Back to basics: Fundamental Concepts and Special Considerations in RNA Isolation
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The document outlines the fundamental concepts and considerations related to RNA isolation, including types of RNA, handling and stabilization methods, and specific challenges associated with different sample types. It emphasizes the importance of proper sample collection, homogenization techniques, and the use of specialized kits for maximizing RNA yield and purity. The content also includes legal disclaimers regarding the use of QIAGEN products for molecular biology applications.
Back to basics: Fundamental Concepts and Special Considerations in RNA Isolation
- 1. Sample to Insight Back to basics: Fundamental concepts and special considerations in RNA isolation Abhishek Sharma, M.Sc. Senior Global Market Manager, Sample Technologies RNA Back to basics: Fundamental concepts and special considerations in RNA isolation 1
- 2. Sample to Insight Legal disclaimer QIAGEN products shown here are intended for molecular biology applications. These products are not intended for the diagnosis, prevention or treatment of a disease. For up-to-date licensing information and product-specific disclaimers, see the respective QIAGEN kit handbook or user manual. QIAGEN kit handbooks and user manuals are available at www.qiagen.com or can be requested from QIAGEN Technical Services or your local distributor. Back to basics: Fundamental concepts and special considerations in RNA isolation 2
- 3. Sample to Insight Agenda RNA universe – RNA types and their role in cells1 Handling RNA – General remarks2 Stabilization of RNA in sample3 RNA isolation – Special considerations4 miRNA and exosome RNA purifications5 QIAGEN solutions for quality RNA6 Back to basics: Fundamental concepts and special considerations in RNA isolation 3
- 4. Sample to Insight Agenda RNA universe – RNA types and their role in cells1 Handling RNA – General remarks2 Stabilization of RNA in sample3 RNA isolation – Special considerations4 miRNA and exosome RNA purifications5 QIAGEN solutions for quality RNA6 Back to basics: Fundamental concepts and special considerations in RNA isolation 4
- 5. Sample to Insight RNA universe Name: Ribonucleic acid Abbreviation: RNA Destination: Throughout the cell (nucleus, nucleolus, cytoplasm, ribosomes, mitochondria, chloroplasts, and endoplasmic reticulum) and in exosomes for communication between cells Types: • Messenger RNA (mRNA), transcribed from DNA, serves as a template for synthesis of proteins • Ribosomal RNA (rRNA) present in ribosomes for protein synthesis • Transfer RNA (tRNA) deliver amino acids to the ribosomes for protein synthesis • miRNAs are noncoding RNAs that mediate post- transcriptional gene regulation • Long non-coding RNAs (lncRNA) range from 200 nucleotides to100 kb in length with diverse functions including epigenetics, alternative splicing and nuclear import. To get the complete picture: • Download our RNA Universe App: www.qiagen.com/qdm/app/universe/login.aspx Did you know? Thirty scientists have received Nobel Prizes for research on RNA Back to basics: Fundamental concepts and special considerations in RNA isolation 5
- 6. Sample to Insight RNA distribution in cells RNA content of a typical human cell Parameter Amount Total RNA per cell <1–30 pg Proportion of total RNA in nucleus ~14% DNA:RNA in nucleus ~2:1 mRNA molecules 2 x 105 – 1 x 106 Typical mRNA size 1900 nt RNA distribution in a typical mammalian cell RNA species Relative amount rRNA (28S, 18S, 5S) 80–85% tRNAs, snRNAs, low MW species 15–20% mRNAs 1–5% mRNA classification based on abundance Abundance Copies/cell No. of different messages/cell Abundance of each message Low 5–15 11,000 <0.004% Intermediate 200–400 500 <0.1% High 12,000 <10 3% Back to basics: Fundamental concepts and special considerations in RNA isolation 6
- 7. Sample to Insight Generic gene expression workflow Back to basics: Fundamental concepts and special considerations in RNA isolation 7 Sample collection Disruption Purification cDNA synthesis Analysis
