The Gadd45 family plays a critical role in several cellular functions, including genomic stability, cell cycle regulation and apoptosis. Gadd45a is transcriptionally activated by the tumour suppressor gene p53, which is mutated in more than 50% of human tumours. Studies performed by the applicant have demonstrated that Gadd45a is an important negative regulator of T cell proliferation. Lack of Gadd45a leads to the development of an autoimmune disease remarkably similar to human lupus. Little is known about the molecular mechanism that leads to this autoimmune disease, which affects approximately 0.5% of the world's population. Recently, the applicant demonstrated that T cells derived from Gadd45a-null mice showed constitutive p38 activation, hyper-proliferative response and lower threshold of activation leading to lupus. Gadd45a is a p38 inhibitor in T cells.
Gadd45a prevents phosphorylation of tyr323 in p38, inhibiting its activation. The applicant has obtained a patent ¿Modulating p38 Kinase activity¿ (PCT App lication# PCT/US2005/003379) that describes how inhibition of phosphorylation of tyr323 in p38 is a key therapeutic target in autoimmune diseases such as lupus, rheumatoid arthritis, Crohn's disease, multiple sclerosis and some types of leukemias. The main goals of this project are a) characterization of the Gadd45 family as autoimmune disease suppressor and/or tumour suppressor genes, and b) analysis of the molecular mechanism to obtain a therapeutic target in the treatment autoimmune diseases and/or tumours.
We will generate and characterize deficient murine models in Gadd45a, Gadd45b and Gadd45g and double knockouts Gadd45ab-/-, Gadd45ag-/- and Gadd45bg-/-. We will analyse proliferation, apoptosis, differentiation and production of cytokines in T cells. The results of this project should allow us to discover new key therapeutic targets to fight against autoimmune diseases and/or cancer
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