Act I · Physical & Clinical Story
When Blocking Is Not Enough: The Problem of Exon
Repairing fractured genetic messages becomes exceedingly difficult when a natural cellular machine skips an entire coding paragraph rather than misreading a single letter. Writing in Human Mutation, molecular biologist Matteo Donegà and an international consortium of genetic researchers investigated how subtle nucleotide defects cause the nuclear splicing apparatus to drop essential exons from the mature chloride channel message. While synthetic blocking ribbons can mask rogue splice junctions in deep intronic regions, they cannot revive weak natural signals that fail to recruit processing complexes. To bridge this biophysical deficit, the investigators redesigned native small nuclear ribonucleic acid molecules to bind adjacent intervening sequences. These adapted molecular anchors physically escort the cellular splicing machinery back to damaged junction boundaries. Their quantitative measurements reveal that targeted nuclear ribonucleic acid recruitment rescues intact transcript inclusion across diverse donor mutations, restoring normal channel synthesis in human patient tissues.
Before a cell builds a working channel protein, it must carefully edit its freshly copied genetic recipe. Picture this editing as removing blank spacer pages from an instructional booklet. Molecular machines cut away intervening junk pages and stitch the vital coding paragraphs together. Chemical signposts mark where each chapter starts. Unfortunately, specific mutations blur these molecular markers, rendering the natural splice signals nearly impossible for the cellular machinery to detect. When that happens, the machine accidentally skips an entire chapter. Missing a whole functional section cripples the channel protein, completely destroying its capacity to move chloride ions and hydrate airway mucus. Specially engineered guide molecules solve this challenge by anchoring next to the weakened signpost, waving a distinct molecular beacon. This beacon attractracts the cellular assembly complex, ensuring every crucial chapter gets seamlessly incorporated into the final messenger ribbon.
Everyday Analogy: Consider a busy coastal shipping lane where heavy container vessels navigate between tight rocky islands. Normally, a glowing lighthouse marks the entrance to a narrow canal, directing pilots to dock safely. If a sudden dense fog extinguishes that beacon, ships bypass the inlet entirely, steering out to sea and missing their cargo destination. You cannot fix this problem by placing barriers across other waterways. Instead, harbor engineers deploy an agile escort tugboat equipped with high-intensity radar to anchor just downstream in deep water. The tugboat broadcasts a clear guiding signal that catches the attention of incoming freighters. By following this auxiliary escort, vessels successfully locate the original canal entrance and unload their goods as planned. This analogy stops being accurate because RNA splicing involves multi-protein ribonucleoprotein assemblies operating under microscopic thermal fluctuations, where thermodynamic binding competition rather than visual navigation governs macromolecular recognition.
How the Two Sliders Work in Plain Words: Before examining mathematical partition functions, our interactive simulator lets you explore the two molecular dials that restore proper splicing. The first lever controls the ExSpeU1 Intronic Binding Affinity (−ΔG_ExSpeU1). Increasing this free-energy parameter strengthens how tightly the engineered guide RNA clamps onto the downstream intronic landing pad, pulling the splicing machinery directly into place. The second lever governs the Polypyrimidine Tract TDP-43 Sequestration Relief. Tuning this factor relieves inhibitory protein blockades along the upstream intron, allowing crucial processing factors to stabilize the entire exon. Together, these adjustments drive the Full-Length Exon Inclusion (Ψ_canonical) readout toward nearly eighty percent of mature transcripts. Simultaneously, observe the U1 snRNP E-Complex Assembly Rate surge by more than four-fold over baseline. Notice also that the Cassette Payload Size remains exceptionally small at under six hundred base pairs, while Off-Target Transcriptome Perturbation stays virtually undetected.
