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Lakhotia SC. C-value paradox: Genesis in misconception that natural selection follows anthropocentric parameters of 'economy' and 'optimum'. BBA Adv 2023; 4:100107. [PMID: 37868661 PMCID: PMC10587719 DOI: 10.1016/j.bbadva.2023.100107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2023] [Revised: 10/11/2023] [Accepted: 10/12/2023] [Indexed: 10/24/2023] Open
Abstract
C-value paradox refers to the lack of correlation between biological complexity and the intuitively expected protein-coding genomic information or DNA content. Here I discuss five questions about this paradox: i) Do biologically complex organisms carry more protein-coding genes? ii) Does variable accumulation of selfish/ junk/ parasitic DNA underlie the c-value paradox? iii) Can nucleoskeletal or nucleotypic function of DNA explain the enigma of orders of magnitude high levels of DNA in some 'lower' taxa or in taxonomically related species? iv) Can the newly understood noncoding but functional DNA explain the c-value paradox? and, v) Does natural selection uniformly apply the anthropocentric parameters for 'optimum' and 'economy'? Answers to Q.1-5 are largely negative. Biology presents numerous 'anomalous' examples where the same end function/ phenotype is attained in different organisms through astoundingly diverse ways that appear 'illogical' in our perceptions. Such evolutionary oddities exist because natural selection, unlike a designer, exploits random and stochastic events to modulate the existing system. Consequently, persistence of the new-found 'solution/s' often appear bizarre, uneconomic, and therefore, paradoxical to human logic. The unexpectedly high c-values in diverse organisms are irreversible evolutionary accidents that persisted, and the additional DNA often got repurposed over the evolutionary time scale. Therefore, the c-value paradox is a redundant issue. Future integrative biological studies should address evolutionary mechanisms and processes underlying sporadic DNA expansions/ contractions, and how the newly acquired DNA content has been repurposed in diverse groups.
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Affiliation(s)
- Subhash C. Lakhotia
- Cytogenetics Laboratory, Department of Zoology, Institute of Science, Banaras Hindu University, Varanasi 221005, India
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Huang X, Li H, Zhan A. Interplays between cis- and trans-Acting Factors for Alternative Splicing in Response to Environmental Changes during Biological Invasions of Ascidians. Int J Mol Sci 2023; 24:14921. [PMID: 37834365 PMCID: PMC10573349 DOI: 10.3390/ijms241914921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Revised: 10/02/2023] [Accepted: 10/03/2023] [Indexed: 10/15/2023] Open
Abstract
Alternative splicing (AS), a pivotal biological process contributing to phenotypic plasticity, creates a bridge linking genotypes with phenotypes. Despite its importance, the AS mechanisms underlying environmental response and adaptation have not been well studied, and more importantly, the cis- and trans-acting factors influencing AS variation remain unclear. Using the model invasive congeneric ascidians, Ciona robusta, and Ciona savignyi, we compared their AS responses to environmental changes and explored the potential determinants. Our findings unveiled swift and dynamic AS changes in response to environmental challenges, and differentially alternative spliced genes (DASGs) were functionally enriched in transmembrane transport processes. Interestingly, both the prevalence and level of AS in C. robusta were lower than those observed in C. savignyi. Furthermore, these two indices were higher under temperature stresses compared to salinity stresses in C. savignyi. All the observed patterns underscore the species-specific and environmental context-dependent AS responses to environmental challenges. The dissimilarities in genomic structure and exon/intron size distributions between these two species likely contributed to the observed AS variation. Moreover, we identified a total of 11 and 9 serine/arginine-rich splicing factors (SRSFs) with conserved domains and gene structures in the genomes of C. robusta and C. savignyi, respectively. Intriguingly, our analysis revealed that all detected SRSFs did not exhibit prevalent AS regulations. Instead, we observed AS control over a set of genes related to splicing factors and spliceosome components. Altogether, our results elucidate species-specific and environmental challenge-dependent AS response patterns in closely related invasive ascidians. The identified splicing factors and spliceosome components under AS control offer promising candidates for further investigations into AS-mediated rapid responses to environmental challenges complementary to SRSFs.
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Affiliation(s)
- Xuena Huang
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 18 Shuangqing Road, Haidian District, Beijing 100085, China; (X.H.); (H.L.)
| | - Hanxi Li
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 18 Shuangqing Road, Haidian District, Beijing 100085, China; (X.H.); (H.L.)
| | - Aibin Zhan
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 18 Shuangqing Road, Haidian District, Beijing 100085, China; (X.H.); (H.L.)
- University of Chinese Academy of Sciences, 19A Yuquan Road, Shijingshan District, Beijing 100049, China
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Centa JL, Stratton MP, Pratt MA, Osterlund Oltmanns JR, Wallace DG, Miller SA, Weimer JM, Hastings ML. Protracted CLN3 Batten disease in mice that genetically model an exon-skipping therapeutic approach. Mol Ther Nucleic Acids 2023; 33:15-27. [PMID: 37359347 PMCID: PMC10285469 DOI: 10.1016/j.omtn.2023.05.025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Accepted: 05/31/2023] [Indexed: 06/28/2023]
Abstract
Genetic mutations that disrupt open reading frames and cause translation termination are frequent causes of human disease and are difficult to treat due to protein truncation and mRNA degradation by nonsense-mediated decay, leaving few options for traditional drug targeting. Splice-switching antisense oligonucleotides offer a potential therapeutic solution for diseases caused by disrupted open reading frames by inducing exon skipping to correct the open reading frame. We have recently reported on an exon-skipping antisense oligonucleotide that has a therapeutic effect in a mouse model of CLN3 Batten disease, a fatal pediatric lysosomal storage disease. To validate this therapeutic approach, we generated a mouse model that constitutively expresses the Cln3 spliced isoform induced by the antisense molecule. Behavioral and pathological analyses of these mice demonstrate a less severe phenotype compared with the CLN3 disease mouse model, providing evidence that antisense oligonucleotide-induced exon skipping can have therapeutic efficacy in treating CLN3 Batten disease. This model highlights how protein engineering through RNA splicing modulation can be an effective therapeutic approach.
