Biology subjects

Chuang, T.-J.

Publications and source records attributed to Chuang, T.-J..

6 recordsLinked to original sources

bioRxiv2023

Hematopoietic Transfer of the Anti-Cancer and Lifespan-Extending Capabilities of A Genetically Engineered Blood System

A causal relationship exists among the aging process, organ decay and dis-function, and the occurrence of various diseases including cancer. A genetically engineered mouse model, termed Klf1K74R/K74R or Klf1(K74R), carrying mutation on the well-conserved sumoylation site of the hematopoietic transcription factor KLF1/ EKLF has been generated that possesses extended lifespan and healthy characteristics including cancer resistance. We show that the healthy longevity characteristics of the Klf1(K74R) mice, as exemplified by their higher anti- cancer capability, are likely gender-, age- and genetic background-independent. Significantly, the anti-cancer capability, in particular that against melanoma as well as hepatocellular carcinoma, and lifespan-extending property of Klf1(K74R) mice could be transferred to wild-type mice via transplantation of their bone marrow mononuclear cells at young age of the latter. Furthermore, NK(K74R) cells carry higher in vitro cancer cell-killing ability than wild type NK cells. Targeted/global gene expression profiling analysis has identified changes of the expression of specific proteins, including the immune checkpoint factors PDCD and CD274, and cellular pathways in the leukocytes of the Klf1(K74R) that are in the directions of anti-cancer and/or anti-aging. This study demonstrates the feasibility of developing a transferable hematopoietic/ blood system for long-term anti-cancer and, potentially, for anti-aging.

cancer biology↗

bioRxiv2022

Large-scale benchmarking of circRNA detection tools reveals large differences in sensitivity but not in precision

The detection of circular RNA molecules (circRNAs) is typically based on short-read RNA sequencing data processed by computational detection tools. During the last decade, a plethora of such tools have been developed, but a systematic comparison with orthogonal validation is missing. Here, we set up a circRNA detection tool benchmarking study, in which 16 tools were used and detected over 315,000 unique circRNAs in three deeply sequenced human cell types. Next, 1,516 predicted circRNAs were empirically validated using three orthogonal methods. Generally, tool-specific precision values are high and similar (median of 98.8%, 96.3%, and 95.5% for qPCR, RNase R, and amplicon sequencing, respectively) whereas the sensitivity and number of predicted circRNAs (ranging from 1,372 to 58,032) are the most significant tool differentiators. Furthermore, we demonstrate the complementarity of tools through the increase in detection sensitivity by considering the union of highly-precise tool combinations while keeping the number of false discoveries low. Finally, based on the benchmarking results, recommendations are put forward for circRNA detection and validation.

genomics↗

bioRxiv2022

Assessing the impacts of various factors related to identification, conservation, biogenesis, and function on circular RNA reliability

Circular RNAs (circRNAs) are non-polyadenylated RNAs with a continuous loop structure characterized by a non-co-linear back-splice junction (BSJ). While dozens of computational tools have been developed and identified millions of circRNA candidates in diverse species, it remains a major challenge for determining circRNA reliability due to various types of false positives. Here, we systematically assess the impacts of numerous factors related to identification, conservation, biogenesis, and function on circRNA reliability by comparisons of circRNA expression from mock (total RNAs) and the corresponding co-linear/polyadenylated RNA-depleted datasets based on three different RNA treatment approaches. Eight important indicators of circRNA reliability are determined. The relative contribution to variability explained analyses further reveal that the relative importance of these factors in affecting circRNA reliability is conservation level of circRNA > full-length circular sequences > supporting BSJ read count > both BSJ donor and acceptor splice sites at the same co-linear transcript isoforms > both BSJ donor and acceptor splice sites at the annotated exon boundaries > BSJs detected by multiple tools > supporting functional features > both BSJ donor and acceptor splice sites undergoing alternative splicing. By extracting RT-independent circRNAs, circRNAs passing multiple experimental validations, and database-specific circRNAs, we showed the additive effects of these important factors in determining circRNA reliability. This study thus provides a useful guideline and an important resource for selecting high-confidence circRNAs for further investigations.

bioinformatics↗

bioRxiv2022

Detecting intragenic trans-splicing events with hybrid transcriptome sequencing in cancer cells

