Browsing Department of molecular bacteriology (MOBA) by Subjects
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A clonotypic Vγ4Jγ1/Vδ5Dδ2Jδ1 innate γδ T-cell population restricted to the CCR6⁺CD27⁻ subset.Here we investigate the TCR repertoire of mouse Vγ4(+) γδ T cells in correlation with their developmental origin and homeostasis. By deep sequencing we identify a high frequency of straight Vδ5Dδ2Jδ1 germline rearrangements without P- and N-nucleotides within the otherwise highly diverse Trd repertoire of Vγ4(+) cells. This sequence is infrequent in CCR6(-)CD27(+) cells, but abundant among CCR6(+)CD27(-) γδ T cells. Using an inducible Rag1 knock-in mouse model, we show that γδ T cells generated in the adult thymus rarely contain this germline-rearranged Vδ5Dδ2Jδ1 sequence, confirming its fetal origin. Single-cell analysis and deep sequencing of the Trg locus reveal a dominant CDR3 junctional motif that completes the TCR repertoire of invariant Vγ4(+)Vδ5(+) cells. In conclusion, this study identifies an innate subset of fetal thymus-derived γδ T cells with an invariant Vγ4(+)Vδ5(+) TCR that is restricted to the CCR6(+)CD27(-) subset of γδ T cells.
Identification of tumor-specific Salmonella Typhimurium promoters and their regulatory logic.Conventional cancer therapies are often limited in effectiveness and exhibit strong side effects. Therefore, alternative therapeutic strategies are demanded. The employment of tumor-colonizing bacteria that exert anticancer effects is such a novel approach that attracts increasing attention. For instance, Salmonella enterica serovar Typhimurium has been used in many animal tumor models as well as in first clinical studies. These bacteria exhibit inherent tumoricidal effects. In addition, they can be used to deliver therapeutic agents. However, bacterial expression has to be restricted to the tumor to prevent toxic substances from harming healthy tissue. Therefore, we screened an S. Typhimurium promoter-trap library to identify promoters that exclusively drive gene expression in the cancerous tissue. Twelve elements could be detected that show reporter gene expression in tumors but not in spleen and liver. In addition, a DNA motif was identified that appears to be necessary for tumor specificity. Now, such tumor-specific promoters can be used to safely express therapeutic proteins by tumor-colonizing S. Typhimurium directly in the neoplasia.
An integrative computational approach to effectively guide experimental identification of regulatory elements in promoters.Transcriptional activity of genes depends on many factors like DNA motifs, conformational characteristics of DNA, melting etc. and there are computational approaches for their identification. However, in real applications, the number of predicted, for example, DNA motifs may be considerably large. In cases when various computational programs are applied, systematic experimental knock out of each of the potential elements obviously becomes nonproductive. Hence, one needs an approach that is able to integrate many heterogeneous computational methods and upon that suggest selected regulatory elements for experimental verification.