Circadian variations in coagulation and fibrinolytic factors among four different strains of mice

This study examined circadian variation in coagulation and fibrinolytic parameters among Jcl:ICR, C3H/HeN, BALB/cA, and C57BL/6J strains of mice. Plasma plasminogen activator inhibitor 1 (PAI-1) levels fluctuated in a circadian manner and peaked in accordance with the mRNA levels at the start of the active phase in all strains. Fibrinogen mRNA levels peaked at the start of rest periods in all strains, although plasma fibrinogen levels remained constant. Strain differences in plasma antithrombin (AT) activity and protein C (PC) levels were then identified. Plasma AT activity was circadian rhythmic only in Jcl:ICR, but not in other strains, although the mRNA levels remained constant in all strains. Levels of plasma PC and its mRNA fluctuated in a circadian manner only in Jcl:ICR mice, whereas those of plasma prothrombin, factor X, factor VII, prothrombin time (PT), and activated partial thrombin time (APTT) remained constant in all strains. These results suggest that genetic heterogeneity underlies phenotypic variations in the circadian rhythmicity of blood coagulation and fibrinolysis. The circadian onset of thrombotic events might be due in part to the rhythmic gene expression of coagulation and fibrinolytic factors. The present study provides fundamental information about mouse strains that will help to understand the circadian variation in blood coagulation and fibrinolysis.     

A mutation in Tpst2 encoding tyrosylprotein sulfotransferase causes dwarfism associated with hypothyroidism

The growth-retarded (grt) mouse has an autosomal recessive, fetal-onset, severe thyroid hypoplasia related to TSH hyporesponsiveness. Through genetic mapping and complementation experiments, we show that grt is a missense mutation of a highly conserved region of the tyrosylprotein sulfotransferase 2 (Tpst2) gene, encoding one of the two Tpst genes implicated in posttranslational tyrosine O-sulfation. We present evidence that the grt mutation leads to a loss of TPST2 activity, and TPST2 isoform has a high degree of substrate preference for TSH receptor (TSHR). The expression of TPST2 can restore TSH-TSHR-mediated cAMP production in fibroblasts derived from grt mice. Therefore, we propose that the tyrosine sulfation of TSHR by TPST2 is crucial for TSH signaling and resultant thyroid gland function.     

Design and synthesis of novel prodrugs of 2'-deoxy-2'-methylidenecytidine activated by membrane dipeptidase overexpressed in tumor tissues

DNA microarray analysis comparing human tumor tissues with normal tissues including hematopoietic progenitor cells resulted in identification of membrane dipeptidase as a prodrug activation enzyme. Novel prodrugs of 2'-deoxy-2'-methylidenecytidine (DMDC) including compound 23 that are activated by membrane dipeptidase (MDP) preferentially in tumor tissue were designed and synthesized to generate the active drug, DMDC, after hydrolysis of the dipeptide bond followed by spontaneous cyclization of the promoiety.     

Liver X receptor antagonists with a phthalimide skeleton derived from thalidomide-related glucosidase inhibitors

Alpha-glucosidase inhibitors with a chlorinated phthalimide or a thiophthalimide skeleton, derived from thalidomide, were found to possess liver X receptor (LXR) antagonistic activity. Novel LXR antagonists with a 2'-substituted phenylphthalimide skeleton were obtained by structural development of glucosidase inhibitors derived from thalidomide.     

Central control of bone remodeling by neuromedin U

Bone remodeling, the function affected in osteoporosis, the most common of bone diseases, comprises two phases: bone formation by matrix-producing osteoblasts and bone resorption by osteoclasts. The demonstration that the anorexigenic hormone leptin inhibits bone formation through a hypothalamic relay suggests that other molecules that affect energy metabolism in the hypothalamus could also modulate bone mass. Neuromedin U (NMU) is an anorexigenic neuropeptide that acts independently of leptin through poorly defined mechanisms. Here we show that Nmu-deficient (Nmu-/-) mice have high bone mass owing to an increase in bone formation; this is more prominent in male mice than female mice. Physiological and cell-based assays indicate that NMU acts in the central nervous system, rather than directly on bone cells, to regulate bone remodeling. Notably, leptin- or sympathetic nervous system-mediated inhibition of bone formation was abolished in Nmu-/- mice, which show an altered bone expression of molecular clock genes (mediators of the inhibition of bone formation by leptin). Moreover, treatment of wild-type mice with a natural agonist for the NMU receptor decreased bone mass. Collectively, these results suggest that NMU may be the first central mediator of leptin-dependent regulation of bone mass identified to date. Given the existence of inhibitors and activators of NMU action, our results may influence the treatment of diseases involving low bone mass, such as osteoporosis.     

Temporally regulated asymmetric neurogenesis causes left-right difference in the zebrafish habenular structures

The habenular neurons on both sides of the zebrafish diencephalon show an asymmetric (laterotopic) axonal projection pattern into the interpeduncular nucleus. We previously revealed that the habenula could be subdivided into medial and lateral subnuclei, and a prominent left-right difference in the size ratio of these subnuclei accounts for the asymmetry in its neural connectivity. In the present study, birth date analysis showed that neural precursors for the lateral subnuclei were born at earlier stages than those for the medial subnuclei. More neurons for the early-born lateral subnuclei were generated on the left side, while more neurons for the late-born medial subnuclei were generated on the right side. Genetic hyperactivation and repression of Notch signaling revealed that differential timing determines both specificity and asymmetry in the neurogenesis of neural precursors for the habenular subnuclei.     

