Orexin/Hypocretin Activates mTOR Complex 1 (mTORC1) via an Erk/Akt-independent and Calcium-stimulated Lysosome v-ATPase Pathway

The lack of the neuropeptide orexin, also known as hypocretin, results in narcolepsy, a chronic sleep disorder characterized by frequent sleep/cataplexy attacks and rapid eye movement sleep abnormalities. However, the downstream pathways of orexin signaling are not clearly understood. Here, we show that orexin activates the mTOR pathway, a central regulator of cell growth and metabolism, in the mouse brain and multiple recombinant cell lines that express the G protein-coupled receptors (GPCRs), orexin 1 receptor (OX1R) or orexin 2 receptor (OX2R). This orexin/GPCR-stimulated mTOR activation is sensitive to rapamycin, an inhibitor of mTOR complex 1 (mTORC1) but is independent of two well known mTORC1 activators, Erk and Akt. Rather, our studies indicate that orexin activates mTORC1 via extracellular calcium influx and the lysosome pathway involving v-ATPase and Rag GTPases. Moreover, a cytoplasmic calcium transient is sufficient to mimic orexin/GPCR signaling to mTORC1 activation in a v-ATPase-dependent manner. Together, our studies suggest that the mTORC1 pathway functions downstream of orexin/GPCR signaling, which plays a crucial role in many physiological and metabolic processes.     

Seeding-dependent maturation of beta2-microglobulin amyloid fibrils at neutral pH

Beta2-microglobulin (beta2-m) is a major component of amyloid fibrils deposited in patients with dialysis-related amyloidosis. Recent studies have focused on the mechanism by which amyloid fibrils are formed under physiological conditions, which had been difficult to reproduce quantitatively. Yamamoto et al. (Yamamoto, S., Hasegawa, K., Yamaguchi, I., Tsutsumi, S., Kardos, J., Goto, Y., Gejyo, F. & Naiki, H. (2004) Biochemistry 43, 11075-11082) showed that a combination of seed fibrils prepared under acidic conditions and a low concentration of sodium dodecyl sulfate below its critical micelle concentration enabled extensive fibril formation at pH 7.0. Here, we found that repeated self-seeding at pH 7.0 with fibrils formed at the same pH causes a marked acceleration of growth, indicating the maturation of fibrils. The observed maturation can be simulated by assuming the existence of two types of fibrils with different growth rates. Importantly, some mutations of beta2-m or the addition of a low concentration of urea, both destabilizing the native conformation, were not enough to extend the fibrils at pH 7.0, and a low concentration of sodium dodecyl sulfate (i.e. 0.5 mM) was essential. Thus, even though the first stage fibrils in patients are unstable and require stabilizing factors to remain at neutral pH, they can adapt to a neutral pH with repeated self-seeding, implying a mechanism of development of amyloid deposition after a long latent period in patients.     

Statins reduce all-cause mortality in chronic obstructive pulmonary disease: a systematic review and meta-analysis of observational studies

Background

Recent observational studies have suggested that use of statins reduces mortality in patients suffering from chronic obstructive pulmonary disease. However, no meta-analysis has reported the pooled hazard ratio of statins to all-cause mortality.

Methods

We searched for eligible articles using five databases. We included randomized controlled trials and cohort studies written in English using original data reporting the hazard ratio of statins to all-cause, cardiovascular-related, cancer-related, or respiratory-related mortality. A fixed model with the confidence interval method was used. Publication bias was evaluated by funnel plot and Begg’s test, and was corrected using Duval’s trim and fill method. Sensitivity analyses were also conducted.

Results

We included 10 out of 128 articles. The pooled hazard ratio of statins to all-cause mortality involving 16269 patients was 0.81 (95% CI: 0.75-0.86, P < 0.001) with moderate heterogeneity (I2 = 52%, P = 0.032). The sensitivity analysis and funnel plot suggested the existence of publication bias. After three possibly unpublished cohorts were imputed, the pooled hazard ratio of 0.83 (95% CI: 0.78-0.88, P < 0.001) still suggested a favorable prognosis in statin-treated patients. The pooled hazard ratio of statins to cardiovascular-related, cancer-related, and respiratory-related mortality were 0.52 (95% CI: 0.27-1.01, P = 0.052), 0.57 (95% CI: 0.32-1.01, P = 0.056), and 0.55 (95% CI: 0.43-0.78, P < 0.001), respectively, although these results were not conclusive as we could not find a sufficient number of original studies dealing with those forms of mortality.

Conclusions

The use of statins for patients suffering from chronic obstructive pulmonary disease may reduce all-cause mortality. This conclusion should be re-evaluated by a registered large-scale randomized controlled trial.     

zds1, a novel gene encoding an ortholog of Zds1 and Zds2, controls sexual differentiation, cell wall integrity and cell morphology in fission yeast

