Function of MYO7A in the human RPE and the validity of shaker1 mice as a model for Usher syndrome 1B.
OBJECTIVE
To investigate the function of MYO7A in human RPE cells and to test the validity of using shaker1 RPE in preclinical studies on therapies for Usher syndrome 1B by comparing human and mouse cells.


METHODS
MYO7A was localized by immunofluorescence. Primary cultures of human and mouse RPE cells were used to measure melanosome motility and rod outer segment (ROS) phagocytosis and digestion. MYO7A was knocked down in the human RPE cells by RNAi to test for a mutant phenotype in melanosome motility.


RESULTS
The distribution of MYO7A in the RPE of human and mouse was found to be comparable, both in vivo and in primary cultures. Primary cultures of human RPE cells phagocytosed and digested ROSs with kinetics comparable to that of primary cultures of mouse RPE cells. Melanosome motility was also comparable, and, after RNAi knockdown, consisted of longer-range fast movements characteristic of melanosomes in shaker1 RPE.


CONCLUSIONS
The localization and function of MYO7A in human RPE cells is comparable to that in mouse RPE cells. Although shaker1 retinas do not undergo degeneration, correction of mutant phenotypes in the shaker1 RPE represents a valid preclinical test for potential therapeutic treatments.
Gibbs
Daniel
D
Department of Pharmacology, University of California at San Diego School of Medicine, La Jolla, California, USA.
Diemer
Tanja
T
Khanobdee
Kornnika
K
Hu
Jane
J
Bok
Dean
D
Williams
David S
DS
D000369:Aged, 80 and over; D000818:Animals; D015153:Blotting, Western; D002478:Cells, Cultured; D004195:Disease Models, Animal; D019084:Fluorescent Antibody Technique, Indirect; D020868:Gene Silencing; D006801:Humans; D008297:Male; D020460:Melanosomes / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D018613:Microscopy, Confocal; D000081412:Myosin VIIa; D009218:Myosins / Q000502:physiology*; D010587:Phagocytosis / Q000502:physiology; D034622:RNA Interference; D055213:Retinal Pigment Epithelium / Q000378:metabolism*; D012374:Rod Cell Outer Segment / Q000502:physiology; D014162:Transfection; D052245:Usher Syndromes / Q000378:metabolism*
C000631455:MYO7A protein, human; C000631456:Myo7a protein, mouse; D000081412:Myosin VIIa; D009218:Myosins