Abstract
Purpose :
Mutations at the Mitf gene can cause retinal and RPE dysfunction and degeneration. The four mutations investigated here, are either spontaneous point mutations, a transgene insertion mutation or a missense mutation induced by the chemical ENU, with varying effects on the eyes of the mice. The purpose of this work was to study the visible changes in the fundus of mice with various mutations in the Mitf gene.
Methods :
The following Mitf mutations were used: Mitfmi-vga9/+, Mitfmi-enu122 (398), Mitfmi-wh/+, Mitfmi-wh/mi and wild type (C5BL/6J) mice as a control. The Micron IV rodent imaging system (Phoenix Research Labs) was used to obtain fundus photographs from mice of 3 months of age. Both bright-field and fluorescence images were acquired. Fluorescein sodium salt 98.5-100.5% (100mg/mL) diluted with distilled water (final concentration 50mg/mL) was administered by an intraperitoneal injection (150 μL).
Results :
Bright-field images showed yellow spots with non-pigmented areas in one mutant (vga9, fig. 1B). These yellow spots are not seen in wild type mice (Fig. 1A). The other mutants showed abnormal non-pigmented areas (Fig. 1C-E). Fluorescein angiography showed apparently normal vasculature in the Mitfmi-vga9/+ and Mitfmi-enu122 eyes (Fig. 2B and C respectively) compared to wild type (Fig. 2A). However, the fluorescence image from the Mitfmi-enu122 (398) (Fig. 2B) mice showed large blurred areas, probably related to the non-pigmented areas in the bright field image (Fig. 1C).
Conclusions :
The MITF protein plays a fundamental role in regulating the fundus pigmentation in mice. Further studies are needed on the retinal vasculature with fluorescein angiograms to determine the effects of Mitf mutations on these structures.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.