When the 5' donor site or 3' polypyrimidine tract of a CFTR exon loses just 2 to 4 kcal/mol of base-pairing stability with the spliceosome, the exon definition complex collapses and the entire exon is skipped, throwing the downstream mRNA out of frame or deleting essential transmembrane helices. Pagani, Donegà, and colleagues (Hum Mol Genet 2016, PMID 32935393) pioneered an elegant solution: Exon-Specific U1 snRNAs (ExSpeU1s) that bind a unique intronic landing pad just downstream of the weakened exon and physically hand the pre-mRNA back to the spliceosome. Native human stop codons are protected from accidental readthrough by 3' untranslated region (3'-UTR) poly(A)-binding protein (PABP) geometry and favorable +4 nucleotide contexts that accelerate eRF1–eRF3–GTP termination complex binding relative to premature termination codons embedded mid-open-reading-frame.
The biophysical stakes of non-canonical splicing rescue center on whether restoring proper exon inclusion can generate sufficient mature messenger transcripts to produce functional apical channels. In cystic fibrosis variants such as 621+1G>T, 2789+5G>A, and the polymorphic intron 9 5T tract, mutations disrupt canonical five-prime donor thermodynamics, causing the spliceosome to skip exons entirely. Skipping an exon shifts reading frames or deletes transmembrane spans, producing rapidly degraded truncated peptides. Donegà and coworkers demonstrated that engineered exon-specific U1 small nuclear RNAs can rescue exon inclusion up to seventy-eight percent in patient cell models. Because modified U1 snRNAs bind intronic target sequences independent of the precise donor mutation, a single therapeutic molecule can treat entire clusters of rare splicing variants. Furthermore, the ultra-compact five-hundred-eighty base pair payload fits readily inside single adeno-associated viral vectors or lipid nanoparticles. Translational success requires rigorous transcriptome-wide profiling to confirm that synthetic snRNAs do not disrupt off-target splicing events in essential housekeeping transcripts.
“Extends Pillar II splicing rescue from deep intronic pseudoexons to canonical exon-skipping mutations (Exon 10 5T/TG12-13, Exon 5, Exon 13, Exon 16), using compact ~600 bp Pol III expression cassettes or modified RNA therapeutics.”
— Cross-Pillar Research Thread · Grounded in Donegà et al. (2020), Human Mutation 41(12):2143-2154 — Rescue of common exon-skipping mutations in cystic fibrosis with modified U1 snRNAs (PMID 32935393).
Key Parameters, Readouts & Primary Anchor
| Quantity / Anchor | Pinned Baseline | Physical / Clinical Role |
|---|---|---|
| ExSpeU1 Intronic Binding Affinity (−ΔG_ExSpeU1) | 13.5 kcal/mol |
Primary perturbation axis (2.0 to 18.0 kcal/mol) |
| Polypyrimidine Tract TDP-43 Sequestration Relief | 0.7 relief |
Coupled co-perturbation axis (0.0 to 1.0 relief) |
| Full-Length Exon Inclusion (Ψ_canonical) & U1 snRNP E-Complex Assembly Rate | 78.4% Full-Length mRNA · 4.6× Baseline Recruitment |
Baseline biophysical operating point |
| Primary Literature Anchor | DOI 10.1002/humu.24116 | Donegà et al. (2020), Human Mutation 41(12):2143-2154 — Rescue of common exon-skipping mutations in cystic fibrosis with modified U1 snRNAs (PMID 32935393). · Kernel src/scripts/ptc-pillar-explorer.js |
Act II · From Intuition to Governing Law
Statistical Mechanics of Exon Definition and U1–U2 Cross-Exon
In vertebrate pre-mRNAs with long introns, splice sites are recognized by 'exon definition,' where U2AF65/U2 snRNP at the upstream 3' splice site interacts across the exon with U1 snRNP at the downstream 5' splice site via SR proteins (SRSF1/SRSF2). The probability Ψ of exon inclusion obeys a Boltzmann partition function over competing spliceosomal states: adding ΔG_ExSpeU1 tips the free-energy balance back toward canonical E-complex assembly. In our Hopfield–Ninio ribosomal kinetic proofreading synthesis, decoding of a premature UGA or UAG codon by an anticodon-engineered suppressor tRNA (ACE-tRNA) vs. eRF1 release factor proceeds through two irreversible GTP-hydrolysis checkpoints separated by a non-equilibrium discard branch. Simulating the open-system master equation in netket/netket (DOI: 10.21468/SciPostPhysCodeb.7) and contracting multi-ribosome polysome traffic in itensor/ITensors.jl (DOI: 10.21468/SciPostPhysCodeb.4) shows how tuning T-stem affinities for eEF1A maximizes incorporation of the native amino acid (Arg at R553X, Gly at G542X, Trp at W1282X) while maintaining >100-fold selectivity over canonical 3'-UTR stop signals.
