Mutant Best1 Expression and Impaired Phagocytosis in an iPSC Model of Autosomal Recessive Bestrophinopathy.

Autosomal recessive bestrophinopathy (ARB) is caused by mutations in the gene BEST1 which encodes bestrophin 1 (Best1), an anion channel expressed in retinal pigment epithelial (RPE) cells. It has been hypothesized that ARB represents the human null phenotype for BEST1 and that this occurs due to nonsense mediated decay (NMD). To test this hypothesis, we generated induced pluripotent stem cells (iPSCs) from a patient with ARB and her parents.

Mutant Fibulin-3 Causes Proteoglycan Accumulation and Impaired Diffusion Across Bruch's Membrane.

Purpose: The mutation R345W in EFEMP1 (fibulin-3) causes macular degeneration. This study sought to determine whether proteoglycan content and diffusion across Bruch's membrane are altered in Efemp1ki/ki mice carrying this mutation or in Efemp1-/- mice.

Methods: Proteoglycans in mouse Bruch's membranes were stained with Cupromeronic Blue (CB).

Early AMD-like defects in the RPE and retinal degeneration in aged mice with RPE-specific deletion of or .

Purpose: To examine the effects of autophagy deficiency induced by RPE-specific deletion of or in mice as a function of age.

Methods: Conditional knockout mice with a floxed allele of or were crossed with inducible transgenic mice. -directed RPE-specific Cre recombinase expression was induced with doxycycline feeding in the resulting mice.

Deletion of Efemp1 Is Protective Against the Development of Sub-RPE Deposits in Mouse Eyes.

Purpose: EFEMP1 (fibulin-3) is mutated in Malattia Leventinese/Doyne's honeycomb retinal dystrophy (ML/DHRD), an inherited macular dystrophy similar to AMD. Both ML/DHRD and AMD are characterized by the presence of sub-RPE deposits. Efemp1 knockout mice do not develop sub-RPE deposits.

Bestrophin 1 and retinal disease.

Mutations in the gene BEST1 are causally associated with as many as five clinically distinct retinal degenerative diseases, which are collectively referred to as the "bestrophinopathies". These five associated diseases are: Best vitelliform macular dystrophy, autosomal recessive bestrophinopathy, adult-onset vitelliform macular dystrophy, autosomal dominant vitreoretinochoroidopathy, and retinitis pigmentosa. The most common of these is Best vitelliform macular dystrophy.

Role of Fibulin 3 in Aging-Related Joint Changes and Osteoarthritis Pathogenesis in Human and Mouse Knee Cartilage.

Objective: The EFEMP1 gene encoding fibulin 3 is specifically expressed in the superficial zone (SZ) of articular cartilage. The aims of this study were to examine the expression patterns of fibulin 3 in the knee joints during aging and during osteoarthritis (OA) and to determine the role of fibulin 3 in the pathogenesis of OA.

Methods: Immunohistochemical analysis was performed on normal and OA knee cartilage samples from humans and mice.

Control of Maintenance and Regeneration of Planarian Eyes by ovo.

Purpose: Following decapitation, the planarian Schmidtea mediterranea regenerates its head and eyes. The gene ovo is required for eye maintenance and regeneration in response to wounding. In this study, we investigated whether eye regeneration in S.

Autosomal Recessive Bestrophinopathy Is Not Associated With the Loss of Bestrophin-1 Anion Channel Function in a Patient With a Novel BEST1 Mutation.

Purpose: Mutations in BEST1, encoding bestrophin-1 (Best1), cause autosomal recessive bestrophinopathy (ARB). Encoding bestrophin-1 is a pentameric anion channel localized to the basolateral plasma membrane of the RPE. Here, we characterize the effects of the mutations R141H (CGC > CAC) and I366fsX18 (c.

Bestrophin-1 influences transepithelial electrical properties and Ca2+ signaling in human retinal pigment epithelium.

