We therefore bred Src fl/fl animals into two models of intestinal tumourigenesis driven by Apc loss: the Apc Min/+ and Lgr5Cre ER Apc fl/fl mice.
We find that the dependence on RAC1 for crypt hyperproliferation is translated to a tumor model driven by Apc loss in LGR5 ISCs.
Recently, it has been shown that in a mouse model of colorectal cancer driven by Apc allelic loss, early and late neoplasms exhibit defects in epithelial barrier maintenance, leading to microbial invasion, which triggers tumour-elicited inflammation and contributes to tumour growth (Grivennikov et al., 2012).
As clonal deletion in negative selection is driven by APCs presenting self-ligand, we analyzed the presence of APCs immunohistochemically using MHC-II expression.
This immune response is driven by APCs which, in the female genital tract, include macrophages, dendritic cells, Langerhans cells, and epithelial cells of the cervix and endometrium.
We have used a transcriptional reporter assay for TCF activity driven by APC-insensitive N'Δβ-CATENIN, to test a collection of clinical-trial tested small molecules (Microsource 1040 library) (Fig 1A).
Since Ivermectin repressed TCF reporter activity driven by APC-insensitive N'Δβ-CATENIN, we sought to test whether this drug could affect downstream activation of β-CATENIN/TCF, focusing on C-terminal phosphorylation of β-CATENIN itself, which is required for full TCF complex transcriptional activity (Hino et al, 2005; Fang et al, 2007; Zhao et al, 2010).
Although 129 and B6 mice are both H2b, these strains are mismatched for multiple minor histocompatibility antigens, demonstrated by the fact that 129 mice reject B6 skin grafts acutely (MST 16 days) and B6 APC drive vigorous proliferation of 129 CD4+ T cells in vitro as judged by CFSE dilution (64% of cells>1 division at day 7, data not shown).
These data indicate that STAT1 signalling plays an important role in Treg generation not only in the IFN-γ protocol but also in TGF-β-based protocols where T cells are driven by allogeneic APC.
However, signalling pathways in APC that drive autoimmunity are not completely understood.
This impact of PAR location in the caveolar domain has been pointed out for the endothelial activation of PAR1 by activated protein C (APC), to drive signalling in a direction very distinct from that triggered by thrombin in platelets [ 151].
