A large multi-ethnic genome-wide association study identifies novel genetic loci for intraocular pressure.

Elevated intraocular pressure (IOP) is a major risk factor for glaucoma, a leading cause of blindness. IOP heritability has been estimated to up to 67%, and to date only 11 IOP loci have been reported, accounting for 1.5% of IOP variability. Here, we conduct a genome-wide association study of IOP in 69,756 untreated individuals of European, Latino, Asian, and African ancestry. Multiple longitudinal IOP measurements were collected through electronic health records and, in total, 356,987 measurements were included. We identify 47 genome-wide significant IOP-associated loci (P < 5 × 10-8); of the 40 novel loci, 14 replicate at Bonferroni significance in an external genome-wide association study analysis of 37,930 individuals of European and Asian descent. We further examine their effect on the risk of glaucoma within our discovery sample. Using longitudinal IOP measurements from electronic health records improves our power to identify new variants, which together explain 3.7% of IOP variation

GpnmbR150X allele must be present in bone marrow derived cells to mediate DBA/2J glaucoma

<p>Abstract</p> <p>Background</p> <p>The <it>Gpnmb </it>gene encodes a transmembrane protein whose function(s) remain largely unknown. Here, we assess if a mutant allele of <it>Gpnmb </it>confers susceptibility to glaucoma by altering immune functions. DBA/2J mice have a mutant <it>Gpnmb </it>gene and they develop a form of glaucoma preceded by a pigment dispersing iris disease and abnormalities of the immunosuppressive ocular microenvironment.</p> <p>Results</p> <p>We find that the <it>Gpnmb </it>genotype of bone-marrow derived cell lineages significantly influences the iris disease and the elevation of intraocular pressure. GPNMB localizes to multiple cell types, including pigment producing cells, bone marrow derived F4/80 positive antigen-presenting cells (APCs) of the iris and dendritic cells. We show that APCs of DBA/2J mice fail to induce antigen induced immune deviation (a form of tolerance) when treated with TGFβ2. This demonstrates that some of the immune abnormalities previously identified in DBA/2J mice result from intrinsic defects in APCs. However, the tested APC defects are not dependent on a mutant <it>Gpnmb </it>gene. Finally, we show that the <it>Gpnmb </it>mediated iris disease does not require elevated IL18 or mature B or T lymphocytes.</p> <p>Conclusion</p> <p>These results establish a role for <it>Gpnmb </it>in bone marrow derived lineages. They suggest that affects of <it>Gpnmb </it>on innate immunity influence susceptibility to glaucoma in DBA/2J mice.</p

GLIS1 regulates trabecular meshwork function and intraocular pressure and is associated with glaucoma in humans.

Chronically elevated intraocular pressure (IOP) is the major risk factor of primary open-angle glaucoma, a leading cause of blindness. Dysfunction of the trabecular meshwork (TM), which controls the outflow of aqueous humor (AqH) from the anterior chamber, is the major cause of elevated IOP. Here, we demonstrate that mice deficient in the Krüppel-like zinc finger transcriptional factor GLI-similar-1 (GLIS1) develop chronically elevated IOP. Magnetic resonance imaging and histopathological analysis reveal that deficiency in GLIS1 expression induces progressive degeneration of the TM, leading to inefficient AqH drainage from the anterior chamber and elevated IOP. Transcriptome and cistrome analyses identified several glaucoma- and extracellular matrix-associated genes as direct transcriptional targets of GLIS1. We also identified a significant association between GLIS1 variant rs941125 and glaucoma in humans (P = 4.73 × 1

A multiethnic genome-wide analysis of 19,420 individuals identifies novel loci associated with axial length and shared genetic influences with refractive error and myopia

