Ocular Albinism Type 1: More Than Meets The Eye

Shen, Bin; Samaraweera, Preminda; Rosenberg, Benjamin; Orlow, Seth J.

doi:10.1034/j.1600-0749.2001.140403.x

Cited by 38 publications

(36 citation statements)

References 25 publications

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“…Some of these families lack significant sequence homology with the mammalian GPCRs. There are also some atypical GPCRs with uncertain relation to other GPCRs, like the ocular albinism gene (OA1) (Shen et al, 2001) and the vomeronasal receptors found in vertebrates (Lane et al, 2002). A summary of the receptors used to construct the HMMs is shown in Table 1.…”

Section: Resultsmentioning

confidence: 99%

The Repertoire of G-Protein–Coupled Receptors in Fully Sequenced Genomes

2005

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The superfamily of G-protein-coupled receptors (GPCRs) is one of the largest and most studied families of proteins. We created Hidden Markov Models derived from sorted groups of GPCRs from our previous detailed phylogenetic classification of human GPCRs and added several other models derived from receptors not found in mammals. We used these models to search entire Genscan data sets from 13 species whose genomes are nearly completely sequenced. We found more than 5000 unique GPCRs that were divided into 15 main groups, and the largest one, the Rhodopsin family, was subdivided into 13 subclasses. The results show that the main families in the human genome, Glutamate, Rhodopsin, Adhesion, Frizzled, and Secretin, arose before the split of nematodes from the chordate lineage. Moreover, several of the subgroups of the Rhodopsin family arose before the split of the linage leading to vertebrates. We also searched expressed sequence tag (EST) databases and identified more than 20,000 sequences that match GPCRs. Although the GPCRs represent typically 1 to 2% of the Genscan predictions, the ESTs that match GPCRs are typically only 0.01 to 0.001%, indicating that GPCRs in most of the groups are expressed at low levels. We also provide searchable data sets that may be used for annotation and further detailed analysis of the GPCR family. This study provides an extensive overview of the expansion of the gene repertoire for families and subgroups of GPCRs.A tremendous amount of primary sequence information has been made available from the recent sequencing projects, providing a near-to-full coverage of the entire genome from a diversity of animal species. The fully sequenced genomes include the mammals mouse and human, two species from the bony fish line (pufferfish Takifugu rubripes and zebrafish Danio rerio), two protochordates from the tunicate linage (Ciona intestinalis and Ciona savignyi) together with two nematodes (Caenorhabditis elegans and Caenorhabditis briggsae), and the insects fruit fly (Drosophila melanogaster) and mosquito (Anopheles gambiae). Moreover, the plants thale cress (Arabidopsis thaliana) and rice (Oryza sativa) are sequenced, as well as several unicellular species of yeast from the fungi linage such as the bakers' yeast (Schizosaccharomyces pombe) and budding yeast (Saccharomyces cerevisiae).

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Section: Resultsmentioning

confidence: 99%

The Repertoire of G-Protein–Coupled Receptors in Fully Sequenced Genomes

2005

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“…Shroom2 and ocular albinism in humans RPE pigmentation deficiencies in humans with Type I X-linked ocular albinism result in a loss of visual acuity stemming from defective melanosome biogenesis and hypopigmentation of the RPE (Shen et al, 2001). Mutations in the OA1 gene are thought to underlie X-linked ocular albinism, but mutations in this gene have not been identified in all individuals (Bassi et al, 1995;Schiaffino et al, 1995a;Tijmes et al, 1998).…”

Section: Shroom2 and The Shroom Family Of Proteinsmentioning

confidence: 99%

Shroom2 (APXL) regulates melanosome biogenesis and localization in the retinal pigment epithelium

et al. 2006

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Shroom family proteins have been implicated in the control of the actin cytoskeleton, but so far only a single family member has been studied in the context of developing embryos. Here, we show that the Shroom-family protein,Shroom2 (previously known as APXL) is both necessary and sufficient to govern the localization of pigment granules at the apical surface of epithelial cells. In Xenopus embryos that lack Shroom2 function, we observed defects in pigmentation of the eye that stem from failure of melanosomes to mature and to associate with the apical cell surface. Ectopic expression of Shroom2 in naïve epithelial cells facilitates apical pigment accumulation, and this activity specifically requires the Rab27a GTPase. Most interestingly, we find that Shroom2, like Shroom3 (previously called Shroom),is sufficient to induce a dramatic apical accumulation of the microtubule-nucleating protein γ-tubulin at the apical surfaces of naïve epithelial cells. Together, our data identify Shroom2 as a central regulator of RPE pigmentation, and suggest that, despite their diverse biological roles, Shroom family proteins share a common activity. Finally,because the locus encoding human SHROOM2 lies within the critical region for two distinct forms of ocular albinism, it is possible that SHROOM2mutations may be a contributing factor in these human visual system disorders.

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“…(Oa1 is in set A in Table 1 because mutations do not affect platelets, etc., but Oa1 deficiency also results in giant melanosomes). There are various theories as to how such giant melanosomes are formed, for example a failure to export melanosomal proteins from late endosomes to melanosomes, a proposed stage in the routing (51). The giant ÔmelanosomesÕ here would in fact be late endosomes that had swollen by accumulation of melanosomal proteins and melanin.…”

Section: Making the Melanosome (And Other Organelles)mentioning

confidence: 99%

The Color Loci of Mice – A Genetic Century

Bennett

Lamoreux

2003

Pigment Cell Research

441

381

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Color loci in mammals are those genetic loci in which mutations can affect pigmentation of the hair, skin, and/or eyes. In the mouse, over 800 phenotypic alleles are now known, at 127 identified color loci. As the number of color loci passed 100 only recently, we celebrate this ÔcenturyÕ with an overview of these loci, especially the 59 that have been cloned and sequenced. These fall into a number of functional groups representing melanocyte development and differentiation, melanosomal components, organelle biogenesis, organelle transport, control of pigment-type switching, and some systemic effects. A human ortholog has been identified in all cases, and the majority of these human genes are found to be loci for human disorders, often affecting other body systems as well as pigmentation. We expect that a significant number of color loci remain to be identified. Nonetheless, the large number known already provide a treasury of resources for reconstruction of the mechanisms, at the subcellular, cellular and tissue levels, that produce a functional pigmentary system and contribute to the normal development and functioning of many other organ systems. The mutant mice also provide valuable models for the study of human disease.

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Ocular Albinism Type 1: More Than Meets The Eye

Cited by 38 publications

References 25 publications

The Repertoire of G-Protein–Coupled Receptors in Fully Sequenced Genomes

The Repertoire of G-Protein–Coupled Receptors in Fully Sequenced Genomes

Shroom2 (APXL) regulates melanosome biogenesis and localization in the retinal pigment epithelium

The Color Loci of Mice – A Genetic Century

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