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Mori, A.

Publications and source records attributed to Mori, A..

3 recordsLinked to original sources
bioRxiv2023

Comprehensive IsomiR sequencing profile of human pancreatic islets and EndoC-βH1 beta-cells

Aims/HypothesisMiRNAs play a crucial role in regulating the islet transcriptome, influencing beta cell functions and pathways. Emerging evidence suggests that during biogenesis a single miRNA locus can generate various sequences, known as isomiRNAs (isomiRs). However, a comprehensive profiling analysis of isomiRs in human pancreatic islets and beta cells is still lacking. This study aims to unveil the isomiRs expression profile in Laser Capture Microdissected (LCM) human pancreatic islets (HI) from non-diabetic donors and in the human beta cell line EndoC-{beta}H1, in order to shed light on novel molecular mechanisms governing beta cell function. MethodsRNA was extracted from LCM HI deriving from n=19 non-diabetic donors and from EndoC-{beta}H1 beta cells. Small RNA-seq was performed. Data were processed with the sRNAbench online pipeline for miRNAs/isomiRs quantification. Results were further validated using an external miRNA-seq database (isomiRdb). ResultsIn both HI and EndoC-{beta}H1, isomiRs accounted for a substantial proportion of total miRNA reads (HI: 59.4+/-1.9%; EndoC-{beta}H1: 43.8+/-0.6%). Among isomiRs, the most prevalent types were 3-end modifications, including trimming (HI=71.8+/-2.8%; EndoC-{beta}H1=55.8+/-1.0%) and extension (HI: 12.1+/-1.9%; EndoC-{beta}H1: 17.4+/-0.9%), followed by non-templated addition (HI: 9.8+/-0.9%; EndoC-{beta}H1: 14.0+/-1.2%). The analysis of the composition of the n=10 most expressed miRNAs highlighted a significant contribution of reads assigned to isomiRs. For instance, the most abundant miRNA, miR-375-3p, resulted from 59.7+/-2.4% of canonical and 40.3+/-2.4% of isomiRs in EndoC-{beta}H1 and from 45.3+/-2.0% of canonical and 54.7+/-2.0% of isomiR reads in HI. Interestingly, miR-7-5p, a beta cell-specific miRNA, was predominantly expressed as an isomiR both in EndoC-{beta}H1 (65.3+/-2.7%) and in HI (82.4+/-1.4%). To identify a reliable beta cell isomiR signature, common sequences detected in HI and EndoC-{beta}H1 were filtered based on their contribution to total miRNA expression, ultimately resulting in a set of 46 isomiRs. The expression of the isomiR signature in beta cells was further evaluated using an external database, isomiRdb, which contains small-RNA sequencing data from 99 different human cell types. This analysis revealed a significant enrichment of 11 out of the 46 isomiRs in beta cells compared to other cell types. The signature was functionally characterized through regression analysis with clinical and metabolic parameters related to beta cell function in non-diabetic individuals, demonstrating a significant negative correlation between basal insulin secretion and isomiR-411-5p, but not with its corresponding canonical miRNA. Conclusion/InterpretationThis study provides a comprehensive profile of isomiR expression in pancreatic islets and beta cells, highlighting the potential significance of isomiRs as novel regulators of beta cell function. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=114 SRC="FIGDIR/small/566223v1_ufig1.gif" ALT="Figure 1"> View larger version (52K): org.highwire.dtl.DTLVardef@145f36borg.highwire.dtl.DTLVardef@1701433org.highwire.dtl.DTLVardef@13e5866org.highwire.dtl.DTLVardef@1dbe50_HPS_FORMAT_FIGEXP M_FIG C_FIG Research in ContextO_ST_ABSWhat is already know about this subject?C_ST_ABS- isomiRs are sequence variants of microRNAs (miRNAs) and may have distinct functional role respect to the canonical sequence. - isomiRs show cell/tissue specificity and are involved in multiple disease contexts. What is the key question?- What is the profile of isomiRs in human pancreatic islets (HI) and in beta cells? - Do isomiRs have a functional role in beta cells? What are the new findings?- IsomiRs represent a relevant fraction of total miRNAs in HI and beta cells. - 3end miRNA sequence modifications are the major fraction of isomiRs in beta cells. - A set of n=11 isomiRs, more expressed than their canonical miRNAs, are enriched in beta cells compared to the other human cell types. - Specific isomiRs are associated with beta cell glucose sensitivity and basal insulin secretion. How might this impact on clinical practice in the foreseeable future?- A comprehensive profile of isomiRs in beta cells may improve our understanding of molecular mechanisms driving beta cell function and dysfunction. - A highly detailed and granular view of miRNAs sequence variants and their expression levels may help in the design of novel therapeutic RNA-based strategies.

