Structure of the Atg12–Atg5 conjugate reveals a platform for stimulating Atg8–PE conjugation

Atg12 is conjugated to Atg5 through enzymatic reactions similar to ubiquitination. The Atg12–Atg5 conjugate functions as an E3‐like enzyme to promote lipidation of Atg8, whereas lipidated Atg8 has essential roles in both autophagosome formation and selective cargo recognition during autophagy. However, the molecular role of Atg12 modification in these processes has remained elusive. Here, we report the crystal structure of the Atg12–Atg5 conjugate. In addition to the isopeptide linkage, Atg12 forms hydrophobic and hydrophilic interactions with Atg5, thereby fixing its position on Atg5. Structural comparison with unmodified Atg5 and mutational analyses showed that Atg12 modification neither induces a conformational change in Atg5 nor creates a functionally important architecture. Rather, Atg12 functions as a binding module for Atg3, the E2 enzyme for Atg8, thus endowing Atg5 with the ability to interact with Atg3 to facilitate Atg8 lipidation.     

Evaluation of high sensitive C-reactive protein and 5-10 methylenetetrahydrofolate reductase genotype in Japanese young adults

Primary objective: To carry out a preliminary evaluation of subclinical inflammation and its genetic background in young adults.

Research design: Fifty-five healthy Japanese young adults aged 19–27 years (37 males and 18 females, mean age: 22.3 years), and 58 healthy Japanese adults aged 40 to 60 years (21 males and 37 females, mean age: 51.5 years) were included in this study.

Methods and procedures: We measured plasma high-sensitive C-reactive protein (hs-CRP) levels and screened for the C677T polymorphism of the 5-10 methylenetetrahydrofolate reductase gene (MTHFR), which is considered a genetic risk factor for atherosclerosis, by HinfI digestion.

Main outcomes and results: Hs-CRP levels of the young adult group were significantly lower than the levels of the middle aged group (0.014±0.030 mg/dl vs. 0.031±0.040 mg/dl, p=0.005). The levels were significantly higher in males than in females (0.028±0.019 mg/dl vs. 0.013±0.010 mg/dl, p=0.008) among young adults. Furthermore, we evaluated the relationship of the C677T genotype and hs-CRP values, but found no association between them.

Conclusions: Although the sample size is limited, our preliminary study demonstrated the profiles of hs-CRP in Japanese young adults. Further investigation will be needed to establish the guidelines for customized school health education using sensitive laboratory and genetic markers.     

Development of simple sequence repeat markers and construction of a high-density linkage map of Capsicum annuum

To facilitate marker-assisted breeding and genetic analyses of pepper (Capsicum annuum), we developed non-redundant 2- or 3-base simple sequence repeat (SSR) markers from enriched C. annuum genomic libraries and from C. annuum cDNA sequences in public databases. The SSR-enriched libraries were constructed using combinations of three restriction enzymes (AluI, HaeIII, and RsaI) and two biotinylated oligonucleotides [b(GA)₁₅ and b(CA)₁₅]. Ultimately, we obtained 1,736 genomic SSR markers and 1,344 cDNA-derived SSR markers from 6,528 clones and 13,003 sequences, respectively. We mapped 597 markers, including 265 of the newly developed SSR markers, onto a linkage map by using doubled-haploid (DH) lines derived from an intraspecific cross of two pure lines of C. annuum (K9-11 × MZC-180). The map, designated as the KL-DH map, consisted of 12 linkage groups. The map covered a genetic distance of 2,028 cM, and the average distance between markers was less than 4 cM. The frame structure of the KL-DH map was compared with the published standard conserved ortholog set II (COSII) map, which was derived from an interspecific F₂ population (C. frutescens × C. annuum), by using tomato (Solanum lycopersicum) chromosomal sequences to bridge the two maps. The intraspecific KL-DH map constructed in this study and the interspecific COSII map were similar in map length and marker distribution, suggesting that the KL-DH map covers nearly the whole genome of C. annuum.     

