Related Experiment Video
Updated: May 8, 2025
Probe-based Real-time PCR Approaches for Quantitative Measurement of microRNAs
Published on: April 14, 2015
Detection of miR-133a-5p Using a Molecular Beacon Probe for Investigating Postmortem Intervals
Eun Hye Lee1, Mingyoung Jeong1,2, Kwangmin Park2,3
1Department of Forensic Science, Graduate School, Catholic University of Pusan, Busan 46252, Republic of Korea.
Abstract:
Background: When a body is discovered at a crime or murder scene, it is crucial to examine the body and estimate its postmortem interval (PMI). Accurate estimation of PMI is vital for identifying suspects and providing clues to resolve the case. MicroRNAs (miRNAs or miRs) are small non-coding RNAs that remain relatively stable in the cell nucleus even after death-related changes occur. Objective: This study developed a molecular beacon probe for mmu-miR-133a-5p and assessed its use in mouse muscle tissue at temperatures of 4 °C and 21 °C to estimate the PMI. Methods: A total of 36 healthy adult male BALB/c mice were divided into 9 PMI time points (0, 2, 6, 8, and 10 days) with 3 mice per time point, and they were exposed to 4 °C and 21 °C. Next, the expression pattern of mmu-miR-133a in the skeletal muscle tissue over a 10-day PMI period was analyzed using the developed molecular beacon probe. Results: The molecular beacon (MB) probe was designed for optimal thermodynamic stability with a hairpin structure that opened in the presence of mmu-miR-133a-5p, thus separating the fluorophore from the quencher and resulting in a strong fluorescence signal at 495 nm. Fluorescence intensity increased with mmu-miR-133a-5p concentration from 1 ng/μL to 1000 ng/μL and exhibited a strong correlation (R2 = 0.9966) and a detection limit of 1 ng/μL. Subsequently, the expression level of mmu-miR-133a-5p was observed to be stable in mouse skeletal muscle tissue at both 4 °C and 21 °C. Conclusions: This user-friendly assay can complete measurements in just 30 min after RNA extraction and is suitable for point-of-care testing, and it possesses the potential to improve existing complex and time-consuming methods for PMI estimation.
Insights
A new molecular beacon probe accurately estimates postmortem interval (PMI) using microRNA (miRNA) expression in mouse muscle tissue. This rapid assay offers a user-friendly method for forensic science and point-of-care testing.
Area of Science:
- Forensic Science
- Molecular Biology
- Biochemistry
Background:
- Accurate postmortem interval (PMI) estimation is critical in forensic investigations.
- MicroRNAs (miRNAs) are stable molecules suitable for postmortem analysis.
- Existing PMI estimation methods are often complex and time-consuming.
Purpose of the Study:
- To develop a molecular beacon probe for quantifying mmu-miR-133a-5p.
- To assess the utility of this probe for PMI estimation in mouse muscle tissue.
- To evaluate the stability of mmu-miR-133a-5p expression at different temperatures.
Main Methods:
- A molecular beacon (MB) probe was designed for mmu-miR-133a-5p detection.
- Mouse skeletal muscle tissues were collected at various time points (0-10 days) postmortem.
- Tissue samples were stored at 4 °C and 21 °C, and miRNA expression was analyzed using the MB probe.
Main Results:
- The MB probe demonstrated high specificity and sensitivity, with a detection limit of 1 ng/μL.
- A strong correlation (R² = 0.9966) was observed between fluorescence intensity and miRNA concentration.
- mmu-miR-133a-5p expression remained stable in mouse skeletal muscle tissue at both tested temperatures.
Conclusions:
- The developed MB probe is a reliable tool for quantifying mmu-miR-133a-5p.
- This assay provides a rapid (30 min post-RNA extraction) and user-friendly method for PMI estimation.
- The assay has potential for point-of-care applications in forensic investigations.