- 8. Sample to Insight Agenda RNA universe – RNA types and their role in cells1 Handling RNA – General remarks2 Stabilization of RNA in sample3 RNA isolation – Special considerations4 miRNA and exosome RNA purifications5 QIAGEN solutions for quality RNA6 Back to basics: Fundamental concepts and special considerations in RNA isolation 8
- 9. Sample to Insight Handling RNA – The key factors Working quickly but carefully is key! General handling • Always wear latex or vinyl gloves to prevent RNase contamination • Change gloves frequently and keep tubes closed whenever possible Disposable plasticware • The use of sterile, disposable polypropylene tubes is recommended • These tubes are generally RNase-free and do not require pretreatment to inactivate RNases Non-disposable plasticware • Non-disposable plasticware should be treated before use to ensure that it is RNase-free • Rinse thoroughly with 0.1 M NaOH, 1 mM EDTA followed by RNase-free water • Alternatively, chloroform-resistant plasticware can be rinsed with chloroform to inactivate RNases Back to basics: Fundamental concepts and special considerations in RNA isolation 9
- 10. Sample to Insight Handling RNA – The key factors Glassware • Glassware should be cleaned with a detergent, thoroughly rinsed, and oven baked at 240°C for at least 4 hours before use • Autoclaving alone will not fully inactivate many RNases • An alternative is DEPC treatment: Fill glassware with 0.1% DEPC (0.1% in water), incubate overnight (12 hours) at 37°C, and then autoclave or heat to 100°C for 15 min Electrophoresis tanks • Electrophoresis tanks should be cleaned with detergent solution (e.g., 0.5% SDS), thoroughly rinsed with RNase-free water, and then rinsed with ethanol and allowed to dry • Plastics used for some electrophoresis tanks are not resistant to ethanol For complete tips, go to www.qiagen.com/qdm/rna/resources/ Working quickly but carefully is key! Back to basics: Fundamental concepts and special considerations in RNA isolation 10
- 11. Sample to Insight Agenda RNA universe – RNA types and their role in cells1 Handling RNA – General remarks2 Stabilization of RNA in sample3 RNA isolation – Special considerations4 miRNA and exosome RNA purifications5 QIAGEN solutions for quality RNA6 Back to basics: Fundamental concepts and special considerations in RNA isolation 11
- 12. Sample to Insight Generic gene expression workflow Back to basics: Fundamental concepts and special considerations in RNA isolation 12 Sample collection Disruption Purification cDNA synthesis Analysis
- 13. Sample to Insight Sample collection and stabilization Back to basics: Fundamental concepts and special considerations in RNA isolation 13 Changes in mRNA levels following sample harvesting mRNA level Sample harvest and processing
- 14. Sample to Insight RNAlater RNA Stabilization Reagent Purification of RNA without degradation Back to basics: Fundamental concepts and special considerations in RNA isolation 14
- 15. Sample to Insight Immediate RNA stabilization at room temperature Storage and transport of samples at ambient temperature RNAprotect Reagent • Cells • Bacteria • Saliva RNAlater RNA Stabilization Reagent • Freshly harvested tissue Sample RNA stabilization RNA stabilization and purification Tissues RNAlater® RNA Stabilization Reagent RNAlater TissueProtect Tubes RNeasy® Protect Kits Mammalian cells RNAprotect® Cell Reagent RNeasy Protect Cell Mini Kit Human saliva RNAprotect Saliva Reagent RNeasy Protect Saliva Mini Kit Human blood PAXgene™ Blood RNA Tubes PAXgene Blood RNA Kit Bacteria RNAprotect Bacteria Reagent RNeasy Protect Bacteria Kits Back to basics: Fundamental concepts and special considerations in RNA isolation 15
- 16. Sample to Insight Generic gene expression workflow Sample collection Disruption Purification cDNA synthesis Analysis Back to basics: Fundamental concepts and special considerations in RNA isolation 16
- 17. Sample to Insight Agenda RNA universe – RNA types and their role in cells1 Handling RNA – General remarks2 Stabilization of RNA in sample3 RNA isolation – Special considerations4 Step 1: Sample disruption and homogenization4.1 Step 2: Isolating RNA from different samples – tips and tricks4.2 Step 3: gDNA removal for sensitive applications4.3 miRNA and exosome RNA purifications5 QIAGEN solutions for quality RNA6 Back to basics: Fundamental concepts and special considerations in RNA isolation 17