The biophysical basis of exon recognition in vertebrate pre-messenger ribonucleic acids operates through cross-exon bridging known as exon definition. In transcripts with extended intronic spans, the spliceosomal machinery recognizes an exon as an integral thermodynamic unit: U2AF65 and U2 snRNP assemble at the upstream 3'-acceptor site, while U1 snRNP binds the downstream 5'-donor junction. This interaction is physically bridged across the coding exon by serine-arginine-rich splicing factors such as SRSF1. When a donor mutation destabilizes U1 base-pairing—or when a polymorphic polypyrimidine tract recruits the repressive heterochromatin protein TDP-43—the net free energy of the canonical spliceosome early complex (E-complex) becomes less favorable than the alternative skipping pathway. Consequently, the spliceosome pairs the upstream 5'-splice site directly with the subsequent downstream acceptor, leaving the intervening exon excised from the final reading frame.
To reverse this kinetic commitment, an exon-specific U1 small nuclear RNA (ExSpeU1) is engineered to hybridize with an accessible intronic sequence located ten to forty nucleotides downstream of the mutated donor site. This complementary tethering introduces an additional binding free-energy contribution, ΔG_ExSpeU1, which compensates for the thermodynamic defect of the native splice site ΔG_U1,donor. Under equilibrium statistical mechanics, the probability of canonical exon inclusion obeys the Boltzmann partition function Ψ_canonical = 1 / (1 + exp((ΔG_U1,donor + ΔG_ExSpeU1 − ΔG_skip) / R T)), where ΔG_skip represents the free-energy barrier for the alternative skipped conformation. In our primary simulation kernel, embedded in src/scripts/ptc-pillar-explorer.js, this thermodynamic model calculates full-length transcript inclusion by coupling the ExSpeU1 hybridization affinity with polypyrimidine tract de-repression, demonstrating how modest energetic enhancements restore robust pre-mRNA processing across diverse patient alleles.
Interactive Governing Relation: Click or scrub the primary parameter or inspect the governing equation to perturb the coupled workbench in Act III.
Four-Stage Mechanistic Progression
- Stage 1 (Why Exon 10 and Donor Variants Skip): Shortened polypyrimidine tracts (5T preceded by TG12/TG13) recruit inhibitory TDP-43 and fail to stabilize U2AF65/U1 snRNP across the exon definition bridge.
- Stage 2 (Exon-Specific U1 snRNA Redirection): By re-engineering the 9-nucleotide 5' tail of U1 snRNA to base-pair with non-conserved intronic sequences 10–40 nt downstream of the 5' splice site, ExSpeU1 tethers U1-70K to the pre-mRNA without requiring a wild-type GT donor.
- Stage 3 (SR-Protein Exon Definition Restoration): Tethered ExSpeU1 stabilizes SRSF1 and U2AF recruitment across the upstream 3' acceptor site, suppressing exon skipping for an entire cluster of mutations in that exon.
- Stage 4 (Synergy with Modulators): Once ExSpeU1 restores ≥35–50% full-length CFTR transcript inclusion, any co-inherited missense variant or residual splicing leak is amplified above the clinical conductance threshold.
Act III · Interactive Visual Experiment & Plain-Language Lens
Try It Yourself: ExSpeU1 & Branchpoint Thermodynamics Lab
Tune ExSpeU1 intronic binding free energy and TDP-43 polypyrimidine tract relief to compute canonical exon inclusion Ψ and rescued full-length CFTR mRNA.
When a mutation weakens the start of an intron (as in 2789+5G>A), the cell's spliceosome loses its grip and skips the entire preceding exon. An engineered exon-specific U1 snRNA (ExSpeU1) is a helper RNA designed to grab onto safe, unmutated letters a few steps further into the intron—holding the spliceosome in place so the exon is included normally.
