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Method Article
micro-RNAs (miRNAs) are short and highly homologous RNA sequences, serving as post-transcriptional regulators of messenger RNAs (mRNAs). Current miRNA detection methods vary in sensitivity and specificity. We describe a protocol that combines in situ hybridization and immunostaining for concurrent detection of miRNA and protein molecules on mouse heart tissue sections.
micro-RNAs (miRNAs) are single-stranded RNA transcripts that bind to messenger RNAs (mRNAs) and inhibit their translation or promote their degradation. To date, miRNAs have been implicated in a large number of biological and disease processes, which has signified the need for the reliable detection methods of miRNA transcripts. Here, we describe a detailed protocol for digoxigenin-labeled (DIG) Locked Nucleic Acid (LNA) probe-based miRNA detection, combined with protein immunostaining on mouse heart sections. First, we performed an in situ hybridization technique using the probe to identify miRNA-182 expression in heart sections from control and cardiac hypertrophy mice. Next, we performed immunostaining for cardiac Troponin T (cTnT) protein, on the same sections, to co-localize miRNA-182 with the cardiomyocyte cells. Using this protocol, we were able to detect miRNA-182 through an alkaline phosphatase based colorimetric assay, and cTnT through fluorescent staining. This protocol can be used to detect the expression of any miRNA of interest through DIG-labeled LNA probes, and relevant protein expression on mouse heart tissue sections.
micro-RNAs (miRNAs) are short (18–25 nucleotides), single-stranded, noncoding RNAs that function as negative regulators of gene expression at the post-transcriptional level by inhibiting messenger RNA (mRNA) translation and/or promoting mRNA degradation1. miRNAs are transcribed from introns or exons of coding or noncoding genes and are cleaved in the nucleus by DROSHA, to precursor miRNAs (pre-miRNAs), which are short stem-loop structures of 70 nucleotides2. Following cytoplasmic export, pre-miRNAs are further processed by DICER into mature miRNAs that span 18–25 nucleotides3,4. Subsequently, the RNA-induced silencing complex (RISC) incorporates these miRNAs as single-stranded RNAs, which allows for their binding to the 3' untranslated region (3'-UTR) of their target mRNAs to suppress their expression3,5.
Within the last three decades, since they were first identified, miRNAs have emerged to master regulators of gene expression, whose own expression levels are tightly controlled6. Roles for miRNAs have been described in organ development7,8,9,10,11,12, maintenance of homeostasis13,14, as well as disease contexts that include neurological15,16,17,18,19, cardiovascular20, autoimmune conditions21,22, cancers23,24, and others25. The increasing appreciation for the relevance of miRNA expression patterns has brought forward the need for reliable detection methods of miRNA transcripts. Such methods include Real Time PCR, microarrays, Northern Blotting, in situ hybridization and others, which vary in the sensitivity, specificity, and quantitative power, predominantly due to the fact that miRNA transcripts are comprised of short and highly homologous sequences6.
We recently reported an important role for miRNA-182 in the development of the myocardial hypertrophy26, a condition describing the structural adaptation of the heart in response to elevated hemodynamic demands27,28. Cardiac hypertrophy is characterized by the increase in the myocardial mass, which, if associated with maladaptive remodeling29, can lead to increased risk for heart failure, a condition accounting for 8.5% of all deaths attributable to cardiovascular disease30.
Here, we describe our protocol that combines in situ hybridization with a digoxigenin-labeled (DIG) Locked Nucleic Acid (LNA) probe and immunostaining for the concurrent detection of miRNA and protein molecules on mouse heart tissue sections, in our model of cardiac hypertrophy.
Mouse heart tissue samples for this study were obtained in compliance with the relevant laws and institutional guidelines and were approved by Yale University Institutional Animal Care and Use Committee.
1. Solution Preparation
2. Tissue Preparation
NOTE: The mouse heart sections used here were prepared by Yale Pathology Tissue Services, from Formalin-Fixed/Paraffin-embedded tissue, cut at 5 μm and positioned on charged slides.
