The IFNL4 Gene Is a Noncanonical Interferon Gene with a Unique but Evolutionarily Conserved Regulation

Area of Science:

• Immunology
• Molecular Biology
• Genetics

Background:

• Interferon lambda 4 (IFN-λ4) is a recently identified interferon lambda family member.
• Genetic studies suggest IFNL4 plays a proviral and anti-inflammatory role, contrasting with typical interferon functions.
• The protein product of IFNL4 is indistinguishable in vitro from other interferon lambda family members.

Purpose of the Study:

• To investigate the gene regulation of IFNL4.
• To understand why IFNL4 exhibits atypical phenotypes in patients.
• To compare IFNL4 gene regulation with canonical antiviral interferons.

Main Methods:

• Analysis of IFNL4 gene regulation.
• Investigating induction by viral infection and interferon regulatory factors (IRFs).
• Functional analysis of the IFNL4 promoter, including IRF3 binding sites.

Main Results:

• IFNL4 gene expression is poorly induced by viral infection or IRF overexpression.
• This lack of induction is evolutionarily conserved.
• Modifying the IFNL4 promoter to include an IRF3 binding site restored induction.

Conclusions:

• The transcriptional regulation of IFNL4 is radically different from canonical interferons.
• This noncanonical regulation likely explains the observed atypical phenotypes of IFNL4 in humans.
• IFNL4's unique gene regulation underpins its distinct biological functions.