- 18. Sample to Insight Sample disruption and homogenization Disruption and homogenization are two distinct steps Disruption • Complete disruption of tissue structure, cell walls, and plasma membranes of cells is required to release all the RNA contained in the sample • Different samples require different methods to achieve complete disruption • Incomplete disruption results in significantly reduced yields Homogenization • Homogenization is necessary to reduce the viscosity of the cell lysates produced by disruption • Homogenization shears the high molecular weight genomic DNA and other high molecular weight cellular components to create a homogeneous lysate • Incomplete homogenization results in inefficient binding of RNA and therefore significantly reduced yields Efficient disruption and homogenization is an absolute requirement. Back to basics: Fundamental concepts and special considerations in RNA isolation 18
- 19. Sample to Insight Manual disruption using a mortar and pestle Classical method Using liquid nitrogen to freeze the sample Mortar and pestle to grind the tissue to a powder Powdered sample needs to be resuspended in a chaotropic lysis buffer Shear the genomic DNA with a needle and syringe which improves the efficiency of removing the genomic DNA from the columns Approach works well but is incomplete Genomic DNA is high in molecular weight which adds viscosity to the sample clogging spin filters Back to basics: Fundamental concepts and special considerations in RNA isolation 19
- 20. Sample to Insight Comparison of RNA yields with different homogenization methods QIAshredder – fast and simple homogenization of cell lysates Back to basics: Fundamental concepts and special considerations in RNA isolation 20
- 21. Sample to Insight Systems for mechanical disruption and homogenization Human/animal tissue Plant tissue Human/animal tissue Plant tissue Bacteria Yeast Human/animal tissue Plant tissue Bacteria Yeast Replacing methods such as manual disruption using a mortar and pestle Up to 48 or 192 samples/run TissueLyser II 1 sample/run TissueRuptor Up to 12 samples/run TissueLyser LT Back to basics: Fundamental concepts and special considerations in RNA isolation 21
- 22. Sample to Insight Effective tissue disruption Various rat tissues were disrupted using the TissueLyser LT or TissueLyser II RNA was purified from 20 mg samples on the QIAcube using the RNeasy Fibrous Tissue Mini Kit (skin, heart and lung) or RNeasy Lipid Tissue Mini Kit (brain) Back to basics: Fundamental concepts and special considerations in RNA isolation 22 RNA yields RNA yield (ng/µl)
- 23. Sample to Insight Generic gene expression workflow Sample collection Disruption Purification cDNA synthesis Analysis Back to basics: Fundamental concepts and special considerations in RNA isolation 23
- 24. Sample to Insight Agenda RNA universe – RNA types and their role in cells1 Handling RNA – General remarks2 Stabilization of RNA in sample3 RNA isolation – Special considerations4 Step 1: Sample disruption and homogenization4.1 Step 2: Isolating RNA from different samples – tips and tricks4.2 Step 3: gDNA removal for sensitive applications4.3 miRNA and exosome RNA purifications5 QIAGEN solutions for quality RNA6 Back to basics: Fundamental concepts and special considerations in RNA isolation 24
- 25. Sample to Insight Precipitation vs. spin columns Precipitation Spin columns Cheap, no kits required, scalable Higher material cost Longer handling and incubation times Fast, easy to use Several rounds of precipitation are often required for decent purity High purity Risk to lose RNA pellet, especially with small samples Special formats for different sample types and sizes, including very small samples Back to basics: Fundamental concepts and special considerations in RNA isolation
