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Aliaksei Holik

Chromatin remodelling ATPase Brg-1 is an essential factor for the maintenance of the intestinal crypt stem cell and adenoma formation. Aliaksei Holik. Restoration of BRG-1 function leads to the reversion of a cancer phenotype. BRG-1 and cancer.

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Aliaksei Holik

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  1. Chromatin remodelling ATPase Brg-1 is an essential factor for the maintenance of the intestinal crypt stem cell and adenoma formation Aliaksei Holik

  2. Restoration of BRG-1 function leads to the reversion of a cancer phenotype BRG-1 and cancer BRG-1 mutations are found in human cancer cell lines and in primary cancers Heterozygous deletion of Brg-1 in mice promotes tumourigenesis via Brg-1 haploinsufficiency

  3. Suggested mechanisms of BRG1 role in tumourigenesis p53 BRCA1 RB/p21 BRG-1 c-Fos Wnt-pathway

  4. Wnt pathway Willert K., Jones K. A. Genes Dev. 2006;20:1394-1404

  5. Small intestine architecture Villus Transit amplifying cells Crypt Stem cell

  6. Generation of conditional knock-out using Cre-loxP techniques loxP strategy

  7. Brg-1-deficient cells in small intestine are repopulated with wild-type cells AhCre-ERT BRG-1 Day 3 Day 5 Day 7

  8. Brg-1-deficient small intestinal epithelium appears to be normal at day 4 post induction Control BRG-1 Brg1fl/fl VillinCre-ERT

  9. VillinCre-Brg1fl/fl VillinCre+Brg1fl/fl Brg1-deficient small intestinal epithelium displays no difference in mitosis and apoptosis levels p-values: Mitosis – 0.629 Apoptosis – 0.057

  10. VillinCre-Brg1fl/fl VillinCre+Brg1fl/fl Brg1-deficient small intestinal epithelium displays no difference in mitosis and apoptosis levels

  11. Inactivation of Brg-1 in small intestinal epithelium leads to rapid crypt loss Control Day 4 Day 5 Day 7 Brg1fl/fl

  12. Brg-1 loss leads to the failure of the crypt stem cell Brg1+ Brg1- Brg1- Transit amplifying cells Active stem cell

  13. VillinCre-Brg1fl/fl VillinCre+Brg1fl/fl Loss of Brg-1 results in reduced expression of intestinal stem cell markers p-value < 0.05

  14. Generation of double knock-out using Cre-loxP techniques

  15. Brg-1/Apc double mutant cells are selectively eliminated in small intestine Small intestine of Brg1fl/fl/Apcfl/fl mouse at day 7 post induction BRG-1 -catenin

  16. Control Brg1fl/fl Brg1fl/flApcfl/fl Apcfl/fl Brg-1-deficiency rescues lethal phenotype of Apc deletion in double knock-out mice Median survival Apcfl/fl=8 Brg1fl/flApcfl/fl=14, P=0.0010

  17. Brg-1 deletion removes a portion of Apc-deficient cells decreasing tumour burden Brg1- Apc- Brg1-/Apc-

  18. Brg-1 deletion removes a portion of Apc-deficient cells decreasing tumour burden Brg1- Apc- Brg1-/Apc-

  19. Adenoma progression depends on the cell of origin Microadenoma Transit amplifying cells Stem cell Adenoma

  20. Conclusions • Brg-1 is a crucial factor for the maintenance of the adult tissue stem cell in small intestine. • Brg-1 loss is incompatible with activation of the Wnt pathway in the murine small intestine • Targeting the intestinal stem cell provides an attractive concept for the removal of potentially malignant lesions in individuals with genetic predisposition to colorectal cancer

  21. Acknowledgements • The Darwin Trust of Edinburgh • Alan Clarke • Boris Shorning • ARC group

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