Luciferase reporter assay

The aim of a luciferase reporter assay is to measure gene expression or transcriptional activity by detecting the light emitted when luciferase, a reporter enzyme, reacts with its substrate. It helps assess promoter activity, regulatory element function, or the effect of specific factors on gene expression.

In a luciferase reporter assay:

  1. A DNA construct with a luciferase gene under the control of a promoter or regulatory element is introduced into cells.

  2. If the promoter is active, luciferase is expressed.

  3. The luciferase enzyme reacts with its substrate (e.g., luciferin) to produce light.

  4. The emitted light is measured, reflecting the activity of the promoter or regulatory element.

  5. This quantification allows researchers to assess the strength and regulation of the promoter in response to various stimuli.

Luciferase reporter assay 

Aim of the miRNA luciferase reporter assay:


The aim is to determine whether miR-6073 directly targets the 3’ untranslated region (3’UTR) of the N-WASP mRNA and to identify the specific binding sites involved.

Rationale:

MicroRNAs (miRNAs) regulate gene expression by binding to the 3’UTRs of target mRNAs, leading to translational repression or mRNA degradation. The luciferase reporter assay is used to assess whether miR-6073 interacts with the N-WASP 3’UTR and reduces luciferase activity, indicating direct regulation by the miRNA.

How it works:

1. A luciferase reporter plasmid is constructed, where the 3’UTR of N-WASP mRNA is inserted downstream of the Renilla luciferase open reading frame (ORF).

2. The reporter plasmid is co-transfected into cells with or without the miR-6073 mimic. If miR-6073 binds to the 3’UTR, luciferase expression will decrease.

3. Mutations (Mut1-4) are introduced in predicted miR-6073 binding sites to identify which sites are essential for miRNA binding and regulation.

4. Reduced luciferase activity in the WT reporter (and not in the mutants) confirms that miR-6073 directly targets specific sites in the 3’UTR.

Conclusion:

This assay provides functional evidence of miR-6073’s interaction with the 3’UTR of N-WASP, elucidating its role in post-transcriptional regulation.