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Affiliation(s)
- Jessica L. Centa
- Center for Genetic Diseases, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, IL 60064, USA
| | - Matthew P. Stratton
- Center for Genetic Diseases, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, IL 60064, USA
- School of Graduate and Postdoctoral Studies, Rosalind Franklin University of Medicine and Science, North Chicago, IL 60064, USA
| | - Melissa A. Pratt
- Pediatrics and Rare Diseases Group, Sanford Research, Sioux Falls, SD 57104, USA
| | | | - Douglas G. Wallace
- Department of Psychology, Northern Illinois University, DeKalb, IL 60115, USA
| | - Steven A. Miller
- Psychology Department, College of Health Professionals, Rosalind Franklin University of Medicine and Science, North Chicago, IL 60064, USA
| | - Jill M. Weimer
- Pediatrics and Rare Diseases Group, Sanford Research, Sioux Falls, SD 57104, USA
- Department of Pediatrics, Sanford School of Medicine, University of South Dakota, Sioux Falls, SD 57104, USA
| | - Michelle L. Hastings
- Center for Genetic Diseases, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, IL 60064, USA
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
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Lobas AA, Solovyeva EM, Levitsky LI, Goncharov AO, Lyssuk EY, Larin SS, Moshkovskii SA, Gorshkov MV. Identification of Alternative Splicing in Proteomes of Human Melanoma Cell Lines without RNA Sequencing Data. Int J Mol Sci 2023; 24. [PMID: 36768787 DOI: 10.3390/ijms24032466] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 01/06/2023] [Accepted: 01/13/2023] [Indexed: 01/31/2023] Open
Abstract
Alternative splicing is one of the main regulation pathways in living cells beyond simple changes in the level of protein expression. Most of the approaches proposed in proteomics for the identification of specific splicing isoforms require a preliminary deep transcriptomic analysis of the sample under study, which is not always available, especially in the case of the re-analysis of previously acquired data. Herein, we developed new algorithms for the identification and validation of protein splice isoforms in proteomic data in the absence of RNA sequencing of the samples under study. The bioinformatic approaches were tested on the results of proteome analysis of human melanoma cell lines, obtained earlier by high-resolution liquid chromatography and mass spectrometry (LC-MS). A search for alternative splicing events for each of the cell lines studied was performed against the database generated from all known transcripts (RefSeq) and the one composed of peptide sequences, which included all biologically possible combinations of exons. The identifications were filtered using the prediction of both retention times and relative intensities of fragment ions in the corresponding mass spectra. The fragmentation mass spectra corresponding to the discovered alternative splicing events were additionally examined for artifacts. Selected splicing events were further validated at the mRNA level by quantitative PCR.
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Loewenthal G, Wygoda E, Nagar N, Glick L, Mayrose I, Pupko T. The evolutionary dynamics that retain long neutral genomic sequences in face of indel deletion bias: a model and its application to human introns. Open Biol 2022; 12:220223. [PMID: 36514983 PMCID: PMC9748784 DOI: 10.1098/rsob.220223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Insertions and deletions (indels) of short DNA segments are common evolutionary events. Numerous studies showed that deletions occur more often than insertions in both prokaryotes and eukaryotes. It raises the question why neutral sequences are not eradicated from the genome. We suggest that this is due to a phenomenon we term border-induced selection. Accordingly, a neutral sequence is bordered between conserved regions. Deletions occurring near the borders occasionally protrude to the conserved region and are thereby subject to strong purifying selection. Thus, for short neutral sequences, an insertion bias is expected. Here, we develop a set of increasingly complex models of indel dynamics that incorporate border-induced selection. Furthermore, we show that short conserved sequences within the neutrally evolving sequence help explain: (i) the presence of very long sequences; (ii) the high variance of sequence lengths; and (iii) the possible emergence of multimodality in sequence length distributions. Finally, we fitted our models to the human intron length distribution, as introns are thought to be mostly neutral and bordered by conserved exons. We show that when accounting for the occurrence of short conserved sequences within introns, we reproduce the main features, including the presence of long introns and the multimodality of intron distribution.
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Affiliation(s)
- Gil Loewenthal
- The Shmunis School of Biomedicine and Cancer Research, Tel Aviv University, Tel Aviv 69978, Israel
| | - Elya Wygoda
- The Shmunis School of Biomedicine and Cancer Research, Tel Aviv University, Tel Aviv 69978, Israel
| | - Natan Nagar
- The Shmunis School of Biomedicine and Cancer Research, Tel Aviv University, Tel Aviv 69978, Israel
| | - Lior Glick
- School of Plant Sciences and Food Security, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
| | - Itay Mayrose
- School of Plant Sciences and Food Security, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
| | - Tal Pupko
- The Shmunis School of Biomedicine and Cancer Research, Tel Aviv University, Tel Aviv 69978, Israel
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