Methods and kits for labeling cellular molecules
Methods of uniquely labeling or barcoding molecules within a cell, a plurality of cells, and/or a tissue are provided. Kits for uniquely labeling or barcoding molecules within a cell, a plurality of cells, and/or a tissue are also provided. The molecules to be labeled may include, but are not limited to, RNAs, cDNAs, DNAs, proteins, peptides, and/or antigens.
1. A method of labeling genomic DNA with cell-specific tags, the method comprising:
(a) providing a plurality of fixed and permeabilized cells, wherein each of the plurality of fixed, permeabilized cells comprises genomic DNA;
(b) fragmenting the genomic DNA within the cells to produce a plurality of genomic DNA fragments, and appending a nucleic acid adapter in a non-target-specific manner to the ends of the plurality of genomic DNA fragments within the cells, thereby producing a plurality of adapter-coupled genomic DNA fragments;
(c) dividing the plurality of cells comprising the adapter-coupled genomic DNA fragments into a plurality of aliquots, wherein each aliquot of the plurality of aliquots comprises more than one cell;
(d) coupling nucleic acid tags to the adapter-coupled genomic DNA fragments within cells of the plurality of aliquots, thereby generating tagged genomic DNA fragments, wherein each of the nucleic acid tags comprises:
i) a barcode sequence, and
ii) a 3′ hybridization sequence located 3′ of the barcode sequence and/or a 5′ hybridization sequence located 5′ of the barcode sequence,
wherein multiple distinct barcode sequences are present among the nucleic acid tags used in the plurality of aliquots, and
wherein the barcode sequences present in each individual aliquot of the plurality of aliquots are specific to the individual aliquot;
(e) combining the cells from the plurality of aliquots;
(f) dividing the combined cells from the plurality of aliquots into a plurality of samples, wherein each sample of the plurality of samples comprises more than one cell;
(g) lysing the cells in the plurality of samples to release the tagged genomic DNA fragments; and
(h) amplifying the released tagged genomic DNA fragments in the plurality of samples using amplification primers,
wherein at least a portion of the amplification primers used in each sample comprise an index sequence,
wherein multiple distinct index sequences are present among the amplification primers used in the plurality of samples, and
wherein the index sequences present in each individual sample of the plurality of samples are specific to the individual sample.
2. The method of claim 1 , wherein steps (c) through (e) are repeated one or more times, thereby producing repeatedly tagged genomic DNA fragments.
3. The method of claim 2 , wherein steps (c) through (e) are repeated a number of times sufficient to generate at least as many distinct combinations of barcode sequences among the repeatedly tagged genomic DNA molecules as the number of cells in the plurality of cells.
4. The method of claim 2 , wherein steps (c) through (e) are repeated a number of times sufficient to provide a greater than 50%, 90%, 95%, or 99% probability that the repeatedly tagged genomic DNA fragments originating from a given individual cell comprise a unique combination of barcode sequences relative to the combinations of barcode sequences present among the repeatedly tagged genomic DNA fragments originating from the other cells of the plurality of cells.
5. The method of claim 1 , wherein the coupling in step (d) comprises ligating a 3′ end of a nucleic acid tag to a 5′ end of an adapter-coupled genomic DNA fragment.
6. The method of claim 5 , wherein the 3′ end of the nucleic acid tag is present within the 3′ hybridization sequence of the nucleic acid tag, and wherein the 3′ end of the nucleic acid tag is brought into proximity of the 5′ end of the adapter-coupled genomic DNA fragment by being preannealed to a linker nucleic acid strand that is complementary to the 3′ hybridization sequence and to a sequence at a 5′ end of the adapter-coupled genomic DNA fragment.
7. The method of claim 6 , wherein the coupling is stopped by introducing a plurality of ligation stop oligos that are complementary to all or part of the linker nucleic acid strand.
8. The method of claim 2 , wherein the coupling in step (d) during the one or more times that steps (c) to (e) are repeated comprises ligating a 3′ end of a nucleic acid tag to the 5′ end of a tagged or repeatedly tagged genomic DNA fragment.
9. The method of claim 8 , wherein the 3 ′ end of the nucleic acid tag is present within the 3′ hybridization sequence, and wherein the 3′ end of the nucleic acid tag is brought into proximity of the 5′ end of the tagged or repeatedly tagged genomic DNA fragment by being preannealed to a secondary linker nucleic acid strand that is complementary to the 3′ hybridization sequence of the nucleic acid tag and to the 5′ hybridization sequence of a previously coupled nucleic acid tag.
10. The method of claim 9 , wherein the coupling is stopped by introducing a plurality of secondary ligation stop oligos that are complementary to all or part of the secondary linker nucleic acid strand.
11. The method of claim 1 , wherein the nucleic acid adapter and/or nucleic acid tags are DNA molecules.
12. The method of claim 1 , further comprising, prior to step (a), fixing and/or permeabilizing the plurality of cells.
13. The method of claim 2 , wherein the nucleic acid tags that are coupled to the repeatedly tagged genomic DNA fragments during the last of the one or more times that steps (c) to (e) are repeated comprise one or more elements selected from the group consisting of a random nucleotide sequence to prevent counting of PCR duplicates, a capture agent, and a next-generation sequencing (NGS) adapter sequence.
14. The method of claim 13 , wherein the capture agent comprises biotin.
15. The method of claim 1 , further comprising, prior to step (h), isolating the tagged genomic DNA fragments released during step (g) using a binding agent.
16. The method of claim 15 , wherein the binding agent comprises streptavidin.
17. The method of claim 1 , wherein the barcode sequences present within the nucleic acid tags each comprise at least 8 nucleotides.
18. The method of claim 1 , wherein one or more of the amplification primers further comprises one or more elements selected from the group consisting of a flow-cell binding sequence, an NGS primer binding sequence, and an NGS adapter sequence.
19. The method of claim 1 , wherein the cells are lysed in step (g) in the presence of a protease.
20. The method of claim 19 , wherein the protease is proteinase K.
21. The method of claim 1 , further comprising:
(i) size selecting the tagged genomic DNA fragments amplified in step (h) using solid-phase reversible immobilization (SPRI) beads.
22. The method of claim 1 , further comprising:
(j) sequencing the tagged genomic DNA fragments amplified in step (h).
23. The method of claim 22 , further comprising:
(k) grouping the sequencing reads obtained in (j) by barcode sequence and/or index sequence.
24. The method of claim 23 , wherein steps (c) to (e) have been repeated one or more times, thereby producing repeatedly tagged genomic DNA fragments each comprising multiple barcode sequences, and wherein the sequencing reads are grouped by any combination of two or more sequences selected from the multiple barcode sequences and the index sequence.
25. The method of claim 1 , wherein the plurality of cells comprise mammalian cells.
26. The method of claim 1 , wherein the fragmenting is performed using a DNase.
27. The method of claim 11 , wherein the nucleic acid adapter is a double-stranded DNA molecule.
28. The method of claim 1 , wherein the nucleic acid tags used in the plurality of aliquots comprise 96 distinct barcode sequences.
29. The method of claim 28 , wherein the plurality of aliquots comprises 96 aliquots distributed in a 96-well plate.
30. The method of claim 29 , wherein each of the 96 distinct barcode sequences is present in only one of the 96 aliquots.