3. Hybridization
4. Stringency Washes
5. DIG Antibody Detection
6. cTnT Antibody Detection
7. Mounting and Imaging
miRNA in situ hybridization was optimized on mouse heart sections using a scramble miRNA and U6-snRNA, which served as negative and positive controls respectively. Positive staining is indicated in blue, while the negative staining is indicated by the lack of color development (Figure 1A-1B). Cardiomyocyte specific expression of miRNA-182 was assessed in heart sections from control and PlGF overexpressing mice. The mice carrying the ...
miRNA transcript detection can be achieved through different techniques that vary in sensitivity, specificity and quantitative power. Here, we demonstrate the coupling of miRNA in situ hybridization with immunostaining and describe a protocol that allows for concurrent assessment of the expression levels of miRNA and protein molecules, on the same heart sections. We first show how to perform in situ hybridization of DIG-labeled LNA miRNA probes on paraffin embedded heart sections. Next, we describe how ...
The authors have nothing to disclose.
We would like to thank Athanasios Papangelis, for critical comments on the manuscript. FM is supported by the Biotechnology and Biological Sciences Research Council (BBSRC; BB/M009424/1). IP is supported by the American Heart Association Scientist Development Grant (17SDG33060002).
Name | Company | Catalog Number | Comments |
Diethylpyrocarbonate | Sigma Aldrich | D5758 | DEPC |
Phosphate buffered saline | Sigma Aldrich | P4417 | PBS |
Tween-20 | American Bioanalytical | AB02038 | non-ionic surfactant |
Histoclear | National Diagnostics | HS-200 | |
Proteinase K, recombinant, PCR Grade | Sigma Aldrich | 3115879001 | ProK |
Paraformaldehyde | Sigma Aldrich | P6148 | PFA |
Sodium Chloride | ThermoFisher | S271 | NaCl |
Magnesium Chloride Hexahydrate | ThermoFisher | M33 | MgCl2 |
Tris | Sigma Aldrich | T6066 | |
Hydrochloric Acid Solution, 1 N | ThermoFisher | SA48 | HCl |
Hydrochloric Acid Solution, 12 N | ThermoFisher | S25358 | HCl |
1-Methylimidazole | Sigma Aldrich | 336092 | |
N-(3-Dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride | Sigma Aldrich | 39391 | EDC |
Hydrogen peroxide solution H2O2 | Sigma Aldrich | 216763 | H2O2 |
Trisodium citrate dihydrate | Sigma Aldrich | S1804 | Sodium Citrate |
miRCURY LNA miRNA ISH Buffer Set (FFPE) | Qiagen | 339450 | scramble miRNA/U6 snRNA |
miRCURY LNA mmu-miR-182 detection probe | QIagen | YD00615701 | 5'-DIG and 3'-DIG labelled |
Levamisol hydrochloride | Sigma Aldrich | 31742 | |
Bovine Serum Albumin | Sigma Aldrich | A9647 | BSA |
NBT/BCIP Tablets | Sigma Aldrich | 11697471001 | NBT-BCIP |
Potassium Chloride | ThermoFisher | P217 | KCl |
DAPI solution (1mg/ml) | ThermoFisher | 62248 | DAPI |
Glass coverslip | ThermoFisher | 12-545E | Glass coverslip |
Plastic coverslip | Grace Bio-Labs | HS40 22mmX40mmX0.25mm | RNA-ase free plastic coverslip |
Anti-Digoxigenin-AP, Fab fragments | Sigma Aldrich | 11093274910 | DIG antibody |
Hydrophobic barrier pen | Vector Laboratories | H-4000 | Pap pen |
Anti-Cardiac Troponin T antibody | Abcam | ab92546 | cTnT antibody |
Goat anti-Rabbit IgG (H+L) Cross-Absorbed Secondary Antibody, Alexa Fluor 568 | ThermoFisher | A-11011 | anti-rabbit-568 antibody |
Dako Fluorescence Mounting Medium | DAKO | S3023 | mounting medium |
Sheep serum | Sigma Aldrich | S3772 | |
Goat serum | Sigma Aldrich | G9023 | |
Deionized Formamide | American Bioanalytical | AB00600 | |
Hybridization Oven | ThermoFisher | UVP HB-1000 Hybridizer |
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