Topical ocular sodium 4-phenylbutyrate rescues glaucoma in a myocilin mouse model of primary open-angle glaucoma

PURPOSE. Mutations in the myocilin gene (MYOC) are the most common known genetic cause of primary open-angle glaucoma (POAG). The purpose of this study was to determine whether topical ocular sodium 4-phenylbutyrate (PBA) treatment rescues glaucoma phenotypes in a mouse model of myocilin-associated glaucoma (Tg-MYOC Y437H mice). METHODS. Tg-MYOC Y437H mice were treated with PBA eye drops (n ϭ 10) or sterile PBS (n ϭ 8) twice daily for 5 months. Long-term safety and effectiveness of topical PBA (0.2%) on glaucoma phenotypes were examined by measuring intraocular pressure (IOP) and pattern ERG (PERG), performing slit lamp evaluation of the anterior chamber, analyzing histologic sections of the anterior segment, and comparing myocilin levels in the aqueous humor and trabecular meshwork of Tg-MYOC Y437H mice. Sci. 2012;53: 1557-1565 RESULTS. Tg-MYO

Tethering Recombination Initiation Proteins in Saccharomyces cerevisiae Promotes Double Strand Break Formation

Meiotic recombination in Saccharomyces cerevisiae is initiated by the creation of DNA double strand breaks (DSBs), an event requiring 10 recombination initiation proteins. Published data indicate that these 10 proteins form three main interaction subgroups [(Spo11-Rec102-Rec104-Ski8), (Rec114-Rec107-Mei4), and (Mre11-Rad50-Xrs2)], but certain components from each subgroup may also interact. Although several of the protein–protein interactions have been defined, the mechanism for DSB formation has been challenging to define. Using a variation of the approach pioneered by others, we have tethered 8 of the 10 initiation proteins to a recombination coldspot and discovered that in addition to Spo11, 6 others (Rec102, Rec104, Ski8, Rec114, Rec107, and Mei4) promote DSB formation at the coldspot, albeit with different frequencies. Of the 8 proteins tested, only Mre11 was unable to cause DSBs even though it binds to UASGAL at GAL2. Our results suggest there may be several ways that the recombination initiation proteins can associate to form a functional initiation complex that can create DSBs

SEM images of freeze-dried C57BL/6J (B6) and DBA/2J (D2) melanosomes.

<p>The left column contains images recorded in the in-lens detector configuration (IL) and the right column shows micrographs acquired in the out-lens configuration (OL). A direct comparison shows that B6 melanosomes (A and B) have a rather smooth and featureless surface, whereas the D2 organelles (C and D) have an irregular surface. The samples were subjected to the identical preparation protocol. All scale bars represent 500 nm.</p

SAXS data for suspended melanosomes from C57BL/6J (B6) and DBA/2J (D2) mice.

<p>Melanosomes were exposed to photons at <i>E</i> = 12.8 keV for 10 s. (A) Comparison of scattering intensities for both phenotypes, in the range of 0.05 to 4.5 nm⁻¹. (B) Analysis of B6 melanosome structure by fitting a model of independent scatterers to the <i>q</i>-interval 0.07 nm⁻¹<<i>q</i><0.27 nm⁻¹. The resulting fitting parameters in the power law are <i>p</i>₁ = 4.034±0.001 (small <i>q</i>-values), <i>p</i>₂ = 3.887±0.118 (high <i>q</i>-values) und <i>R</i>_B6 = 22.57±5.57 nm (radius of gyration of melanosomal subunits). (C) Analysis of D2 melanosome structure by fitting a model of dependent scatterers to data within the <i>q</i>-interval 0.05 nm⁻¹<<i>q</i><0.27 nm⁻¹. The determined parameters are <i>p</i>₁ = 2.56 (modified power law at small <i>q</i>-values), <i>p</i>₂ = 3.60 (power law at high <i>q</i>-values) and <i>R</i>_D2 = 31.32±1.71 nm (radius of gyration of melanosomal subunits). In (B) and (C) the terms that contribute to the fit model used are labeled A1, A2 and A3. The analyzed data points are shown in green.</p

Correlation of maps generated by optical phase-contrast microscopy, cryo microscopy and darkfield cryo-STXM.

<p>Melanosomes of the genotypes C57BL/6J (B6) and DBA/2J (D2) are shown in tiles (A–C) and (D–F), respectively. In both cases, the sample is embedded in an amorphous ice matrix. The optical micrographs, recorded at 100 K, are superimposed with a semi-transparent (B and E) and an opaque (C and F) STXM map. Note that despite the fact that melanosome density is comparable in the two samples, the STXM images feature significant differences in signal intensity as well as the spatial distribution of that signal, revealing structural differences between the melanosomes of the two genotypes. The area of the scanned regions is 20.4×20.4 µm².</p

X-ray scattering data for cryogenically prepared melanosomes from C57BL/6J (B6) and DBA/2J (D2) mice.

<p>(A) Normalized intensity histograms derived from darkfield STXM maps of B6 and D2 samples like those shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0090884#pone-0090884-g002" target="_blank">Fig. 2</a>. The intensity of scatter for the D2 melanosomes is higher and has a broader distribution, than that for the B6 sample. The photon energy was 7.9 keV. (B) Sum of 13 background-corrected scattering events, i.e. <i>hits</i>, for a B6 sample. The scattering pattern is anisotropic. (C) Sum of 13 background-corrected scattering events for a D2 sample. The scattering pattern is isotropic. In (B) and (C), intensity is color-coded on a logarithmic scale. The horizontal bars in (B) and (C), which are devoid of signal, correspond to insensitive regions of the PILATUS, and separate the three detector modules. The artificial look of the regions in the centers is due to the stacking of two semi-transparent beamstops.</p

Genome-wide association analyses identify multiple loci associated with central corneal thickness and keratoconus

Central corneal thickness (CCT) is associated with eye conditions including keratoconus and glaucoma. We performed a meta-analysis on &gt;20,000 individuals in European and Asian populations that identified 16 new loci associated with CCT at genome-wide significance (P &lt; 5 × 10?8). We further showed that 2 CCT-associated loci, FOXO1 and FNDC3B, conferred relatively large risks for keratoconus in 2 cohorts with 874 cases and 6,085 controls (rs2721051 near FOXO1 had odds ratio (OR) = 1.62, 95% confidence interval (CI) = 1.4–1.88, P = 2.7 × 10?10, and rs4894535 in FNDC3B had OR = 1.47, 95% CI = 1.29–1.68, P = 4.9 × 10?9). FNDC3B was also associated with primary open-angle glaucoma (P = 5.6 × 10?4; tested in 3 cohorts with 2,979 cases and 7,399 controls). Further analyses implicate the collagen and extracellular matrix pathways in the regulation of CC