Bestrophin 1

Bestrophin 1

Bestrophin 1 is a protein that plays a crucial role in maintaining the normal function of the retina. It is encoded by the BEST1 gene and is primarily expressed in the retinal pigment epithelium (RPE) cells. Mutations in the BEST1 gene have been associated with various retinal disorders, including Best vitelliform macular dystrophy (BVMD) and autosomal recessive bestrophinopathy (ARB).

Structure

The Bestrophin 1 protein consists of 585 amino acids and has a predicted molecular weight of approximately 68 kDa. It is composed of four transmembrane domains, with both the N- and C-termini located in the cytoplasm. The transmembrane domains form a pore-like structure that allows the passage of chloride ions across the cell membrane.

Function

Bestrophin 1 functions as a calcium-activated chloride channel in the RPE cells. It plays a crucial role in the transport of ions and water across the RPE layer, which is essential for maintaining the integrity of the retina. The chloride ions transported by Bestrophin 1 are involved in various cellular processes, including cell volume regulation and pH balance.

Clinical Significance

Mutations in the BEST1 gene can lead to the development of retinal disorders. Best vitelliform macular dystrophy (BVMD), also known as Best disease, is one such disorder. BVMD is characterized by the accumulation of lipofuscin deposits in the macula, leading to progressive vision loss. It is inherited in an autosomal dominant manner, and mutations in the BEST1 gene are responsible for the majority of BVMD cases.

Autosomal recessive bestrophinopathy (ARB) is another retinal disorder associated with mutations in the BEST1 gene. ARB is characterized by early-onset macular dystrophy, with symptoms including decreased visual acuity, macular atrophy, and abnormal electrooculogram (EOG) responses.

Research and Future Directions

Research on Bestrophin 1 and its associated retinal disorders is ongoing. Scientists are investigating the underlying mechanisms of Bestrophin 1 function and the impact of different mutations on its activity. Understanding these mechanisms can potentially lead to the development of targeted therapies for retinal disorders caused by BEST1 gene mutations.

Furthermore, the role of Bestrophin 1 in other tissues and organs is also being explored. Recent studies have suggested its involvement in the regulation of calcium signaling and fluid secretion in various epithelial tissues, including the respiratory and gastrointestinal systems.

References

1. Petrukhin K, Koisti MJ, Bakall B, et al. Identification of the gene responsible for Best macular dystrophy. Nat Genet. 1998;19(3):241-247. doi:10.1038/915

2. Burgess R, Millar ID, Leroy BP, et al. Biallelic mutation of BEST1 causes a distinct retinopathy in humans. Am J Hum Genet. 2008;82(1):19-31. doi:10.1016/j.ajhg.2007.09.003