जीनोमिक डीएनए से 5-hydroxymethylcytosine के चुनिंदा कब्जा
Summary
वर्णित एक दो कदम लेबलिंग β glucosyltransferase (β-GT) प्रक्रिया का उपयोग कर 5-HMC एक azide ग्लूकोज हस्तांतरण, रसायन शास्त्र क्लिक द्वारा पीछा करने के लिए आसान और घनत्व स्वतंत्र संवर्धन के लिए एक बायोटिन linker हस्तांतरण. यह कुशल और विशिष्ट लेबलिंग विधि अत्यंत कम पृष्ठभूमि और उच्च throughput epigenomic मानचित्रण के साथ अगली पीढ़ी के अनुक्रमण के माध्यम से 5 HMC के संवर्धन के लिए सक्षम बनाता है.
Abstract
5-methylcytosine (5-mC) constitutes ~2-8% of the total cytosines in human genomic DNA and impacts a broad range of biological functions, including gene expression, maintenance of genome integrity, parental imprinting, X-chromosome inactivation, regulation of development, aging, and cancer1. Recently, the presence of an oxidized 5-mC, 5-hydroxymethylcytosine (5-hmC), was discovered in mammalian cells, in particular in embryonic stem (ES) cells and neuronal cells2-4. 5-hmC is generated by oxidation of 5-mC catalyzed by TET family iron (II)/α-ketoglutarate-dependent dioxygenases2, 3. 5-hmC is proposed to be involved in the maintenance of embryonic stem (mES) cell, normal hematopoiesis and malignancies, and zygote development2, 5-10. To better understand the function of 5-hmC, a reliable and straightforward sequencing system is essential. Traditional bisulfite sequencing cannot distinguish 5-hmC from 5-mC11. To unravel the biology of 5-hmC, we have developed a highly efficient and selective chemical approach to label and capture 5-hmC, taking advantage of a bacteriophage enzyme that adds a glucose moiety to 5-hmC specifically12.
Here we describe a straightforward two-step procedure for selective chemical labeling of 5-hmC. In the first labeling step, 5-hmC in genomic DNA is labeled with a 6-azide-glucose catalyzed by β-GT, a glucosyltransferase from T4 bacteriophage, in a way that transfers the 6-azide-glucose to 5-hmC from the modified cofactor, UDP-6-N3-Glc (6-N3UDPG). In the second step, biotinylation, a disulfide biotin linker is attached to the azide group by click chemistry. Both steps are highly specific and efficient, leading to complete labeling regardless of the abundance of 5-hmC in genomic regions and giving extremely low background. Following biotinylation of 5-hmC, the 5-hmC-containing DNA fragments are then selectively captured using streptavidin beads in a density-independent manner. The resulting 5-hmC-enriched DNA fragments could be used for downstream analyses, including next-generation sequencing.
Our selective labeling and capture protocol confers high sensitivity, applicable to any source of genomic DNA with variable/diverse 5-hmC abundances. Although the main purpose of this protocol is its downstream application (i.e., next-generation sequencing to map out the 5-hmC distribution in genome), it is compatible with single-molecule, real-time SMRT (DNA) sequencing, which is capable of delivering single-base resolution sequencing of 5-hmC.
Protocol
Discussion
5 hydroxymethylcytosine (5 HMC) एक हाल ही में पहचाना कुछ स्तनधारी प्रकार की कोशिकाओं में पर्याप्त मात्रा में मौजूद epigenetic संशोधन है. यहाँ प्रस्तुत विधि 5-HMC जीनोम चौड़ा वितरण का निर्धारण करने के लिए है. हम टी -4 जीवाणुभोजी β glucosyltr…
Disclosures
The authors have nothing to disclose.
Acknowledgements
इस अध्ययन के हिस्से में स्वास्थ्य के राष्ट्रीय संस्थान (GM071440 से CH और NS051630/MH076090/MH078972 तक पी.जे. करने के लिए) द्वारा समर्थित किया गया था.
Materials
| Name | Company | Catalog # | Comment |
| Reagents | |||
| 5M Sodium chloride (NaCl) | Promega | V4221 | |
| 0.5M pH8.0 Ethylenediaminetetraacetic acid (EDTA) | Promega | V4231 | |
| 1M Trizma base (Tris) pH7.5 | Invitrogen | 15567-027) | |
| HEPES 1M, pH7.4 | Invitrogen | 15630 | |
| Magnesium chloride (MgCl2) 1M | Ambion | AM9530G | |
| Dimethyl sulfoxide (DMSO) | Sigma | D8418 | |
| Tween 20 | Fisher BioReagents | BP337-100 | |
| DBCO-S-S-PEG3-Biotin conjugate | Click Chemistry Tools | A112P3 | |
| 1,4-Dithiothreitol, ultrapure (DTT) Superpure | Invitrogen | 15508-013 | |
| QIAquick Nucleotide Removal Kit | Qiagen | 28304 | |
| Micro Bio-Spin 6 Column | Bio-Rad | 732-6222 | |
| Dynabeads MyOne | Invitrogen | 650-01 | |
| Streptavidin C1 | |||
| Qiagen MinElute PCR Purification Kit | Qiagen | 28004 | |
| UltraPure Agarose | Invitrogen | 16500500 | |
| UDP-6-N3-glucose | Active Motif | 55013 | |
| Enzyme | |||
| β-glucosyltransferase (β-GT) | New England Biolab | M0357 | |
| Equipment | |||
| Sonication device | Covaris | ||
| Desktop centrifuge | |||
| Water bath | Fisher Scientific | ||
| Gel running apparatus | Bio-Rad | ||
| NanoDrop1000 | Thermo Scientific | ||
| Labquake Tube Shaker | Barnstead | ||
| Labquake Tube Shaker | Thermolyne | ||
| Magnetic Separation Stand | Promega | Z5342 | |
| Qubit 2.0 Fluorometer | Invitrogen | ||
| Reagent setup 10 X β-GT Reaction Buffer (500 mM HEPES pH 7.9, 250 mM MgCl2) 2 X Binding and washing (B&W) buffer (10 mM Tris pH 7.5, 1 mM EDTA, 2 M NaCl, 0.02% Tween 20). |
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