- 26. Sample to Insight Special considerations for various sample types Isolating RNA from heart, muscle and other fibrous tissues • Contractile proteins, connective tissue and collagen can interfere with the isolation process • Sample needs to be treated with a protease or phenol containing lysis reagents • Maintain proper conditions that do not degrade RNA, e.g., use RNase-free proteinase K • RNA was isolated using the RNeasy Fibrous Tissue Mini Kit • Real-time, quantitative RT-PCR was performed with 100 ng total RNA using the QuantiTect Probe RT-PCR Kit and primers and probes specific for alpha-actin Back to basics: Fundamental concepts and special considerations in RNA isolation 26
- 27. Sample to Insight RNA from FFPE samples Minimize the effects of FFPE storage on RNA transcripts • Remove and fix tissue as quickly as possible • Use tissue samples no more than 5 mm thick and do not over-fix (max. 24 hours) • Use high-quality reagents for paraffin embedding, without additives • Avoid sample staining, if possible • Store FFPE samples appropriately • RNA remains intact for up to 1 year when stored at 4ºC • Use an appropriate deparaffinization step • Have a crosslink reversal step during RNA isolation The complete FFPE guide: Critical factors for molecular analysis of FFPE samples Back to basics: Fundamental concepts and special considerations in RNA isolation 27
- 28. Sample to Insight miRNeasy FFPE Kit Successful detection of miRNA and mRNA from the same eluate • Rat liver tissue was formalin fixed for 24 hours or 60 hours, followed by purification of total RNA including miRNA • Purified RNA was used as a template in quantitative, real-time RT-PCR using the miScript PCR System Back to basics: Fundamental concepts and special considerations in RNA isolation 28 CT value
- 29. Sample to Insight Isolating RNA from human blood samples • Very small amounts of RNA • RNA integrity - Presence of RNases • Cellular RNA or exosomal RNA • Contaminants interfere with downstream RNA analysis • Contaminants include anticoagulants – heparin and EDTA, and naturally occurring enzyme inhibitors Back to basics: Fundamental concepts and special considerations in RNA isolation 29
- 30. Sample to Insight Isolating RNA from plant samples • Several plant metabolites – difficult to remove • As a general guideline, healthy, young tissues are recommended ◦ Young tissues yield more RNA compared to older ones as they contain more cells and fewer metabolites • Many “home-made” protocols for RNA isolation recommend growing plants in darkness for 1 to 2 days before harvesting to prevent high levels of plant metabolite accumulation Back to basics: Fundamental concepts and special considerations in RNA isolation 30
- 31. Sample to Insight Dedicated kits could solve the problems with RNA isolation Reproducible purification of intact RNA from plant tissues – the RNeasy Plant Mini Kit Tomato Arabidopsis Cotton Maize Canola RNA isolated from the leaves of five plant species • Frozen plant leaves were disrupted using the TissueLyser II (2 x 1 min) • RNA was purified using the RNeasy Plant Mini Kit; analyzed on a 1.2% formaldehyde agarose gel • The sharp and equally intense ribosomal RNA bands indicate reproducible purification of intact RNA Back to basics: Fundamental concepts and special considerations in RNA isolation 31
- 32. Sample to Insight Isolating RNA from bacteria and viruses • Bacterial mRNA has no 5’ cap and only rarely has a poly-A tail • mRNA isolation by hybrid capture is impossible • The RNeasy Protect Bacteria Kit makes bacterial gene expression studies possible • When purifying viral RNA and DNA from plasma and serum, a major challenge is to concentrate the nucleic acids, as they may be extremely diluted in a large sample volume • QIAamp Kits allow purification of viral nucleic acids from starting volumes as high as 5 ml Amplification of RNA from plasma • RT-PCR products of a 1026 nt RNA fragment purified from plasma • Serial tenfold dilutions were added to plasma and purified using the QIAamp Viral RNA Mini Kit Back to basics: Fundamental concepts and special considerations in RNA isolation 32 Gene expressed (%)
- 33. Sample to Insight Agenda RNA universe – RNA types and their role in cells1 Handling RNA – General remarks2 Stabilization of RNA in sample3 RNA isolation – Special considerations4 Step 1: Sample disruption and homogenization4.1 Step 2: Isolating RNA from different samples – tips and tricks4.2 Step 3: gDNA removal for sensitive applications4.3 miRNA and exosome RNA purifications5 QIAGEN solutions for quality RNA6 Back to basics: Fundamental concepts and special considerations in RNA isolation 33