molecular biology↗
bioRxiv2023

Development of digital Hi-C assay

Abstracts Enhancers are genomic elements and contain all necessary cis-regulatory contexts. Such enhancers are convened to the appropriate promoter of target genes for gene regulations even though the enhancers and the promoters are apart a few mega-base pairs away from each other. In addition to physical distance, nucleotide mutations in enhancers influence a partial group of the target genes. Those make it more complicated to reveal the paired relationship between enhancer and promoter of target genes. Recently, advanced computational approaches are employed to predict such interactions. One approach requires a large number of different high-throughput datasets to predict such interactions; however, in practical aspects, all datasets for tissues and conditions of interest are not available. Whereas the alternative approach requires only genome sequences for particular predictions, their predictions are insufficient for practical applications. We address those issues by developing the digital Hi-C assay with a transformer-algorithm basis. This assay allows us to create models from simple/small/limited sequence-based datasets only. We apply the trained models to be able to identify long-distance interactions of genomic loci and three-dimensional (3D) genomic architectures in any other tissue/cell datasets; additionally, we demonstrated the predictions of genomic contexts by analysing the prediction patterns around the target locus in the three following genomic-context problems: enhancer-promoter interactions (i.e., promoter-capture Hi-C), the CTCF-enriched regions, and TAD-boundary regions. Because our approach adopted a sequence-based approach, we can predict the long-distance interactions of genomic loci by using the genomic sequences of the users interest (e.g., input sequences from high-throughput assay datasets such as ATAC-seq and ChIP-seq assays). Consequently, we provide an opportunity to predict interactions of genomic loci from a minimum dataset.

bioinformatics↗
bioRxiv2022

The role of rice SOG1 and SOG1-like in DNA damage response

Higher plants are constantly exposed to environmental stresses, and therefore complicated defense systems, including DNA damage response (DDR) and DNA repair systems, have developed to protect plant cells. In Arabidopsis, the transcription factor SUPPRESSOR OF GAMMA RESPONSE 1 (SOG1) has been reported to play a key role in DDR. Here, we focus on DDR in rice--thought to be a simpler system compared with Arabidopsis due to lack of induction of endocycle even under DNA damage stress. Rice SOG1 (OsSOG1) and SOG1-like (OsSGL) were identified as putative AtSOG1 orthologs with complete or partial conservation of the serine-glutamine (SQ) motifs involved in activation via phosphorylation. In addition to OsSOG1- or OsSGL-knockout mutants, OsSOG1 non-phosphorylatable mutants (OsSOG1-7A) were generated by homologous recombination-mediated gene targeting. Based on DNA damage susceptibility and transcriptome analysis using these mutants, we demonstrated that OsSOG1, but not OsSGL, plays a central role in the DDR and DNA repair. OsSOG1 regulated target genes via CTT (N)7 AAG motifs reported previously as AtSOG1 recognition sites. The loss of transcription activities and DNA damage tolerance of OsSOG1-7A was not complete compared with OsSOG1-knockout mutants, raising the possibility that another phosphorylation site might be involved in the activation of OsSOG1. Furthermore, our findings have highlighted differences in SOG1-mediated DDR between rice and Arabidopsis, especially regarding induction of cell-cycle arrest and endocycle arrest, revealing rice-specific DDR mechanisms. One sentence summaryRice transcription factor SUPPRESSOR OF GAMMA RESPONSE 1 controls DNA damage response and DNA repair through activation via phosphorylation and the direct regulation of expression of numerous genes.

plant biology↗