Biology subjects

Petkau, G.

Publications and source records attributed to Petkau, G..

6 recordsLinked to original sources

bioRxiv2025

Differential regulation of TCR-induced ZFP36 and ZFP36L1 expression by cyclosporin A in CD8+ T cells

CD8+ T cells target infected or malignant cells via the production of pro-inflammatory cytokines and direct target cell killing. Members of the ZFP36-family of RNA binding proteins, ZFP36 and ZFP36L1 regulate these functions in T cells via the regulation of mRNA stability and protein translation. We investigate the regulation of ZFP36 and ZFP36L1 expression using in vitro differentiated OT1 TCR transgenic memory-like T cells. We characterise the differential kinetics and sensitivity of ZFP36 and ZFP36L1 to antigen affinity and PMA versus ionomycin stimulation. By selectively inhibiting TCR-induced signalling pathways, we find that p38 MAPK, MEK1/2 and PKC contribute to inducing both ZFP36 and ZFP36L1 expression. By contrast, inhibition of calcineurin using cyclosporin A potently inhibits ZFP36L1 expression while increasing and prolonging ZFP36 expression. The Zfp36 promoter contains many binding sites for the transcription factors ELK-1/4 and few binding sites for NFAT, while the Zfp36l1 promoter contains many NFAT binding sites and few ELK1/4 binding sites. Our findings suggest that regulation of divergent transcription factors enable calcineurin to act as a signalling node that mediates the differential regulation of ZFP36 and ZFP36L1 during T cell activation.

immunology↗

bioRxiv2023

Zfp36l1 establishes the high affinity CD8 T cell response by directly linking TCR affinity to cytokine sensing

How individual T cells compete for and respond to IL2 at the molecular level, and, as a consequence, how this shapes population dynamics and the selection of high affinity clones is still poorly understood. Here we describe how the RNA binding protein ZFP36L1, acts as a sensor of TCR affinity to promote clonal expansion of high affinity CD8 T cells. As part of an incoherent feed forward loop ZFP36L1 has a non-redundant role in suppressing negative regulators of cytokine signalling and mediating a selection mechanism based on competition for IL2. We suggest that ZFP36L1 acts as a sensor of antigen affinity and establishes dominance of high affinity T cells by installing a hierarchical response to IL2.

immunology↗

bioRxiv2023

MicroRNA-221/222-expression in HSC and MPP safeguards their quiescence and multipotency by downregulating stress-independent and dependent expression of IEG and of several myelo/granulopoiesis-enhancing target genes.

The microRNA cluster-221/222 is expressed in hematopoietic stem cells (HSC) and multipotent progenitors (MPP). To study its function in hematopoiesis, we generated mice, in which this cluster is selectively deleted by Vav-cre in HSC and, thus, in all hematopoietic cells. Fluorescence-activated cell sorting analyses of the lineage-negative HSC and MPP compartments in bone marrow at unperturbed, steady state hematopoiesis detect strong activation of HSC to MPP, as well as increased granulocytes in the periphery, induced by miR-221/222-deficiency. Short-term social stress on mice also activates HSC to MPP, but the time of stress is too short to detect further increases in granulocyte numbers. Single cell deep mRNA sequencing identifies Fos as direct, and Jun as well as six other immediate early genes (IEG) as indirect targets of miR-221/222 at unperturbed hematopoiesis. Three of these IEG - Klf6, Nr4a1 and Zfp36 - have previously been found to influence myelo/granulopoiesis. Short stress induces higher levels of the same, and an even larger number of IEGs, now also in MPP, indicating, that stress and miR-221/222 both activate HSC to MPP by IEG upregulation in perturbed hematopoiesis. Furthermore, combined stress and miR-221/222-deficiency rapidly increase numbers of myelo/granulocyte progenitors (MEP, GMP) in bone marrow. Additional indirect miR-221/222-targets become detectable in MPP, of which H3f3b has previously been found to influence myelopoiesis. In serial transplantations, miR-221/222-deficient HSC retain their capacity to home to, and become resident in bone marrow, but they loose their lymphopoietic capacities, thus their multipotency. Our results suggest, that miR-221/222-expression in HSC and MPP safeguards their quiescence and multipotency by downregulating the expression of IEG and of myelo/granulopoiesis-enhancing target genes. Since miR-221/222 is also expressed in human HSC and MPP, its expression should improve clinical settings of human bone marrow transplantations.

immunology↗

bioRxiv2022

Polypyrimidine Tract Binding Protein 1 regulates the activation of mouse CD8 T cells

We show that the RNA-binding protein Polypyrimidine Tract Binding Protein 1 (PTBP1) is dispensable for the development of naive mouse CD8 T cells, but is necessary for the optimal expansion and production of effector molecules by antigen-specific CD8 T cells in vivo. PTBP1 has an essential role in regulating the early events following activation of the naive CD8 T cell leading to IL-2 and TNF production. It is also required to protect activated CD8 T cells from apoptosis. PTBP1 controls alternative splicing of over 400 genes in naive CD8 T cells in addition to regulating the abundance of [~]200 mRNAs. PTBP1 is required for the nuclear accumulation of c-Fos, NFATc2 and NFATc3, but not NFATc1. This selective effect on NFAT proteins correlates with PTBP1-promoted expression of the shorter A{beta}1 isoform and exon 13 skipped A{beta}2 isoform of the catalytic A-subunit of calcineurin phosphatase. These findings reveal a crucial role for PTBP1 in regulating CD8 T cell activation.

immunology↗

bioRxiv2021

The timing of differentiation and potency of CD8 effector function is set by RNA binding proteins

CD8+ T cell differentiation into effector cells is initiated early after antigen encounter by signals from the T cell antigen receptor and costimulatory molecules. The molecular mechanisms that determine the timing and rate of differentiation however are not defined. Here we show that the RNA binding proteins (RBP) ZFP36 and ZFP36L1 limit the rate of differentiation of activated naive CD8+ T cells and the potency of the resulting cytotoxic lymphocytes. The RBP act in an early and short temporal window to enforce dependency on costimulation via CD28 for full T cell activation and effector differentiation by directly binding mRNA of NF-B, IRF8 and NOTCH1 transcription factors and cytokines, including IL2. Their absence in T cells, or the adoptive transfer of a small numbers of CD8+ T cells lacking the RBP, promotes resilience to influenza A virus infection without immunopathology. These findings highlight ZFP36 and ZFP36L1 as nodes for the integration of the early T cell activation signals determining the speed and quality of the CD8 response.

immunology↗

bioRxiv2019

Stromal cell-contact dependent PI3K and APRIL induced NF-κB signaling complement each other to prevent mitochondrial- and endoplasmic reticulum stress induced cell death of bone marrow plasma cells

Persistence of long-lived, memory plasma cells in the bone marrow depends on survival factors available in the bone marrow, provided in niches organized by stromal cells. Here we describe that ex vivo we can prevent apoptosis of bone marrow plasma cells by supplying direct cell contact with stromal cells and the soluble cytokine APRIL. Integrin-mediated contact of bone marrow plasma cells with stromal cells activates the PI3K signaling pathway, leading to critical inactivation of FoxO1/3 and preventing the activation of mitochondrial stress-associated effector caspases 3 and 7. Likely, inhibition of PI3K signaling in vivo ablates bone marrow plasma cells. APRIL signaling, via the NF-{kappa}B pathway, blocks activation of the endoplasmic reticulum stress-associated initiator caspase 12. Thus, stromal cell-contact induced PI3K and APRIL-induced NF-{kappa}B signaling provide necessary and complementary signals to maintain bone marrow memory plasma cells.

immunology↗