Biology subjects

Ikeda, N.

Publications and source records attributed to Ikeda, N..

5 recordsLinked to original sources

bioRxiv2025

Secreted protein methyltransferase METTL9 catalyzes Nπ-histidine methylation of extracellular plasma proteins

Post-translational modifications (PTMs) of proteins alter their biophysical properties, thus affecting their activity, localization and interactions. These reactions are principally intracellular events; however, to date, only phosphorylation has been shown to occur within the extracellular space. Here, we identified METTL9 as the first secreted methyltransferase responsible for N{pi}-histidine methylation. METTL9 undergoes N-linked glycosylation, thereby forming dimers via disulfide bonds. Using a split-luciferase complementary assay, we revealed that N-glycosylated METTL9 is secreted extracellularly via the ER-Golgi pathway. Endogenous METTL9 is highly expressed in HL60 cells during neutrophil-like differentiation and secreted extracellularly. METTL9 catalyzes N{pi}-methylhistidine formation in plasma proteins, in which the thyroxine transporter transthyretin (TTR) and copper transporter ceruloplasmin are identified as substrates for methylation in vitro. Both methylations occur at the His-x-His motif, a recognition sequence for METTL9, and TTR methylation decreases its binding affinity to zinc. Our results establish that histidine methylation is the second extracellular PTM, following phosphorylation.

biochemistry↗

bioRxiv2025

Genotype-first approach revealed unrecognized breed-specific genetic diseases in dogs

Numerous dogs are affected by genetic diseases because of their unique breeding situation. The identification of pathogenic variants in dogs not only has veterinary benefits but also leads to the development of new human disease models. However, fewer pathogenic variants have been identified in dogs than in humans, and standard genetic approaches, such as large-scale case/control studies and family analyses, often fail to identify novel causative variants in dogs. To address this, we applied a genotype-first approach by developing a multiplex polymerase chain reaction (PCR)-based targeted sequencing method for dogs, analyzing 203 genes--most of which are related to human disease--from 6,333 dogs collected from a veterinary hospital, and characterizing pathogenic variant carriers. In total, 120 pathogenic variants in 83 genes were identified. Frequent pathogenic variants were enriched in specific dog breeds. Dogs homozygous for a pathogenic CHEK2 variant, frequently identified in French Bulldogs (5.74%, homozygous), showed a five-fold increased risk of cancer (P = 3.45 x 10-2). A pathogenic NOD2 variant was detected in half of the Italian Greyhounds. However, their medical records did not document the typical clinical symptoms observed in humans with NOD2 deficiency. Some pathogenic variants were present in three or fewer dogs, and 11.0% of these dogs exhibited symptoms potentially associated with gene defects. These rare variants could become common within a short period due to the canine breeding system to induce breed-specific genetic diseases. These findings suggest that the genotype-first approach successfully identified unrecognized breed-specific genetic diseases. Further characterization of dogs with pathogenic variants enable to define clinical diagnosis, providing an important spontaneous model for human genetic diseases.

genomics↗

bioRxiv2021

CCR4 blockade leads to clinical activity and prolongs survival in a canine model of advanced prostate cancer

Targeting regulatory T cell (Treg) infiltration is an emerging strategy for cancer immunotherapy. However, the efficacy of this strategy in advanced prostate cancer remains unclear. Here, we describe the therapeutic efficacy of this strategy in a canine model of advanced prostate cancer. We used dogs with naturally occurring prostate cancer to study the molecular mechanism underlying Treg infiltration into tumor tissues and the effect of anti-Treg treatment. We found that tumor-infiltrating Tregs were associated with poor prognosis in dogs bearing spontaneous prostate cancer. RNA sequencing and protein analyses showed that Treg infiltration was mediated by interaction between the tumor-producing chemokine, CCL17, and the receptor CCR4 expressed on Tregs. Dogs with advanced prostate cancer responded to mogamulizumab, a monoclonal antibody targeting CCR4, with improved survival and low incidence of clinically relevant adverse events. Exploratory analyses showed urinary CCL17 concentration and BRAFV595E mutation to be independently predictive of the response to mogamulizumab. Analysis of a publicly available transcriptomic dataset of human prostate cancer showed that the CCL17/CCR4 axis correlated with the Treg marker, Foxp3. In silico survival analyses showed that high expression of CCL17 was associated with poor prognosis. Immunohistochemistry confirmed that tumor-infiltrating Tregs expressed CCR4 in human patients with prostate cancer. These findings suggest that anti-Treg treatment through the blocking of CCR4 is a promising therapeutic approach for advanced prostate cancer. One Sentence SummaryTargeting regulatory T cell infiltration by CCR4 blockade induces objective responses and improves survival in a canine model of prostate cancer.