Purpose: Mutations in BEST1, encoding Bestrophin-1 (Best1), cause Best vitelliform macular dystrophy (BVMD) and other inherited retinal degenerative diseases. Best1 is an integral membrane protein localized to the basolateral plasma membrane of the retinal pigment epithelium (RPE). Data from numerous in vitro and in vivo models have demonstrated that Best1 regulates intracellular Ca2+ levels.

Soluble adenylyl cyclase in the eye.

Adenylyl cyclases (ACs) are a family of enzymes which convert ATP to cAMP, an essential intermediate in many signal transduction pathways. Of the 10 AC genes in man, 9 fall into the category of transmembrane ACs (tmACs), which associate with G-protein coupled receptors (GPCRs) and are activated by forskolin. The 10th AC, termed soluble AC (sAC) is neither activated by forskolin nor does it interact with GPCRs.

Disease-causing mutations associated with four bestrophinopathies exhibit disparate effects on the localization, but not the oligomerization, of Bestrophin-1.

BEST1 encodes Bestrophin-1 (Best1), a homo-oligomeric, integral membrane protein localized to the basolateral plasma membrane of the retinal pigment epithelium. Mutations in BEST1 cause five distinct retinal degenerative diseases, including adult vitelliform macular dystrophy (AVMD), autosomal recessive bestrophinopathy (ARB), autosomal dominant vitreoretinochoroidopathy (ADVIRC), and retinitis pigmentosa (RP). The mechanisms underlying these diseases and why mutations cause one disease over another are, for the most part, unknown.

Differential effects of Best disease causing missense mutations on bestrophin-1 trafficking.

Mutations in bestrophin-1 (Best1) cause Best vitelliform macular dystrophy (BVMD), a dominantly inherited retinal degenerative disease. Best1 is a homo-oligomeric anion channel localized to the basolateral surface of retinal pigment epithelial (RPE) cells. A number of Best1 mutants mislocalize in Madin-Darby canine kidney (MDCK) cells.

Regulation of anterior chamber drainage by bicarbonate-sensitive soluble adenylyl cyclase in the ciliary body.

Glaucoma is a leading cause of blindness affecting as many as 2.2 million Americans. All current glaucoma treatment strategies aim to reduce intraocular pressure (IOP).

Relationship of stokes radius to the rate of diffusion across Bruch's membrane.

Purpose: To determine the effect of Stokes radius (R(S)) on the diffusion of molecules through Bruch's membrane (BM), and to establish a system suitable for the analysis of diffusion through small (<2 mm(2)) samples of BM.

Methods: Porcine BM/choroid (BM/Ch) was mounted in a modified Ussing chamber. A concentration gradient was simultaneously established for four tracers with R(S) values ranging from <1.

Suppression of Ca2+ signaling in a mouse model of Best disease.

Mutations in BEST1, encoding bestrophin-1 (Best1), cause Best vitelliform macular dystrophy (BVMD), a dominantly inherited macular degeneration characterized by a diminished electrooculogram light peak (LP), lipofuscin in retinal pigment epithelial cells (RPE), and fluid- and debris-filled retinal detachments. To understand the pathogenesis of BVMD we generated knock-in mice carrying the BVMD-causing mutation W93C in Best1. Both Best1(+/W93C)and Best1(W93C/W93C) mice had normal ERG a- and b-waves, but exhibited an altered LP luminance response reminiscent of that observed in BVMD patients.

Fibulin-4 deficiency results in ascending aortic aneurysms: a potential link between abnormal smooth muscle cell phenotype and aneurysm progression.

Rationale: Loss of fibulin-4 during embryogenesis results in perinatal lethality because of aneurysm rupture, and defective elastic fiber assembly has been proposed as an underlying cause for the aneurysm phenotype. However, aneurysms are never seen in mice deficient for elastin, or for fibulin-5, which absence also leads to compromised elastic fibers.

Objective: We sought to determine the mechanism of aneurysm development in the absence of fibulin-4 and establish the role of fibulin-4 in aortic development.

