ABSTRACT
Autoimmune diseases are characterized by the immune system mounting a response against self. The exact etiology of autoimmune diseases and autoimmunity remain unclear. Here, we demonstrate that Δ133p53, an isoform of the tumor suppressor protein p53, is involved in the development of autoimmunity. We have previously generated a mouse model of Δ133p53 (Δ122p53). Δ122p53 mice develop an autoimmune/ inflammation-like phenotype that includes the production of autoantibodies, elevated levels of pro-inflammatory cytokines and lymphocyte aggregations in various organs. Microarray analysis reveals that expression of Δ122p53 induces a number of pro-inflammatory genes, including the STAT1 pathway and interferon-related transcription profile. Comparative genetic signatures have been observed in human SLE (systemic lupus erythematosus) patients, and we show that Δ133p53 regulates STAT1 in human cells. Our findings provide the first evidence of a role for p53 isoforms in the development of autoimmune disease.
Subject(s)
Autoimmune Diseases/metabolism , Inflammation/metabolism , Tumor Suppressor Protein p53/metabolism , Animals , Autoantibodies/blood , Autoimmune Diseases/genetics , Autoimmunity/genetics , Cell Line, Tumor , Cytokines/metabolism , Gene Expression Profiling , Humans , Inflammation/genetics , Lupus Erythematosus, Systemic/immunology , Lupus Erythematosus, Systemic/metabolism , Lupus Erythematosus, Systemic/pathology , Lymphocytes/immunology , Lymphocytes/metabolism , Mice , Protein Isoforms/genetics , Protein Isoforms/immunology , Protein Isoforms/metabolism , STAT1 Transcription Factor/metabolism , Signal Transduction , Tumor Suppressor Protein p53/genetics , Tumor Suppressor Protein p53/immunologyABSTRACT
The p53 protein is a pivotal tumor suppressor that is frequently mutated in many human cancers, although precisely how p53 prevents tumors is still unclear. To add to its complexity, several isoforms of human p53 have now been reported. The Δ133p53 isoform is generated from an alternative transcription initiation site in intron 4 of the p53 gene (Tp53) and lacks the N-terminus. Elevated levels of Δ133p53 have been observed in a variety of tumors. To explore the functions of Δ133p53, we created a mouse expressing an N-terminal deletion mutant of p53 (Δ122p53) that corresponds to Δ133p53. Δ122p53 mice show decreased survival and a different and more aggressive tumor spectrum compared with p53 null mice, implying that Δ122p53 is a dominant oncogene. Consistent with this, Δ122p53 also confers a marked proliferative advantage on cells and reduced apoptosis. In addition to tumor development, Δ122p53 mice show a profound proinflammatory phenotype having increased serum concentrations of interleukin-6 and other proinflammatory cytokines and lymphocyte aggregates in the lung and liver as well as other pathologies. Based on these observations, we propose that human Δ133p53 also functions to promote cell proliferation and inflammation, one or both of which contribute to tumor development.