Introduction: Long axial length (AL) is a risk factor for myopia. Although family studies indicate that AL has an important genetic component with heritability estimates up to 0.94, there have been few reports of AL-associated loci.Methods: Here, we conducted a multiethnic genome-wide association study (GWAS) of AL in 19,420 adults of European, Latino, Asian, and African ancestry from the Genetic Epidemiology Research on Adult Health and Aging (GERA) cohort, with replication in a subset of the Consortium for Refractive Error and Myopia (CREAM) cohorts of European or Asian ancestry. We further examined the effect of the identified loci on the mean spherical equivalent (MSE) within the GERA cohort. We also performed genome-wide genetic correlation analyses to quantify the genetic overlap between AL and MSE or myopia risk in the GERA European ancestry sample.Results: Our multiethnic GWA analysis of AL identified a total of 16 genomic loci, of which 5 are novel. We found that all AL-associated loci were significantly associated with MSE after Bonferroni correction. We also found that AL was genetically correlated with MSE (rg = −0.83; SE, 0.04; p = 1.95 × 10−89) and myopia (rg = 0.80; SE, 0.05; p = 2.84 × 10−55). Finally, we estimated the array heritability for AL in the GERA European ancestry sample using LD score regression, and found an overall heritability estimate of 0.37 (s.e. = 0.04).Discussion: In this large and multiethnic study, we identified novel loci, associated with AL at a genome-wide significance level, increasing substantially our understanding of the etiology of AL variation. Our results also demonstrate an association between AL-associated loci and MSE and a shared genetic basis between AL and myopia risk

Genome-wide meta-analysis identifies 127 open-angle glaucoma loci with consistent effect across ancestries

Primary open-angle glaucoma (POAG), is a heritable common cause of blindness world-wide. To identify risk loci, we conduct a large multi-ethnic meta-analysis of genome-wide association studies on a total of 34,179 cases and 349,321 controls, identifying 44 previously unreported risk loci and confirming 83 loci that were previously known. The majority of loci have broadly consistent effects across European, Asian and African ancestries. Cross-ancestry data improve fine-mapping of causal variants for several loci. Integration of multiple lines of genetic evidence support the functional relevance of the identified POAG risk loci and highlight potential contributions of several genes to POAG pathogenesis, including SVEP1, RERE, VCAM1, ZNF638, CLIC5, SLC2A12, YAP1, MXRA5, and SMAD6. Several drug compounds targeting POAG risk genes may be potential glaucoma therapeutic candidates. Primary open-angle glaucoma (POAG) is highly heritable, yet not well understood from a genetic perspective. Here, the authors perform a meta-analysis of genome-wide association studies in 34,179 POAG cases, identifying 44 previously unreported risk loci and mapping effects across multiple ethnicities

Subunit Dissociation is Sufficient for Light‐Induced Translocation of Rod Transducin

Photoreceptor illumination causes a massive redistribution of G protein subunits, arrestins and recoverin between inner and outer compartments. In light, rod G protein transducin (Gt) moves from the outer segments (OS) to the inner compartments, whereas arrestin moves from the inner compartments to the OS. This phenomenon is thought to be important for light and dark adaptation. Many groups presented evidence that movement of Gt and arrestin requires molecular motors. However, we show that ATP is not required for redistribution, ruling out active transport or gating mechanisms. We demonstrate that GTP binding causes rod Gt release from membranes and movement to the inner compartments. Moreover, we show that rod Gt translocates if the GαGβ γ subunits are induced to dissociate by a synthetic peptide (mSIRK) in the dark. Thus, our results support a simple model of Gt translocation: upon activation, subunits dissociate, leave the OS membranes and disperse throughout the cell. We also investigated the striking difference between rod Gt, which is capable of re‐localization and cone Gt, which does not re‐localize upon activation. Our experiments suggest that cone Gt subunits do not dissociate upon activation (GTPγS binding) and remain localized to the OS. We infer from our studies that in vivo, most G proteins do not dissociate upon activation. Rod transducin has this unique ability in order to re‐localize within the cells. This research is supported by NIH grants GM 060019 (V.Z.S) and AHA 0515233B (D.H.R

Molecular Mechanism of Light‐dependent Translocation of the G Protein Transducin

One of the most exciting areas in cell biology is the signal‐dependent translocation of receptors, G proteins, and other signaling molecules. Photoreceptor illumination causes a massive redistribution of signaling proteins between cellular compartments. The G protein transducin (Gt) moves from the outer segments (OS) to the inner compartments, whereas arrestin moves from the inner compartments to the OS. This phenomenon is thought to be important for the processes of light and dark adaptation. Here, we addressed the mechanism of translocation by asking if this process occurs by active transport or passive diffusion. We tested the role of ATP in Gt movement using acutely cultured retinas permiabilized with Staphylococcal α‐toxin. We found that ATP is not required for relocalization, and GTPγ S is required, which rules out active transport as the mechanism. Further, our data indicates that the crucial molecular event required for Gt movement is membrane solubilization of rod Gt. Activation of Gt with GTPγ S caused about 50% elution of rod Gt from OS membranes. In sharp contrast to rod Gt, cone Gt did not undergo significant redistribution or elution in presence of GTPγ S. Thus, Gt movement is specific and unique to rod photoreceptors. Our data demonstrate that GTP binding to Gt is necessary and sufficient for movement, and we conclude that GTP‐induced solublization leads to diffusion of rod Gt down its concentration gradient. This research is supported by NIH grants GM 060019 and NEI 012982 (V.Z.S

