p53 increases MHC class I expression by upregulating the endoplasmic reticulum aminopeptidase ERAP1

Area of Science:

• Immunology
• Molecular Biology
• Cancer Research

Background:

• The p53 tumor suppressor protein plays a critical role in cellular responses to stress and in preventing cancer.
• Major Histocompatibility Complex I (MHC I) molecules are essential for immune surveillance, presenting antigens to cytotoxic T lymphocytes.
• Dysregulation of MHC I expression is a common mechanism for tumor cells to evade immune detection.

Purpose of the Study:

• To investigate the role of p53 in regulating MHC I expression.
• To elucidate the molecular mechanisms by which p53 influences MHC I surface presentation.
• To explore the implications of this pathway in cancer and viral infections.

Main Methods:

• Comparative analysis of MHC I expression in p53-deficient versus wild-type HCT116 cancer cell lines.
• Chromatin immunoprecipitation sequencing (ChIP-seq) to identify p53 binding sites.
• Gene expression analysis to assess the impact of p53 on ERAP1.
• Experimental validation in A549 cells infected with H1N1 influenza virus.

Main Results:

• p53-deficient HCT116 cells exhibit significantly lower MHC I surface expression compared to wild-type cells.
• p53 directly upregulates the expression of Endoplasmic Reticulum Aminopeptidase 1 (ERAP1) by binding to the ERAP1 gene.
• Silencing p53 leads to reduced ERAP1 protein levels and consequently decreased MHC I expression.
• In H1N1-infected A549 cells, p53 activation by the virus results in ERAP1 upregulation and increased MHC I expression.

Conclusions:

• p53 is a key regulator of MHC I expression through the induction of ERAP1.
• This p53-ERAP1-MHC I axis is important for cancer immunosurveillance and the host response to viral infections.
• The findings uncover a novel link between p53's tumor-suppressive functions and immune system recognition of diseased cells.