GO:0045292 mRNA cis splicing, via spliceosome: Mechanism, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0045292 describes the spliceosome-catalyzed joining of exons from the same primary RNA transcript after intron removal, producing a mature mRNA.
• The reaction proceeds through stepwise exon definition and two transesterification steps, with dynamic rearrangements of small nuclear ribonucleoproteins and associated helicases such as Brr2.
• Cis-splicing is distinct from trans-splicing, which joins exons from separate transcripts; both occur in some organisms, but GO:0045292 is restricted to cis-splicing.
• Regulation occurs at multiple levels, including alternative splicing decisions, RNA-binding protein activity, and post-translational modifications such as lysine acetylation.
• Dysregulation of cis-splicing is linked to cancer, neurodegeneration, and viral pathogenesis, including HIV-1 tat splicing controlled by hnRNP A1.
• CRISPR-based knockout, point mutation, knock-in, and overexpression models enable causal dissection of spliceosomal genes and regulatory elements.
Description
mRNA cis splicing, via spliceosome (GO:0045292) is the biological process in which a single primary RNA transcript undergoes spliceosomal catalysis to remove introns and join exons, yielding an mRNA composed exclusively of exon sequences from that same transcript. This definition distinguishes cis-splicing from trans-splicing, where exons from separate RNA molecules are joined, as observed in organisms such as Entosiphon sulcatum. The spliceosome is a highly dynamic ribonucleoprotein machine that recognizes splice sites, pairs exons, and catalyzes two sequential transesterification reactions. Researchers study GO:0045292 because it is central to gene expression, and its disruption or misregulation alters transcript diversity and protein output. The process is also a therapeutic target, with approaches such as SMaRT exploiting splicing mechanisms for therapeutic purposes. Understanding the molecular players and regulatory layers of cis-splicing is therefore essential for basic biology and disease-oriented research.
mRNA cis splicing, via spliceosome At A Glance
| GO ID | GO:0045292 |
|---|---|
| GO term | mRNA cis splicing, via spliceosome |
| Ontology | biological_process |
| Synonym | nuclear mRNA cis splicing, via spliceosome; nuclear mRNA cis splicing, via U2-type spliceosome; splicing |
| Major function | Removal of introns and joining of exons from the same primary transcript to produce mature mRNA via spliceosomal catalysis |
| Catalytic core | Spliceosome, including U1, U2, U4/U6, and U5 snRNPs and associated proteins |
| Key regulatory factors | RNA helicases such as Brr2, RNA-binding proteins, and post-translational modifications |
| Distinction | Cis-splicing joins exons from the same transcript, unlike trans-splicing which joins exons from separate transcripts |
What Is GO:0045292?
In plain terms, GO:0045292 describes the standard splicing reaction that occurs within one RNA molecule: introns are removed and exons are ligated together by the spliceosome to form a mature mRNA. The definition emphasizes that the joined exon segments all originate from the same primary transcript, which distinguishes this process from trans-splicing events that combine exons from different RNA molecules.
Why Is mRNA cis splicing, via spliceosome Important in Cell Biology?
GO:0045292 is fundamental to gene expression because it defines how most eukaryotic protein-coding transcripts remove introns and ligate exons to generate translatable mRNA. The process is tightly coupled to transcription, RNA quality control, and alternative splicing decisions that expand proteome diversity. Defects in spliceosomal components or regulatory RNA-binding proteins can cause disease, including cancer and neurological disorders, and can influence viral replication through effects on viral RNA processing. Moreover, understanding cis-splicing mechanisms supports therapeutic strategies that manipulate splicing, such as SMaRT. Because spliceosomal rearrangements are dynamic and regulated by helicases and modifications, experimental models that perturb individual components are critical for causal inference.
• Produces mature mRNA from primary transcripts, enabling protein synthesis.
• Expands transcriptome and proteome diversity through alternative splicing decisions.
• Requires coordinated action of snRNPs and helicases such as Brr2.
• Is distinct from trans-splicing, which can occur in parallel in some organisms.
• Is regulated by RNA-binding proteins and post-translational modifications like lysine acetylation.
