| 1. |
- Quebatte, Maxime, et al.
(författare)
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The BatR/BatS Two-Component Regulatory System Controls the Adaptive Response of Bartonella henselae during Human Endothelial Cell Infection
- 2010
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Ingår i: Journal of Bacteriology. - 0021-9193 .- 1098-5530. ; 192:13, s. 3352-3367
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Tidskriftsartikel (refereegranskat)abstract
- Here, we report the first comprehensive study of Bartonella henselae gene expression during infection of human endothelial cells. Expression of the main cluster of upregulated genes, comprising the VirB type IV secretion system and its secreted protein substrates, is shown to be under the positive control of the transcriptional regulator BatR. We demonstrate binding of BatR to the promoters of the virB operon and a substrate-encoding gene and provide biochemical evidence that BatR and BatS constitute a functional two-component regulatory system. Moreover, in contrast to the acid-inducible (pH 5.5) homologs ChvG/ChvI of Agrobacterium tumefaciens, BatR/BatS are optimally activated at the physiological pH of blood (pH 7.4). By conservation analysis of the BatR regulon, we show that BatR/BatS are uniquely adapted to upregulate a genus-specific virulence regulon during hemotropic infection in mammals. Thus, we propose that BatR/BatS two-component system homologs represent vertically inherited pH sensors that control the expression of horizontally transmitted gene sets critical for the diverse host-associated life styles of the alphaproteobacteria.
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| 2. |
- Saxena, Meera, et al.
(författare)
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A Pygopus 2-Histone Interaction Is Critical for Cancer Cell Dedifferentiation and Progression in Malignant Breast Cancer
- 2020
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Ingår i: Cancer Research. - : AMER ASSOC CANCER RESEARCH. - 0008-5472 .- 1538-7445. ; 80:17, s. 3631-3648
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Tidskriftsartikel (refereegranskat)abstract
- Pygopus 2 (Pygo2) is a coactivator of Wnt/b-catenin signaling that can bind bi- or trimethylated lysine 4 of histone-3 (H3K4me(2/3)) and participate in chromatin reading and writing. It remains unknown whether the Pygo2-H3K4me(2/3) association has a functional relevance in breast cancer progression in vivo. To investigate the functional relevance of histone-binding activity of Pygo2 in malignant progression of breast cancer, we generated a knock-in mouse model where binding of Pygo2 to H3K4me(2/3) was rendered ineffective. Loss of Pygo2-histone interaction resulted in smaller, differentiated, and less metastatic tumors, due, in part, to decreased canonical Wnt/b-catenin signaling. RNA- and ATAC-sequencing analyses of tumor-derived cell lines revealed downregulation of TGF beta signaling and upregulation of differentiation pathways such as PDGFR signaling. Increased differentiation correlated with a luminal cell fate that could be reversed by inhibition of PDGFR activity. Mechanistically, the Pygo2-histone interaction potentiated Wnt/beta-catenin signaling, in part, by repressing the expression of Wnt signaling antagonists. Furthermore, Pygo2 and beta-catenin regulated the expression of miR-29 family members, which, in turn, repressed PDGFR expression to promote dedifferentiation of wild-type Pygo2 mammary epithelial tumor cells. Collectively, these results demonstrate that the histone binding function of Pygo2 is important for driving dedifferentiation and malignancy of breast tumors, and loss of this binding activates various differentiation pathways that attenuate primary tumor growth and metastasis formation. Interfering with the Pygo2-H3K4me(2/3) interaction may therefore serve as an attractive therapeutic target for metastatic breast cancer. Significance: Pygo2 represents a potential therapeutic target in metastatic breast cancer, as its histone-binding capability promotes beta-catenin-mediated Wnt signaling and transcriptional control in breast cancer cell dedifferentiation, EMT, and metastasis.
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