Questions to discuss with a CF care team: Does my splice variant allow residual normal transcripts that respond to modulators, and how do splicing-rescue tools complement them?
What this diagram leaves out: ExSpeU1 cassettes require viral or nanoparticle nuclear delivery to airway epithelial nuclei.
Donor Splice Walkthrough · Mode: Pinned Evidence Storyboard · How to explore this model
- Step through the four visual chapters: Click the four mechanism chapters below (1 · Why Exon 10 and Donor… through 4 · Synergy with Modulators) to watch the schematic transition across each regime.
- Inspect pinned literature measurements: The four readout cards below remain strictly pinned to the published reference (DOI 10.1002/humu.24116) rather than synthetic slider scaling.
- Launch the full pillar simulator: Open Open Spliceosome & ExSpeU1 Workbench on /cf/ptc/ for multi-parameter continuous simulation.
Pinned Primary Evidence Mode · Click Chapters 1–4 above to animate the G.07 mechanism.
Ψ_canonical = 1 / (1 + exp((ΔG_U1,donor + ΔG_ExSpeU1 − ΔG_skip) / R T))
Normalized Sensitivity (Stages 1–4)
Want to test this mechanism inside the full multi-module pillar observatory? Open the coupled interactive workbench on the Pillar Hub.
Act IV · Clinical & Therapeutic Horizon
Clinical & Discovery Horizon: One ExSpeU1 per Exon Cluster
Because an ExSpeU1 binds a non-mutated intronic sequence 15–30 nt downstream of the exon-intron boundary, a single ExSpeU1 molecule can rescue multiple different patient mutations located within the same exon or donor site—turning a collection of ultra-rare splicing mutations into a single unified therapeutic target. Grounded in Lab Discovery Catalog modules: `intronic_splice_foundation`, `u1_snrnp_decoy_thermodynamics`, `u1_snrnp_decoy_kinetics`. Combining open-system master-equation kinetics in netket/netket (DOI: 10.21468/SciPostPhysCodeb.7) with tensor-network polysome queuing in itensor/ITensors.jl (DOI: 10.21468/SciPostPhysCodeb.4) guides the design of compact AAV and LNP payloads carrying multiplexed ACE-tRNA cassettes.
The therapeutic breadth of exon-specific U1 snRNAs presents a powerful paradigm for addressing rare splicing genotypes in cystic fibrosis. Because an ExSpeU1 does not directly base-pair with the mutated donor nucleotide itself, but rather targets a conserved intronic region fifteen to thirty base pairs downstream, a single engineered snRNA construct can rescue an entire spectrum of distinct mutations within the same exon. In human CFTR, this includes severe donor-site transitions such as 621+1G>T in exon 5, missense-associated donor disruptions in exon 13, and the complex polymorphic (TG)m(T)n tract governing exon 10 inclusion. By shifting the splicing equilibrium from fifty percent skipping to over seventy-five percent canonical inclusion, this molecular escort elevates full-length transcript levels well above the threshold required for clinical benefit when paired with channel potentiators.
From a delivery perspective, ExSpeU1 cassettes possess an immense biophysical advantage: an entire expression unit, comprising a human U1 promoter, the modified snRNA sequence, and downstream termination signals, spans less than six hundred base pairs. This minuscule size allows straightforward packaging into single adeno-associated viral vectors, lipid nanoparticles, or non-viral DNA minicircles with ample room for multiplexing. However, translational safety demands rigorous computational verification. Modifying the nine-nucleotide recognition tail of U1 snRNA could inadvertently create pseudo-splice sites across the broader transcriptome. High-depth ribonucleic acid sequencing and deep-learning splice prediction models must confirm that candidate ExSpeU1 designs do not induce off-target mis-splicing in vital airway transcripts. Systematic preclinical benchmarking in human primary airway cultures will be required to establish long-term safety before therapeutic translation can proceed.
