Biology subjects

Matta, B.

Publications and source records attributed to Matta, B..

2 recordsLinked to original sources

bioRxiv2023

STK25 is an IRF5 kinase that promotes TLR7/8-mediated inflammation

Toll-like receptors (TLRs) represent a subset of pattern-recognition receptors (PRRs) employed by the innate immune system to detect pathogen-associated molecular patterns (PAMPs) and initiate the response to invading microbes. The transcription factor interferon regulatory factor 5 (IRF5) functions as an important mediator of the inflammatory response downstream of MyD88-dependent TLR activation. While the dysregulation of IRF5 activity has been implicated in the development of several autoimmune diseases including systemic lupus erythematosus (SLE) and rheumatoid arthritis, the factors that modulate TLR-induced IRF5 post-translational modifications (PTMs) are poorly understood. Therefore, the focus of this study was to identify and characterize the role(s) of novel kinases in the regulation of TLR7/8 signaling. We performed a kinome-wide siRNA screen in human THP-1 monocytic cells to identify mediators of TLR7/8-induced TNF- and IL-6 production. We identified serine/threonine protein kinase 25 (STK25) as a positive regulator of proinflammatory cytokine release in response to TLR7/8 activation in human primary myeloid cells. We determined that STK25 phosphorylates IRF5 in vitro via multiple biochemical assays. Phosphopeptide mapping by mass spectrometry revealed that STK25 phosphorylates IRF5 at a highly conserved residue, Thr265, that leads to the transcriptional activation of IRF5 in HEK293T cells. We determined that STK25 undergoes autophosphorylation in response to a variety of TLR triggers in multiple immune cell types. We demonstrated that R848-induced IRF5 nuclear translocation and proinflammatory cytokine production was significantly attenuated in immune cells from Stk25-deficient mice compared to wild-type. Finally, we determined that STK25 autophosphorylation is increased at steady-state in peripheral blood mononuclear cells (PBMCs) from SLE donors compared to healthy controls. Thus, our findings implicate STK25 as an important regulator of TLR7/8 signaling through the modulation of IRF5 activation. Significance StatementThe transcription factor IRF5 functions as a master regulator of innate and adaptive immunity. While the hyperactivation of IRF5 has been implicated in the pathogenesis of systemic lupus erythematosus (SLE), the mechanisms leading to the modulation of IRF5 activity are incompletely understood. Here, we conducted a screen of the human kinome to identify IRF5 kinases that function as positive regulators of TLR-induced inflammation. We demonstrate that STK25 directly phosphorylates IRF5 to drive proinflammatory cytokine responses downstream of TLR activation in both human and murine primary immune cells. Altogether, our findings implicate STK25 as a potential therapeutic target for the management of IRF5-mediated immunological disorders.

biochemistry↗

bioRxiv2023

Identification of pan-cancer/testis genes and validation of therapeutic targeting in triple-negative breast cancer: Lin28a- and Siglece-based vaccination induces anti-tumor immunity and inhibits metastasis

BackgroundCancer-testis (CT) genes are targets for tumor antigen-specific immunotherapy given that their expression is normally restricted to the immune-privileged testis in healthy individuals with aberrant expression in tumor tissues. While they represent targetable germ-tissue antigens and play important functional roles in tumorigenesis, there is currently no standardized approach for identifying clinically relevant CT genes. Optimized algorithms and validated methods for accurate prediction of reliable CT antigens with high immunogenicity are also lacking. MethodsSequencing data from the Genotype-Tissue Expression (GTEx) and The Genomic Data Commons (GDC) databases was utilized for the development of a bioinformatic pipeline to identify CT exclusive genes. A CT germness score was calculated based on the number of CT genes expressed within a tumor type and their degree of expression. The impact of tumor germness with clinical outcome was evaluated using healthy GTEx and GDC tumor samples. We then used a triple-negative breast cancer mouse model to develop and test an algorithm that predicts epitope immunogenicity based on the identification of germline sequences with strong MHCI and MHCII binding affinities. Germline sequences for CT genes were synthesized as long synthetic peptide vaccines and tested in the 4T1 triple-negative model of invasive breast cancer with Poly(I:C) adjuvant. Vaccine immunogenicity was determined by flow cytometric analysis of in vitro and in vivo T cell responses. Primary tumor growth and lung metastasis was evaluated by histopathology, flow cytometry and colony formation assay. ResultsWe developed a new bioinformatic pipeline to reliably identify CT exclusive genes as immunogenic targets for immunotherapy. We identified CT genes that are exclusively expressed within the testis, lack detectable thymic expression, and are significantly expressed in multiple tumor types. High tumor germness correlated with tumor progression but not with tumor mutation burden, supporting CT antigens as appealing targets in low mutation burden tumors. Importantly, tumor germness also correlated with markers of anti-tumor immunity. Vaccination of 4T1 tumor bearing mice with Siglece and Lin28a antigens resulted in increased T cell anti-tumor immunity and reduced primary tumor growth and lung metastases. ConclusionOur results present a novel strategy for the identification of highly immunogenic CT antigens for the development of targeted vaccines that induce anti-tumor immunity and inhibit metastasis.

bioinformatics↗