ChIRP Method for High-Resolution lncRNA Binding Site Mapping
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Solution Overview
Problem
Current methods for studying RNA occupancy at chromatin are limited to single gene loci and lack high-resolution mapping of long non-coding RNA (lncRNA) binding sites, hindering the understanding of their roles in chromatin regulation.
Innovation Solution
A method called Chromatin Isolation by RNA Purification (ChIRP) involves cross-linking cellular contents, fragmenting them, and using non-overlapping oligonucleotides with affinity tags to isolate RNA-bound complexes, allowing for the analysis of RNA, protein, and genomic DNA interactions with high stringency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional methods are used to study RNA occupancy, then analysis at single gene locus is possible, but genome-wide high-resolution mapping is not achieved
Solution Approach 1:
The method segments the chromatin into small fragments after crosslinking, allowing high-resolution mapping of RNA binding sites across the entire genome. This fragmentation enables precise localization of lncRNA binding sites while maintaining the ability to perform genome-wide analysis simultaneously.
Solution Approach 2:
The patent uses biotinylated oligonucleotides as intermediaries that hybridize to the target lncRNA and facilitate its isolation from chromatin complexes. This intermediary approach enables specific enrichment of RNA-bound complexes for high-resolution mapping while simplifying the overall workflow.
2Loss of information
If indirect effects of lincRNA perturbation are used to infer roles, then functional analysis is possible, but exact binding locations and mechanisms remain unclear
Solution Approach 1:
The method performs crosslinking of chromatin to lncRNA complexes before fragmentation and isolation, preserving the spatial information of binding locations. This preliminary crosslinking action ensures that binding sites are maintained through subsequent processing steps, enabling direct observation of lncRNA functions and mechanisms rather than relying on indirect perturbation analysis.
3Measurement precision
If high stringency conditions are used for oligonucleotide hybridization, then specific target RNA isolation is achieved, but binding site mapping resolution is reduced
Solution Approach 1:
Crosslinking is performed before oligonucleotide hybridization, creating stable complexes that preserve binding locations. This preliminary crosslinking ensures that subsequent high-stringency hybridization conditions will not disrupt the complexes, allowing both high-resolution mapping and specific isolation to be achieved simultaneously.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
ChIRP enables the identification of lncRNA binding sites genome-wide with high specificity and sensitivity, revealing detailed interactions and mechanisms of lncRNAs in chromatin regulation, such as HOTAIR's role in recruiting Polycomb domains.
Implementation Method 1
cross-linking the contents of a cell using a heat stable crosslinking agent to produce cross-linked ribonucleotide complexes
Implementation Method 2
contacting the complexes with a plurality of non-overlapping oligonucleotides comprise an affinity tag and that are complementary to a specific target RNA of the cell under high stringency conditions
Data Source
AI summary
A method of sample analysis is provided. In certain cases, the method comprises: a) cross-linking the contents of a cell using a heat stable crosslinking agent to produce cross-linked ribonucleotide complexes; b) fragmenting the cross-linked ribonucleotide complexes to produce complexes comprising protein, RNA fragments and, optionally, genomic DNA fragments; c) contacting the complexes with a plurality of non-overlapping oligonucleotides comprise an affinity tag and that are complementary to a specific target RNA of the cell under high stringency conditions that include high temperature; d) isolating complexes that contain the oligonucleotides using the affinity tag to produce isolated complexes; e) enzymatically releasing the protein, RNA fragments and/or the genomic DNA fragments from the isolated complexes to produce a released component, without reversing the crosslinking; and f) analyzing the released component.