Matrix-Embedded Osteocytes Regulate Mobilization of Hematopoietic Stem/Progenitor Cells

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Distribution and development of P2Y1-purinoceptors in the mouse retina

There is increasing evidence that ATP acts on purinergic receptors and mediates synaptic transmission in the retina. In a previous study, we raised the possibility that P2X-purinoceptors, presumably P2X₂-purinoceptors in OFF-cholinergic amacrine cells, play a key role in the formation of OFF pathway-specific modulation. In this study, we examined whether the P2Y₁-purinoceptors can function in cholinergic amacrine cells in the mouse retina since cholinergic amacrine cells in the rat retina express P2Y₁-purinoceptors. P2Y₁-purinoceptors were shown to be expressed in dendrites of both ON- and OFF-cholinergic amacrine cells in adults. At postnatal day 7, there was immunoreactivity for P2Y₁-purinoceptors in the soma of cholinergic amacrine cells. At postnatal day 14, weak immunoreactivity for P2Y₁-purinoceptors was detected in the dendrites but not in the soma of cholinergic amacrine cells. At postnatal day 21, strong immunoreactivity for P2Y₁-purinoceptors was detected in dendrites of cholinergic amacrine cells. The expression pattern of P2Y₁-purinoceptors was not affected by visual experience. We concluded that P2Y₁-purinoceptors are not involved in the OFF-pathway-specific signal transmission in cholinergic amacrine cells of the mouse retina.     

Crystallographic Observation of pH-Induced Conformational Changes in the Amyelois transitella Pheromone-Binding Protein AtraPBP1

The navel orangeworm, Amyelois transitella is a major agricultural pest causing large losses in a variety of tree crops. Control of this insect pest may be achieved by interfering with olfactory pathways to block detection of female-produced sex pheromones and consequently, disrupt mating. The first component of this pathway is the pheromone-binding protein AtraPBP1, which recognizes the pheromone and presents it to the odorant receptor housed in a sensory neuron of the male antennae. Release of the ligand depends on a pH-induced conformational change associated with the acidity of the membrane surface. To characterize this conformational change and to understand how pheromones bind, we have determined the high resolution crystal structures of AtraPBP1 in complex with two main constituents of the sex pheromone, i.e., (11Z,13Z)-hexadecadienal and (11Z,13Z)-hexadecadienol. Comparison with the structure of the unliganded form demonstrates a large ∼90° movement of the C-terminal helix which is observed in other pheromone- or odorant-binding proteins accompanied by an unpredicted 37° displacement of the N-terminal helix. Molecular dynamic trajectories suggest that the conformational change of the α1 helix facilitates the movement of the C-terminal helix.     

LORETA Current Source Density for Duration Mismatch Negativity and Neuropsychological Assessment in Early Schizophrenia

Introduction

Patients with schizophrenia elicit cognitive decline from the early phase of the illness. Mismatch negativity (MMN) has been shown to be associated with cognitive function. We investigated the current source density of duration mismatch negativity (dMMN), by using low-resolution brain electromagnetic tomography (LORETA), and neuropsychological performance in subjects with early schizophrenia.

Methods

Data were obtained from 20 patients meeting DSM-IV criteria for schizophrenia or schizophreniform disorder, and 20 healthy control (HC) subjects. An auditory odd-ball paradigm was used to measure dMMN. Neuropsychological performance was evaluated by the brief assessment of cognition in schizophrenia Japanese version (BACS-J).

Results

Patients showed smaller dMMN amplitudes than those in the HC subjects. LORETA current density for dMMN was significantly lower in patients compared to HC subjects, especially in the temporal lobes. dMMN current density in the frontal lobe was positively correlated with working memory performance in patients.

Conclusions

This is the first study to identify brain regions showing smaller dMMN current density in early schizophrenia. Further, poor working memory was associated with decreased dMMN current density in patients. These results are likely to help understand the neural basis for cognitive impairment of schizophrenia.