Efficient collection of a large number of mutations by mutagenesis of DNA damage response defective animals.

With the development of massive parallel sequencing technology, it has become easier to establish new model organisms that are ideally suited to the specific biological phenomena of interest. Considering the history of research using classical model organisms, we believe that the efficient construction and sharing of gene mutation libraries will facilitate the progress of studies using these new model organisms. Using C. elegans, we applied the TMP/UV mutagenesis method to animals lacking function in the DNA damage response genes atm-1 and xpc-1. This method produces genetic mutations three times more efficiently than mutagenesis of wild-type animals. Furthermore, we confirmed that the use of next-generation sequencing and the elimination of false positives through machine learning could automate the process of mutation identification with an accuracy of over 95%. Eventually, we sequenced the whole genomes of 488 strains and isolated 981 novel mutations generated by the present method; these strains have been made available to anyone who wants to use them. Since the targeted DNA damage response genes are well conserved and the mutagens used in this study are also effective in a variety of species, we believe that our method is generally applicable to a wide range of animal species.

Effects of concomitant use of prasugrel with edoxaban on bleeding time, pharmacodynamics, and pharmacokinetics of edoxaban in healthy elderly Japanese male subjects: a clinical pharmacology study.

BACKGROUND: Dual therapy with a direct oral anticoagulant (DOAC) plus a P2Y12 receptor inhibitor is recommended in patients with nonvalvular atrial fibrillation who undergo percutaneous coronary intervention. Thus, we evaluated the effects of DOAC edoxaban plus P2Y12 receptor inhibitor prasugrel on bleeding time (BT), and pharmacodynamics (PD) and pharmacokinetics (PK) of edoxaban in healthy elderly Japanese male subjects. METHODS: A single-center, clinical pharmacology study with randomized, open-label, repeated dosing enrolled 24 participants in two groups of 12 receiving 30 mg edoxaban once daily for 3 days; then 30 mg edoxaban plus 2.5 mg prasugrel (Group 1) or 30 mg edoxaban plus 3.75 mg prasugrel (Group 2) once daily for 5 days. Primary endpoint was BT by the Ivy method. Secondary endpoints were the PD parameters of prothrombin time (PT), activated partial thromboplastin time (aPTT), prothrombin fragment F1 + 2 (F1 + 2), and P2Y12 reaction units (PRU), and PK profiles of edoxaban alone and in combination with prasugrel. RESULTS: Geometric least squares mean of BT ratios (vs. baseline) for 3-day edoxaban treatment were 1.097 (90% confidence interval (CI) 0.911-1.321) in Group 1 and 1.327 (90% CI 1.035-1.703) in Group 2; for 5-day edoxaban plus 2.5 mg and 3.75 mg prasugrel, they were 1.581 (90% CI 1.197-2.087) and 1.996 (90% CI 1.482-2.690), respectively. Contributions of prasugrel to the effects (edoxaban + prasugrel/edoxaban) were 1.442 (90% CI 1.096-1.897) in Group 1 and 1.504 (90% CI 1.172-1.930) in Group 2. Edoxaban prolonged PT and aPTT and decreased F1 + 2. Adding on prasugrel did not appreciably change PT, aPTT, or F1 + 2. Prasugrel reduced PRU, whereas edoxaban had no effect on PRU. We recorded 26 adverse events; 23 were treatment-emergent (positive fecal occult blood test). All participants with adverse events recovered during follow-up. CONCLUSIONS: Coadministration of 2.5 mg and 3.75 mg prasugrel with 30 mg edoxaban prolonged BT in healthy elderly Japanese male subjects. The effect was dependent on the dose of prasugrel. Prasugrel did not affect PD or PK profiles of edoxaban. Edoxaban had no effect on PD of prasugrel. TRIAL REGISTRATION: Japan Registry of Clinical Trials No. jRCTs071190006; registration date, 26-April-2019.

Relationship Between Platelet Reactivity and Ischemic and Bleeding Events After Percutaneous Coronary Intervention in East Asian Patients: 1-Year Results of the PENDULUM Registry.

Background The balance between ischemic and bleeding events and their association with platelet reactivity in patients receiving antiplatelet therapy after percutaneous coronary intervention (PCI), which differs among regions, is not fully evaluated for East Asians. We examined ischemic/bleeding events and platelet reactivity in Japanese patients undergoing PCI and determined associations between high/low platelet reactivity and clinical outcomes. Methods and Results PENDULUM (Platelet Reactivity in Patients with Drug Eluting Stent and Balancing Risk of Bleeding and Ischemic Event) is a prospective, multicenter registry of Japanese patients with PCI. Primary end points were incidence of first major adverse cardiac and cerebrovascular events (MACCE) and first major bleeding events at 12 months post-PCI. Platelet reactivity (P2Y12 reaction unit [PRU] value) was measured at 12 to 48 hours post-PCI; patients were grouped as having high PRU (>208), optimal PRU (>85 to ≤208), and low PRU (≤85). MACCE and major bleeding occurred in 4.4% and 2.8% of 6267 patients, respectively. The mean±SD PRU value was 182.1±77.1. MACCE was significantly higher in the high PRU (5.7%; n=2227) versus the optimal PRU group (3.6%; n=3002). The hazard ratio (HR) for high PRU versus optimal PRU level was significantly higher for MACCE (adjusted HR, 1.53; 95% CI, 1.14-2.06 [P=0.004]); stent thrombosis followed the same trend. Incidence of major bleeding did not differ significantly between groups. A high PRU level was significantly associated with MACCE in both patients with and patients without acute coronary syndrome. Conclusions These real-world data suggest an association between high platelet reactivity and cardiovascular events in Japanese patients undergoing PCI. The trend was the same in both patients with and patients without acute coronary syndrome. REGISTRATION URL: https://www.umin.ac.jp/ctr. Unique identifier: UMIN 000020332.

