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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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Hoxa3-lacZ expression in major blood vessels. (A-E) Prominent expression (blue) was detected by whole-mount X-Gal staining of 6 wk old Hoxa3-lacZ transgenic mice in external jugular vein (panel A), aortic arch (AA) and all major vessels in the aortic arch region including innominate and left carotid artery, pulmonary vein (PA), and subclavian artery (panel B); strong expression was also detected in the descending thoracic aorta (DA) and intercostal arteries (panel C), as well as the common iliac artery and proximal femoral artery (panel D); Hoxa3-lacZ expression in the common carotid artery exhibits a distinct anterior boundary near the branch point into facial and occipital carotid arteries (panel E); anterior points to the top in panels A-C, and E, and to the right in panel D; please note the distal expression boundary in the femoral artery just below the branch point of the internal iliac. LA: left atrium; LV: left ventricle; RA: right atrium; thy: thyroid gland.
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Figure 2: Hoxa3-lacZ expression in major blood vessels. (A-E) Prominent expression (blue) was detected by whole-mount X-Gal staining of 6 wk old Hoxa3-lacZ transgenic mice in external jugular vein (panel A), aortic arch (AA) and all major vessels in the aortic arch region including innominate and left carotid artery, pulmonary vein (PA), and subclavian artery (panel B); strong expression was also detected in the descending thoracic aorta (DA) and intercostal arteries (panel C), as well as the common iliac artery and proximal femoral artery (panel D); Hoxa3-lacZ expression in the common carotid artery exhibits a distinct anterior boundary near the branch point into facial and occipital carotid arteries (panel E); anterior points to the top in panels A-C, and E, and to the right in panel D; please note the distal expression boundary in the femoral artery just below the branch point of the internal iliac. LA: left atrium; LV: left ventricle; RA: right atrium; thy: thyroid gland.

Mentions: To gain further support for the emerging concept of distinct zones of Hox activity in the adult vascular network, we prepared a Hoxa3-lacZ transgene construct that contained 11.5 kb of genomic sequences located directly upstream of the Hoxa3 translational start site (see Materials and Methods). Analysis of independent Hoxa3-lacZ transgenic mice (n = 4) at 11 d, 6 wks, and ≥ 8 wks post natum revealed a reproducible pattern of lacZ expression in most major blood vessels (common carotid arteries, aortic arch, dorsal aorta and inter-costal arteries, pulmonary and renal arteries, cardinal and jugular veins, proximal femoral arteries and veins) (Fig. 2A–E). Remarkably, the distinct anterior expression boundary near the cranial branch point of the common carotid arteries (Fig. 2E) was approximately at the same anterior-posterior level as the expression boundary in the jugular veins (Fig. 2A), and these expression boundaries roughly correspond to the anterior Hoxa3 expression limit at the somite s4/5 boundary during embryonic development [22]. Hoxa3-lacZ expression in the dorsal aorta and inferior vena cava extended beyond the iliac branching point into the most caudal blood vessels of the tail, as well as the proximal limb vessels, including expression in the proximal segments of the femoral artery and vein that reached just to the branch of the epigastric artery (Fig. 2D).


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)

Hoxa3-lacZ expression in major blood vessels. (A-E) Prominent expression (blue) was detected by whole-mount X-Gal staining of 6 wk old Hoxa3-lacZ transgenic mice in external jugular vein (panel A), aortic arch (AA) and all major vessels in the aortic arch region including innominate and left carotid artery, pulmonary vein (PA), and subclavian artery (panel B); strong expression was also detected in the descending thoracic aorta (DA) and intercostal arteries (panel C), as well as the common iliac artery and proximal femoral artery (panel D); Hoxa3-lacZ expression in the common carotid artery exhibits a distinct anterior boundary near the branch point into facial and occipital carotid arteries (panel E); anterior points to the top in panels A-C, and E, and to the right in panel D; please note the distal expression boundary in the femoral artery just below the branch point of the internal iliac. LA: left atrium; LV: left ventricle; RA: right atrium; thy: thyroid gland.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 2: Hoxa3-lacZ expression in major blood vessels. (A-E) Prominent expression (blue) was detected by whole-mount X-Gal staining of 6 wk old Hoxa3-lacZ transgenic mice in external jugular vein (panel A), aortic arch (AA) and all major vessels in the aortic arch region including innominate and left carotid artery, pulmonary vein (PA), and subclavian artery (panel B); strong expression was also detected in the descending thoracic aorta (DA) and intercostal arteries (panel C), as well as the common iliac artery and proximal femoral artery (panel D); Hoxa3-lacZ expression in the common carotid artery exhibits a distinct anterior boundary near the branch point into facial and occipital carotid arteries (panel E); anterior points to the top in panels A-C, and E, and to the right in panel D; please note the distal expression boundary in the femoral artery just below the branch point of the internal iliac. LA: left atrium; LV: left ventricle; RA: right atrium; thy: thyroid gland.
Mentions: To gain further support for the emerging concept of distinct zones of Hox activity in the adult vascular network, we prepared a Hoxa3-lacZ transgene construct that contained 11.5 kb of genomic sequences located directly upstream of the Hoxa3 translational start site (see Materials and Methods). Analysis of independent Hoxa3-lacZ transgenic mice (n = 4) at 11 d, 6 wks, and ≥ 8 wks post natum revealed a reproducible pattern of lacZ expression in most major blood vessels (common carotid arteries, aortic arch, dorsal aorta and inter-costal arteries, pulmonary and renal arteries, cardinal and jugular veins, proximal femoral arteries and veins) (Fig. 2A–E). Remarkably, the distinct anterior expression boundary near the cranial branch point of the common carotid arteries (Fig. 2E) was approximately at the same anterior-posterior level as the expression boundary in the jugular veins (Fig. 2A), and these expression boundaries roughly correspond to the anterior Hoxa3 expression limit at the somite s4/5 boundary during embryonic development [22]. Hoxa3-lacZ expression in the dorsal aorta and inferior vena cava extended beyond the iliac branching point into the most caudal blood vessels of the tail, as well as the proximal limb vessels, including expression in the proximal segments of the femoral artery and vein that reached just to the branch of the epigastric artery (Fig. 2D).

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