DDIT3 and KAT2A Proteins Regulate TNFRSF10A and TNFRSF10B Expression in Endoplasmic Reticulum Stress-mediated Apoptosis in Human Lung Cancer Cells

Area of Science:

• Molecular Biology
• Cell Biology
• Cancer Research

Background:

• Tumor necrosis factor receptor superfamily member 10A (TNFRSF10A) and 10B (TNFRSF10B) are cell surface receptors crucial for initiating apoptosis via the extrinsic pathway.
• The transcriptional regulation mechanisms governing TNFRSF10A and TNFRSF10B expression are not well understood.

Purpose of the Study:

• To elucidate the transcriptional mechanisms regulating TNFRSF10A and TNFRSF10B expression.
• To investigate the roles of DDIT3 and KAT2A in the regulation of these apoptosis-related genes.

Main Methods:

• Bioinformatic analysis to identify potential transcription factor binding sites in the TNFRSF10A promoter.
• Co-immunoprecipitation assays to confirm protein-protein interactions (DDIT3, phospho-JUN, KAT2A).
• Luciferase reporter assays to assess promoter activity upon gene knockdown.
• Chromatin immunoprecipitation (ChIP) assays to investigate protein binding to promoter regions and histone modifications.

Main Results:

• Identified DDIT3 and AP-1 binding sites in the TNFRSF10A promoter and a DDIT3 binding site in the TNFRSF10B promoter.
• Demonstrated that DDIT3 interacts with phospho-JUN, and this complex binds to the AP-1 site in the TNFRSF10A promoter.
• Showed that KAT2A interacts with DDIT3 and that KAT2A knockdown reduces TNFRSF10A and TNFRSF10B expression and promoter activity.
• Provided evidence that KAT2A may be part of a complex involving DDIT3 and phospho-JUN, potentially acetylating H3K9/K14.
• Confirmed that TNFRSF10A mediates apoptosis induced by endoplasmic reticulum stress in lung cancer cells.

Conclusions:

• DDIT3 and KAT2A act cooperatively to up-regulate the expression of TNFRSF10A and TNFRSF10B.
• This study uncovers novel mechanisms of endoplasmic reticulum stress-induced apoptosis regulation through TNFRSF10A and TNFRSF10B.
• The findings offer insights into potential therapeutic strategies involving anticancer drugs that mediate apoptosis.