PURPOSE: The VMD2 gene, mutated in Best macular dystrophy (BMD) encodes bestrophin, a 68-kDa basolateral plasma membrane protein expressed in retinal pigment epithelial (RPE) cells. BMD is characterized by a depressed light peak (LP) in the electro-oculogram. Bestrophin is thought to be the Cl channel that generates the LP. The goal was to generate an animal model of BMD and to determine the effects of bestrophin overexpression on the RPE-generated components of the ERG. METHODS: Bestrophin or bestrophin mutants (W93C or R218C) were overexpressed in the RPE of rats by injection of replication-defective adenovirus. Immunofluorescence microscopy and ERG recordings were used to study subsequent effects. RESULTS: Bestrophin was confined to the basolateral plasma membrane of the RPE. Neither wild-type (wt) nor mutant bestrophin affected the a- or b-waves of the ERG. Wt bestrophin, however, increased the c-wave and fast oscillation (FO), but not the LP. In contrast, both mutants had little or no effect on the c-wave and FO, but did reduce LP amplitude. LP amplitudes across a range of stimuli were not altered by wt bestrophin, though the luminance response function was desensitized. LP response functions were unaffected by bestrophin R218C but were significantly altered by bestrophin W93C. CONCLUSIONS: A model of BMD was developed in the present study. Because overexpression of wt bestrophin shifted luminance response but did not alter the range of LP response amplitudes, the authors conclude that the rate-limiting step for generating LP amplitude occurs before activation of bestrophin or that bestrophin does not directly generate the LP conductance.
PURPOSE: The VMD2 gene, mutated in Best macular dystrophy (BMD) encodes bestrophin, a 68-kDa basolateral plasma membrane protein expressed in retinal pigment epithelial (RPE) cells. BMD is characterized by a depressed light peak (LP) in the electro-oculogram. Bestrophin is thought to be the Cl channel that generates the LP. The goal was to generate an animal model of BMD and to determine the effects of bestrophin overexpression on the RPE-generated components of the ERG. METHODS: Bestrophin or bestrophin mutants (W93C or R218C) were overexpressed in the RPE of rats by injection of replication-defective adenovirus. Immunofluorescence microscopy and ERG recordings were used to study subsequent effects. RESULTS: Bestrophin was confined to the basolateral plasma membrane of the RPE. Neither wild-type (wt) nor mutant bestrophin affected the a- or b-waves of the ERG. Wt bestrophin, however, increased the c-wave and fast oscillation (FO), but not the LP. In contrast, both mutants had little or no effect on the c-wave and FO, but did reduce LP amplitude. LP amplitudes across a range of stimuli were not altered by wt bestrophin, though the luminance response function was desensitized. LP response functions were unaffected by bestrophin R218C but were significantly altered by bestrophin W93C. CONCLUSIONS: A model of BMD was developed in the present study. Because overexpression of wt bestrophin shifted luminance response but did not alter the range of LP response amplitudes, the authors conclude that the rate-limiting step for generating LP amplitude occurs before activation of bestrophin or that bestrophin does not directly generate the LP conductance.
Authors: B Bakall; T Marknell; S Ingvast; M J Koisti; O Sandgren; W Li; A A Bergen; S Andreasson; T Rosenberg; K Petrukhin; C Wadelius Journal: Hum Genet Date: 1999-05 Impact factor: 4.132
Authors: A D Marmorstein; L Y Marmorstein; M Rayborn; X Wang; J G Hollyfield; K Petrukhin Journal: Proc Natl Acad Sci U S A Date: 2000-11-07 Impact factor: 11.205
Authors: K Petrukhin; M J Koisti; B Bakall; W Li; G Xie; T Marknell; O Sandgren; K Forsman; G Holmgren; S Andreasson; M Vujic; A A Bergen; V McGarty-Dugan; D Figueroa; C P Austin; M L Metzker; C T Caskey; C Wadelius Journal: Nat Genet Date: 1998-07 Impact factor: 38.330
Authors: G M Caldwell; L E Kakuk; I B Griesinger; S A Simpson; N J Nowak; K W Small; I H Maumenee; P J Rosenfeld; P A Sieving; T B Shows; R Ayyagari Journal: Genomics Date: 1999-05-15 Impact factor: 5.736
Authors: A D Marmorstein; Y C Gan; V L Bonilha; S C Finnemann; K G Csaky; E Rodriguez-Boulan Journal: J Cell Biol Date: 1998-08-10 Impact factor: 10.539
Authors: Adiv A Johnson; Karina E Guziewicz; C Justin Lee; Ravi C Kalathur; Jose S Pulido; Lihua Y Marmorstein; Alan D Marmorstein Journal: Prog Retin Eye Res Date: 2017-01-30 Impact factor: 21.198
Authors: Karina E Guziewicz; Barbara Zangerl; Sarah J Lindauer; Robert F Mullins; Lynne S Sandmeyer; Bruce H Grahn; Edwin M Stone; Gregory M Acland; Gustavo D Aguirre Journal: Invest Ophthalmol Vis Sci Date: 2007-05 Impact factor: 4.799