Roles of neuropeptides in O,O,S-trimethylphosphorothioate (OOS-TMP)-induced anorexia in mice

O,O,S-Trimethylphosphorothioate (OOS-TMP), an impurity present in various organophosphorus insecticides, has previously been shown to induce hypophagia. The major goal of this study was to investigate its mechanism of action. Both intracerebroventricular (i.c.v.) and intraperitoneal (i.p.) injection transiently induced hypophagia at a dose of 5mg/kg within 6h, without causing lung injury. Hypophagia was accompanied by up-regulation of corticotropin releasing factor (CRF) (2.92+/-0.45 vs. 1.7+/-0.5, at 2h after i.c.v., 3.40+/-1.38 vs. 1.76+/-0.41 at 6h after i.p., P<0.05) in the hypothalamus. After i.c.v. injection, hypophagia recovered by 6h after dosing. At doses higher than 5mg/kg, i.c.v. injection induced continuous hypophagia from 20min to 72h after dosing, accompanied by hypothermia and lung injury. OOS-TMP was considered to induce hypophagia through enhancing expression of CRF.     

Diverse DNA modification in marine prokaryotic and viral communities

DNA chemical modifications, including methylation, are widespread and play important roles in prokaryotes and viruses. However, current knowledge of these modification systems is severely biased towards a limited number of culturable prokaryotes, despite the fact that a vast majority of microorganisms have not yet been cultured. Here, using single-molecule real-time sequencing, we conducted culture-independent ‘metaepigenomic’ analyses (an integrated analysis of metagenomics and epigenomics) of marine microbial communities. A total of 233 and 163 metagenomic-assembled genomes (MAGs) were constructed from diverse prokaryotes and viruses, respectively, and 220 modified motifs and 276 DNA methyltransferases (MTases) were identified. Most of the MTase genes were not genetically linked with the endonuclease genes predicted to be involved in defense mechanisms against extracellular DNA. The MTase-motif correspondence found in the MAGs revealed 10 novel pairs, 5 of which showed novel specificities and experimentally confirmed the catalytic specificities of the MTases. We revealed novel alternative specificities in MTases that are highly conserved in Alphaproteobacteria, which may enhance our understanding of the co-evolutionary history of the methylation systems and the genomes. Our findings highlight diverse unexplored DNA modifications that potentially affect the ecology and evolution of prokaryotes and viruses in nature.     

Erebosis,a new cell death mechanism during homeostatic turnover of gut enterocytes

Many adult tissues are composed of differentiated cells and stem cells, each working in a coordinated manner to maintain tissue homeostasis during physiological cell turnover. Old differentiated cells are believed to typically die by apoptosis. Here, we discovered a previously uncharacterized, new phenomenon, which we name erebosis based on the ancient Greek word erebos (“complete darkness”), in the gut enterocytes of adult Drosophila. Cells that undergo erebosis lose cytoskeleton, cell adhesion, organelles and fluorescent proteins, but accumulate Angiotensin-converting enzyme (Ance). Their nuclei become flat and occasionally difficult to detect. Erebotic cells do not have characteristic features of apoptosis, necrosis, or autophagic cell death. Inhibition of apoptosis prevents neither the gut cell turnover nor erebosis. We hypothesize that erebosis is a cell death mechanism for the enterocyte flux to mediate tissue homeostasis in the gut.

It has been believed that gut enterocytes continuously die through apoptosis. However, this study shows that gut enterocytes die through a novel cell death mechanism, named erebosis. Erobotic cells lack the characteristic features of apoptotic, necrotic or autophagic cell death; instead they lose their cytoskeleton, cell adhesion and organelles, and their nuclei become flat and indistinct.     

MetaPlatanus: a metagenome assembler that combines long-range sequence links and species-specific features

De novo metagenome assembly is effective in assembling multiple draft genomes, including those of uncultured organisms. However, heterogeneity in the metagenome hinders assembly and introduces interspecies misassembly deleterious for downstream analysis. For this purpose, we developed a hybrid metagenome assembler, MetaPlatanus. First, as a characteristic function, it assembles the basic contigs from accurate short reads and then iteratively utilizes long-range sequence links, species-specific sequence compositions, and coverage depth. The binning information was also used to improve contiguity. Benchmarking using mock datasets consisting of known bacteria with long reads or mate pairs revealed the high contiguity MetaPlatanus with a few interspecies misassemblies. For published human gut data with nanopore reads from potable sequencers, MetaPlatanus assembled many biologically important elements, such as coding genes, gene clusters, viral sequences, and over-half bacterial genomes. In the benchmark with published human saliva data with high-throughput nanopore reads, the superiority of MetaPlatanus was considerably more evident. We found that some high-abundance bacterial genomes were assembled only by MetaPlatanus as near-complete. Furthermore, MetaPlatanus can circumvent the limitations of highly fragmented assemblies and frequent interspecies misassembles obtained by the other tools. Overall, the study demonstrates that MetaPlatanus could be an effective approach for exploring large-scale structures in metagenomes.