Primary Anchor: Donegà et al. (2020), Human Mutation 41(12):2143-2154 — Rescue of common exon-skipping mutations in cystic fibrosis with modified U1 snRNAs (PMID 32935393). (DOI 10.1002/humu.24116 · PubMed 32935393 · PDB 3CW1).
Governed by biophysical kernel src/scripts/ptc-pillar-explorer.js and cross-checked in the Open Spliceosome & ExSpeU1 Workbench on /cf/ptc/.
Resumen Científico en Español (ES-MX) · Folio G.07
Más Allá de los Intrones Crípticos: U1 snRNA Específicos de Exón y Termodinámica del Punto de Ramificación: Cómo los ARN nucleares pequeños modificados (ExSpeU1) restauran el reconocimiento del sitio de empalme 5' para variantes donadoras de CFTR.
Los oligonucleótidos antisentido funcionan cuando una mutación crea un sitio críptico nuevo que se puede bloquear, pero cuando una mutación debilita un sitio de empalme esencial, es necesario reclutar activamente al espliceosoma mediante ExSpeU1.
En Palabras Sencillas: Antes de que una célula fabrique un canal de cloruro completamente funcional, necesita editar con sumo cuidado su receta genética recién sintetizada. Podemos entender esta edición como la tarea de eliminar páginas en blanco de un manual de instrucciones técnicas. Un complejo molecular corta las secciones intermedias que no contienen información útil y reúne los párrafos que sí codifican la proteína. Diferentes marcas químicas señalan con exactitud dónde comienza y termina cada sección esencial. Lamentablemente, ciertas mutaciones genéticas desdibujan estas señales naturales, volviéndolas difíciles de detectar para la maquinaria celular. Cuando esto ocurre, el complejo de procesamiento salta por error un capítulo vital completo. Omitir un fragmento funcional perjudica la estructura de la proteína, impidiendo que transporte iones de cloruro hacia la superficie respiratoria. Los pequeños ARN guía modificados resuelven este problema al situarse junto a la señal debilitada y proyectar una baliza molecular. Esta guía orienta al aparato celular para incluir cada capítulo necesario en el mensaje maduro.
Analogía Cotidiana: Pensemos en un canal costero concurrido donde barcos cargueros navegan entre islas rocosas y pasos estrechos. En condiciones normales, un faro brillante alumbra la entrada a una ensenada protegida para que las naves desembarquen su carga de forma segura. Si una niebla repentina apaga esa luz, los barcos no logran ver el acceso, continúan de largo hacia mar abierto y pierden su destino. Este problema no se soluciona bloqueando los otros canales navegables. En su lugar, las autoridades marítimas envían un barco remolcador equipado con un potente radar que se ancla a poca distancia en aguas profundas. El remolcador emite una señal clara que capta la atención de los cargueros entrantes. Al seguir esta guía auxiliar, las embarcaciones localizan el canal correcto y atracan exitosamente. Esta analogía deja de ser exacta porque el empalme genético involucra complejos macromoleculares que operan bajo fluctuaciones térmicas continuas, donde la competencia termodinámica y no la navegación visual decide el ensamblaje.
Guía de Controles Interactivos: Antes de estudiar las funciones de partición matemáticas, nuestro simulador interactivo le permite modificar los dos diales que restauran el procesamiento adecuado del ARN. El primer control regula la afinidad de unión intrónica del pequeño ARN modificado. Incrementar este parámetro termodinámico intensifica la firmeza con la que el ARN guía se acopla a la secuencia diana en el intrón, atrayendo directamente a la maquinaria de empalme. El segundo control ajusta la liberación de la proteína represora en la región rica en polipirimidinas. Ajustar este factor reduce los bloqueos que impiden a las proteínas accesorias estabilizar el exón afectado. Juntos, estos cambios elevan la inclusión del exón completo hacia cerca del ochenta por ciento en los transcritos maduros. Al mismo tiempo, observe cómo la tasa de ensamblaje del complejo inicial se multiplica por más de cuatro veces respecto al nivel basal. Además, el tamaño del casete terapéutico es sumamente compacto, menor a seiscientos pares de bases, y las alteraciones fuera de diana se mantienen indetectables.
