Biology subjects

Finsterbusch, K.

Publications and source records attributed to Finsterbusch, K..

4 recordsLinked to original sources

bioRxiv2025

The ubiquitin E3 ligase Huwe1 facilitates viral and self RNA sensing by RIG-I-like receptors

RIG-I-like receptors (RLRs) are cytoplasmic RNA sensors that promote type I and type III interferon (IFN) production in response to RNA ligands of viral or endogenous origin. The RLR pathway is tightly regulated by dynamic post-translational modifications, including ubiquitination. Huwe1 is a HECT domain-containing giant ubiquitin E3 ligase that has not been implicated in the RLR or IFN pathway. Here, we investigated whether Huwe1 is required for type I IFN induction downstream of RLRs. We demonstrate that loss of Huwe1 severely attenuates the expression of IFN-{beta}, IFN-{lambda}1 and IFN-stimulated genes (ISGs) in ADAR1-deficient human cells and primary murine bone-marrow derived macrophages, in which unedited self RNAs that serve as RLR ligands accumulate. In addition, depletion of Huwe1 reduces the induction of type I and III IFNs upon transfection with synthetic viral RNA mimetics or infection with a picornavirus. Using proteomics, we identified several putative Huwe1 substrates, which include key components of the RLR pathway (MAVS, TRAFs). We demonstrate that these substrates interact with Huwe1 and that Huwe1 is essential for the activity of TRAF5 in type I IFN induction. Collectively, our results put Huwe1 on the map as an important ubiquitin E3 ligase in the RLR pathway and provide new insights into ubiquitin-dependent regulation of cell-intrinsic antiviral immune pathways.

immunology↗

bioRxiv2023

Regulation of BCR-mediated Ca2+ mobilization by MIZ1-TIMBIM4 safeguards IgG1+ GC B cell positive selection

The transition from IgM to affinity-matured IgG antibodies is vital for effective humoral immunity. This is facilitated by germinal centers (GCs) through affinity maturation and preferential accumulation of IgG+ B cells over IgM+ B cells. However, it is not known whether the positive selection of the different immunoglobulin isotypes within GCs varies in its dependency on specific transcriptional mechanisms. Here, we identified IgG1+ GC B cell transcription factor dependency using CRISPR-Cas9 and conditional mouse genetics. We found that MIZ1 was specifically required for IgG1+ GC B cell survival during positive selection, whereas IgM+ GC B cells were largely independent. Mechanistically, MIZ1 induced TMBIM4, an ancestral anti-apoptotic protein that regulated inositol trisphosphate receptor mediated Ca2+ mobilization downstream of IgG1. The MIZ1-TMBIM4 axis prevented mitochondrial dysfunction-induced IgG1+ GC cell death caused by excessive Ca2+ accumulation. This study uncovers a unique immunoglobulin isotype-specific dependency, on a hitherto unidentified mechanism in GC positive selection.

immunology↗

bioRxiv2022

Emergence of new subgenomic mRNAs in SARS-CoV-2

Two mutations occurred in SARS-CoV-2 early during the COVID-19 pandemic that have come to define circulating virus lineages1: first a change in the spike protein (D614G) that defines the B.1 lineage and second, a double substitution in the nucleocapsid protein (R203K, G204R) that defines the B.1.1 lineage, which has subsequently given rise to three Variants of Concern: Alpha, Gamma and Omicron. While the latter mutations appear unremarkable at the protein level, there are dramatic implications at the nucleotide level: the GGG[->]AAC substitution generates a new Transcription Regulatory Sequence (TRS) motif, driving SARS-CoV-2 to express a novel subgenomic mRNA (sgmRNA) encoding a truncated C-terminal portion of nucleocapsid (N.iORF3), which is an inhibitor of type I interferon production. We find that N.iORF3 also emerged independently within the Iota variant, and further show that additional TRS motifs have convergently evolved to express novel sgmRNAs; notably upstream of Spike within the nsp16 coding region of ORF1b, which is expressed during human infection. Our findings demonstrate that SARS-CoV-2 is undergoing evolutionary changes at the functional RNA level in addition to the amino acid level, reminiscent of eukaryotic evolution. Greater attention to this aspect in the assessment of emerging strains of SARS-CoV-2 is warranted.

microbiology↗

bioRxiv2021

Broad human and animal coronavirus neutralisation by SARS-CoV-2 S2-targeted vaccination

Several common-cold coronaviruses (HCoVs) are endemic in humans and several variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have emerged during the current Coronavirus disease 2019 (COVID-19) pandemic. Whilst antibody cross-reactivity with the Spike glycoproteins (S) of diverse coronaviruses has been documented, it remains unclear whether such antibody responses, typically targeting the conserved S2 subunit, contribute to or mediate protection, when induced naturally or through vaccination. Using a mouse model, we show that prior HCoV-OC43 S immunity primes neutralising antibody responses to otherwise subimmunogenic SARS-CoV-2 S exposure and promotes S2-targeting antibody responses. Moreover, mouse vaccination with SARS-CoV-2 S2 elicits antibodies that neutralise diverse animal and human alphacoronaviruses and betacoronaviruses in vitro, and protects against SARS-CoV-2 challenge in vivo. Lastly, in mice with a history of SARS-CoV-2 Wuhan-based S vaccination, further S2 vaccination induces stronger and broader neutralising antibody response than booster Wuhan S vaccination, suggesting it may prevent repertoire focusing caused by repeated homologous vaccination. The data presented here establish the protective value of an S2-targeting vaccine and support the notion that S2 vaccination may better prepare the immune system to respond to the changing nature of the S1 subunit in SARS-CoV-2 variants of concern (VOCs), as well as to unpredictable, yet inevitable future coronavirus zoonoses.

immunology↗