Trans-splicing can generate non-co-linear (NCL) transcripts that consist of exons in an order topologically inconsistent with the corresponding DNA template. Detecting trans-spliced RNAs (ts-RNAs) may be interfered by false positives from experimental artifacts, circular RNAs (circRNAs), and genetic rearrangements. Particularly, intragenic ts-RNAs, which are derived from separate precursor mRNA molecules of the same genes, are often mistaken for circRNAs through analyses of high-throughput transcriptome sequencing (RNA-seq) data. In addition, the biogenesis and function of ts-RNAs remain elusive. Here we developed a bioinformatics pipeline, NCLscan-hybrid, with the integration of long and short RNA-seq reads to minimize false positives and identify intragenic ts-RNAs. We utilized two features of long reads, out-of-circle and rolling circle, to distinguish intragenic ts-RNAs from circRNAs. We also designed multiple experimental validation steps to examine each type of false positives and successfully confirmed an intragenic ts-RNA (ts-ARFGEF1) in breast cancer cells. On the basis of ectopic expression and CRISPR-based endogenous genome modification experiments, we confirmed that ts-ARFGEF1 formation was significantly dependent on the reverse complementary sequences in the flanking introns of the NCL junction. Subsequent in vitro and in vivo experiments demonstrated that ts-ARFGEF1 silencing can significantly inhibit tumor cell growth. We further showed the regulatory role of ts-ARFGEF1 in p53-mediated apoptosis through affecting the PERK/eIF2a/ATF4/CHOP signaling pathway in breast cancer cells. This study thus described both bioinformatics procedures and experimental validation steps for rigorous characterization of transcriptionally non-co-linear RNAs, expanding the discovery of this important but understudied class of RNAs.

bioinformatics↗

bioRxiv2019

Genome-wide, integrative analysis implicates circular RNA dysregulation in autism and the corresponding circular RNA-microRNA-mRNA regulatory axes

Circular RNAs (circRNAs), a class of long non-coding RNAs, are known to be enriched in mammalian brain and neural tissues. While the effects of regulatory genetic variants on gene expression in autism spectrum disorder (ASD) have been widely reported, the role of circRNAs in ASD remains largely unknown. Here, we performed genome-wide circRNA expression profiling in post-mortem brains from individuals with ASD and controls and identified 60 circRNAs and three co-regulated modules that were perturbed in ASD. By integrating circRNA, microRNA, and mRNA dysregulation data derived from the same cortex samples, we identified 8,170 ASD-associated circRNA-microRNA-mRNA interactions. Putative targets of the axes were enriched for ASD risk genes and genes encoding inhibitory postsynaptic density (PSD) proteins, but not for genes implicated in monogenetic forms of other brain disorders or genes encoding excitatory PSD proteins. This result reflects the previous observation that ASD-derived organoids exhibit overproduction of inhibitory neurons. We further confirmed that some ASD risk genes (NLGN1, STAG1, HSD11B1, VIP, and UBA6) were indeed regulated by an upregulated circRNA (circARID1A) via sponging a downregulated microRNA (miR-204-3p) in human neuronal cells. We provided a systems-level view of landscape of circRNA regulatory networks in ASD cortex samples. We also provided multiple lines of evidence for the functional role of ASD for circRNA dysregulation and a rich set of ASD-associated circRNA candidates and the corresponding circRNA-miRNA-mRNA axes, particularly those involving ASD risk genes. Our findings thus support a role for circRNA dysregulation and the corresponding circRNA-microRNA-mRNA axes in ASD pathophysiology.

bioinformatics↗

bioRxiv2018

Nonsynonymous A-to-I RNA editing contributes to burden of deleterious missense variants in healthy individuals

ABSTARCTAdenosine-to-inosine (A-to-I) RNA editing is a very common post-transcriptional modification that can lead to A-to-G changes at the RNA level and compensate for G-to-A genomic changes to a certain extent. It has been shown that each healthy individual can carry dozens of missense variants predicted to be severely deleterious. Why strongly detrimental variants are preserved in a population and not eliminated by negative natural selection remains mostly unclear. Here we ask if RNA editing correlates with the burden of deleterious A/G polymorphisms in a population. Integrating genome and transcriptome sequencing data from 447 human lymphoblastoid cell lines, we show that nonsynonymous editing activities (prevalence/level) are negatively correlated with the deleteriousness of A-to-G genomic changes and positively correlated with that of G-to-A genomic changes within the population. We find a significantly negative correlation between nonsynonymous editing activities and allele frequency of A within the population. This negative editing-allele frequency correlation is particularly strong when editing sites are located in highly important genes/loci. Examinations of deleterious missense variants from the 1000 genomes project further show a significantly higher mutational burden in G-to-A changes than in other types of changes. The level of the mutational burden in G-to-A changes increases with increasing deleterious effects of the changes. Moreover, the deleteriousness of G-to-A changes is significantly positively correlated with the percentage of binding motif of editing enzymes at the variants. Overall, we show that nonsynonymous editing contributes to the increased burden of G-to-A missense mutations in healthy individuals, expanding RNA editing in pathogenomics studies.

evolutionary biology↗