A mechanism for gene-environment interaction in the etiology of congenital scoliosis

Congenital scoliosis, a lateral curvature of the spine caused by vertebral defects, occurs in approximately 1 in 1,000 live births. Here we demonstrate that haploinsufficiency of Notch signaling pathway genes in humans can cause this congenital abnormality. We also show that in a mouse model, the combination of this genetic risk factor with an environmental condition (short-term gestational hypoxia) significantly increases the penetrance and severity of vertebral defects. We demonstrate that hypoxia disrupts FGF signaling, leading to a temporary failure of embryonic somitogenesis. Our results potentially provide a mechanism for the genesis of a host of common sporadic congenital abnormalities through gene-environment interaction.     

Computational design of high-affinity epitope scaffolds by backbone grafting of a linear epitope

Computational grafting of functional motifs onto scaffold proteins is a promising way to engineer novel proteins with pre-specified functionalities. Typically, protein grafting involves the transplantation of protein side chains from a functional motif onto structurally homologous regions of scaffold proteins. Using this approach, we previously transplanted the human immunodeficiency virus 2F5 and 4E10 epitopes onto heterologous proteins to design novel "epitope-scaffold" antigens. However, side-chain grafting is limited by the availability of scaffolds with compatible backbone for a given epitope structure and offers no route to modify backbone structure to improve mimicry or binding affinity. To address this, we report here a new and more aggressive computational method-backbone grafting of linear motifs-that transplants the backbone and side chains of linear functional motifs onto scaffold proteins. To test this method, we first used side-chain grafting to design new 2F5 epitope scaffolds with improved biophysical characteristics. We then independently transplanted the 2F5 epitope onto three of the same parent scaffolds using the newly developed backbone grafting procedure. Crystal structures of side-chain and backbone grafting designs showed close agreement with both the computational models and the desired epitope structure. In two cases, backbone grafting scaffolds bound antibody 2F5 with 30- and 9-fold higher affinity than corresponding side-chain grafting designs. These results demonstrate that flexible backbone methods for epitope grafting can significantly improve binding affinities over those achieved by fixed backbone methods alone. Backbone grafting of linear motifs is a general method to transplant functional motifs when backbone remodeling of the target scaffold is necessary.     

Penetration and differentiation of cephalic neural crest‐derived cells in the developing mouse telencephalon

Neural crest (NC) cells originate from the neural folds and migrate into the various embryonic regions where they differentiate into multiple cell types. A population of cephalic neural crest‐derived cells (NCDCs) penetrates back into the developing forebrain to differentiate into microvascular pericytes, but little is known about when and how cephalic NCDCs invade the telencephalon and differentiate into pericytes. Using a transgenic mouse line in which NCDCs are genetically labeled with enhanced green fluorescent protein (EGFP), we observed that NCDCs started to invade the telencephalon together with endothelial cells from embryonic day (E) 9.5. A majority of NCDCs located in the telencephalon expressed pericyte markers, that is, PDGFRβ and NG2, and differentiated into pericytes around E11.5. Surprisingly, many of the NC‐derived pericytes express p75, an undifferentiated NCDC marker at E11.5, as well as NCDCs in the mesenchyme. At the same time, a minor population of NCDCs that located separately from blood vessels in the telencephalon were NG2‐negative and some of these NCDCs also expressed p75. Proliferation and differentiation of pericytes appeared to occur in a specific mesenchymal region where blood vessels penetrated into the telencephalon. These results indicate that (i) NCDCs penetrate back into the telencephalon in parallel with angiogenesis, (ii) many NC‐derived pericytes may be still in pre‐mature states even though after differentiation into pericytes in the early developing stages, (iii) a small minority of NCDCs may retain undifferentiated states in the developing telencephalon, and (iv) a majority of NCDCs proliferate and differentiate into pericytes in the mesenchyme around the telencephalon.     

Comparing methods of acquiring mammalian endozoochorous seed dispersal distance distributions

Research on endozoochorous seed dispersal is needed to further understand plant ecology and evolution. There are several methods for calculating the distribution of seed dispersal distances, although many studies use the “combination of gut retention time and movement data” (CGM) method to determine the potential seed dispersal distance distribution (PSD). However, there have been no evaluations of between PSD values acquired by CGM and seed dispersal distance distributions calculated using other methods. The main purpose of this study was to compare methods of determining seed dispersal distance distributions using raccoon dogs (Nyctereutes procyonoides). We calculated estimated seed dispersal distance distribution (ESD) using the bait-marker method and PSD using the CGM method. There were no differences between the ESD and PSD results with regard to basic dispersal distance distributions. The results indicate that if the region from which animal movement data was acquired and the region from which markers for the bait-marker method have been collected are the same, the distance distributions using the two methods may match. Additionally, though there were differences in seed mimic gut retention times (GRTs) between the two baits used (median GRT, fruits: 8 h 50 min, animal materials: 12 h 55 min), there were no differences in PSD between the two baits. This indicates that disperser movement has a stronger effect on dispersal distance distribution than GRT when using the CGM method.     

Structure of the human GINS complex and its assembly and functional interface in replication initiation

The eukaryotic GINS complex is essential for the establishment of DNA replication forks and replisome progression. We report the crystal structure of the human GINS complex. The heterotetrameric complex adopts a pseudo symmetrical layered structure comprising two heterodimers, creating four subunit-subunit interfaces. The subunit structures of the heterodimers consist of two alternating domains. The C-terminal domains of the Sld5 and Psf1 subunits are connected by linker regions to the core complex, and the C-terminal domain of Sld5 is important for core complex assembly. In contrast, the C-terminal domain of Psf1 does not contribute to the stability of the complex but is crucial for chromatin binding and replication activity. These data suggest that the core complex ensures a stable platform for the C-terminal domain of Psf1 to act as a key interaction interface for other proteins in the replication-initiation process.     

Design, synthesis and biological activity of selective and orally available TF/FVIIa complex inhibitors containing non-amidine P1 ligands

We found the novel selective and orally available non-amidine TF/FVIIa complex inhibitor 21e, 4-({[(1S)-(aminocarbonyl)-3-methylbutyl]amino}carbonyl)-2'-({[4- (aminomethyl)phenyl]amino}carbonyl)-4'-(methylamino)biphenyl-2- carboxylic acid. The derivatives were synthesized by conversions of the isobutyl moiety and the introduction of alkylamino groups to 4'-position of the central phenyl ring of compounds 2a and 2b reported previously. Some compounds show increased in vitro anti-TF/FVIIa and PT prolongation activities. Among them, compound 21e reached and sustained micromolar plasma concentration levels of up to 2h after oral administration in mice. Moreover, compound 21e did not prolong the bleeding time even at the highest dose level in cynomolgus monkeys, while PT was prolonged 3.7-fold increases at this dose.