Abstract 15280: Functional Interactions of the Osteogenic-Related Transcription Factors Runx2, Vdr and Nfkb to Regulate the Transcription of Osteopontin (opn) During Cardiac Calcification in Mice
Introduction: Cardiovascular calcification is prevalent in coronary artery diseases (CAD) enhancing morbidity and mortality in western countries. Mice were used as model for dystrophic cardiac calcification (DCC) following freeze-thaw-injury. Because calcification is an active process sharing common features with osteogenesis we examined the expression of osteogenic-related transcription factors and their corresponding downstream target-genes during the pathological calcification.
Methods: A panel of eleven osteogenic-related transcription factors (Runx2, Sox9, Vdr, Nfkb, Msx1, Msx2, Twist1, Smad1, Smad2, Smad3, and Smad4) and twelve osteogenic-related downstream target-genes (Akp2, Bglap II, Osterix, Phex, Dmp1, IBSP, Col1a2, MMP2, MMP8, MMP9, MMP13, and Opn) were selected and analyzed for gene expression three days after injury using qPCR quantification in myocardial tissues from DCC-susceptible C3H/He and DCC-resistant C57BL/6 mice.
Results and discussion: Among the tested osteogenic-related transcription factors significant increase in gene expression was observed for Runx2, Sox9, Vdr and Nfκb in DCC-susceptible mice compared to DCC-resistant mice. Especially the gene expression of Runx2 was 30-fold higher in mice susceptible for calcification than in resistant mice. For the osteogenic-related downstream-genes a significant up-regulation was observed for Opn (372.55-fold and 64.44-fold of induction in susceptible and C57BL/6 resistant, respectively, p= 0,028). To test whether the transcription of Opn is directly regulated by Runx2, Sox9, Vdr and Nfkb we functionally analyzed the Opn promoter in luciferase reporter gene assays. While Sox9 does not change reporter gene expression, transfection of Nfκb strongly activates the Opn promoter. Furthermore our analysis clearly shows a functional interaction of Vdr and Runx2 to activate the Opn promoter.
Conclusion: Based on our data we suggest a functional interaction of Runx2, Vdr and Nfκb in the transcriptional regulation of Opn involved in cardiovascular calcification.
- © 2011 by American Heart Association, Inc.