mice.


METHODS
The mouse Best2 gene was disrupted by replacing exons 1, 2, and part of exon 3 with a Lac Z. The expression profile of Bestrophin-2 (Best2) was examined using RT-PCR, X-gal staining, and immunohistochemistry. Intraocular pressure (IOP) was measured by anterior chamber cannulation.


RESULTS
RT-PCR of mouse tissues revealed Best2 mRNA in eye, colon, nasal epithelia, trachea, brain, lung, and kidney. X-gal staining, confirmed expression in colon epithelia and in the eye, in the nonpigmented epithelia (NPE). Best2 was not expressed in RPE cells. Best2 protein was observed only in NPE and colon epithelia. The absence of Best2 had no obvious deleterious effect on the mice. However, the Best2-/- mice were found to have significantly (P < 0.02) diminished IOP with respect to the Best2+/+ and Best2+/- littermates. The Best2-/- and Best2+/- mice responded better to the carbonic anhydrase inhibitor brinzolamide than did their Best2+/+ littermates, although the beta-blocker timolol brought IOP to the same level, regardless of genotype.


CONCLUSIONS
Best2 plays a role in the generation of IOP by regulating formation of aqueous humor, and inhibition of Best2 function represents an attractive new avenue for regulating IOP in individuals with glaucoma.
Bakall
Benjamin
B
Department of Ophthalmology and Vision Science, University of Arizona, Tucson, Arizona.
McLaughlin
Precious
P
Stanton
J Brett
JB
Zhang
Youwen
Y
Hartzell
H Criss
HC
Marmorstein
Lihua Y
LY
Marmorstein
Alan D
AD
D000818:Animals; D001082:Aqueous Humor / Q000378:metabolism; D000075002:Bestrophins; D015153:Blotting, Western; D018118:Chloride Channels / Q000502:physiology*; D002924:Ciliary Body / Q000166:cytology; D004847:Epithelial Cells / Q000378:metabolism; D015870:Gene Expression / Q000502:physiology; D020869:Gene Expression Profiling; D007124:Immunoenzyme Techniques; D007429:Intraocular Pressure / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014162:Transfection
C497463:Best2 protein, mouse; D000075002:Bestrophins; D018118:Chloride Channels; D012333:RNA, Messenger