Two major arms of the inflammatory response are the NF-jB and c-Jun N-terminal kinase (JNK) pathways. Here, we show that enteropathogenic Escherichia coli (EPEC) employs the type III secretion system to target these two signalling arms by injecting host cells with two effector proteins, NleC and NleD. We provide evidence that NleC and NleD are Zn-dependent endopeptidases that specifically clip and inactivate RelA (p65) and JNK, respectively, thus blocking NF-jB and AP-1 activation. We show that NleC and NleD co-operate and complement other EPEC effectors in accomplishing maximal inhibition of IL-8 secretion. This is a remarkable example of a pathogen using multiple effectors to manipulate systematically the host inflammatory response signalling network.
Upon DNA damage, a cytosolic form of the mitochondrial enzyme fumarase moves into the nucleus where, by virtue of its enzymatic activity, it participates in the cell's response to DNA damage. This potentially explains its known role as a tumor suppressor.
Haematological and solid cancers catabolise the semi-essential amino acid arginine to drive cell proliferation. However, the resulting low arginine microenvironment also impairs chimeric antigen receptor T cells (CAR-T) cell proliferation, limiting their efficacy in clinical trials against haematological and solid malignancies. T cells are susceptible to the low arginine microenvironment due to the low expression of the arginine re-synthesis enzymes argininosuccinate synthase (ASS) and ornithine transcarbamylase (OTC). We demonstrate T cells can be re-engineered to express functional ASS or OTC enzymes, in concert with different chimeric antigen receptors. Enzyme modifications increase CAR-T cell proliferation, with no loss of CAR cytotoxicity or increased exhaustion. In vivo, enzyme-modified CAR-T cells lead to enhanced clearance of leukaemia or solid tumour burden, providing the first metabolic modification to enhance CAR-T cell therapies.
Neuroblastoma is the most common paediatric solid tumour and prognosis remains poor for high-risk cases despite the use of multimodal treatment. Analysis of public drug sensitivity data showed neuroblastoma lines to be sensitive to indisulam, a molecular glue that selectively targets RNA splicing factor RBM39 for proteosomal degradation via DCAF15-E3-ubiquitin ligase. In neuroblastoma models, indisulam induces rapid loss of RBM39, accumulation of splicing errors and growth inhibition in a DCAF15-dependent manner. Integrative analysis of RNAseq and proteomics data highlight a distinct disruption to cell cycle and metabolism. Metabolic profiling demonstrates metabolome perturbations and mitochondrial dysfunction resulting from indisulam. Complete tumour regression without relapse was observed in both xenograft and the Th-MYCN transgenic model of neuroblastoma after indisulam treatment, with RBM39 loss, RNA splicing and metabolic changes confirmed in vivo. Our data show that dual-targeting of metabolism and RNA splicing with anticancer indisulam is a promising therapeutic approach for high-risk neuroblastoma.
The dynamic behavior of the nucleolus plays a role in the detection of and response to DNA damage of cells. Two nucleolar proteins, p14 ARF /p19 ARF and B23, were shown to translocate out of the nucleolus after exposure of cells to DNAdamaging agents. This translocation affects multiple cellular functions, such as DNA repair, proliferation, and survival. In this study, we identify a pathway and scrutinize the mechanisms leading to the translocation of these proteins after exposure of cells to DNA-damaging agents. We show that redistribution of B23 and p19
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