Spatial analysis of DNA methylation
Provided herein are methods of identifying a methylation status of an analyte in a biological sample. Also provided herein are methods that combine identifying the methylation status with spatial technology to identify the location of a methylation status in a biological sample.
1. A method for identifying methylation status of a nucleic acid in a biological sample, the method comprising:
(a) contacting the biological sample with a substrate;
(b) deaminating the nucleic acid in the biological sample;
(c) contacting the deaminated nucleic acid with a plurality of probes comprising a first probe and a second probe, wherein the first probe and the second probe hybridize to the deaminated nucleic acid and wherein:
the first probe comprises (i) a sequence complementary to a first sequence of the deaminated nucleic acid and (ii) a sequence complementary to a capture domain of a capture probe; and
the second probe comprises a sequence complementary to a second sequence of the deaminated nucleic acid;
(d) ligating the first probe and the second probe, thereby generating a ligation product;
(e) hybridizing the ligation product to the capture probe; and
(f) determining (i) the sequence of a spatial barcode of the capture probe, or the complement thereof, and (ii) all or part of the sequence of the ligation product, or a complement thereof, and using the determined sequences of (i) and (ii) to identify the methylation status of the nucleic acid in the biological sample.
2. The method of claim 1 , wherein the substrate comprises an array comprising the plurality of capture probes, wherein a capture probe of the plurality of capture probes comprises (i) the spatial barcode and (ii) the capture domain.
3. The method of claim 1 , further comprising, between steps (d) and (e):
aligning the substrate with a second substrate comprising an array, such that at least a portion of the biological sample is aligned with at least a portion of the array, wherein the array comprises the plurality of capture probes and wherein a capture probe of the plurality of capture probes comprises (i) the spatial barcode and (ii) the capture domain; and
when the biological sample is aligned with at least a portion of the array, (i) releasing the ligation product from the deaminated nucleic acid and (ii) migrating the ligation product from the biological sample to the array.
4. The method of claim 3 , wherein the substrate does not comprise an array of capture probes.
5. The method of claim 1 , wherein the ligating comprises enzymatic ligation or chemical ligation, and wherein the enzymatic ligation utilizes a ligase selected from a splintR ligase, a single stranded DNA ligase, or a T4 DNA ligase.
6. The method of claim 1 , wherein the nucleic acid is genomic DNA.
7. The method of claim 1 , wherein the biological sample is a tissue section sample.
8. The method of claim 1 , wherein the biological sample is a fixed sample, a frozen sample, a fresh sample, or a fresh frozen sample.
9. The method of claim 1 , wherein the deaminating comprises contacting the biological sample with a composition comprising sodium bisulfite.
10. The method of claim 1 , wherein the deaminating comprises treating the biological sample with an enzyme.
11. The method of claim 10 , wherein the enzyme is a cytidine deaminase or a demethylase.
12. The method of claim 1 , wherein the capture probe further comprises one or more functional domains, a unique molecular identifier, a cleavage domain, or combinations thereof.
13. The method of claim 1 , further comprising extending the capture probe using the ligation product as a template.
14. The method of claim 1 , wherein the determining comprises sequencing (i) all or a part of the sequence of the ligation product, or a complement thereof, and (ii) the spatial barcode, or a complement thereof.
15. The method of claim 1 , wherein at least one deaminated nucleotide is located (i) between the first sequence and the second sequence, (ii) in the first sequence, and/or (iii) in the second sequence.