Alternative splicing generates a novel CARD9 isoform

Area of Science:

• Immunology
• Molecular Biology
• Genetics

Background:

• CARD9 (Caspase Recruitment Domain Family, member 9) is crucial for innate immune signaling against pathogens.
• CARD9 deficiency compromises host defense, increasing susceptibility to infections.
• Understanding CARD9's functional diversity is key to immune regulation.

Purpose of the Study:

• To identify and characterize novel CARD9 transcripts.
• To investigate the structural and functional differences between CARD9 and its new isoform, CARD9-N.
• To explore the potential immune regulatory roles of CARD9-N.

Main Methods:

• Integrated bioinformatics and molecular biology techniques were employed.
• Structural and functional characterization of the novel CARD9-N transcript.
• Analysis of molecular weight, isoelectric point, phosphorylation sites, and dimerization stability.

Main Results:

• A novel human CARD9 transcript, CARD9-N, was identified.
• CARD9-N possesses a distinct N-terminal region, lacking coding exons E1 and E2 but including a novel N3' sequence.
• Significant structural and functional differences observed, including altered dimerization stability and absence of the CARD domain in CARD9-N.

Conclusions:

• The novel CARD9-N isoform exhibits unique structural and functional properties compared to CARD9.
• The absence of the CARD domain in CARD9-N may lead to distinct immune activation mechanisms.
• These findings expand our understanding of CARD9's functional diversity in immune responses and disorders.