The role of the mesenchyme homeobox genes in the regulation of vascular endothelial cell function

dc.contributor.authorNorthcott, Josette M. D.
dc.contributor.examiningcommitteeTriggs-Raine, Barbara (Biochemistry and Medical Genetics) Davie, James (Biochemistry and Medical Genetics) Czubryt, Michael (Physiology) Srivastava, Ashok (University of Montreal)en_US
dc.contributor.supervisorWigle, Jeffrey (Biochemistry and Medical Genetics)en_US
dc.date.accessioned2012-11-13T16:44:46Z
dc.date.available2012-11-13T16:44:46Z
dc.date.issued2007-01en_US
dc.date.issued2011-12-10en_US
dc.degree.disciplineBiochemistry and Medical Geneticsen_US
dc.degree.levelDoctor of Philosophy (Ph.D.)en_US
dc.description.abstractThe mesenchyme homeobox genes, MEOX1 and MEOX2, encode homeodomain transcription factors. Studies of Meox1/Meox2 knockout mice established that these proteins are partially redundant during development, suggesting that they may regulate common target genes. In the adult vasculature, MEOX2 is expressed in vascular smooth muscle and endothelial cells. MEOX2 has been demonstrated to: i) inhibit proliferation, ii) activate apoptosis and iii) induce senescence. In contrast, the role of MEOX1 has not been studied in the vasculature. Currently, there are two known target genes of MEOX2: cyclin-dependent kinase inhibitor 1A (CDKN1A/p21CIP1/WAF1) and cyclin-dependent kinase inhibitor 2A (CDKN2A/p16INK4a), which regulate transient (quiescent) and permanent (senescent) cell cycle arrest. Senescence is postulated to contribute to the development of atherosclerotic vascular disease by promoting endothelial dysfunction. We hypothesized that MEOX1 and MEOX2 would activate both p21CIP1/WAF1 and p16INK4a expression, as well as induce apoptosis, cell cycle arrest and senescence in endothelial cells. Furthermore, we postulated that the majority of newly identified MEOX target genes in endothelial cells would be regulated by both MEOX1 and MEOX2. MEOX proteins were expressed in human endothelial cells via adenoviral transduction. Levels of target gene expression were measured by luciferase reporter gene assays, western blot and quantitative real-time PCR. Electrophoretic mobility shift assays were used to demonstrate MEOX binding to DNA. Cellular proliferation, senescence, and apoptosis were evaluated. For the identification of novel target genes, microarrays were used to compare levels of gene expression in endothelial cells transduced with MEOX constructs or control virus. Both MEOX1 and MEOX2 activated p21CIP1/WAF1 and p16INK4a gene transcription, inhibited proliferation and induced apoptosis and senescence in endothelial cells. MEOX activation of p21CIP1/WAF1 transcription occurs via a DNA-binding independent mechanism that requires the SP1 transcription factor. In contrast, MEOX activation of p16INK4a transcription is dependent upon DNA-binding. Microarray analysis revealed that both MEOX1 and MEOX2 increased the expression of intercellular adhesion molecule 1 (ICAM-1) and decreased the expression of nitric oxide synthase 3 (NOS3/eNOS). Taken together, we conclude that MEOX1 and MEOX2 have similar target genes in endothelial cells including p21CIP1/WAF1, p16INK4a and eNOS. As increased endothelial senescence and decreased nitric oxide production are hallmarks of endothelial dysfunction, this study proposes a role for the MEOX proteins in the progression of atherosclerotic vascular disease.en_US
dc.description.noteFebruary 2013en_US
dc.identifier.citationDouville JM, Wigle JT. Regulation and function of homeodomain proteins in the embryonic and adult vascular systems. Can J Physiol Pharmacol. 2007 Jan;85(1):55-65. Review. PubMed PMID: 17487245en_US
dc.identifier.citationDouville JM, Cheung DY, Herbert KL, Moffatt T, Wigle JT. Mechanisms of MEOX1 and MEOX2 regulation of the cyclin dependent kinase inhibitors p21 and p16 in vascular endothelial cells. PLoS One. 2011;6(12):e29099. Epub 2011 Dec 20. PubMed PMID: 22206000en_US
dc.identifier.urihttp://hdl.handle.net/1993/11243
dc.language.isoengen_US
dc.publisherNRC Research Pressen_US
dc.publisherPLoS Oneen_US
dc.rightsopen accessen_US
dc.subjectendothelial cellsen_US
dc.subjecthomeodomain proteinsen_US
dc.titleThe role of the mesenchyme homeobox genes in the regulation of vascular endothelial cell functionen_US
dc.typedoctoral thesisen_US
Files
Original bundle
Now showing 1 - 1 of 1
Loading...
Thumbnail Image
Name:
Northcott_Josette.pdf
Size:
13.48 MB
Format:
Adobe Portable Document Format
Description:
License bundle
Now showing 1 - 1 of 1
Loading...
Thumbnail Image
Name:
license.txt
Size:
2.25 KB
Format:
Item-specific license agreed to upon submission
Description: