Cloning and expression of a cDNA encoding mouse indoleamine 2,3-dioxygenase

Area of Science:

• Immunology
• Molecular Biology
• Cancer Research

Background:

• Interferon-gamma (IFN-gamma) induces indoleamine 2,3-dioxygenase (IDO), depleting tryptophan and potentially causing allograft rejection.
• Understanding the mechanism of IDO induction is critical for managing transplant outcomes and cancer immunity.

Purpose of the Study:

• To isolate and characterize cDNA clones encoding mouse indoleamine 2,3-dioxygenase (IDO).
• To elucidate the molecular mechanisms underlying IFN-gamma-mediated IDO induction in mouse tumor cells.

Main Methods:

• Screening of mouse cell lines for IFN-gamma-induced IDO.
• Preparation of cDNA library from IFN-gamma/dibutyryl cyclic AMP (Bt2cAMP)-treated CMT-93 cells.
• Isolation of mouse IDO cDNA using human IDO cDNA as a probe.
• Sequence analysis, homology comparison, and functional expression studies.

Main Results:

• IDO was induced by IFN-gamma in 7 of 25 mouse cell lines, with highest induction in CMT-93 rectal cancer cells.
• IDO induction in CMT-93 cells was further enhanced by Bt2cAMP.
• Isolated mouse IDO cDNA encodes a 407-amino acid protein with 61% homology to human IDO.
• Transient expression confirmed high IDO activity, and Northern analysis showed IFN-gamma induces IDO mRNA, potentiated by Bt2cAMP.

Conclusions:

• The study successfully isolated and characterized mouse IDO cDNA, providing a tool to study its role in immune responses.
• IFN-gamma is a key inducer of IDO mRNA in mouse tumor cells, with Bt2cAMP acting as a potentiating factor.
• This research deepens the understanding of IDO regulation, relevant to allograft rejection and cancer immunotherapy.