• Impacts viral pathogenesis, exemplified by hnRNP A1 regulation of HIV-1 tat splicing.
• Provides targets for therapeutic splicing modulation, including SMaRT approaches.
• Can be studied with CRISPR knockout, point mutation, knock-in, and overexpression models.
• Dysregulation is associated with cancer and neurodegeneration through altered splicing programs.
• Plant cis-splicing regulators affect agronomic traits such as heading date and plant height.
What Happens During mRNA cis splicing, via spliceosome?
Exon definition and splice site recognition
In simple terms: The spliceosome first identifies which parts of the RNA are exons and which are introns.
Cis-splicing begins with recognition of splice sites and exon definition, a stepwise process in which splicing factors and small nuclear ribonucleoproteins (snRNPs) assemble across exons and introns. This early recognition is coordinated with transcription and influences subsequent alternative splicing decisions. The U1 snRNP binds the 5' splice site, while U2AF and other factors help define the 3' splice site and branch point, setting the stage for spliceosome assembly.
Spliceosome assembly and dynamic rearrangements
In simple terms: A large molecular machine called the spliceosome builds up on the RNA and rearranges itself to become active.
After initial recognition, the spliceosome assembles through the ordered addition of U1, U2, U4/U6, and U5 snRNPs and numerous associated proteins. ATP-dependent RNA helicases, including Brr2, drive critical rearrangements that remodel RNA-RNA and RNA-protein interactions. These dynamic transitions ensure that the spliceosome reaches a catalytically active conformation while maintaining fidelity of splice site pairing.
Catalysis: two transesterification reactions
In simple terms: The spliceosome cuts the RNA at the intron boundaries and stitches the exons together in two chemical steps.
Catalysis proceeds via two sequential transesterification reactions: first, the branch point adenosine attacks the 5' splice site, forming a lariat intermediate; second, the 3' hydroxyl of the upstream exon attacks the 3' splice site, joining the exons and releasing the intron lariat. This chemistry is carried out by the spliceosomal active site, which is composed of RNA and protein components and is remodeled by helicases such as Brr2. The result is an mRNA composed only of exon sequences from the same primary transcript, as defined for GO:0045292.
Regulation by RNA-binding proteins and modifications
In simple terms: Helper proteins and chemical tags on splicing factors can speed up, slow down, or redirect the splicing process.
Cis-splicing is regulated by cis-acting elements and trans-acting RNA-binding proteins that influence splice site selection. For example, hnRNP A1 regulates HIV-1 tat splicing via a novel intron silencer element, demonstrating how a single RNA-binding protein can control viral cis-splicing. Post-translational modifications, such as lysine acetylation, can modulate RNA-binding protein activity and thereby affect alternative pre-mRNA splicing. In plants, the OsLHY-OsSCL30/OsDHT1 regulatory cascade coordinates heading date and plant height through pre-mRNA splicing modulation, illustrating conserved regulatory logic.
Coupling to downstream mRNA processing and export
In simple terms: After splicing, the mRNA is prepared for its journey out of the nucleus and for translation.
Following catalysis, the spliced mRNA is released from the spliceosome and becomes available for downstream processing, including 5' capping, 3' end formation, and nuclear export. The exon junction complex deposited during splicing marks the mRNA and influences its fate, including nonsense-mediated decay and translation efficiency. These coupling events ensure that only correctly cis-spliced transcripts contribute to the proteome, linking GO:0045292 to broader gene expression control.
