Biology subjects

Yamaji, T.

Publications and source records attributed to Yamaji, T..

9 recordsLinked to original sources

bioRxiv2025

Rad27/FEN1 prevents accumulation of unprocessed Okazaki fragments and ribosomal DNA copy number changes

DNA copy number changes are the most frequent genomic alterations in cancer cells. The ribosomal DNA (rDNA) region is particularly vulnerable to such changes due to its repetitive nature. Here, we demonstrate that Rad27/FEN-1, a structure-specific nuclease in budding yeast, plays a crucial role in maintaining rDNA stability. The production of extrachromosomal rDNA circles and severe chromosomal rDNA instability are observed in the rad27{Delta} mutant, independently of Fob1-mediated DNA replication fork arrest and DNA double-strand break (DSB) formation in the rDNA. The rad27{Delta} mutant accumulates unprocessed Okazaki fragments in the rDNA region, without inducing DSB formation. Similar rDNA instability is observed in DNA ligaseCdc9-deficient cells. Furthermore, we show that Exonuclease 1 and PCNA can compensate for the loss of Rad27 function in the rDNA stabilization. These findings highlight the importance of proper Okazaki fragment processing in preventing non-DSB-induced rDNA copy number changes.

molecular biology↗

bioRxiv2023

The cholesterol pathway of the Golgi stress response induces cell death and transcription of Golgi-related genes through metabolic dysregulation of phosphatidylinositol-4-phosphate

The Golgi stress response is an important cytoprotective system that enhances Golgi function in response to cellular demand, while cells damaged by prolonged Golgi stress undergo cell death to ensure the survival of organisms. OSW-1, a natural compound with anticancer activity, acts as a potent inhibitor of OSBP that transports cholesterol and phosphatidylinositol-4-phosphate (PI4P) at contact sites between the endoplasmic reticulum and the Golgi apparatus. Previously, we reported that OSW-1 induces the Golgi stress response, resulting in Golgi stress-induced transcription and cell death. However, the underlying molecular mechanism has been unknown. To reveal the mechanism of a novel pathway of the Golgi stress response regulating transcriptional induction and cell death (the cholesterol pathway), we performed a genome-wide knockout screen and found that transcriptional induction as well as cell death induced by OSW-1 was repressed in HeLa cells deficient in factors involved in the PI4P metabolism, such as PITPNB and PI4KB genes. Our data indicate that OSW-1 induces Golgi stress-dependent transcriptional induction and cell death through dysregulation of the PI4P metabolism in the Golgi apparatus.

cell biology↗

bioRxiv2021

Whole-genome sequencing of Vero E6 (C1008) and comparative analysis of four Vero cell sublines

The Vero cell line is an immortalized cell line established from kidney epithelial cells of the African green monkey. A variety of sublines have been established from the original cell line, which display different characteristics. In this study, we determined the whole-genome sequence of Vero E6 (C1008) and performed comparative analysis among Vero JCRB 0111, Vero CCL-81, Vero 76 and Vero E6. Analysis of the copy number changes and loss of heterozygosity revealed that all sublines share a large deletion and loss of heterozygosity on chromosome 12, which harbors type I interferon and CDKN2 gene clusters. We identified a substantial number of genetic differences among the sublines including single nucleotide variants, indels, and copy number variations. The spectrum of single nucleotide variants indicated a close genetic relationship between Vero JCRB0111 and Vero CCL-81, and between Vero 76 and Vero E6, and a considerable genetic gap between the former two and the latter two lines. In contrast, we confirmed the pattern of genomic integration sites of simian endogenous retroviral sequences, which was consistent among the sublines. We identified subline-specific/enriched loss of function and missense variants, which potentially contribute to the differences in response to viral infection among the Vero sublines. In particular, we focused on Vero E6-specific/enriched variants and identified four genes (IL1RAP, TRIM25, RB1CC1, and ATG2A) that contained missense variants specific or enriched in Vero E6. In addition, we found that V739I variants of ACE2, which functions as the receptor for SARS-CoV-2, were heterozygous in Vero JCRB0111, Vero CCL-81, and Vero 76; however, Vero E6 contained the allele with isoleucine, resulting from the loss of one of the X chromosomes.