Identification of MFRP and the secreted serine proteases PRSS56 and ADAMTS19 as part of a molecular network involved in ocular growth regulation.

Precise regulation of ocular size is a critical determinant of normal visual acuity. Although it is generally accepted that ocular growth relies on a cascade of signaling events transmitted from the retina to the sclera, the factors and mechanism(s) involved are poorly understood. Recent studies have highlighted the importance of the retinal secreted serine protease PRSS56 and transmembrane glycoprotein MFRP, a factor predominantly expressed in the retinal pigment epithelium (RPE), in ocular size determination. Mutations in PRSS56 and MFRP constitute a major cause of nanophthalmos, a condition characterized by severe reduction in ocular axial length/extreme hyperopia. Interestingly, common variants of these genes have been implicated in myopia, a condition associated with ocular elongation. Consistent with these findings, mice with loss of function mutation in PRSS56 or MFRP exhibit a reduction in ocular axial length. However, the molecular network and cellular processes involved in PRSS56- and MFRP-mediated ocular axial growth remain elusive. Here, we show that Adamts19 expression is significantly upregulated in the retina of mice lacking either Prss56 or Mfrp. Importantly, using genetic mouse models, we demonstrate that while ADAMTS19 is not required for ocular growth during normal development, its inactivation exacerbates ocular axial length reduction in Prss56 and Mfrp mutant mice. These results suggest that the upregulation of retinal Adamts19 is part of an adaptive molecular response to counteract impaired ocular growth. Using a complementary genetic approach, we show that loss of PRSS56 or MFRP function prevents excessive ocular axial growth in a mouse model of early-onset myopia caused by a null mutation in Irbp, thus, demonstrating that PRSS56 and MFRP are also required for pathological ocular elongation. Collectively, our findings provide new insights into the molecular network involved in ocular axial growth and support a role for molecular crosstalk between the retina and RPE involved in refractive development

Determining immune components necessary for progression of pigment dispersing disease to glaucoma in DBA/2J mice.

BACKGROUND: The molecular mechanisms causing pigment dispersion syndrome (PDS) and the pathway(s) by which it progresses to pigmentary glaucoma are not known. Mutations in two melanosomal protein genes (Tyrp1b and GpnmbR150X) are responsible for pigment dispersing iris disease, which progresses to intraocular pressure (IOP) elevation and subsequent glaucoma in DBA/2J mice. Melanosomal defects along with ocular immune abnormalities play a role in the propagation of pigment dispersion and progression to IOP elevation. Here, we tested the role of specific immune components in the progression of the iris disease and high IOP. RESULTS: We tested the role of NK cells in disease etiology by genetically modifying the B6.D2-GpnmbR150XTyrp1b strain, which develops the same iris disease as DBA/2J mice. Our findings demonstrate that neither diminishing NK mediated cytotoxic activity (Prf1 mutation) nor NK cell depletion (Il2rg mutation) has any influence on the severity or timing of GpnmbR150XTyrp1b mediated iris disease. Since DBA/2J mice are deficient in CD94, an important immune modulator that often acts as an immune suppressor, we generated DBA/2J mice sufficient in CD94. Sufficiency of CD94 failed to alter either the iris disease or the subsequent IOP elevation. Additionally CD94 status had no detected effect on glaucomatous optic nerve damage. CONCLUSION: Our previous data implicate immune components in the manifestation of pigment dispersion and/or IOP elevation in DBA/2J mice. The current study eliminates important immune components, specifically NK cells and CD94 deficiency, as critical in the progression of iris disease and glaucoma. This narrows the field of possible immune components responsible for disease progression. BMC Genet 2014 Mar 28; 15(1):4