Key Genes Involved in GO:0045292 mRNA cis splicing, via spliceosome
The following genes and proteins are central to mRNA cis splicing, via spliceosome, based on published literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| BRR2 | ATP-dependent RNA helicase that drives spliceosomal rearrangements | Studied for its role in spliceosome activation and regulation by cis- and trans-acting factors |
| HNRNPA1 | RNA-binding protein that regulates splice site selection | Regulates HIV-1 tat splicing via an intron silencer element |
| U1 snRNP components | Recognize the 5' splice site during early spliceosome assembly | Key for exon definition and splice site pairing |
| U2 snRNP components | Recognize the branch point and 3' splice site region | Essential for spliceosome assembly and catalysis |
| U4/U6 snRNP components | Form the tri-snRNP that enters the spliceosome | Required for catalytic activation and dynamic rearrangements |
| U5 snRNP components | Stabilize the catalytic core and interact with Brr2 | Critical for spliceosome activation and fidelity |
| OsSCL30 | Plant splicing factor involved in heading date and plant height regulation | Component of the OsLHY-OsSCL30/OsDHT1 cascade |
| OsDHT1 | Plant splicing-related factor affecting agronomic traits | Regulated by OsLHY and OsSCL30 in rice |
| OsLHY | Transcription factor that modulates pre-mRNA splicing in rice | Coordinates heading date and plant height via splicing |
| SMaRT components | Engineered splicing factors for therapeutic splicing modulation | Used in therapeutic strategies targeting splicing |
| Acetylation-related enzymes | Modify RNA-binding proteins to regulate splicing | Lysine acetylation influences alternative splicing |
| Exon junction complex proteins | Deposited during splicing to mark exon-exon junctions | Influence mRNA export, translation, and decay |
| Spliceosomal helicases | Remodel RNA-RNA and RNA-protein interactions | Regulate spliceosome dynamics and fidelity |
| Branch point binding proteins | Recognize the branch point sequence | Essential for early spliceosome assembly |
| 3' splice site factors | Define the 3' splice site and promote catalysis | Required for exon joining |
| 5' splice site factors | Define the 5' splice site and U1 snRNP binding | Critical for exon definition |
| RNA-binding proteins | Modulate splice site selection and alternative splicing | Targets for understanding splicing regulation |
How Is mRNA cis splicing, via spliceosome Regulated?
Cis-splicing is regulated at multiple levels. RNA-binding proteins and cis-acting elements control splice site selection and alternative splicing decisions. Post-translational modifications, such as lysine acetylation, can alter RNA-binding protein activity and thereby influence splicing outcomes. Spliceosomal helicases like Brr2 are regulated by cis- and trans-acting mechanisms that ensure proper rearrangements during the splicing cycle. In plants, a regulatory cascade involving OsLHY, OsSCL30, and OsDHT1 modulates pre-mRNA splicing to coordinate heading date and plant height. Viral factors can also hijack splicing regulation, as seen with hnRNP A1 controlling HIV-1 tat splicing. These layers of regulation allow cells to respond to developmental and environmental cues by changing mRNA isoform production.
mRNA cis splicing, via spliceosome and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| HNRNPA1 | HIV-1 tat splicing regulation | Knockout or overexpression in HIV-1 infection models |
| BRR2 | Spliceosomal dysfunction and cancer | Point mutation or knockout in cancer cell lines |
| OsSCL30 | Rice heading date and plant height | Knockout or knock-in in rice |
| OsDHT1 | Rice agronomic traits | Overexpression or knockout in rice |
| Acetylation-related enzymes | Alternative splicing regulation in cancer | Point mutation or knockout in cancer cells |
Cancer and splicing dysregulation
Altered cis-splicing can contribute to cancer by changing the expression of oncogenes and tumor suppressors through alternative exon inclusion or skipping. RNA-binding proteins and spliceosomal components are frequently dysregulated in tumors, and their modification status, such as lysine acetylation, can affect splicing programs. Studying GO:0045292 in cancer models helps identify splicing events that drive proliferation, survival, and metastasis.
Neurodegeneration and spliceosomal dysfunction
Neurons are particularly sensitive to splicing defects because they rely on diverse mRNA isoforms for synaptic function and survival. Mutations or misregulation of spliceosomal factors can lead to neurodegeneration, and RNA-binding proteins that control cis-splicing are implicated in neurological disease. Experimental models that perturb splicing factors can reveal causal links between cis-splicing and neuronal phenotypes.
Viral pathogenesis and host splicing control
Viruses often depend on host cis-splicing machinery for their replication. For example, hnRNP A1 regulates HIV-1 tat splicing via a novel intron silencer element, directly linking host RNA-binding proteins to viral gene expression. Understanding how GO:0045292 is co-opted by viruses can inform antiviral strategies and reveal general principles of splicing regulation.
