A novel splice variant of folate receptor 4 predominantly expressed in regulatory T cells

Abstract

Abstract Background Regulatory T cells (Tregs) are required for proper maintenance of immunological self-tolerance and immune homeostasis. Folate receptor 4 (FR4) is expressed at high levels in transforming growth factor-beta (TGF-β)-induced Tregs and natural Tregs. Moreover, antibody-mediated targeting of FR4 is sufficient to mediate Treg depletion. Results In this study, we describe a novel FR4 transcript variant, FR4D3, in which exon 3 is deleted. The mRNA of FR4D3 encodes a FR4 variant truncated by 189 bp. FR4D3 was found to be predominantly expressed in CD4+CD25+ Treg cells. Overexpression of FR4D3 in CD4+CD25+ Treg cells in vitro stimulated proliferation, which may modulate the ability of these cells to bind and incorporate folic acid. Conclusions Our results suggested that high levels of FR4D3 may be critical to support the substantial proliferative capacity of Treg cells.

Keywords

• Folate receptor 4
• Variant
• Regulatory T cells
• Proliferation