Silencing of microRNA-155 in mice during acute inflammatory response leads to derepression of c/ebp Beta and down-regulation of G-CSF

microRNA-155 (miR-155) has been implicated as a central regulator of the immune system, but its function during acute inflammatory responses is still poorly understood. Here we show that exposure of cultured macrophages and mice to lipopolysaccharide (LPS) leads to up-regulation of miR-155 and that the transcription factor c/ebp Beta is a direct target of miR-155. Interestingly, expression profiling of LPS-stimulated macrophages combined with overexpression and silencing of miR-155 in murine macrophages and human monocytic cells uncovered marked changes in the expression of granulocyte colony-stimulating factor (G-CSF), a central regulator of granulopoiesis during inflammatory responses. Consistent with these data, we show that silencing of miR-155 in LPS-treated mice by systemically administered LNA-antimiR results in derepression of the c/ebp Beta isoforms and down-regulation of G-CSF expression in mouse splenocytes. Finally, we report for the first time on miR-155 silencing in vivo in a mouse inflammation model, which underscores the potential of miR-155 antagonists in the development of novel therapeutics for treatment of chronic inflammatory diseases

DBA2J db/db mice are susceptible to early albuminuria and glomerulosclerosis that correlates with systemic insulin resistance

Diabetic nephropathy (DN) is the leading cause of kidney failure in the world. To understand important mechanisms underlying this condition, and to develop new therapies, good animal models are required. In mouse models of type 1 diabetes, the DBA/2J strain has been shown to be more susceptible to develop kidney disease than other common strains. We hypothesized this would also be the case in type 2 diabetes. We studied db/db and wild-type (wt) DBA/2J mice and compared these with the db/db BLKS/J mouse, which is currently the most widely used type 2 DN model. Mice were analyzed from age 6 to 12 wk for systemic insulin resistance, albuminuria, and glomerular histopathological and ultrastructural changes. Body weight and nonfasted blood glucose were increased by 8 wk in both genders, while systemic insulin resistance commenced by 6 wk in female and 8 wk in male db/db DBA/2J mice. The urinary albumin-to-creatinine ratio (ACR) was closely linked to systemic insulin resistance in both sexes and was increased ~50-fold by 12 wk of age in the db/db DBA/2J cohort. Glomerulosclerosis, foot process effacement, and glomerular basement membrane thickening were observed at 12 wk of age in db/db DBA/2J mice. Compared with db/db BLKS/J mice, db/db DBA/2J mice had significantly increased levels of urinary ACR, but similar glomerular histopathological and ultrastructural changes. The db/db DBA/2J mouse is a robust model of early-stage albuminuric DN, and its levels of albuminuria correlate closely with systemic insulin resistance. This mouse model will be helpful in defining early mechanisms of DN and ultimately the development of novel therapies. </jats:p

The function of BCL9 in Wnt/beta-catenin signaling and colorectal cancer cells.

BACKGROUND: Most cases of colorectal cancer are initiated by hyperactivation of the Wnt/beta-catenin pathway due to mutations in the APC tumour suppressor, or in beta-catenin itself. A recently discovered component of this pathway is Legless, which is essential for Wnt-induced transcription during Drosophila development. Limited functional information is available for its two mammalian relatives, BCL9 and B9L/BCL9-2: like Legless, these proteins bind to beta-catenin, and RNAi-mediated depletion of B9L/BCL9-2 has revealed that this protein is required for efficient beta-catenin-mediated transcription in mammalian cell lines. No loss-of-function data are available for BCL9. METHODS: We have used overexpression of dominant-negative forms of BCL9, and RNAi-mediated depletion, to study its function in human cell lines with elevated Wnt pathway activity, including colorectal cancer cells. RESULTS: We found that BCL9 is required for efficient beta-catenin-mediated transcription in Wnt-stimulated HEK 293 cells, and in the SW480 colorectal cancer cell line whose Wnt pathway is active due to APC mutation. Dominant-negative mutants of BCL9 indicated that its function depends not only on its beta-catenin ligand, but also on an unknown ligand of its C-terminus. Finally, we show that BCL9 and B9L are both Wnt-inducible genes, hyperexpressed in colorectal cancer cell lines, indicating that they are part of a positive feedback loop. CONCLUSION: BCL9 is required for efficient beta-catenin-mediated transcription in human cell lines whose Wnt pathway is active, including colorectal cancer cells, indicating its potential as a drug target in colorectal cancer.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are

The function of BCL9 in Wnt/beta-catenin signaling and colorectal cancer cells.

BACKGROUND: Most cases of colorectal cancer are initiated by hyperactivation of the Wnt/beta-catenin pathway due to mutations in the APC tumour suppressor, or in beta-catenin itself. A recently discovered component of this pathway is Legless, which is essential for Wnt-induced transcription during Drosophila development. Limited functional information is available for its two mammalian relatives, BCL9 and B9L/BCL9-2: like Legless, these proteins bind to beta-catenin, and RNAi-mediated depletion of B9L/BCL9-2 has revealed that this protein is required for efficient beta-catenin-mediated transcription in mammalian cell lines. No loss-of-function data are available for BCL9. METHODS: We have used overexpression of dominant-negative forms of BCL9, and RNAi-mediated depletion, to study its function in human cell lines with elevated Wnt pathway activity, including colorectal cancer cells. RESULTS: We found that BCL9 is required for efficient beta-catenin-mediated transcription in Wnt-stimulated HEK 293 cells, and in the SW480 colorectal cancer cell line whose Wnt pathway is active due to APC mutation. Dominant-negative mutants of BCL9 indicated that its function depends not only on its beta-catenin ligand, but also on an unknown ligand of its C-terminus. Finally, we show that BCL9 and B9L are both Wnt-inducible genes, hyperexpressed in colorectal cancer cell lines, indicating that they are part of a positive feedback loop. CONCLUSION: BCL9 is required for efficient beta-catenin-mediated transcription in human cell lines whose Wnt pathway is active, including colorectal cancer cells, indicating its potential as a drug target in colorectal cancer.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are

The function of BCL9 in Wnt/β-catenin signaling and colorectal cancer cells-2

-qPCR, after induction of Wnt pathway activity in HEK 293 cells by addition of Wnt3A-conditioned medium, or 20 mM LiCl, for 6 hours. Statistical significance (p < 0.01) relative to Wnt-stimulated cells (arbitrarily set to 100) is indicated by asterisks. , Transcript levels of and in Wnt-stimulated HEK 293 cells, measured by RT-qPCR as in , after overexpression of wt or mutant FLAG-BCL9, or FLAG-BCL9-2. Statistical significance relative to Wnt-stimulated cells (arbitrarily set to 100) is indicated by asterisks (*, p < 0.05; **, p < 0.005). , Transcript levels of , , , and relative to (as internal control) in HEK 293 (with or without Wnt stimulation), SW480 or HCT116 cells. Statistical significance relative to uninduced HEK 293 cells is indicated by asterisks (*, p < 0.01; **, p < 0.001).<p><b>Copyright information:</b></p><p>Taken from "The function of BCL9 in Wnt/β-catenin signaling and colorectal cancer cells"</p><p>http://www.biomedcentral.com/1471-2407/8/199</p><p>BMC Cancer 2008;8():199-199.</p><p>Published online 15 Jul 2008</p><p>PMCID:PMC2478683.</p><p></p