Mutations in human bestrophin-1 (hBest1) are associated with Best vitelliform macular dystrophy (BVMD), adult-onset vitelliform macular dystrophy (AVMD), and autosomal dominant vitreoretinochoroidopathy (ADVIRC), but the precise function of hBest1 remains in doubt and the mechanisms linking hBest1 dysfunction with disease are unknown. There is strong evidence that hBest1 is an anion (Cl) channel. There is also evidence that hBest1 regulates voltage-gated Ca channels. This application will test the hypothesis that hBest1 is a multifunctional protein that is both a Cl channel, possibly with both plasma membrane and intracellular functions, and a regulator of other ion channels, including Ca channels. Mutations in hBest1 are hypothesized to produce retinal disease by disrupting ion transport in the retina at the level of the retinal pigment epithelium (RPE). We suggest that disruption of ion transport across the RPE results in abnormal fluid content and composition in the space between photoreceptors and RPE. This compromises the interaction between RPE and photoreceptors and favors accumulation of retinoid-derived pigments and development of vitelliform lesions. In this application, we will investigate the functions and pathophysiological mechanisms of hBest1 using a combination of molecular, genetic, and electrophysiological approaches with cultured cells transfected with hBest1 and hBest1 mutants, transgenic mice with disrupted or mutant hBest1 genes, and freshly-isolated and cultured retinal pigment epithelial cells. These studies will not only provide important insights into the mechanisms of vitelliform macular dystrophies, but will also shed light on the role of ion transport across the retinal pigment epithelium on normal retinal homeostasis.

Public Health Relevance

This research addresses the mechanisms of macular degeneration, one of the major causes of blindness. Specifically, we will investigate how dysfunction of a protein called bestrophin causes an inherited juvenile-onset form of macular degeneration. We expect that these studies will provide insights into the mechanisms of macular degeneration and the mechanisms that maintain normal retinal function.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
5R01EY014852-07
Application #
7780353
Study Section
Biology and Diseases of the Posterior Eye Study Section (BDPE)
Program Officer
Mariani, Andrew P
Project Start
2003-08-01
Project End
2012-02-29
Budget Start
2010-03-01
Budget End
2011-02-28
Support Year
7
Fiscal Year
2010
Total Cost
$383,625
Indirect Cost
Name
Emory University
Department
Anatomy/Cell Biology
Type
Schools of Medicine
DUNS #
066469933
City
Atlanta
State
GA
Country
United States
Zip Code
30322
Cruz-Rangel, Silvia; De Jesús-Pérez, José J; Aréchiga-Figueroa, Iván A et al. (2017) Extracellular protons enable activation of the calcium-dependent chloride channel TMEM16A. J Physiol 595:1515-1531
Fisher, Skylar Id; Hartzell, H Criss (2017) Poring over furrows. Elife 6:
Whitlock, Jarred M; Hartzell, H Criss (2017) Anoctamins/TMEM16 Proteins: Chloride Channels Flirting with Lipids and Extracellular Vesicles. Annu Rev Physiol 79:119-143
De Jesús-Pérez, José J; Cruz-Rangel, Silvia; Espino-Saldaña, Ángeles E et al. (2017) Phosphatidylinositol 4,5-bisphosphate, cholesterol, and fatty acids modulate the calcium-activated chloride channel TMEM16A (ANO1). Biochim Biophys Acta 1863:299-312
Jiang, Tao; Yu, Kuai; Hartzell, H Criss et al. (2017) Lipids and ions traverse the membrane by the same physical pathway in the nhTMEM16 scramblase. Elife 6:
Whitlock, Jarred M; Hartzell, H Criss (2016) A Pore Idea: the ion conduction pathway of TMEM16/ANO proteins is composed partly of lipid. Pflugers Arch 468:455-73
Contreras-Vite, Juan A; Cruz-Rangel, Silvia; De Jesús-Pérez, José J et al. (2016) Revealing the activation pathway for TMEM16A chloride channels from macroscopic currents and kinetic models. Pflugers Arch 468:1241-57
Hartzell, H Criss; Whitlock, Jarred M (2016) TMEM16 chloride channels are two-faced. J Gen Physiol 148:367-373
Griffin, Danielle A; Johnson, Ryan W; Whitlock, Jarred M et al. (2016) Defective membrane fusion and repair in Anoctamin5-deficient muscular dystrophy. Hum Mol Genet 25:1900-1911
Lee, Jesun; Jung, Jooyoung; Tak, Min Ho et al. (2015) Two helices in the third intracellular loop determine anoctamin 1 (TMEM16A) activation by calcium. Pflugers Arch 467:1677-87

Showing the most recent 10 out of 59 publications