Truncation of PITX2 differentially affects its activity on physiological targets.

The bicoid-like transcription factor PITX2 has been previously described to interact with the pituitary-specific POU homeodomain factor POU1F1 (human ortholog of PIT-1) to achieve cell-specific expression of prolactin (PRL) and GH in pituitary somatolactotroph cells. In this work, we have investigated the functional properties of three PITX2 mutants reported in Axenfeld-Rieger syndrome patients relative to the regulation of these genes, using reporter genes under the control of human PRL (hPRL), hGH, or POU1F1 promoters transfected in nonpituitary and pituitary cell lines. Among the three mutations studied, Y167X and E101X introduce a premature stop codon, and F104L leads to an amino acid substitution.

Expression of 8-oxoguanine DNA glycosylase (Ogg1) in mouse retina.

Purpose: The retina is highly exposed to oxidative stress due to the high level of oxygen consumption in this tissue and its exposure to light. The main DNA base lesion generated by oxygen free radicals is 8-oxoguanine (8-oxoG). However, its presence in retinal cells and the mechanisms underlying its repair remain undetermined.

Morphologic and electroretinographic phenotype of SR-BI knockout mice after a long-term atherogenic diet.

Purpose: To evaluate functional and ultrastructural changes in the retina of scavenger receptor B1 (SR-BI) knockout (KO) mice consuming a high fat cholate (HFC) diet.

Methods: Three-month-old male KO and wild-type (WT) mice were fed an HFC diet for 30 weeks. After diet supplementation, plasma cholesterol levels and electroretinograms were analyzed.

Sirt1 involvement in rd10 mouse retinal degeneration.

Purpose: Sirtuin1 (Sirt1) is an NAD(+)-dependent deacetylase involved in development, cell survival, stress resistance, energy metabolism, and aging. It is expressed in the mammalian central nervous system (CNS) and is activated during processes associated with neuroprotection. The retinal degeneration 10 (rd10) mouse model of retinitis pigmentosa (RP) was used to investigate the possible role of Sirt1 in this type of retinal degeneration.

ATM localization and gene expression in the adult mouse eye.

Purpose: High levels of metabolism and oxygen consumption in most adult murine ocular compartments, combined with exposure to light and ultraviolet (UV) radiation, are major sources of oxidative stress, causing DNA damage in ocular cells. Of all mammalian body cells, photoreceptor cells consume the largest amount of oxygen and generate the highest levels of oxidative damage. The accumulation of such damage throughout life is a major factor of aging tissues.

Novel mouse model of monocular amaurosis fugax.

Background And Purpose: Retinal ischemia is a major cause of visual impairment and is associated with a high risk of subsequent ischemic stroke. The retina and its projections are easily accessible for experimental procedures and functional evaluation. We created and characterized a mouse model of global and transient retinal ischemia and provide a comprehensive chronologic profile of some genes that display altered expression during ischemia.

Three new PAX6 mutations including one causing an unusual ophthalmic phenotype associated with neurodevelopmental abnormalities.

Purpose: The PAX6 gene was first described as a candidate for human aniridia. However, PAX6 expression is not restricted to the eye and it appears to be crucial for brain development. We studied PAX6 mutations in a large spectrum of patients who presented with aniridia phenotypes, Peters' anomaly, and anterior segment malformations associated or not with neurological anomalies.

Identification of four new PITX2 gene mutations in patients with Axenfeld-Rieger syndrome.

Purpose: Axenfeld Rieger syndrome (ARS) is an autosomal dominant inherited disorder affecting development of the ocular anterior chamber, abdomen, teeth and facial structures. The PITX2 gene is a major gene encoding a major transcription factor associated with ARS.

Methods: ARS patients were collected from six unrelated families.

Identification of the first intragenic deletion of the PITX2 gene causing an Axenfeld-Rieger Syndrome: case report.

Background: Axenfeld-Rieger syndrome (ARS) is characterized by bilateral congenital abnormalities of the anterior segment of the eye associated with abnormalities of the teeth, midface, and umbilicus. Most cases of ARS are caused by mutations in the genes encoding PITX2 or FOXC1. Here we describe a family affected by a severe form of ARS.

A subset of patients with epithelial basement membrane corneal dystrophy have mutations in TGFBI/BIGH3.

Epithelial basement membrane corneal dystrophy (EBMD), also known as Cogan microcystic epithelial dystrophy or map-dot-fingerprint dystrophy, is a common bilateral epithelial dystrophy. Usually, this disease is not considered to be inherited although several families with autosomal dominant inheritance have been described. We report the analysis of two families with an autosomal dominant pattern of inheritance as well as the analysis of single affected individuals; we identified two different point mutations in the TGFBI/BIGH3 genes, genes known to be associated with other corneal dystrophies.

Eight previously unidentified mutations found in the OA1 ocular albinism gene.

Background: Ocular albinism type 1 (OA1) is an X-linked ocular disorder characterized by a severe reduction in visual acuity, nystagmus, hypopigmentation of the retinal pigmented epithelium, foveal hypoplasia, macromelanosomes in pigmented skin and eye cells, and misrouting of the optical tracts. This disease is primarily caused by mutations in the OA1 gene.

Methods: The ophthalmologic phenotype of the patients and their family members was characterized.

Prosaposin gene expression in normal and dystrophic RCS rat retina.

Purpose: To identify proteins secreted by the retinal pigment epithelium (RPE) and to analyze their cellular distribution in normal and pathologic rat retinas at various stages of eye development.

Methods: A cDNA library was constructed with RNA isolated from porcine RPE sheets and screened by using the yeast signal sequence trap system. In situ hybridization, immunohistochemistry, and semiquantitative RT-PCR analysis were performed on rat retinas.

VEGF and KDR gene expression during human embryonic and fetal eye development.

Purpose: It is important to understand the development of the normal retinal vascular system, because it may provide clues for understanding the mechanisms underlying the neovascularization associated with several retinopathies of infancy and adulthood. However, little is known about normal human ocular vascularization. VEGF is a key growth factor during vascular development and one of its receptors, KDR, plays a pivotal role in endothelial cell proliferation and differentiation.

The beta3 integrin gene is expressed at high levels in the major haematopoietic and lymphoid organs, vascular system, and skeleton during mouse embryo development.

Integrins are a family of cell surface molecules that mediate the attachment of cells to the extracellular matrix (ECM). These alphabeta heterodimers are involved in many biological processes. We used northern blotting and in situ hybridization to study the pattern of beta3 integrin gene expression during mouse embryogenesis.

Identification of novel genes and altered signaling pathways in the retinal pigment epithelium during the Royal College of Surgeons rat retinal degeneration.

Shed photoreceptor outer segments (POS) are phagocytosed by RPE cells in a circadian manner. The homozygous deletion of the c-mer gene abolishes the ingestion phase of this phagocytosis in the Royal College of Surgeons (RCS) rat strain, which in turn leads to the death of photoreceptor cells. We identified RPE transcripts for which the expression is modulated by the abrogation of POS phagocytosis.

Mutational analysis of the OA1 gene in ocular albinism.

Ocular albinism type 1 (OA1) is an X-linked disorder, mainly characterized by a severe reduction in visual acuity, foveal hypoplasia, nystagmus, hypopigmentation of the retina, the presence of macromelanosomes in the skin and eyes, and the misrouting of optic pathways, resulting in the loss of stereoscopic vision. We screened the OA1 gene for mutations in three unrelated Canadian and French families and in two isolated patients with OA1. We found three different missense mutations and two different nonsense mutations, three of which were novel.