cancer biology↗

bioRxiv2020

Circumstances and factors of sleep-related sudden infant deaths in Japan

Background Sudden unexpected death in infancy (SUDI) comprises both natural and unnatural causes of death. However, a few epidemiological surveys have investigated SUDI in Japan.Objective This retrospective study was conducted to investigate the recent trends of circumstances and risk factors of sleep-related SUDI cases.Methods Forensic pathology sections from eight universities participated in the selection of subjects from 2013 to 2018. Data obtained from the checklist form were analyzed based on information at postmortem.Results There were 259 SUDI cases consisting of 145 male infants and 114 female infants with a mean birth weight of 2888 ± 553 and 2750 ± 370 g, respectively. Deaths most frequently occurred among infants at 1 month of age (18%). According to population-based analyses, the odds ratio (95% confidence interval) of mother’s age ≤19 years was 11.1 (6.9–17.7) compared with ages 30–39. The odds ratio for the fourth- and later born infants was 5.2 (3.4–7.9) compared with the frequency of first-born infants. The most frequent time of day for discovery was between 7 and 8 o’clock. Co-sleeping was recorded for 61%, and the prone position was found for 40% of cases at discovery. Mother’s smoking habit exhibited an adds ratio of 4.5 (2.9–5.8).Conclusion This study confirmed the trends that have been observed for sudden infant death syndrome; particularly, very high odds ratios were evident for teenage mothers and later birth order in comparison with those in other developed countries. The child of a young mother tended to die within 2 months of age. To our knowledge, this is the first report of an extensive survey of sleep-related SUDI in Japan.View Full Text

pathology↗

bioRxiv2018

Stretching combined with repetitive small length changes of the plantar flexor muscles enhances their passive extensibility for longer duration than conventional static stretching, while not compromising strength

Static stretching increases flexibility but can decrease muscle strength, and the method to avoid the latter has been longed for. In this study, a novel stretching modality was developed that provides repetitive small length changes to the plantar flexor muscles undergoing passive static stretching (\"local vibration stretching,\"). We investigated the effects of local vibration stretching on muscle strength, flexibility and its persistence. Plantar flexion strength and maximal ankle joint dorsiflexion angle (dorsiflexion range of motion) were measured for 10 healthy young males before (pre) and immediately after (post) three types of stretching: static stretching, local vibration stretching at 15 Hz, and no intervention (control). The dorsiflexion range of motion was measured also at 15, 30, and 60 min post-stretching. Elongation of the medial gastrocnemius and Achilles tendon was determined by ultrasonography. Plantar flexion strength significantly decreased by 4.3 {+/-} 3.5 % in static stretching but not in local vibration stretching. The dorsiflexion range of motion significantly increased both in static stretching (7.2 {+/-} 8.1 %) and local vibration stretching (11.2 {+/-} 14.6 %) which was accompanied by a significantly larger muscle elongation but not tendon elongation. Elevated dorsiflexion range of motion was maintained until 30 min after the local vibration stretching while it returned to baseline level (pre-intervention) in 15 min after the static stretching. All variables remained unchanged in the control condition. In conclusion, local vibration stretching improves extensibility of the muscle belly without decreasing strength, and the increased flexibility is retained longer than static stretching.

physiology↗