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Evidence for Hox-specified positional identities in adult vasculature.

Pruett ND, Visconti RP, Jacobs DF, Scholz D, McQuinn T, Sundberg JP, Awgulewitsch A - BMC Dev. Biol. (2008)

Bottom Line: These reporter gene patterns were validated as authentic indicators of endogenous gene expression by immunolabeling and PCR analysis.Furthermore, we show that persistent reporter gene expression in cultured cells derived from vessel explants facilitates in vitro characterization of phenotypic properties as exemplified by the differential response of Hoxc11-lacZ-positive versus-negative cells in migration assays and to serum.The data support a conceptual model of Hox-specified positional identities in adult blood vessels, which is of likely relevance for understanding the mechanisms underlying regional physiological diversities in the cardiovascular system.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Medicine, Medical University of South Carolina, 96 Jonathan Lucas Street, Charleston, SC 29425, USA. pruettnd@musc.edu

ABSTRACT

Background: The concept of specifying positional information in the adult cardiovascular system is largely unexplored. While the Hox transcriptional regulators have to be viewed as excellent candidates for assuming such a role, little is known about their presumptive cardiovascular control functions and in vivo expression patterns.

Results: We demonstrate that conventional reporter gene analysis in transgenic mice is a useful approach for defining highly complex Hox expression patterns in the adult vascular network as exemplified by our lacZ reporter gene models for Hoxa3 and Hoxc11. These mice revealed expression in subsets of vascular smooth muscle cells (VSMCs) and endothelial cells (ECs) located in distinct regions of the vasculature that roughly correspond to the embryonic expression domains of the two genes. These reporter gene patterns were validated as authentic indicators of endogenous gene expression by immunolabeling and PCR analysis. Furthermore, we show that persistent reporter gene expression in cultured cells derived from vessel explants facilitates in vitro characterization of phenotypic properties as exemplified by the differential response of Hoxc11-lacZ-positive versus-negative cells in migration assays and to serum.

Conclusion: The data support a conceptual model of Hox-specified positional identities in adult blood vessels, which is of likely relevance for understanding the mechanisms underlying regional physiological diversities in the cardiovascular system. The data also demonstrate that conventional Hox reporter gene mice are useful tools for visualizing complex Hox expression patterns in the vascular network that might be unattainable otherwise. Finally, these mice are a resource for the isolation and phenotypic characterization of specific subpopulations of vascular cells marked by distinct Hox expression profiles.

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Hoxc11- and Hoxa3-lacZ expression patterns in blood vessel sections of 6 wk old transgenic mice. (A, B) Cross sections of the distal femoral artery (panel A) and femoral vein (B) show restriction of Hoxc11-lacZ expression in subsets of VSMCs in arterial and venous vessel walls as indicated by X-Gal staining (blue). (C-F) Cross sections of X-Gal-stained iliac artery (C), descending thoracic aorta (D), intercostal artery (E), and common carotid artery (F) of Hoxa3-lacZ transgenic mice indicate strong β-gal expression (blue) in the VSMCs of the vessel walls, whereas X-Gal staining in the flattened endothelial cells lining the intimal laminae is difficult to discern. adv: adventitia eem: external elastic membrane, iem: internal elastic membrane, in: intima, m: media. Space bars: 25 μm in all panels.
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Figure 3: Hoxc11- and Hoxa3-lacZ expression patterns in blood vessel sections of 6 wk old transgenic mice. (A, B) Cross sections of the distal femoral artery (panel A) and femoral vein (B) show restriction of Hoxc11-lacZ expression in subsets of VSMCs in arterial and venous vessel walls as indicated by X-Gal staining (blue). (C-F) Cross sections of X-Gal-stained iliac artery (C), descending thoracic aorta (D), intercostal artery (E), and common carotid artery (F) of Hoxa3-lacZ transgenic mice indicate strong β-gal expression (blue) in the VSMCs of the vessel walls, whereas X-Gal staining in the flattened endothelial cells lining the intimal laminae is difficult to discern. adv: adventitia eem: external elastic membrane, iem: internal elastic membrane, in: intima, m: media. Space bars: 25 μm in all panels.

Mentions: To determine reporter gene expression patterns in vessel walls, we analyzed sections of X-Gal-stained blood vessels from adult Hoxc11-lacZ and Hoxa3-lacZ mice (≥ 6 wks). As exemplified by data shown in Figure 3, Hoxc11-lacZ expression was observed predominantly, if not exclusively, in subsets of VSMCs of the major blood vessels of the lower hindlimb, including arteries (Fig. 3A) and veins (Fig. 3B). Overall, the Hoxa3-lacZ-expressing vessel walls of the iliac artery, the descending thoracic aorta, the intercostal arteries, and the common carotid arteries (Fig. 3C–F) exhibited similar patterns as the Hoxc11-lacZ-expressing walls of the lower limb, including prominent expression in VSMCs. Due to their flat morphology, expression in epithelial cells lining the intimal lamina was difficult to discern based on X-Gal staining in either case (i.e. Hoxc11-lacZ and Hoxa3-lacZ transgenic mice). This was resolved by performing immunofluorescent labeling studies using β-gal-specific antibodies, which detected endothelial β-gal expression in the common carotids of Hoxa3-lacZ mice, but not in the tibial/femoral arteries of Hoxc11-lacZ mice (data not shown).


