What is a reporter cell line?
Cell lines are useful tools for scientific research since they represent more natural biological systems than cell-free assays.
As well as serving as models for tissue types or specific disease states, cell lines can be engineered to express exogenous proteins, including reporters.
The term reporter refers to the fact that the expressed protein is easily measured, typically via luminescent or fluorescent detection.
By using a reporter as a surrogate for a gene of interest, researchers can investigate the regulation of gene activation and expression.
How does a reporter cell line work?
So, how does a reporter cell line work?
Although this will vary to some extent depending on the aim of the study, the reporter gene is typically inserted downstream of the response element specifically recognized by a transcription factor of interest.
When the transcription factor binds the response element, the reporter gene is expressed, ultimately resulting in a measurable signal.
Critically, because gene expression only occurs under certain conditions, reporter cell lines allow researchers to explore how those conditions might be manipulated to modify cellular behaviors.
IL-15 responsive luciferase reporter cell line
Let’s put this into context.
Suppose you’re developing a drug to inhibit IL-15 signaling, which is dysregulated in chronic inflammation and cancer.
IL-15 exerts its effects through the STAT5 signaling pathway, so you might choose a reporter cell line that constitutively expresses the IL-15 receptor and features a luciferase reporter gene under the control of STAT5 response elements.
By treating the IL-15 responsive cells with drug candidates, then adding IL-15 and measuring luciferase activity, you can easily see which compounds have greatest efficacy against the IL-15 signaling pathway.
Advantages of reporter cell lines
A major advantage of using reporter cell lines is that they can simplify experimental workflows.
For example, one way of monitoring IL-15 receptor signaling is to use an ELISA for measuring levels of phosphorylated STAT5 in cell lysates.
This can be a fairly lengthy process, involving one or more antibody incubations and multiple wash steps.
By using a reporter cell line in place of the regular cells, the need for complicated downstream processing is avoided.
Instead, reporter expression can be measured with a suitable reader after any experimental treatments have been performed.
Because the resultant signal is proportional to the level of gene activation, this approach provides a quantitative measurement, unlike other methods such as western blot.
For these reasons, reporter cell lines lend themselves well to high throughput applications, including compound screening for drug discovery, as well as various toxicity studies.
In addition, reporter cell lines can be useful controls for verifying orthogonal data.
Advantages of luciferase
While many different reporters are available, luciferase is one of the most widely used.
The luciferase enzyme converts its substrate, luciferin, into oxyluciferin, a process that produces a luminescent signal.
Unlike fluorescence, the reaction does not require light excitation.
As a result, luciferase reporter cell lines have only minimal autofluorescence and produce readouts that are virtually free of unwanted background signal.
Low autofluorescence can especially be beneficial for compound screening applications since many small molecule drugs naturally autofluoresce and can be mistakenly identified as hits.
Selecting reporter cell lines
When it comes to selecting a reporter cell line, there are several important factors to consider.
The first of these is the cell type; if you’re already using a particular cell line for your research, you may want your reporter cell line to match.
You’ll also want to think about the signaling pathway, which should be relevant to your area of interest.
A growing number of reporter cell lines are available, covering signaling pathways that include IL-15, Notch, Hippo, Myc, Wnt, and many more.
Finally, you’ll want to see proof of validation.
This should include confirmation that the reporter cell line expresses the target, such as by Western blot or flow cytometry; functional validation through treatment with a reference control compound; and stability testing to safeguard performance over time.
BPS Bioscience
BPS Bioscience has developed numerous reporter cell lines, including custom products, that are applicable for a wide range of research applications. To learn more, contact us today.
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