Plant development and agronomic traits
In rice, the OsLHY-OsSCL30/OsDHT1 regulatory cascade coordinates heading date and plant height through pre-mRNA splicing modulation, showing that cis-splicing regulation impacts agriculturally important traits. This highlights the broad relevance of GO:0045292 beyond human disease and provides a model for studying splicing in development.
From mRNA cis splicing, via spliceosome-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Is a spliceosomal gene essential for cis-splicing? | CRISPR knockout cell line |
| Does a specific point mutation alter splice site selection? | CRISPR point mutation knock-in |
| How does a disease-associated variant affect splicing? | Knock-in of the variant in a model cell line |
| Where does a splicing factor localize during the cell cycle? | Tagged knock-in with fluorescent protein |
| Does overexpression of a splicing factor change isoform ratios? | Overexpression cell line |
| Can a splicing regulator rescue a phenotype? | Rescue with wild-type or mutant knock-in |
How to Study the mRNA cis splicing, via spliceosome Process
| Method | What It Measures | Typical Application |
|---|---|---|
| RNA-seq | Transcript abundance and splice junction usage | Detect cis-splicing changes after gene perturbation |
| RIP-seq | RNA-binding protein occupancy | Identify splicing factor targets |
| Mass spectrometry | Protein interactions and post-translational modifications | Study acetylation effects on splicing |
| In vitro splicing assays | Spliceosome assembly and catalysis | Analyze helicase function and mutations |
| CRISPR knockout | Loss-of-function phenotypes | Test essentiality of splicing factors |
| CRISPR point mutation | Specific amino acid or nucleotide changes | Dissect catalytic and regulatory residues |
| Knock-in reporter | Localization and dynamics of splicing factors | Image spliceosome components in cells |
| Overexpression | Gain-of-function effects on splicing | Test dosage sensitivity of splicing regulators |
RNA-seq and isoform quantification
RNA sequencing measures transcript abundance and splice junction usage, allowing researchers to detect changes in cis-splicing events after perturbation of candidate genes. By comparing knockout, point-mutant, or overexpression models to controls, one can identify exons and introns whose inclusion or skipping depends on the factor of interest.
Spliceosome assembly and helicase assays
Biochemical assays can monitor spliceosome assembly and catalytic steps, including the action of helicases such as Brr2. These methods reveal how mutations or modifications affect dynamic rearrangements and splice site pairing.
RNA-binding protein and modification analysis
RNA immunoprecipitation and mass spectrometry can identify RNA-binding proteins and their post-translational modifications, such as lysine acetylation, that regulate cis-splicing. These approaches connect specific modifications to changes in splicing outcomes.
CRISPR-based perturbation and phenotyping
CRISPR knockout, point mutation, knock-in, and overexpression models enable causal testing of splicing factors in disease and development. Phenotypic readouts can include growth, viability, viral replication, and plant traits, depending on the model system.
How CRISPR Can Be Used to Study GO:0045292 mRNA cis splicing, via spliceosome
Knockout
CRISPR knockout of spliceosomal genes or RNA-binding proteins can reveal their requirement for cis-splicing and downstream phenotypes. For example, knocking out HNRNPA1 or BRR2 orthologs can test their roles in splice site selection and spliceosome activation. Knockout models are also used to identify essential exons and compensatory pathways.
Point Mutation
Point mutations introduced by CRISPR can mimic disease-associated variants or disrupt catalytic residues in splicing factors. Such models help determine whether a specific amino acid change alters splice site choice, helicase activity, or modification status.
Knock-in
Knock-in of tags, reporters, or disease variants allows precise tracking and functional analysis of splicing components. Tagged knock-in lines can be used to image spliceosome dynamics, while variant knock-in lines test causality in disease models.
Overexpression
Overexpression of splicing factors or regulatory proteins can reveal dosage-sensitive effects on cis-splicing and isoform ratios. This approach is useful for studying gain-of-function mechanisms and for validating therapeutic targets.
