FOXP3 interacts with hnRNPF to modulate pre-mRNA alternative splicing

Area of Science:

• Immunology
• Molecular Biology
• Gene Regulation

Background:

• Forkhead box protein 3 (FOXP3) is crucial for regulatory T cell (Treg) development and function, primarily by controlling gene transcription.
• RNA alternative splicing is a key regulatory mechanism in biological processes and disease.
• The precise mechanisms by which FOXP3 influences Treg function beyond direct transcriptional control are not fully understood.

Purpose of the Study:

• To investigate the role of FOXP3 in regulating RNA alternative splicing.
• To identify potential protein interactions between FOXP3 and splicing factors.
• To elucidate how FOXP3-mediated splicing modulation affects Treg function.

Main Methods:

• Co-immunoprecipitation assays to detect protein-protein interactions between FOXP3 and heterogeneous nuclear ribonucleoprotein F (hnRNPF).
• Analysis of FOXP3 and hnRNPF binding domains using specific protein regions.
• Assessment of hnRNPF's pre-mRNA binding activity and its modulation by FOXP3.
• Functional assays of regulatory T cells with altered hnRNPF expression.

Main Results:

• FOXP3 directly interacts with hnRNPF via its exon 2 region and hnRNPF's second quasi-RNA recognition motif (qRRM).
• FOXP3 binding inhibits hnRNPF's ability to bind target pre-mRNA, thereby modulating alternative splicing.
• Overexpression of hnRNPF in Tregs impairs their suppressive capacity.

Conclusions:

• FOXP3 regulates RNA alternative splicing by interacting with and inhibiting hnRNPF.
• This novel mechanism highlights a new way FOXP3 controls Treg function.
• Modulation of alternative splicing by FOXP3 is critical for maintaining Treg suppressive activity.