University of the Ryukyus · Faculty of Medicine

Research keywords分子人類学・Link・生命情報科学・表現型可塑性・Amphibian・Haplotype・(biology)・Hindlimb

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• Urodele amphibian newt bridges the missing link in evo-devo of the pancreas2025 · BACKGROUND: The pancreas exhibits diverse structures and roles across vertebrates. The pancreas has evolved to include both endocrine and exocrine cells, a change that occurred during the transition from fish to amphibian. This event emphasizes the evolutionary significance of amphibians. However, research has focused predominantly on anuran amphibians, with urodeles, such as newts, remaining underexplored. In this study, we investigated the development of the pancreas using Pleurodeles waltl as a model species of urodele. RESULTS: The newt pancreas consists of a single organ with exocrine tissue characterized by acinar structures and endocrine tissue forming islets. Notably, the newt possesses unique pancreas-like tissues on their intestines. We found that disruption of the newt Pancreatic and Duodenal Homeobox (Pdx) 1 gene resulted in an underdeveloped pancreas. Conversely, disruption of the Pdx2 paralog in newt had no significant impact on pancreatic development. CONCLUSION: The newt pancreas shows a morphology similar to that of the mammalian pancreas, which includes both exocrine and endocrine tissues. These results highlight the intermediate evolutionary position of the newt in the context of the evolution of pancreatic development. Our findings indicate that characterization of the newt pancreas will be crucial for understanding the evolutionary progression of pancreatic function in vertebrates.
• Novel function of Hox13 in regulating outgrowth of the newt hindlimb bud through interaction with Fgf10 and Tbx42025 · 5'Hox genes regulate pattern formation along the axes of the limb. Previously, we showed that Hoxa13/Hoxd13 double-mutant newts lacked all digits of the forelimbs during development and regeneration, showing that newt Hox13 is necessary for digit formation in development and regeneration. In addition, we found another unique phenotype. Some of the Hox13 crispant newts showed hindlimb defects, in which whole or almost whole hindlimbs were lost, suggesting a novel function of Hox13 in limb development. Using germline mutants, we showed that mutation in Hox13 led to hindlimb defects. The limb buds of Hox13 crispants formed, however, did not show outgrowth. Expression of Fgf10 and Tbx4, which are involved in limb outgrowth, decreased in the hindlimb buds of Hox13 crispants. In addition, hindlimb defects were observed in both Fgf10 and Tbx4 crispant newts. Finally, Fgf10 and Tbx4 interacted with Hox13 genetically. Our results revealed a novel function of Hox13 in regulating the outgrowth of the newt hindlimb bud through interaction with Fgf10 and Tbx4.
• Genome-wide association studies for pelvic organ prolapse in the Japanese population2024 · Pelvic organ prolapse (POP) affects approximately 40% of elderly women, characterized by thedescent of the pelvic organs into the vaginal cavity. Here we present the results of a genome-wideassociation study (GWAS) for susceptibility to POP comprising 771 cases and 76,625 controls in theJapanese population. We identified a significant association of WT1 locus with POP in the Japanesepopulation; rs10742277; odds ratio (OR) = 1.48, 95% confidence interval (CI), 1.29–1.68,P = 6.72 × 10−9. Subsequent cross-ancestry GWAS meta-analysis combining the Japanese data andpreviously reported European data, including 28,857 cases and 622,916 controls, identified FGFR2locus as a novel susceptibility locus to POP (rs7072877; OR = 1.06, 95% CI, 1.04–1.08,P = 4.11 × 10−8). We also observed consistent directions of the effects for 21 out of 24 European GWASderived loci (binomial test P = 2.8 × 10−4), indicating that most of susceptibility loci for POP are sharedacross the Japanese and European populations.
• Natural Selection Signatures in the Hondo and Ryukyu Japanese Subpopulations2023 · Natural selection signatures across Japanese subpopulations are under-explored. Here we conducted genome-wide selection scans with 622,926 single nucleotide polymorphisms for 20,366 Japanese individuals, who were recruited from the main-islands of Japanese Archipelago (Hondo) and the Ryukyu Archipelago (Ryukyu), representing two major Japanese subpopulations. The integrated haplotype score (iHS) analysis identified several signals in one or both subpopulations. We found a novel candidate locus at IKZF2, especially in Ryukyu. Significant signals were observed in the major histocompatibility complex region in both subpopulations. The lead variants differed and demonstrated substantial allele frequency differences between Hondo and Ryukyu. The lead variant in Hondo tags HLA-A*33:03-C*14:03-B*44:03-DRB1*13:02-DQB1*06:04-DPB1*04:01, a haplotype specific to Japanese and Korean. While in Ryukyu, the lead variant tags DRB1*15:01-DQB1*06:02, which had been recognized as a genetic risk factor for narcolepsy. In contrast, it is reported to confer protective effects against type 1 diabetes and human T lymphotropic virus type 1-associated myelopathy/tropical spastic paraparesis. The FastSMC analysis identified 8 loci potentially affected by selection within the past 20-150 generations, including 2 novel candidate loci. The analysis also showed differences in selection patterns of ALDH2 between Hondo and Ryukyu, a gene recognized to be specifically targeted by selection in East Asian. In summary, our study provided insights into the selection signatures within the Japanese and nominated potential sources of selection pressure.

• 古代ゲノム解析による島嶼地域への定住プロセスの解明2023 · 基盤研究(B)
• 生活習慣病リスクと関連する疾患感受性ミトコンドリアゲノム多型の網羅的探索2023 · 基盤研究(C)
• 遺伝系統樹と言語系統樹の矛盾を検討する2023 · 挑戦的研究(萌芽)
• 琉球列島における先史人類および文化の形成2023 · 学術変革領域研究(A)

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