PBLD Knockout Cell Line (HEK293)

Phenazine biosynthesis-like domain-containing protein (PBLD) and Cedrelone have been identified as tumor suppressors. However, their roles in virus infection remain unclear. Here, we demonstrate that PBLD upregulates the type I interferon (IFN-I) response through activating NF-kappaB (NF-κB) signaling pathway to resist viral infection in cells and mice. Mechanistically, PBLD activates NF-κB signaling pathway during viral infection via blocking tripartite motif containing 21 (TRIM21)-mediated phosphorylated inhibitory kappa B kinase beta (IKKβ) degradation. Furthermore, we show Cedrelone inhibits viral replication by increasing the PBLD protein expression and subsequently activating NF-κB-mediated IFN-I response. Furthermore, the therapeutic potential of Cedrelone lies in its ability to enhance antiviral immunity in primary macrophages and to promote survival and reduce lung tissue damage in HSV-1-infected mice in a PBLD-dependent manner. Consequently, our findings provide a potential combination model that targets PBLD for Cedrelone antiviral drug therapy, potentially paving the way for the development of broad-spectrum antiviral agents.

Recent studies have implicated the phenazine biosynthesis-like domain-containing protein (PBLD) in the negative regulation of the development and progression of various cancers. However, its function in viral infection remains unknown. In this study, we found that PBLD plays important roles in multiple virus infections including BPIV3, SeV, VSV, and HSV-1. Our study revealed that PBLD enhances the expression of type I interferon (IFN-I) and ISGs through interferon regulatory factor 3 (IRF3). Further study indicated that PBLD promotes transcriptional phosphorylation of IRF3 (S385/386), thereby facilitating virus-induced IFN-I production. Interestingly, PBLD mediates virus-triggered mitochondrial apoptosis through its dependence on IRF3 (K313/315). Mechanistically, PBLD facilitated virus-induced apoptosis by recruiting the Puma protein to the mitochondria via IRF3. Additionally, we performed mutational analyses of IRF3, showing that its loss of either transcriptional or apoptotic function markedly increased viral replication. Moreover, macrophages with PBLD deficiency during viral infection exhibited decreased the IFN-I and ISGs expression, exacerbating viral infection. Importantly, mice deficient in PBLD exhibited increased viral replication and susceptibility to SeV infection, leading to decreased survival. Notably, Cedrelone, a chemical activator of PBLD, has the ability to reduce SeV replication. Collectively, we first discovered the new function of PBLD in viral infection, broadening our understanding of potential therapeutic targets and offering new insights for antiviral drug development.

Phenazine biosynthesis-like domain-containing protein (PBLD) has been reported to be involved in the development of many cancers. However, whether PBLD regulates innate immune responses and viral replication is unclear. In this study, although it was found that the activity of PBLD extends to other PRRs, we focused on the RLR pathway activated via the p53-USP4-MAVS axis in response to virus infections. We found that PBLD deubiquitinates and stabilizes MAVS through ubiquitin-specific protease 4 (USP4) to promote antiviral innate immunity. Mechanistically, PBLD activates the transcription of USP4 via the upregulation of p53. USP4, which is a MAVS-interacting protein, substantially stabilizes the MAVS protein by deconjugating K48-linked ubiquitination chains from the MAVS protein at Lys461 during RNA virus infection. Most intriguingly, RNA virus-infected primary macrophages (peritoneal macrophages, PMs, and bone marrow-derived macrophages, BMDMs) and internal organ cells (lung and liver) from PBLD-deficient mice suppress the IFN-I response and promote viral replication. Notably, PBLD-deficient mice are more susceptible to RNA virus infection than their wild-type littermates. Our findings highlight a unique function of PBLD in antiviral innate immunity through the p53-USP4-MAVS signaling, providing a preliminary basis for research on PBLD as a target molecule for treating RNA virus infection.