Somatic mutations and increased lymphangiogenesis observed in a rare case of intramucosal gastric carcinoma with lymph node metastasis.

BACKGROUND AND AIM: Intramucosal gastric adenocarcinoma of the well-moderately differentiated type only exhibits lymph node metastasis in extremely rare cases. We encountered such case and investigated both the lymphangiogenic properties and somatic mutations in the cancer to understand the prometastatic features of early-stage gastric cancer. METHODS: We quantitatively measured the density of lymphatic vessels and identified mutations in 412 cancer-associated genes through next-generation target resequencing of DNA extracted from tumor cells in a formalin-fixed and paraffin-embedded tissue. Functional consequence of the identified mutation was examined in vitro by means of gene transfection, immunoblot, and the quantitative real-time polymerase chain reaction assay. RESULTS: The intramucosal carcinoma was accompanied by abundant lymphatic vessels. The metastatic tumor harbored somatic mutations in NBN, p.P6S, and PAX8, p.R49H. The PAX8R49H showed significantly higher transactivation activity toward E2F1 than the wild-type PAX8 (P< 0.001). CONCLUSIONS: Our data suggest that increased lymphangiogenesis and somatic mutations of NBN and/or PAX8 could facilitate lymph node metastasis from an intramucosal gastric carcinoma. These findings may potentially inform evaluations of the risk of developing lymph node metastasis in patients with intramucosal gastric cancer.

An Aneuploidy-Free and Structurally Defined Balancer Chromosome Toolkit for Caenorhabditis elegans.

Balancer chromosomes are critical tools for genetic research. In C. elegans, reciprocal translocations that lead to aneuploidy have been widely used to maintain lethal and sterile mutations in stable stocks. Here, we generated a set of aneuploidy-free and structurally defined crossover suppressors that contain two overlapping inversions using the CRISPR/Cas9 system. The toolkit includes 13 crossover suppressors and covers approximately 63% of all C. elegans coding genes. Together with the classical intrachromosomal crossover suppressors, the system now covers 89% of the coding genes. We also labeled the created balancers with fluorescent and phenotypic markers. We show that the crossover suppressors are better for embryonic analysis compared with translocational balancers. Additionally, we demonstrate an efficient method to generate lethal alleles by targeting essential genes on a chromosome balanced with a crossover suppressor. The toolkit will allow more efficient experiments in which lethal and sterile mutants can be analyzed.

Enhanced levels of both the membrane-bound and soluble forms of IgM Fc receptor (FcµR) in patients with chronic lymphocytic leukemia.

The association of an IgM-Fc receptor (FcµR) with chronic lymphocytic leukemia (CLL) was suggested more than 30 years ago, but its authenticity has never been formally addressed. We examined the expression of the recently identified FcµR by B and T cells in CLL patients using receptor-specific monoclonal antibodies. CLL B cells (CD5(+)/CD19(+)) expressed much higher levels of FcµR on their cell surface than B cells from healthy donors. Such enhanced expression was more evident in immunoglobulin heavy chain variable region (IGHV)-mutated, CD38(-) or early Rai-stage CLL than in IGHV-unmutated, CD38(+), or advanced Rai-stage CLL. Intriguingly, surface FcµR levels also were significantly elevated in the non-CLL B cells (CD5(-)/CD19(+)) and T cells (CD5(+)/CD19(-)), especially in IGHV-mutated CLL. CLL patients also had high serum titers of FcµR compared with healthy donors, and serum FcµR levels correlated significantly with circulating lymphocyte numbers but not with the IGHV mutation status or Rai stage. The serum FcµR was resolved as an ∼ 40-kDa protein, distinct from the cell surface FcµR of ∼ 60 kDa, and it was produced by both CLL B and non-CLL B cells. Mass spectrometric analysis revealed that the serum FcµR is a soluble form of the receptor encoded by an alternatively spliced FcµR transcript. These findings indicate enhanced levels of both membrane-bound and soluble forms of FcµR in CLL patients.

Silkworm expression and sugar profiling of human immune cell surface receptor, KIR2DL1.