How EDITGENE Supports mRNA cis splicing, via spliceosome Research
Researchers studying mRNA cis splicing, via spliceosome-related genes often need to determine whether a candidate gene is causally involved in splice site selection, spliceosome assembly, or disease-associated splicing changes. EDITGENE provides CRISPR-based models and bioinformatics services to enable such causal experiments.
Contact EDITGENE today to design your custom CRISPR model for mRNA cis splicing, via spliceosome research.
Frequently Asked Questions About mRNA cis splicing, via spliceosome
What is mRNA cis splicing, via spliceosome (GO:0045292)?
It is the spliceosome-catalyzed process that removes introns and joins exons from the same primary RNA transcript to produce mature mRNA.
What genes are involved in mRNA cis splicing, via spliceosome?
Key genes include BRR2, HNRNPA1, snRNP components, and plant regulators such as OsSCL30, OsDHT1, and OsLHY.
How is cis-splicing different from trans-splicing?
Cis-splicing joins exons from the same transcript, while trans-splicing joins exons from separate RNA molecules, as seen in some organisms.
What is the role of Brr2 in splicing?
Brr2 is an ATP-dependent RNA helicase that drives spliceosomal rearrangements and is regulated by cis- and trans-acting mechanisms.
How is cis-splicing regulated?
It is regulated by RNA-binding proteins, cis-acting elements, post-translational modifications such as lysine acetylation, and developmental signals.
Which diseases are linked to splicing defects?
Splicing defects are linked to cancer, neurodegeneration, and viral pathogenesis, including HIV-1 tat splicing regulated by hnRNP A1.
How can CRISPR be used to study cis-splicing?
CRISPR knockout, point mutation, knock-in, and overexpression models allow causal testing of splicing factors and regulatory elements.
What methods measure cis-splicing?
RNA-seq, RIP-seq, mass spectrometry, and in vitro splicing assays are commonly used to measure splicing events and factor activity.
Does cis-splicing occur in plants?
Yes, plant cis-splicing is regulated by factors such as OsLHY, OsSCL30, and OsDHT1, which affect heading date and plant height in rice.
What is the therapeutic relevance of cis-splicing?
Therapeutic strategies such as SMaRT exploit splicing mechanisms, and understanding cis-splicing can inform treatments for splicing-related diseases.
Conclusion
GO:0045292 mRNA cis splicing, via spliceosome is a core biological process that generates mature mRNA from primary transcripts through dynamic spliceosome assembly and catalysis. Its regulation by RNA-binding proteins, helicases, and post-translational modifications influences development, disease, and viral pathogenesis. CRISPR-based models and bioinformatics tools now enable precise causal dissection of cis-splicing mechanisms, supporting both basic discovery and therapeutic development.
References
- 1. Riedmayr LM. 2020. SMaRT for Therapeutic Purposes.. Methods Mol Biol 2079:219-232 PMID: 31728974
- 2. Kristofori P et al.. 2026. Coordinated alternative splicing decisions via stepwise exon definition.. Nucleic Acids Res 54(9) PMID: 42152680
- 3. Absmeier E et al.. 2016. Functions and regulation of the Brr2 RNA helicase during splicing.. Cell Cycle 15(24):3362-3377 PMID: 27792457
- 4. Lu Y et al.. 2026. The OsLHY-OsSCL30/OsDHT1 regulatory cascade coordinates heading date and plant height through Pre-mRNA splicing modulation in rice.. J Adv Res 86:87-102 PMID: 41242494
- 5. Ebel C et al.. 1999. Trans-splicing and cis-splicing in the colourless Euglenoid, Entosiphon sulcatum.. Curr Genet 35(5):542-50 PMID: 10369962
- 6. Keppetipola NM et al.. 2025. Lysine acetylation plays a role in RNA binding protein-regulated alternative pre-mRNA splicing.. bioRxiv PMID: 40672208
- 7. Absmeier E et al.. 2017. Interplay of cis- and trans-regulatory mechanisms in the spliceosomal RNA helicase Brr2.. Cell Cycle 16(1):100-112 PMID: 27880071
- 8. Tange TO et al.. 2001. The hnRNP A1 protein regulates HIV-1 tat splicing via a novel intron silencer element.. EMBO J 20(20):5748-58 PMID: 11598017
