Biology subjects

Baldaccini, M.

Publications and source records attributed to Baldaccini, M..

3 recordsLinked to original sources

bioRxiv2023

Canonical and non-canonical contributions of human Dicer helicase domain in antiviral defense

In mammalian somatic cells, the relative contribution of RNAi and the type I interferon response during viral infection is unclear. The apparent inefficiency of antiviral RNAi might be due to self-limiting properties and mitigating co-factors of the key enzyme Dicer. In particular, the helicase domain of human Dicer appears to be an important restriction factor of its activity. We studied the involvement of several helicase-truncated mutants of human Dicer in the antiviral response. All deletion mutants displayed a PKR-dependent antiviral phenotype against certain viruses and one of them, Dicer N1, acted in a complete RNAi-independent manner. Transcriptomic analyses showed that many genes from the interferon and inflammatory response were upregulated in Dicer N1 expressing cells. We could show that some of these genes appear to be controlled by NF-kB and that blocking this pathway abrogated the antiviral phenotype of Dicer N1. Our findings highlight the crosstalk between Dicer, PKR, and the NF-kB pathway, and suggest that human Dicer may have repurposed its helicase domain to prevent basal activation of antiviral and inflammatory pathways.

molecular biology↗

bioRxiv2021

RACK1 associates with RNA-binding proteins Vigilin and SERBP1 to control dengue virus replication

Dengue virus (DENV), a re-emerging virus transmitted by Aedes mosquitoes, causes severe pathogenesis in humans. No effective treatment is available against this virus. We recently identified the scaffold protein RACK1 as a component of the DENV replication complex, a macromolecular complex essential for viral genome amplification. Here, we show that RACK1 is important for DENV infection. RACK1 mediates DENV replication through binding to the 40S ribosomal subunit. Mass spectrometry analysis of RACK1 partners coupled to a loss-of-function screen identified the RNA binding proteins Vigilin and SERBP1 as DENV host dependency factors. Vigilin and SERBP1 interact with DENV viral RNA (vRNA), forming a ternary complex with RACK1 to mediate viral replication. Overall, our results indicate that RACK1 recruits Vigilin and SERBP1, linking the DENV vRNA to the translation machinery for optimal translation and replication.

microbiology↗

bioRxiv2020

Human Dicer helicase domain acts as an interaction platform to recruit PKR and dsRNA binding proteins during viral infection

The antiviral innate immune response mainly involves type I interferon (IFN) in mammalian cells. The contribution of the RNA silencing machinery remains to be established, but several recent studies indicate that the ribonuclease DICER can generate viral siRNAs in specific conditions. It has also been proposed that type I IFN and RNA silencing could be mutually exclusive antiviral responses. In order to decipher the implication of DICER during infection of human cells with alphaviruses such as the Sindbis virus and Semliki forest virus, we determined its interactome by proteomics analysis. We show that DICER specifically interacts with several double-stranded RNA binding proteins and RNA helicases during viral infection. In particular, proteins such as DHX9, ADAR-1 and the protein kinase RNA-activated (PKR) are enriched with DICER in virus-infected cells. We demonstrate that the helicase domain of DICER is essential for this interaction and that its deletion confers antiviral properties to DICER in an RNAi-independent, PKR-dependent, manner. Author summaryWhile RNAi has been recognized as an efficient antiviral defense system in organisms such as plants and insects, its physiological importance in mammals remains to be determined. DICER is an enzyme involved in cleaving long double-stranded RNAs and is essential for RNAi induction. Using mass spectrometry analysis, we determined its interactome in human cells and showed that RNA binding proteins such as PKR are specifically enriched upon infection with the Sindbis virus or the Semliki forest virus. We determined that the N terminal helicase domain of the DICER protein acts as a platform to recruit these factors during infection and that its deletion confers an antiviral activity to DICER.

microbiology↗