7-Oxopyrrolopyridine-derived DPP4 inhibitors-mitigation of CYP and hERG liabilities via introduction of polar functionalities in the active site

Design, synthesis, and SAR of 7-oxopyrrolopyridine-derived DPP4 inhibitors are described. The preferred stereochemistry of these atropisomeric biaryl analogs has been identified as Sa. Compound (+)-3t, with a K(i) against DPP4, DPP8, and DPP9 of 0.37 nM, 2.2, and 5.7 μM, respectively, showed a significant improvement in insulin response after single doses of 3 and 10 μmol/kg in ob/ob mice.     

The identification of 4,7-disubstituted naphthoic acid derivatives as UDP-competitive antagonists of P2Y14

A weak, UDP-competitive antagonist of the pyrimidinergic receptor P2RY₁₄ with a naphthoic acid core was identified through high-throughput screening. Optimization provided compounds with improved potency but poor pharmacokinetics. Acylglucuronidation was determined to be the major route of metabolism. Increasing the electron-withdrawing nature of the substituents markedly reduced glucuronidation and improved the pharmacokinetic profile. Additional optimization led to the identification of compound 38 which is an 8 nM UDP-competitive antagonist of P2Y₁₄ with a good pharmacokinetic profile.     

A structural characterization of human SCO2

Human Sco2 is a mitochondrial membrane-bound protein involved in copper supply for the assembly of cytochrome c oxidase in eukaryotes. Its precise action is not yet understood. We report here a structural and dynamic characterization by NMR of the apo and copper(I) forms of the soluble fragment. The structural and metal binding features of human Cu(I)Sco2 are similar to the more often studied Sco1 homolog, although the dynamic properties and the conformational disorder are quite different when the apo forms and the copper(I)-loaded forms of the two proteins are compared separately. Such differences are accounted for in terms of the different physicochemical properties in strategic protein locations. The misfunction of the known pathogenic mutations is discussed on the basis of the obtained structure.     

Mitochondrial DNA defects in Saccharomyces cerevisiae caused by functional interactions between DNA polymerase gamma mutations associated with disease in human

The yeast mitochondrial DNA (mtDNA) replicase Mip1 has been used as a model to generate five mutations equivalent to POLG mutations associated with a broad spectrum of diseases in human. All mip1 mutations, alone or in combination in cis or in trans, increase mtDNA instability as measured by petite frequency and Ery(R) mutant accumulation. This phenotype is associated with decreased Mip1 levels in mitochondrial extracts and/or decreased polymerase activity. We have demonstrated that (1) in the mip1(G651S) (hG848S) mutant the high mtDNA instability and increased frequency of point Ery(R) mutations is associated with low Mip1 levels and polymerase activity; (2) in the mip1(A692T-E900G) (hA889T-hE1143G) mutant, A692T is the major contributor to mtDNA instability by decreasing polymerase activity, and E900G acts synergistically by decreasing Mip1 levels; (3) in the mip1(H734Y)/mip1(G807R) (hH932Y/hG1051R) mutant, H734Y is the most deleterious mutation and acts synergistically with G807R as a result of its dominant character; (4) the mip1(E900G) (h1143G) mutation is not neutral but results in a temperature-sensitive phenotype associated with decreased Mip1 levels, a property explaining its synergistic effect with mutations impairing the polymerase activity. Thus, the human E1143G mutation is not a true polymorphism.     

Clonal diversity impacts coral cover in Acropora cervicornis thickets: Potential relationships between density,growth, and polymorphisms

As coral reefs decline, cryptic sources of resistance and resilience to stress may be increasingly important for the persistence of these communities. Among these sources, inter‐ and intraspecific diversity remain understudied on coral reefs but extensively impact a variety of traits in other ecosystems. We use a combination of field and sequencing data at two sites in Florida and two in the Dominican Republic to examine clonal diversity and genetic differentiation of high‐ and low‐density aggregations of the threatened coral Acropora cervicornis in the Caribbean. We find that high‐density aggregations called thickets are composed of up to 30 genotypes at a single site, but 47% of genotypes are also found as isolated, discrete colonies outside these aggregations. Genet–ramet ratios are comparable for thickets (0.636) and isolated colonies after rarefaction (0.569), suggesting the composition of each aggregation is not substantially different and highlighting interactions between colonies as a potential influence on structure. There are no differences in growth rate, but a significant positive correlation between genotypic diversity and coral cover, which may be due to the influence of interactions between colonies on survivorship or fragment retention during asexual reproduction. Many polymorphisms distinguish isolated colonies from thickets despite the shared genotypes found here, including putative nonsynonymous mutations that change amino acid sequence in 25 loci. These results highlight intraspecific diversity as a density‐dependent factor that may impact traits important for the structure and function of coral reefs.     

