The LIM-only protein FHL2 acts as a transcriptional modulator that positively or negatively regulates multiple signaling pathways. We recently reported that FHL2 cooperates with CBP/p300 in the activation of -catenin/TCF target gene cyclin D1. In this paper, we demonstrate that FHL2 is associated with the cyclin D1 promoter at the TCF/CRE site, providing evidence that cyclin D1 is a direct target of FHL2. We show that deficiency of FHL2 greatly reduces the proliferative capacity of spontaneously immortalized mouse fibroblasts which is associated with decreased expression of cyclin D1 and p16INK4a, and hypophosphorylation of Rb. Reexpression of FHL2 in FHL2-null fibroblasts efficiently restores cyclin D1 levels and cell proliferative capacity, indicating that FHL2 is critical for cyclin D1 activation and cell growth. Moreover, ectopic cyclin D1 expression is sufficient to override growth inhibition of immortalized FHL2-null fibroblasts. Gene expression profiling revealed that FHL2 deficiency triggers a broad change of the cell cycle program that is associated with downregulation of several G1/S and G2/M cyclins, E2F transcription factors and DNA replication machinery, thus correlating with reduced cell proliferation. This change also involves downregulation of the negative cell cycle regulators, particularly INK4 inhibitors, which could counteract the decreased expression of cyclins, allowing cells to grow. Our study illustrates that FHL2 can act on different aspects of the cell cycle program to finely regulate cell proliferation.
The LIM-only protein FHL2 regulates cyclin D1 expression and cell proliferation.
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Induction and transcriptional regulation of the co-inhibitory gene module in T cells.
Specimen part
View SamplesRole for naturally occurring CD4+CD25+Foxp3+ regulatory T cells (nTregs) in counterbalancing this process. Using a transgenic murine model for autoimmune-mediated lung disease, we demonstrated that, despite pulmonary inflammation, lung-specific CD8+ T cells can reside quiescently in close proximity to self-antigen. Whereas self-reactive CD8+ T cells in the inflamed lung and lung-draining lymph nodes down-regulated the expression of effector molecules, those located in the spleen appeared to be partly antigen-experienced and displayed a memory-like phenotype. Since ex vivo-reisolated self-reactive CD8+ T cells were very well capable to respond to the antigen in vitro, we investigated a possible contribution of nTregs to the immune control over autoaggressive CD8+ T cells in the lung.
CD4+CD25+Foxp3+ regulatory T cells are dispensable for controlling CD8+ T cell-mediated lung inflammation.
Specimen part
View SamplesWe describe a novel subset of CD8+ DCs in lymphoid organs of nave mice characterized by expression of the CX3CR1 chemokine receptor. CX3CR1+CD8+ DCs lack hallmarks of classical CD8+ DCs, including IL12 secretion, the capacity to cross-present antigen and their developmental independence of the transcriptional factor BatF3. Gene expression profiling showed that CX3CR1+CD8+ DCs resemble CD8- cDCs. The microarray analysis further revealed a unique plasmacytoid DC (PDC) gene signature of CX3CR1+ CD8+ DCs. A PDC relationship of the cells is further supported by the fact that they harbor characteristic D-J immunoglobulin gene rearrangements and that development of CX3CR1+CD8+ DCs requires E2-2, the critical transcriptional regulator of PDCs. Thus, CX3CR1+ CD8+ DCs represent a unique DC subset, related to but distinct from PDCs.
CX3CR1+ CD8alpha+ dendritic cells are a steady-state population related to plasmacytoid dendritic cells.
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View SamplesThe cancer-risk associated rs6983267 single nucleotide polymorphism (SNP) and the accompanying long non-coding RNA CCAT2 in the highly amplified 8q24.21 region has been implicated in cancer predisposition, though causality has not been established. Here, using allele-specific CCAT2 transgenic mice, we demonstrate that CCAT2 overexpression leads to spontaneous myeloid malignancies. CCAT2 is overexpressed in bone marrow and peripheral blood of myelodysplastic/myeloproliferative neoplasms (MDS/MPN) patients. CCAT2 induces global deregulation of gene expression by downregulating EZH2 in vitro and in vivo in an allele-specific manner. We also identified a novel disease-specific RNA mutation (named DNA-to-RNA allelic imbalance, DRAI) at the SNP locus in MDS/MPN patients and CCAT2-transgenic mice. The RNA transcribed from the SNP locus in malignant hematopoietic cells have different allelic composition from the corresponding genomic DNA, a phenomenon rarely observed in normal cells. Our findings provide fundamental insights into the functional role of rs6983267 SNP and CCAT2 in myeloid malignancies.
Cancer-associated rs6983267 SNP and its accompanying long noncoding RNA <i>CCAT2</i> induce myeloid malignancies via unique SNP-specific RNA mutations.
Specimen part
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