genomics↗

bioRxiv2020

Poliovirus-nonsusceptible Vero cell line for the World Health Organization global action plan

Polio or poliomyelitis is a disabling and life-threatening disease caused by poliovirus (PV). As a consequence of global polio vaccination efforts, wild PV serotype 2 has been eradicated, and wild PV serotypes 1- and 3-transmitted cases have been largely eliminated except for in limited regions around the world. However, vaccine-derived PV, pathogenically reverted live PV vaccine strains in vaccinated humans, has become a serious issue. For the global eradication of polio, the World Health Organization is conducting the third edition of the Global Action Plan, which is requesting stringent control of potentially PV-infected materials. To facilitate the mission, we generated a PV-nonsusceptible Vero cell subline, which may serve as an ideal replacement of standard Vero cells to isolate emerging/re-emerging viruses without the risk of generating PV-infected materials.

microbiology↗

bioRxiv2020

Identification of characteristic genomic markers in human hepatoma Huh7 and Huh7.5.1-8 cell lines

The human hepatoma-derived Huh7 cell line and its derivatives (Huh7.5 and Huh7.5.1) have been widely used as a convenient experimental substitute for primary hepatocytes. In particular, these cell lines represent host cells suitable for propagating the hepatitis C virus (HCV) in vitro. The Huh7.5.1-8 cell line, a subline of Huh7.5.1, can propagate HCV more efficiently than its parental cells. To provide genomic information for cells quality control, we performed whole-genome sequencing of Huh7 and Huh7.5.1-8 and identified their characteristic genomic deletions, some of which are applicable to an in-house test for cell authentication. Among the genes related to HCV infection and replication, 53 genes were found to carry missense or loss-of-function mutations likely specific to the Huh7 and/or Huh7.5.1-8. Eight genes, including DDX58 (RIG-I), BAX, EP300, and SPP1 (osteopontin), contained mutations observed only in Huh7.5.1-8 or mutations with higher frequency in Huh7.5.1-8. These mutations might be relevant to phenotypic differences between the two cell lines and may also serve as genetic markers to distinguish Huh7.5.1-8 cells from the ancestral Huh7 cells.

genomics↗

bioRxiv2019

Retrograde Transport of Golgi Enzymes by GOLPH3 Across Maturing Cisternae Regulates Glycan Assembly on Sphingolipids and CellGrowth

Glycans are ubiquitous sugar polymers with major biological functions that are assembled by glyco-enzymes onto cargo molecules during their transport through the Golgi complex. How the Golgi determines glycan assembly is poorly understood. By relying on the Golgi cisternal maturation model and using the glyco-enzyme adaptor and oncoprotein GOLPH3 as a molecular tool, we define the first example of how the Golgi controls glycosylation and associated cell functions. GOLPH3, acting as a component of the cisternal maturation mechanism, selectively binds and recycles a subset of glyco-enzymes of the glycosphingolipid synthetic pathway, hinders their escape to the lysosomes and hence increases their levels through a novel lysosomal degradation-regulated mechanism. This enhances the production of specific growth-inducing glycosphingolipids and reprograms the glycosphingolipid pathway to potentiate mitogenic signaling and cell proliferation. These findings unravel unforeseen organizing principles of Golgi-dependent glycosylation and delineate a paradigm for glycan assembly by the Golgi transport mechanisms. Moreover, they indicate a new role of cisternal maturation as a regulator of glycosylation, and outline a novel mechanism of action for GOLPH3-induced proliferation.

cell biology↗

bioRxiv2019

Population-specific and transethnic genome-wide analyses reveal distinct and shared genetic risks of coronary artery disease

