Biology subjects

Wagner, A. R.

Publications and source records attributed to Wagner, A. R..

3 recordsLinked to original sources

bioRxiv2023

Type I interferon expression requires transcriptional activation of IRF7 by the RNA binding protein SRSF7

Tight regulation of macrophage immune gene expression is required to fight infection without risking harmful inflammation. The contribution of RNA binding proteins (RBPs) to shaping the macrophage response to pathogens remains poorly understood. Transcriptomic analysis revealed that a member of the serine/arginine-rich (SR) family of mRNA processing factors, SRSF7, is required for optimal expression of a cohort of interferon stimulated genes (ISGs) in macrophages. Using genetic and biochemical assays, we discovered that in addition to its canonical role in regulating alternative splicing, SRSF7 drives transcription of interferon regulatory transcription factor 7 (IRF7) to promote antiviral immunity. At the Irf7 promoter, SRSF7 maximizes STAT1 transcription factor binding and RNA polymerase II elongation via cooperation with the H4K20me1 histone methyltransferase KMT5a (SET8). These studies define an unorthodox role for an SR protein in activating transcription and reveal an unappreciated RNA binding protein-chromatin network that orchestrates macrophage antiviral gene expression.

immunology↗

bioRxiv2022

SRSF6 balances mitochondrial-driven innate immune outcomes through alternative splicing of BAX

To mount a protective response to infection while preventing hyperinflammation, gene expression in innate immune cells must be tightly regulated. Despite the importance of pre-mRNA splicing in shaping the proteome, its role in balancing immune outcomes remains understudied. Transcriptomic analysis of murine macrophage cell lines identified Serine/Arginine Rich Splicing factor 6 (SRSF6) as a gatekeeper of mitochondrial homeostasis. SRSF6 orchestrates this by directing alternative splicing of the mitochondrial pore-forming protein BAX. Loss of SRSF6 promotes accumulation of BAX-{kappa}, a variant that sensitizes macrophages to undergo cell death and triggers upregulation of interferon stimulated genes through cGAS sensing of cytosolic mitochondrial DNA. Upon pathogen sensing, macrophages regulate SRSF6 expression to control the liberation of immunogenic mtDNA and adjust the threshold for entry into programmed cell death. This work defines BAX alternative splicing by SRSF6 as a critical node not only in mitochondrial homeostasis, but also in the macrophages response to pathogens.

molecular biology↗

bioRxiv2020

Global transcriptomics analyses reveal specialized roles for splicing regulatory proteins in the macrophage innate immune response

Pathogen sensing via pattern recognition receptors triggers massive reprogramming of macro-phage gene expression. While the signaling cascades and transcription factors that activate these responses are well-known, the role of post-transcriptional RNA processing in modulating innate immune gene expression remains understudied. Recent phosphoproteomics analyses revealed that members of the SR and hnRNP families of splicing regulatory proteins are dynamically post-translationally modified in infected macrophages. To begin to test if these splicing factors play a privileged role in controlling the innate immune transcriptome, we analyzed steady state gene expression and alternatively spliced isoform production in ten SR/hnRNP knockdown RAW 264.7 macrophage cell lines following infection with the bacterial pathogen Salmonella enterica serovar Typhimurium (Salmonella). We identified thousands of transcripts whose abundance was increased or decreased by SR/hnRNP knockdown in macrophages. We observed that different SR/hnRNPs control the expression of distinct gene regulons in uninfected and Salmonella-infected macrophages, with several key innate immune genes (Nos2, Mx1, Il1a) relying on multiple SR/hnRNPs to maintain proper induction and/or repression. Knockdown of SR/hnRNPs promoted differential isoform usage (DIU) for a number of key immune sensors and signaling molecules and many of these splicing changes were again, distinct in uninfected and Salmonella-infected macrophages. Finally, after observing a surprising degree of similarity between the DEGs and DIUs in hnRNP K and U knockdown macrophages, we found that these cells are better able to restrict vesicular stomatitis virus replication than control cells, supporting a role for these hnRNPs in controlling infection outcomes in macrophages ex vivo. Based on these findings, we conclude that many innate immune genes have evolved to rely on one or more splicing regulatory factors to ensure the proper timing and magnitude of their induction, bolstering a model wherein pre-mRNA splicing is a critical regulatory node in the innate immune response.

immunology↗