While screening for genes that reverse the sporulation-deficient phenotype of the ras1delta diploid Schizosaccharomyces pombe strain, we identified zds1. This gene shares sequence homology with the ZDS1 and ZDS2 genes from Saccharomyces cerevisiae, which appear to be involved in multiple cellular events. Expression of Zds1 in ras1delta diploid cells elevated their sporulation rate from 0.3 to 11.2%. Expression of the Zds1 C-terminal region increased the sporulation rate further (to 21.9%) while introduction of the Zds1 N-terminal region had no effect. zds1 expression did not induce sporulation in strains with mutations in genes participating in the downstream MAP kinase cascade. The zds1-disrupted strain is sensitive to CaCl2, and this effect is suppressed by the C-terminal region of Zds1. The growth of the zds1delta strain is markedly inhibited by cold temperatures, while its viability decreased in the stationary phase. Moreover, the zds1delta strain is round in shape and very sensitive to zymolyase, and its cell wall becomes thicker than that of wild type. Thus, zds1 must be required to maintain cell wall integrity. The Zds1-GFP fusion protein localized to the cytosol, the septum, and the cell cortex. Its localization in the septum was dependent on its C-terminal region. Overexpression of the C-terminal region of Zds1 induced multi-septa and abnormal zygotes. We propose that the C-terminal region is the functional domain of Zds1 while the N-terminal region is a negative regulatory region. Thus, Zds1 is involved in multiple cellular events in fission yeast, including sexual differentiation, Ca2+ tolerance, cell wall integrity, viability in the stationary phase, and cell morphology.     

Complete Genome Sequences of Corynebacterium pseudotuberculosis Strains 3/99-5 and 42/02-A, Isolated from Sheep in Scotland and Australia, Respectively

Here, we report the whole-genome sequences of two ovine-pathogenic Corynebacterium pseudotuberculosis isolates: strain 3/99-5, which represents the first C. pseudotuberculosis genome originating from the United Kingdom, and 42/02-A, the second from Australia. These genome sequences will contribute to the objective of determining the global pan-genome of this bacterium.     

Negative selection by IgM superantigen defines a B cell central tolerance compartment and reveals mutations allowing escape

To analyze B lymphocyte central tolerance in a polyclonal immune system, mice were engineered to express a superantigen reactive to IgM of allotype b (IgM(b)). IgM(b/b) mice carrying superantigen were severely B cell lymphopenic, but small numbers of B cells matured. Their sera contained low levels of IgG and occasionally high levels of IgA. In bone marrow, immature B cells were normal in number, but internalized IgM and had a unique gene expression profile, compared with those expressing high levels of surface IgM, including elevated recombinase activator gene expression. A comparable B cell population was defined in wild-type bone marrows, with an abundance suggesting that at steady state ～20% of normal developing B cells are constantly encountering autoantigens in situ. In superantigen-expressing mice, as well as in mice carrying the 3H9 anti-DNA IgH transgene, or 3H9 H along with mutation in the murine κ-deleting element RS, IgM internalization was correlated with CD19 downmodulation. CD19(low) bone marrow cells from 3H9;RS(-/-) mice were enriched in L chains that promote DNA binding. Our results suggest that central tolerance and attendant L chain receptor editing affect a large fraction of normal developing B cells. IgH(a/b) mice carrying the superantigen had a ～50% loss in follicular B cell numbers, suggesting that escape from central tolerance by receptor editing from one IgH allele to another was not a major mechanism. IgM(b) superantigen hosts reconstituted with experimental bone marrow were demonstrated to be useful in revealing pathways involved in central tolerance.     

Can breakfast tryptophan and vitamin B6 intake and morning exposure to sunlight promote morning-typology in young children aged 2 to 6 years?

ABSTRACT: This study tried to examine, from epidemiological and physiologic anthropological (Japanese culture on breakfast) points of view, the integrated effects of the amount of tryptophan and vitamin B6 intake and the following exposure to sunlight on the circadian typology and sleep habits in young Japanese children aged 2 to 6 years, using the newly-evaluated calculating system of tryptophan (Tryptophan Index 2009) and vitamin B6 intake (VitaminB6 Index 2009) at breakfast. The positive and significant correlation was shown between the Morningness-Eveningness (M-E) score and the Tryptophan Index and also the Vitamin B6 Index. This positive correlation between M-E score and amount of tryptophan intake was shown only by children who were exposed to sunlight for longer than 10min after breakfast. These results might support the following hypothesis: higher tryptophan and vitamin B6 intake at breakfast could promote the synthesis of serotonin via light stimulation in the morning in children.     

Distribution of monoclonal antibody subgroups and sequence-based types among Legionella pneumophila serogroup 1 isolates derived from cooling tower water, bathwater, and soil in Japan

Legionella pneumophila serogroup (SG) 1 is the most frequent cause of legionellosis. This study analyzed environmental isolates of L. pneumophila SG 1 in Japan using monoclonal antibody (MAb) typing and sequence-based typing (SBT). Samples were analyzed from bathwater (BW; n = 50), cooling tower water (CT; n = 50), and soil (SO; n = 35). The distribution of MAb types varied by source, with the most prevalent types being Bellingham (42%), Oxford (72%), and OLDA (51%) in BW, CT, and SO, respectively. The ratios of MAb 3/1 positive isolates were 26, 2, and 14% from BW, CT, and SO, respectively. The environmental isolates from BW, CT, and SO were divided into 34 sequence types (STs; index of discrimination [IOD] = 0.973), 8 STs (IOD = 0.448), and 11 STs (IOD = 0.879), respectively. Genetic variation among CT isolates was smaller than seen in BW and SO. ST1 accounted for 74% of the CT isolates. The only common STs between (i) BW and CT, (ii) BW and SO, and (iii) CT and SO were ST1, ST129, and ST48, respectively, suggesting that each environment constitutes an independent habitat.