To elucidate the genetics of coronary artery disease (CAD) in the Japanese population, we conducted a large-scale genome-wide association study (GWAS) of 168,228 Japanese (25,892 cases and 142,336 controls) with genotype imputation using a newly developed reference panel of Japanese haplotypes including 1,782 CAD cases and 3,148 controls. We detected 9 novel disease-susceptibility loci and Japanese-specific rare variants contributing to disease severity and increased cardiovascular mortality. We then conducted a transethnic meta-analysis and discovered 37 additional novel loci. Using the result of the meta-analysis, we derived a polygenic risk score (PRS) for CAD, which outperformed those derived from either Japanese or European GWAS. The PRS prioritized risk factors among various clinical parameters and segregated individuals with increased risk of long-term cardiovascular mortality. Our data improves clinical characterization of CAD genetics and suggests the utility of transethnic meta-analysis for PRS derivation in non-European populations.

genetics↗

bioRxiv2019

Transethnic meta-analysis of genome-wide association studies identifies three new loci and characterizes population-specific differences for coronary artery disease

BackgroundGenome-wide association studies (GWAS) provided many biological insights into coronary artery disease (CAD), but these studies were mainly performed in Europeans. GWAS in diverse populations have the potential to advance our understanding of CAD.\n\nMethods and ResultsWe conducted two GWAS for CAD in the Japanese population, which included 12,494 cases and 28,879 controls, and 2,808 cases and 7,261 controls, respectively. Then, we performed transethnic meta-analysis using the results of the CARDIoGRAMplusC4D 1000 Genomes meta-analysis with UK Biobank. We identified 3 new loci on chromosome 1q21 (CTSS), 10q26 (WDR11-FGFR2), and 11q22 (RDX-FDX1). Quantitative trait locus analyses suggested the association of CTSS and RDX-FDX1 with atherosclerotic immune cells. Tissue/cell type enrichment analysis showed the involvement of arteries, adrenal glands and fat tissues in the development of CAD. Finally, we performed tissue/cell type enrichment analysis using East Asian-frequent and European-frequent variants according to the risk allele frequencies, and identified significant enrichment of adrenal glands in the East Asian-frequent group while the enrichment of arteries and fat tissues was found in the European-frequent group. These findings indicate biological differences in CAD susceptibility between Japanese and Europeans.\n\nConclusionsWe identified 3 new loci for CAD and highlighted the genetic differences between the Japanese and European populations. Moreover, our transethnic analyses showed both shared and unique genetic architectures between the Japanese and Europeans. While most of the underlying genetic bases for CAD are shared, further analyses in diverse populations will be needed to elucidate variations fully.

genetics↗

bioRxiv2019

GWAS identifies nine nephrolithiasis susceptibility loci related with metabolic and crystallization pathways

Nephrolithiasis is a common urological trait disorder with acute pain. Although previous studies have identified various genetic variations associated with nephrolithiasis, the host genetic factors remain largely unidentified. To identify novel nephrolithiasis loci in the Japanese population, we performed large-scale GWAS (Genome wide association study) using 11,130 cases and 187,639 controls, followed by a replication analysis using 2,289 cases and 3,817 controls. The analysis identified 14 significant loci, including 9 novel loci on 2p23.2-3, 6p21.2, 6p12.3, 6q23.2, 16p12.3, 16q12.2, 17q23.2, 19p13.12, and 20q13.2. Interestingly, 10 of the 14 regions showed a significant association with any of 16 quantitative traits, including metabolic, kidney-related, and electrolyte traits, suggesting a common genetic background among nephrolithiasis patients and these quantitative traits. Four novel loci are related to the metabolic pathway, while the remaining 10 loci are associated with the crystallization pathway. Our findings demonstrate the crucial roles of genetic variations in the development of nephrolithiasis.\n\nSIGNIFICANCE STATEMENTNephrolithiasis is a common urothelial disorders with frequent recurrence rate, but its genetic background is largely remained unidentified. Previous GWAS identified 6 genetic factors in total. Here we performed a GWAS using more than 200,000 samples in the Japanese populations, and identified 14 significant loci and nine of them are novel. We also found that 10 of the 14 loci showed a significant association with any of 16 quantitative traits, including metabolic, kidney-related, and electrolyte traits (BMI, eGFR, UA, Ca etc). All 14 significant loci are associate with either metabolic or crystallization pathways. Thus, our findings elucidated the underlying molecular pathogenesis of nephrolithiasis.

genetics↗