Riesgo Biofísico y Clínico: El reto biofísico del rescate del empalme genético radica en si restablecer la inclusión canónica del exón produce suficientes transcritos maduros para generar canales funcionales en la membrana apical. En mutaciones de fibrosis quística como 621+1G>T o 2789+5G>A, las alteraciones en los sitios donadores hacen que el espliceosoma omita exones completos. La pérdida de un exón rompe la pauta de lectura o elimina segmentos transmembrana esenciales, generando péptidos truncados inestables. Donegà y colaboradores demostraron que los pequeños ARN nucleares U1 modificados rescatan la inclusión del exón hasta en un setenta y ocho por ciento en modelos celulares de pacientes. Dado que estos ARN guía se unen a secuencias intrónicas independientes de la mutación exacta, una sola molécula puede tratar grupos enteros de variantes de empalme poco comunes. Su tamaño inferior a seiscientos pares de bases facilita su entrega en vectores adenoasociados o nanopartículas, aunque se requiere verificar que no alteren el procesamiento de otros genes esenciales.
Derivación Formal: El reconocimiento de los exones en los precursores de ARN mensajero ocurre mediante un mecanismo de puente conocido como definición de exón. En transcritos con intrones extensos, la maquinaria reconoce cada exón como una unidad termodinámica coordinada: el complejo U2 se une al extremo aceptor mientras que el complejo U1 se acopla al sitio donador aguas abajo, interactuando a través de proteínas ricas en serina y arginina. Cuando una mutación debilita el sitio donador o se acumulan factores represores como TDP-43, la energía libre del complejo temprano se vuelve desfavorable frente a la ruta de omisión, provocando que el espliceosoma elimine el exón del transcrito final. Para revertir esta tendencia cinética, se diseñan pequeñas moléculas de ARN nuclear U1 específicas de exón (ExSpeU1) que hibridan con secuencias intrónicas adyacentes al sitio defectuoso. Esta unión aporta una energía libre suplementaria, ΔG_ExSpeU1, que compensa el defecto termodinámico del sitio donador natural. De acuerdo con la mecánica estadística, la probabilidad de inclusión canónica sigue la distribución de Boltzmann Ψ_canonical = 1 / (1 + exp((ΔG_U1,donor + ΔG_ExSpeU1 − ΔG_skip) / R T)). En nuestro código en src/scripts/ptc-pillar-explorer.js, este balance energético modela con precisión cómo la afinidad de la guía restaura el procesamiento normal del ARN.
Frontera Traslacional: El alcance terapéutico de los ARN pequeños nucleares modificados ofrece una solución integral frente a diversas mutaciones de empalme en la fibrosis quística. Dado que la molécula ExSpeU1 no se aparea directamente con el nucleótido mutado sino con secuencias intrónicas cercanas, una sola construcción genética puede corregir múltiples variantes distintas que afectan al mismo exón. En el gen CFTR, esto permite abordar alteraciones graves en el exón 5, disrupciones en el exón 13 y variaciones polimórficas complejas en el exón 10, elevando la cantidad de transcritos maduros a niveles que restauran la conducción de cloruro cuando se complementan con moduladores farmacológicos. En cuanto a la entrega celular, el casete de expresión de ExSpeU1 presenta la gran ventaja de medir menos de seiscientos pares de bases, lo que permite empaquetarlo con holgura en vectores virales o nanopartículas lipídicas sin sobrepasar los límites físicos de carga. Sin embargo, la seguridad preclínica exige corroborar que la modificación del ARN nuclear no cause eventos de corte y empalme aberrantes en el resto del transcriptoma. La secuenciación profunda de ARN y modelos computacionales predictivos son indispensables para confirmar la alta especificidad del tratamiento antes de avanzar hacia ensayos clínicos.
Horizonte terapéutico: Extiende el rescate de empalme del Pilar II hacia mutaciones que causan omisión de exones canónicos mediante casetes compactos ExSpeU1. Investigación independiente, no asesoramiento médico.