Fibulin-4 conducts proper elastogenesis via interaction with cross-linking enzyme lysyl oxidase.

Great arteries, as well as lungs and skin, contain elastic fibers as important components to maintain their physiological functions. Although recent studies have revealed that a glycoprotein fibulin-4 (FBLN4) is indispensable for the assembly of mature elastic fibers, it remains to be elucidated how FBLN4 takes part in elastogenesis. Here, we report a dose-dependent requirement for FBLN4 in the development of the elastic fibers in arteries, and a specific role of FBLN4 in recruiting the elastin-cross-linking enzyme, lysyl oxidase (LOX).

Lack of fibulin-3 alters regenerative tissue responses in the primary olfactory pathway.

The adult olfactory epithelium has maintained the ability to reconstitute its olfactory sensory neurons (OSNs) from a basal progenitor cell compartment. This allows for life-long turnover and replacement of receptor components as well as repair of the primary olfactory pathway in response to injury and environmental insults. The present study investigated whether fibulin-3, a glycoprotein in the extracellular matrix and binding partner of tissue inhibitor of metalloproteinases-3 (TIMP-3), plays a role in ongoing plasticity and regenerative events in the adult primary olfactory pathway.

Failure of pelvic organ support in mice deficient in fibulin-3.

Fibulin-5 is crucial for normal elastic fiber synthesis in the vaginal wall; more than 90% of fibulin-5-knockout mice develop pelvic organ prolapse by 20 weeks of age. In contrast, fibulin-1 and -2 deficiencies do not result in similar pathologies, and fibulin-4-knockout mice die shortly after birth. EFEMP1 encodes fibulin-3, an extracellular matrix protein important in the maintenance of abdominal fascia.

Enhanced inflow and outflow rates despite lower IOP in bestrophin-2-deficient mice.

Purpose: Bestrophin-2 (Best2), a putative Cl(-) channel is expressed in the nonpigmented epithelium (NPE). Disruption of Best2 in mice results in a diminished intraocular pressure (IOP). Aqueous humor dynamics were compared in Best2(+/+) and Best2(-/-) mice, to better understand the contribution of Best2 to IOP.

Bestrophin-2 is involved in the generation of intraocular pressure.

Purpose: The bestrophin family of proteins has been demonstrated to generate or regulate Ca2+-activated Cl(-) conductances. Mutations in bestrophin-1 (Best1) cause several blinding eye diseases, but little is known about other bestrophin family members. This study involved disruption of the Best2 gene in mice.

Lack of fibulin-3 causes early aging and herniation, but not macular degeneration in mice.

A mutation in the EFEMP1 gene causes Malattia Leventinese, an inherited macular degenerative disease with strong similarities to age-related macular degeneration. EFEMP1 encodes fibulin-3, an extracellular matrix protein of unknown function. To investigate its biological role, the murine Efemp1 gene was inactivated through targeted disruption.

Formation and progression of sub-retinal pigment epithelium deposits in Efemp1 mutation knock-in mice: a model for the early pathogenic course of macular degeneration.

Malattia leventinese (ML) is a dominantly inherited macular degenerative disease characterized by the presence of sub-retinal pigment epithelium (RPE) deposits. With the exception of an earlier age of onset, ML patients exhibit symptoms and histopathology compatible with the diagnosis of age-related macular degeneration (AMD), the most common cause of incurable blindness. ML is caused by a mutation (R345W) in the gene EFEMP1 which encodes fibulin-3, a protein of unknown function.

The challenge of modeling macular degeneration in mice.

Macular degenerations (MD), age-related or inherited, interfere with the ability to read, drive and recognize faces. Understanding this class of diseases has been challenging because the mouse, the mammal most amenable to genetic manipulation, lacks a macula. Here we discuss whether we can model MD in the mouse, present criteria for an 'ideal' mouse model of MD and discuss how mouse models have contributed to our knowledge of MD by contrasting how well they meet the 'ideal' criteria with how informative they have actually been.