During thymic T cell development, immature CD4(+)/CD8(+) thymocytes develop into either CD4(+)/CD8(-) helper or CD4(-)/CD8(+) CTLs. The molecular mechanisms governing the complex selection and differentiation steps during thymic T cell development are not well understood. Here we developed a novel approach to investigate gene function during thymocyte development. We transfected ex vivo isolated immature thymocytes with gene-specific morpholino antisense oligonucleotides and induced differentiation in cell or organ cultures. A morpholino oligonucleotide specific for CD8alpha strongly reduces CD8 expression. To our knowledge, this is the first demonstrated gene knockdown by morpholino oligonucleotides in primary lymphocytes. Using this approach, we show here that the transcription factor Runx3 is involved in silencing of CD4 expression during CD8 T cell differentiation. Runx3 protein expression appears late in thymocyte differentiation and is confined to mature CD8 single-positive thymocytes, whereas Runx3 mRNA is transcribed in mature CD4 and CD8 thymocytes. Therefore, Runx3 protein expression is regulated at a post-transcriptional level. The knockdown of Runx3 protein expression through morpholino oligonucleotides inhibited the development of CD4(-)/CD8(+) T cells. Instead, mature cells with a CD4(+)/CD8(+) phenotype accumulated. Potential Runx binding sites were identified in the CD4 gene silencer element, which are bound by Runx protein in EMSAs. Mutagenesis of potential Runx binding sites in the CD4 gene silencer abolished silencing activity in a reporter gene assay, indicating that Runx3 is involved in CD4 gene silencing. The experimental approach developed here should be valuable for the functional analysis of other candidate genes in T cell differentiation.
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http://dx.doi.org/10.4049/jimmunol.171.7.3594 | DOI Listing |
Front Immunol
January 2025
Department of Tumor Biological Treatment, The Third Affiliated Hospital of Soochow University, Changzhou, Jiangsu, China.
While biomarkers have been shown to enhance the prognosis of patients with colorectal cancer (CRC) compared to conventional treatments, there is a pressing need to discover novel biomarkers that can assist in assessing the prognostic impact of immunotherapy and in formulating individualized treatment plans. The RUNX family, consisting of RUNX1, RUNX2, and RUNX3, has been recognized as crucial regulators in developmental processes, with dysregulation of these genes also being implicated in tumorigenesis and cancer progression. In our present study, we demonstrated a crucial regulatory role of RUNX in CD8T and CD103CD8T cell-mediated anti-tumor response within the tumor microenvironment (TME) of human CRC.
View Article and Find Full Text PDFSci Rep
December 2024
Department of Life Sciences, University of Siena, Siena, Italy.
The scaffold protein AMBRA1, which participates in the autophagy pathway, also promotes CD4 T cell differentiation to Tregs independent of autophagy through its interactor PP2A. Here we have investigated the role of AMBRA1 in CD8 T cell differentiation to cytotoxic T cells (CTL). AMBRA1 depletion in CD8 T cells was associated with impaired expression of the transcription factors RUNX3 and T-BET that drive CTL differentiation and resulted in impaired acquisition of cytotoxic potential.
View Article and Find Full Text PDFPLoS Genet
December 2024
Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel.
Epigenetics Chromatin
November 2024
Department of Microbiology, Faculty of Science, Chulalongkorn University, Bangkok, 10330, Thailand.
Background: To avoid exaggerated inflammation, innate immune cells adapt to become hypo-responsive or "tolerance" in response to successive exposure to stimuli, which is a part of innate immune memory. Polycomb repressive complex 2 (PRC2) mediates the transcriptional repression by catalyzing histone H3 lysine 27 trimethylation (H3K27me3) but little is known about its role in lipopolysaccharide (LPS)-induced tolerance in macrophages.
Result: We examined the unexplored roles of EED, a component of the PRC2, in LPS tolerant macrophages.
BMC Med Genomics
November 2024
Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, UCLA, Los Angeles, CA, USA.
Background: Rare variants in epigenes (a.k.a.
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