Knockout Mouse Catalog | Cyagen APAC

Foxp3-IRES-mRFP (FIR) Reporter Mouse

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Model Description

Background: C57BL/6J

This reliable Foxp3 reporter mouse model allows you to efficiently monitor and sort Foxp3-expressing cells from different lymphocyte lineages and lymphoid organs, and represents a powerful drug testing tool to:

● Study the modulation of the immune tolerance mechanism in autoimmune diseases

● Treat cancers via immune checkpoint inhibitor discovery



  • Physiological expression and regulation pattern of Foxp3
  • mRFP reporter faithfully mirrors Foxp3 expression



Mornitor Treg activity in immuno-oncology and autoimmunity.


Foxp3 is the regulatory T cell-specific transcription factor that functions as the master regulator of the development and function of regulatory T cells. This Foxp3-IRES-mRFP (FIR) mouse model provides access to direct in vivo detection of Foxp3-expressing cells. In contrast to other existing Foxp3 models generated by random insertion, this knockin mouse line preserves physiological expression of Foxp3 and enables monitoring of endogenous Foxp3.


No deregulation of endogenous Foxp3 expression

  • Endogenous Foxp3 is expressed and functional: reporter gene inserted in the 3'UTR of the endogenous Foxp3 locus
  • The genetic manipulation inserted is controlled
  • Reporter faithfully mirrors Foxp3 expression


Suitable model for your Treg studies

  • Foxp3-expressing cells can be directly detected by monitoring mRFP expression (Fig. 1)
  • Uncompromised immune system: intact function of Treg cells (Fig. 2)
  • Optimum monitoring of Treg cells trafficking and cell sorting


Model Validation

Figure 1. mRFP expression correlates with Foxp3-expressing T cells in vivo.

Left panel: Foxp3 expression was detected in peripheral lymphocytes from Foxp3-IRES-mRFP mice harvested and stained with fluorophore-conjugated anti-CD4 and anti-CD25 antibodies. mRFP expression in CD4 T cells was monitored by flow cytometry.

Right panel: RNA was extracted from different populations of peripheral CD4 T cells purified from FIR mice by FACS. Relative mRNA levels of Foxp3 were determined by TaqMan real-time quantitative PCR, and combined results of two experiments were plotted.


Model Validation

Figure 2. mRFP expression does not compromise the regulatory activity of Foxp3-expressing T cells in vivo. The immunosuppressive function of Foxp3-expressing cells is not impaired when mRFP is co-expressed. CD4+mRFP+ suppressor (S) and CD4+CD25-mRFP- responder (R) T cells were purified by FACS. Suppressor and responder cells were either cultured alone or mixed at indicated ratios (R: S), whereas the number of responder cells remained the same. T cells were activated by soluble anti-CD3 and anti-CD28 antibodies in the presence of irradiated APCs. Three days after stimulation, T cell proliferation was measured by a [3H] thymidine incorporation assay.


*For more validation data please contact us.

Category Strain Name Background Order Amount
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Reporter Mouse Models Foxp3-IRES-mRFP (FIR)  / / /

Price Availability

  • Sex: Female
  • Age: 3 to 8 weeks
  • Customers in Asia Pacific region, excluding Japan.

*If you would like to order male mice, Please contact us.

Digital Resources:

Foxp3-IRES-mRFP (FIR) Reporter Mouse
Mouse Models for
Drug Screening & Assessment
Cyagen Animal Models
Catalog - 2021

1. Wan YY; Flavell RA. 2005. Identifying Foxp3-expressing suppressor T cells with a bicistronic reporter. Proc Natl Acad Sci USA 102 (14) : 5126-31.

2. Gutcher I; Donkor MK; Ma Q; Rudensky AY; Flavell RA; Li MO. 2011. Autocrine Transforming Growth Factor-beta1 Promotes In Vivo Th17 Cell Differentiation. Immunity 34 (3) : 396-408.

3. Chae WJ; Gibson TF; Zelterman D; Hao L; Henegariu O; Bothwell AL. 2010. Ablation of IL-17A abrogates progression of spontaneous intestinal tumorigenesis. Proc Natl Acad Sci USA 107 (12) : 5540-4.

Why work with Cyagen?

With more than 15 years’ experience in genetic engineering, Cyagen offers a complete range of products and services to support the advancement of human disease research. Cyagen is committed to enabling the development of therapeutics for human diseases by providing one-stop research solutions – from custom rodent model generation and breeding, through therapeutic viral packaging and injection, and phenotype analysis to study disease mechanisms, target validation, drug screening and more.

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