Immune cell surface receptors are directly involved in human diseases, and thus represent major drug targets. However, it is generally difficult to obtain sufficient amounts of these receptors for biochemical and structural studies because they often require posttranslational modifications, especially sugar modification. Recently, we have established a bacmid expression system for the baculovirus BmNPV, which directly infects silkworms, an attractive host for the large-scale production of recombinant sugar-modified proteins. Here we produced the human immune cell surface receptor, killer cell Ig-like receptor 2DL1 (KIR2DL1), by using the BmNPV bacmid expression system, in silkworms. By the direct injection of the bacmid DNA, the recombinant KIR2DL1 protein was efficiently expressed, secreted into body fluids, and purified by Ni(2+) affinity column chromatography. We further optimized the expression conditions, and the final yield was 0.2mg/larva. The sugar profiling revealed that the N-linked sugars of the purified protein comprised very few components, two paucimannose-type oligosaccharides, Manalpha1-6Manbeta1-4GlcNAcbeta1-4GlcNAc and Manalpha1-6Manbeta1-4GlcNAcbeta1-4(Fucalpha1-6)GlcNAc. This revealed that the protein product was much more homogeneous than the complex-sugar type product obtained by mammalian cell expression. The surface plasmon resonance analysis demonstrated that the purified KIR2DL1 protein exhibited specific binding to the HLA-Cw4 ligand. Moreover, the CD spectrum showed the proper secondary structure. These results clearly suggested that the silkworm expression system is quite useful for the expression of cell surface receptors that require posttranslational modifications, as well as for their structural and binding studies, due to the relatively homogeneous N-linked sugar modifications.

Efficient silkworm expression of human GPCR (nociceptin receptor) by a Bombyx mori bacmid DNA system.

Guanine nucleotide-binding protein (G protein) coupled receptors (GPCRs) are frequently expressed by a baculovirus expression vector system (BEVS). We recently established a novel BEVS using the bacmid system of Bombyx mori nucleopolyhedrovirus (BmNPV), which is directly applicable for protein expression in silkworms. Here, we report the first example of GPCR expression in silkworms by the simple injection of BmNPV bacmid DNA. Human nociceptin receptor, an inhibitory GPCR, and its fusion protein with inhibitory G protein alpha subunit (G(i)alpha) were both successfully expressed in the fat bodies of silkworm larvae as well as in the BmNPV viral fraction. Its yield was much higher than that from Sf9 cells. The microsomal fractions including the nociceptin receptor fusion, which are easily prepared by only centrifugation steps, exhibited [35S]GTPgammaS-binding activity upon specific stimulation by nociceptin. Therefore, this rapid method is easy-to-use and has a high expression level, and thus will be an important tool for human GPCR production.

Efficient large-scale protein production of larvae and pupae of silkworm by Bombyx mori nuclear polyhedrosis virus bacmid system.

Silkworm is one of the most attractive hosts for large-scale production of eukaryotic proteins as well as recombinant baculoviruses for gene transfer to mammalian cells. The bacmid system of Autographa californica nuclear polyhedrosis virus (AcNPV) has already been established and widely used. However, the AcNPV does not have a potential to infect silkworm. We developed the first practical Bombyx mori nuclear polyhedrosis virus bacmid system directly applicable for the protein expression of silkworm. By using this system, the green fluorescence protein was successfully expressed in silkworm larvae and pupae not only by infection of its recombinant virus but also by direct injection of its bacmid DNA. This method provides the rapid protein production in silkworm as long as 10 days, is free from biohazard, thus will be a powerful tool for the future production factory of recombinant eukaryotic proteins and baculoviruses.

The PGL family proteins associate with germ granules and function redundantly in Caenorhabditis elegans germline development.

PGL-1 is a constitutive protein component of C. elegans germ granules, also known as P granules. Maternally supplied PGL-1 is essential for germline development but only at elevated temperature, raising the possibility that redundant factors provide sufficient function at lower temperatures. We have identified two PGL-1-related proteins, PGL-2 and PGL-3, by sequence analysis of the C. elegans genome and by a yeast two-hybrid screen for proteins that interact with PGL-1. PGL-3 is associated with P granules at all stages of development, while PGL-2 is associated with P granules only during postembryonic development. All three PGL proteins interact with each other in vitro. Furthermore, PGL-1 and PGL-3 are co-immunoprecipitated from embryo extracts, indicating that they are indeed in the same protein complex in vivo. Nevertheless, each PGL protein localizes to P granules independently of the other two. pgl-2 or pgl-3 single-mutant worms do not show obvious defects in germline development. However, pgl-1; pgl-3 (but not pgl-2; pgl-1) double-mutant hermaphrodites and males show significantly enhanced sterility at all temperatures, compared to pgl-1 alone. Mutant hermaphrodites show defects in germline proliferation and in production of healthy gametes and viable embryos. Our findings demonstrate that both PGL-2 and PGL-3 are components of P granules, both interact with PGL-1, and at least PGL-3 functions redundantly with PGL-1 to ensure fertility in both sexes of C. elegans.