Institutional Publications
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Item The landscape of fusion transcripts in plants: a new insight into genome complexity(BioMed Central Ltd, 2024) Chitkara, Pragya; Singh, Ajeet; Gangwar, Rashmi; Bhardwaj, Rohan; Zahra, Shafaque; Arora, Simran; Hamid, Fiza; Arya, Ajay; Sahu, Namrata; Chakraborty, Srija; Ramesh, Madhulika; Kumar, ShaileshBackground Fusion transcripts (FTs), generated by the fusion of genes at the DNA level or RNA-level splicing events significantly contribute to transcriptome diversity. FTs are usually considered unique features of neoplasia and serve as biomarkers and therapeutic targets for multiple cancers. The latest findings show the presence of FTs in normal human physiology. Several discrete reports mentioned the presence of fusion transcripts in planta, has important roles in stress responses, morphological alterations, or traits (e.g. seed size, etc.). Results In this study, we identified 169,197 fusion transcripts in 2795 transcriptome datasets of Arabidopsis thaliana, Cicer arietinum, and Oryza sativa by using a combination of tools, and confirmed the translational activity of 150 fusion transcripts through proteomic datasets. Analysis of the FT junction sequences and their association with epigenetic factors, as revealed by ChIP-Seq datasets, demonstrated an organised process of fusion formation at the DNA level. We investigated the possible impact of three-dimensional chromatin conformation on intra-chromosomal fusion events by leveraging the Hi-C datasets with the incidence of fusion transcripts. We further utilised the longread RNA-Seq datasets to validate the most reoccurring fusion transcripts in each plant species followed by further authentication through RT-PCR and Sanger sequencing. Conclusions Our findings suggest that a significant portion of fusion events may be attributed to alternative splicing during transcription, accounting for numerous fusion events without a proportional increase in the number of RNA pairs. Even non-nuclear DNA transcripts from mitochondria and chloroplasts can participate in intra- and inter-chromosomal fusion formation. Genes in close spatial proximity are more prone to undergoing fusion formation, especially in intra-chromosomal FTs. Most of the fusion transcripts may not undergo translation and serve as long non-coding RNAs. The low validation rate of FTs in plants indicated that the fusion transcripts are expressed at very low levels, like in the case of humans. FTs often originate from parental genes involved in essential biological processes, suggesting their relevance across diverse tissues and stress conditions. This study presents a comprehensive repository of fusion transcripts, offering valuable insights into their roles in vital physiological processes and stress responses.Item The landscape and implications of chimeric RNAs in cervical cancer(Elsevier B.V., 2018) Wu, Peng; Yang, Shuo; Singh, Sandeep; Qin, Fujun; Kumar, Shailesh; Wang, Ling; Ma, Ding; Li, HuiBackground: Gene fusions and fusion products have been proven to be ideal biomarkers and drug targets for cancer. Even though a comprehensive study of cervical cancer has been conducted as part of the Cancer Genome Atlas (TCGA) project, few recurrent gene fusions have been found, and none above 3% of frequency. Methods: We believe that chimeric fusion RNAs generated by intergenic splicing represent a new repertoire of biomarkers and/or therapeutic targets. However, they would be missed when only genome sequences and fusions at DNA level are considered. We performed extensive data mining for chimeric RNAs using both our and TCGA cervical cancer RNA-Seq datasets. Multiple criteria were applied. We analyzed the landscape of chimeric RNAs at various levels, and from different angles. Findings: The chimeric RNA landscape changed as different filters were applied. 15 highly frequent (N10%) chimeric RNAs were identified. LHX6-NDUFA8 was detected exclusively in cervical cancer tissues and Pap smears, but not in normal controls. Mechanistically, it is not due to interstitial deletion, but a product of cis-splicing between adjacent genes. Silencing of another recurrent chimera, SLC2A11-MIF, resulted in cell cycle arrest and reduced cellular proliferation. This effect is unique to the chimera, and not shared by the two parental genes. Interpretation: Highly frequent chimeric RNAs are present in cervical cancers. They can be formed by intergenic splicing. Some have clear implications as potential biomarkers, or for shedding new light on the biology of the disease. Fund: Stand Up To Cancer and the National Science Foundation of China