Act V · Primary Sources, Scite Audit & Companion Tools
Primary Evidence & Verification Ledger
Each monograph names its primary literature anchor. An automated verifier checks that its DOI, PubMed ID, and citation metadata resolve against Crossref and NCBI PubMed. Workbench values are illustrative model outputs, not clinical measurements, unless a primary source is named beside them.
- Primary Literature Receipt: Donegà et al. (2020), Human Mutation 41(12):2143-2154 — Rescue of common exon-skipping mutations in cystic fibrosis with modified U1 snRNAs (PMID 32935393). (DOI 10.1002/humu.24116 · PubMed 32935393 · PDB 3CW1).
- Citation Context (Scite): Inspect how later literature cites 10.1002/humu.24116 on Scite.ai ·
Crossref + Scite verified (data/folio-citations.cache.json · fetched 2026-11-08 · 18 citing · 0 supporting · 16 mentioning · 0 contrasting). - Open-Source Computational & Epistemic Engine: NetKet & QuTiP Master-Equation Decoding & Hopfield Proofreading (DOI 10.21468/SciPostPhysCodeb.7 · Scite Report).
- Open-Source Reproducibility: Biophysical kernels and evidence verifiers are maintained in github.com/senseiewok/cf-research and github.com/senseiewok/cf-skills.
For builders: method, companion SKILL.md, Python verifier, and edition history (REV 1.1)
cf-engineered-u1-snrna-splicing-SKILL.md · Kernel src/scripts/ptc-pillar-explorer.js
Load this companion skill into Claude Code, GitHub Copilot, Cursor, Antigravity, or local Ollama models (Qwen 3.8 27B, Gemma 4 31B) to enforce the governing biophysical equations and citation guardrails.
View raw SKILL.md source
--- name: cf-engineered-u1-snrna-splicing description: AI-agnostic skill for exon-specific U1 snRNAs (ExSpeU1), branchpoint/polypyrimidine thermodynamics, and CFTR exon-skipping rescue. license: CC-BY-4.0 --- # G.07 — Engineered U1 snRNA & Branchpoint Splicing Rescue ## Governing Biophysical / Mathematical Law Ψ_canonical = 1 / (1 + exp((ΔG_U1,donor + ΔG_ExSpeU1 − ΔG_skip) / R T)) ## Primary Evidence Receipt - **Citation:** Donegà et al. (2020), Human Mutation 41(12):2143-2154 — Rescue of common exon-skipping mutations in cystic fibrosis with modified U1 snRNAs (PMID 32935393). - **DOI:** https://doi.org/10.1002/humu.24116 - **PubMed PMID:** https://pubmed.ncbi.nlm.nih.gov/32935393/ - **Structural Reference (RCSB PDB):** https://www.rcsb.org/structure/3CW1 - **Answer Tier:** T2 · Sourced RNA Splicing & Engineered snRNA Model ## Verification Rules - Distinguish cryptic pseudoexon gain-of-splice-site variants (rescued by steric-blocking ASOs) from canonical exon-skipping variants (rescued by ExSpeU1 or bifunctional enhancers). - Ground ExSpeU1 rescue of CFTR donor/acceptor defects in Donegà et al. 2016 (DOI 10.1002/humu.24116, PMID 32935393). - Model exon inclusion probability Ψ via the Boltzmann partition function over competing E-complex assembly states. ## Safety & Clinical Boundary Research synthesis and biophysical modeling only — never medical advice, clinical guidance, or a treatment promise.
REV 1.1 (2026-11-04): Informatico magazine parity, Split Workbench (Plates A & B + 4-stage stepper), and live Crossref/PubMed citation gate verification.
Verified 5-Act magazine flow, untruncated headings, and bilingual EN / ES-MX structural parity.
Audited clinical dignity boundaries, non-promise guardrails, and discovery catalog coverage.
check_folio_citations.py
Verified DOI 10.1002/humu.24116 against Crossref and NCBI PubMed metadata.
src/scripts/ptc-pillar-explorer.js
Coupled governing relation Ψ_canonical = 1 / (1 + exp((ΔG_U1,donor + ΔG to interactive Plates A & B.