An Epstein-Barr virus protein interacts with Notch.

Area of Science:

• Virology
• Molecular Biology
• Cellular Signaling

Background:

• Epstein-Barr virus (EBV) BamHI A mRNAs are highly expressed in nasopharyngeal carcinoma.
• These mRNAs undergo alternative splicing, yielding various open reading frames, including BARF0.
• One identified cDNA, RK-BARF0, encodes a protein with a potential endoplasmic reticulum-targeting signal peptide.

Purpose of the Study:

• To investigate the interaction between the EBV RK-BARF0 protein and Notch4.
• To determine the functional consequences of this interaction on Notch signaling and EBV protein expression.

Main Methods:

• Yeast two-hybrid screening
• Coimmunoprecipitation assays
• Confocal microscopy
• Detection of proteins in EBV-infected cells

Main Results:

• RK-BARF0 protein interacts with the Notch4 ligand binding domain.
• This interaction promotes the nuclear translocation of unprocessed Notch4 via the Notch nuclear localization signal.
• RK-BARF0 induces EBV latent membrane protein 1 (LMP1) expression in EBNA2-negative, EBV-infected cells, dependent on the RK-BARF0/Notch interaction domain.
• Unprocessed Notch4 was detected in immunoprecipitated complexes from EBV-infected cells, confirming RK-BARF0/Notch interaction during infection.

Conclusions:

• The EBV RK-BARF0 protein interacts with Notch4, suggesting a role for EBV in modulating Notch signaling pathways.
• RK-BARF0-induced LMP1 expression in the absence of EBNA2 may explain LMP1 presence during EBV latent infections.