- 34. Sample to Insight Removal of genomic DNA contamination • Trace amounts of genomic DNA in an RNA sample can compromise the accuracy of sensitive applications such as real-time RT-PCR • Both RNA and DNA targets may be amplified, leading to unreliable quantification of the intended RNA target • Eliminate genomic DNA contamination either during RNA purification or just prior to cDNA synthesis • Primer design • DNase digestion (with or without DNase Booster) • gDNA Eliminator Column – RNeasy Plus Kits • gDNA Eliminator Solution – RNeasy Plus Universal Kit • The gDNA Eliminator Solution is a novel non-enzymatic solution, which reduces gDNA contamination of the aqueous phase. It does not contain DNase Why is gDNA removal important? QIAGEN solutions: Back to basics: Fundamental concepts and special considerations in RNA isolation 34
- 35. Sample to Insight Effective elimination of genomic DNA contamination The –RT curves demonstrate that RNA purified using the RNeasy Plus Mini Kit was virtually free of genomic DNA • Total RNA was purified from Jurkat cell samples • 1 x 106 cells per sample • A: RNeasy Plus Mini Kit • B: An RNA purification kit with integrated genomic DNA removal from Supplier AV • Duplicate real-time RT-PCR assays for β-actin were performed with (+RT) or without (-RT) reverse transcriptase Back to basics: Fundamental concepts and special considerations in RNA isolation 35
- 36. Sample to Insight QIAGEN RNA Purification Kits Back to basics: Fundamental concepts and special considerations in RNA isolation
- 37. Sample to Insight Upgrade your expectations – RNeasyPlus Kits RNeasy Plus Procedure – with the gDNA Eliminator spin column Back to basics: Fundamental concepts and special considerations in RNA isolation 37
- 38. Sample to Insight Upgrade your expectations – RNeasy Plus Universal Kits RNeasy Plus Universal Mini Procedure - with the gDNA Eliminator Solution Back to basics: Fundamental concepts and special considerations in RNA isolation 38
- 39. Sample to Insight Agenda RNA universe – RNA types and their role in cells1 Handling RNA – General remarks2 Stabilization of RNA in sample3 RNA isolation – Special considerations4 miRNA and exosome RNA purifications5 QIAGEN solutions for quality RNA6 Back to basics: Fundamental concepts and special considerations in RNA isolation 39
- 40. Sample to Insight miRNA isolation technologies miRNeasy Kits – efficient purification of miRNA from different starting materials • Cells and tissues – miRNeasy Mini Kit • FNB – miRNeasy Micro Kit • FFPE – miRNeasy FFPE Kit • Blood – miRNeasy Serum/Plasma Kit • Serum/plasma – miRNeasy Serum/Plasma Kit • Highly pure RNA without phenol carryover Back to basics: Fundamental concepts and special considerations in RNA isolation 40 OD
- 41. Sample to Insight Exosome isolation technologies Lower the risk of missing your biomarker! exoRNeasy • Exosomal (EVs) RNA isolation • Serum, plasma, CSF and cell culture • Saliva – tested by customer; no protocol developed exoEasy • Exosome (EVs) isolation • Serum, plasma and cell culture Back to basics: Fundamental concepts and special considerations in RNA isolation 41
- 42. Sample to Insight Agenda RNA universe – RNA types and their role in cells1 Handling RNA – General remarks2 Stabilization of RNA in sample3 RNA isolation – Special considerations4 miRNA and exosome RNA purifications5 QIAGEN solutions for quality RNA6 Back to basics: Fundamental concepts and special considerations in RNA isolation 42
- 43. Sample to Insight RNA Selection Wheel Back to basics: Fundamental concepts and special considerations in RNA isolation RNA Selection Wheel
- 44. Sample to Insight RNA resource center www.qiagen.com/qdm/rna/resources/ Back to basics: Fundamental concepts and special considerations in RNA isolation
- 45. Sample to Insight Thank you for your attention! Questions? qiawebinars@qiagen.com Contact QIAGEN: www.qiagen.com/about-us/contact/global-contacts/ Back to basics: Fundamental concepts and special considerations in RNA isolation 45