IFN-gamma Protein, Feline

IFN-gamma (Interferon-gamma), a type II interferon produced by immune cells such as T-cells and NK cells, assumes crucial roles in antimicrobial, antiviral, and antitumor responses by activating effector immune cells and enhancing antigen presentation. Its primary signaling occurs through the JAK-STAT pathway after interaction with its receptor IFNGR1, influencing gene regulation. Upon IFN-gamma binding, the IFNGR1 intracellular domain opens out, facilitating the association of downstream signaling components, including JAK2, JAK1, and STAT1, leading to STAT1 activation, nuclear translocation, and transcription of IFNG-regulated genes. Many of the induced genes are transcription factors, such as IRF1, capable of further driving the regulation of a subsequent wave of transcription. IFN-gamma plays a role in the class I antigen presentation pathway by inducing a replacement of catalytic proteasome subunits with immunoproteasome subunits, thereby increasing the quantity, quality, and repertoire of peptides for class I MHC loading. It enhances the efficiency of peptide generation by inducing the expression of the activator PA28, which associates with the proteasome and alters its proteolytic cleavage preference. Additionally, IFN-gamma up-regulates MHC II complexes on the cell surface by promoting the expression of several key molecules, such as cathepsins B/CTSB, H/CTSH, and L/CTSL, contributing to immune responses. Participating in the regulation of hematopoietic stem cells during development and under homeostatic conditions, IFN-gamma influences their development, quiescence, and differentiation. Existing as a homodimer, IFN-gamma interacts with IFNGR1 via its extracellular domain, a crucial interaction that promotes IFNGR1 dimerization, orchestrating its diverse and critical functions in immune responses and hematopoiesis.