Novel non-coding FOXP3 transcript isoform associated to potential transcriptional interference in human regulatory T...

Area of Science:

• Immunology
• Molecular Biology
• Genetics

Background:

• CD4+ regulatory T cells (T_REGS) are essential for immune tolerance.
• The transcription factor Forkhead Box P3 (FOXP3) is critical for T_REGS differentiation and function.
• An alternative FOXP3 promoter active in T_REGS may alter gene output and cell function.

Purpose of the Study:

• To investigate the transcriptional complexity of the human FOXP3 locus.
• To characterize novel FOXP3 transcriptional products and their functional implications.
• To explore the role of an alternative FOXP3 promoter in T_REGS.

Main Methods:

• Direct RNA sequencing to identify novel FOXP3 transcripts.
• Western blotting and mass spectrometry to assess protein products.
• RNA single-molecule fluorescence in situ hybridization to analyze transcript localization and levels.
• In vitro transcription and transfection experiments.

Main Results:

• Identification of multiple novel FOXP3 transcripts, including a non-coding isoform 'longFOXP3' with an extended 5' UTR.
• Evidence suggests 'longFOXP3' is not translated into protein.
• Transcription from the alternative upstream FOXP3 promoter correlates with reduced FOXP3 mRNA and protein levels.
• Demonstration of intragenic transcriptional interference between the alternative and canonical FOXP3 promoters.

Conclusions:

• The human FOXP3 locus exhibits greater transcriptional complexity than previously annotated.
• The alternative FOXP3 promoter and its non-coding transcript 'longFOXP3' may fine-tune FOXP3 levels in T_REGS via transcriptional interference.
• Further research is needed to fully identify and characterize all coding and non-coding FOXP3 isoforms and their roles in immune regulation.