Evidence for Hox-specified positional identities in adult vasculature.

Pruett ND, Visconti RP, Jacobs DF, Scholz D, McQuinn T, Sundberg JP, Awgulewitsch A - BMC Dev. Biol. (2008)

Hoxc11- and Hoxa3-lacZ expression patterns in blood vessel sections of 6 wk old transgenic mice. (A, B) Cross sections of the distal femoral artery (panel A) and femoral vein (B) show restriction of Hoxc11-lacZ expression in subsets of VSMCs in arterial and venous vessel walls as indicated by X-Gal staining (blue). (C-F) Cross sections of X-Gal-stained iliac artery (C), descending thoracic aorta (D), intercostal artery (E), and common carotid artery (F) of Hoxa3-lacZ transgenic mice indicate strong β-gal expression (blue) in the VSMCs of the vessel walls, whereas X-Gal staining in the flattened endothelial cells lining the intimal laminae is difficult to discern. adv: adventitia eem: external elastic membrane, iem: internal elastic membrane, in: intima, m: media. Space bars: 25 μm in all panels.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2570687&req=5

Figure 3: Hoxc11- and Hoxa3-lacZ expression patterns in blood vessel sections of 6 wk old transgenic mice. (A, B) Cross sections of the distal femoral artery (panel A) and femoral vein (B) show restriction of Hoxc11-lacZ expression in subsets of VSMCs in arterial and venous vessel walls as indicated by X-Gal staining (blue). (C-F) Cross sections of X-Gal-stained iliac artery (C), descending thoracic aorta (D), intercostal artery (E), and common carotid artery (F) of Hoxa3-lacZ transgenic mice indicate strong β-gal expression (blue) in the VSMCs of the vessel walls, whereas X-Gal staining in the flattened endothelial cells lining the intimal laminae is difficult to discern. adv: adventitia eem: external elastic membrane, iem: internal elastic membrane, in: intima, m: media. Space bars: 25 μm in all panels.
Mentions: To determine reporter gene expression patterns in vessel walls, we analyzed sections of X-Gal-stained blood vessels from adult Hoxc11-lacZ and Hoxa3-lacZ mice (≥ 6 wks). As exemplified by data shown in Figure 3, Hoxc11-lacZ expression was observed predominantly, if not exclusively, in subsets of VSMCs of the major blood vessels of the lower hindlimb, including arteries (Fig. 3A) and veins (Fig. 3B). Overall, the Hoxa3-lacZ-expressing vessel walls of the iliac artery, the descending thoracic aorta, the intercostal arteries, and the common carotid arteries (Fig. 3C–F) exhibited similar patterns as the Hoxc11-lacZ-expressing walls of the lower limb, including prominent expression in VSMCs. Due to their flat morphology, expression in epithelial cells lining the intimal lamina was difficult to discern based on X-Gal staining in either case (i.e. Hoxc11-lacZ and Hoxa3-lacZ transgenic mice). This was resolved by performing immunofluorescent labeling studies using β-gal-specific antibodies, which detected endothelial β-gal expression in the common carotids of Hoxa3-lacZ mice, but not in the tibial/femoral arteries of Hoxc11-lacZ mice (data not shown).

Bottom Line: These reporter gene patterns were validated as authentic indicators of endogenous gene expression by immunolabeling and PCR analysis.Furthermore, we show that persistent reporter gene expression in cultured cells derived from vessel explants facilitates in vitro characterization of phenotypic properties as exemplified by the differential response of Hoxc11-lacZ-positive versus-negative cells in migration assays and to serum.The data support a conceptual model of Hox-specified positional identities in adult blood vessels, which is of likely relevance for understanding the mechanisms underlying regional physiological diversities in the cardiovascular system.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Medicine, Medical University of South Carolina, 96 Jonathan Lucas Street, Charleston, SC 29425, USA. pruettnd@musc.edu

ABSTRACT

Background: The concept of specifying positional information in the adult cardiovascular system is largely unexplored. While the Hox transcriptional regulators have to be viewed as excellent candidates for assuming such a role, little is known about their presumptive cardiovascular control functions and in vivo expression patterns.

Results: We demonstrate that conventional reporter gene analysis in transgenic mice is a useful approach for defining highly complex Hox expression patterns in the adult vascular network as exemplified by our lacZ reporter gene models for Hoxa3 and Hoxc11. These mice revealed expression in subsets of vascular smooth muscle cells (VSMCs) and endothelial cells (ECs) located in distinct regions of the vasculature that roughly correspond to the embryonic expression domains of the two genes. These reporter gene patterns were validated as authentic indicators of endogenous gene expression by immunolabeling and PCR analysis. Furthermore, we show that persistent reporter gene expression in cultured cells derived from vessel explants facilitates in vitro characterization of phenotypic properties as exemplified by the differential response of Hoxc11-lacZ-positive versus-negative cells in migration assays and to serum.

Conclusion: The data support a conceptual model of Hox-specified positional identities in adult blood vessels, which is of likely relevance for understanding the mechanisms underlying regional physiological diversities in the cardiovascular system. The data also demonstrate that conventional Hox reporter gene mice are useful tools for visualizing complex Hox expression patterns in the vascular network that might be unattainable otherwise. Finally, these mice are a resource for the isolation and phenotypic characterization of specific subpopulations of vascular cells marked by distinct Hox expression profiles.

Show MeSH
Related in: MedlinePlus