New insights into the dynamics between reef corals and their associated dinoflagellate endosymbionts from population genetic studies

The mutualistic symbioses between reef‐building corals and micro‐algae form the basis of coral reef ecosystems, yet recent environmental changes threaten their survival. Diversity in host‐symbiont pairings on the sub‐species level could be an unrecognized source of functional variation in response to stress. The Caribbean elkhorn coral, Acropora palmata, associates predominantly with one symbiont species (Symbiodinium ‘fitti’), facilitating investigations of individual‐level (genotype) interactions. Individual genotypes of both host and symbiont were resolved across the entire species’ range. Most colonies of a particular animal genotype were dominated by one symbiont genotype (or strain) that may persist in the host for decades or more. While Symbiodinium are primarily clonal, the occurrence of recombinant genotypes indicates sexual recombination is the source of this genetic variation, and some evidence suggests this happens within the host. When these data are examined at spatial scales spanning the entire distribution of A. palmata, gene flow among animal populations was an order of magnitude greater than among populations of the symbiont. This suggests that independent micro‐evolutionary processes created dissimilar population genetic structures between host and symbiont. The lower effective dispersal exhibited by the dinoflagellate raises questions regarding the extent to which populations of host and symbiont can co‐evolve during times of rapid and substantial climate change. However, these findings also support a growing body of evidence, suggesting that genotype‐by‐genotype interactions may provide significant physiological variation, influencing the adaptive potential of symbiotic reef corals to severe selection.     

Unrecognized coral species diversity masks differences in functional ecology

Porites corals are foundation species on Pacific reefs but a confused taxonomy hinders understanding of their ecosystem function and responses to climate change. Here, we show that what has been considered a single species in the eastern tropical Pacific, Porites lobata, includes a morphologically similar yet ecologically distinct species, Porites evermanni. While P. lobata reproduces mainly sexually, P. evermanni dominates in areas where triggerfish prey on bioeroding mussels living within the coral skeleton, thereby generating asexual coral fragments. These fragments proliferate in marginal habitat not colonized by P. lobata. The two Porites species also show a differential bleaching response despite hosting the same dominant symbiont subclade. Thus, hidden diversity within these reef-builders has until now obscured differences in trophic interactions, reproductive dynamics and bleaching susceptibility, indicative of differential responses when confronted with future climate change.     

��-Catenin Is Genetically and Biologically Associated with Cortical Cataract and Future Alzheimer-Related Structural and Functional Brain Changes

Multiple lines of evidence suggest that specific subtypes of age-related cataract (ARC) and Alzheimer disease (AD) are related etiologically. To identify shared genetic factors for ARC and AD, we estimated co-heritability of quantitative measures of cataract subtypes with AD-related brain MRI traits among 1,249 members of the Framingham Eye Study who had a brain MRI scan approximately ten years after the eye exam. Cortical cataract (CC) was found to be co-heritable with future development of AD and with several MRI traits, especially temporal horn volume (THV, ρ = 0.24, P<10⁻⁴). A genome-wide association study using 187,657 single nucleotide polymorphisms (SNPs) for the bivariate outcome of CC and THV identified genome-wide significant association with CTNND2 SNPs rs17183619, rs13155993 and rs13170756 (P<2.6×10⁻⁷). These SNPs were also significantly associated with bivariate outcomes of CC and scores on several highly heritable neuropsychological tests (5.7×10⁻⁹≤P<3.7×10⁻⁶). Statistical interaction was demonstrated between rs17183619 and APP SNP rs2096488 on CC (P = 0.0015) and CC-THV (P = 0.038). A rare CTNND2 missense mutation (G810R) 249 base pairs from rs17183619 altered δ-catenin localization and increased secreted amyloid-β_1–42 in neuronal cell culture. Immunohistopathological analysis of lens tissue obtained from two autopsy-confirmed AD subjects and two non-AD controls revealed elevated expression of δ-catenin in epithelial and cortical regions of lenses from AD subjects compared to controls. Our findings suggest that genetic variation in delta catenin may underlie both cortical lens opacities in mid-life and subsequent MRI and cognitive changes that presage the development of AD.