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Endothelium Expression of Bcl-2 Is Essential for Normal and Pathological Ocular Vascularization.

Zaitoun IS, Johnson RP, Jamali N, Almomani R, Wang S, Sheibani N, Sorenson CM - PLoS ONE (2015)

Bottom Line: In vitro studies indicated that in addition to modulating apoptosis, Bcl-2 expression also impacts endothelial and epithelial cell adhesion, migration and extracellular matrix production.However, studies delineating the cell autonomous role Bcl-2 expression plays in the endothelium during vascular development, pruning and remodeling, and neovascularization are lacking.Thus, Bcl-2 expression in the endothelium plays a significant role during postnatal retinal vascularization, and pathological choroidal but not retinal neovascularization, suggesting vascular bed specific Bcl-2 function in the endothelium.

View Article: PubMed Central - PubMed

Affiliation: Department of Ophthalmology and Visual Sciences, University of Wisconsin, Madison, WI, 53705, United States of America.

ABSTRACT
Bcl-2 is an anti-apoptotic protein with important roles in vascular homeostasis and angiogenesis. Mice globally lacking Bcl-2 (Bcl-2 -/-) are small in stature and succumb to renal failure shortly after weaning as a result of renal hypoplasia/cystic dysplasia. We have shown that Bcl-2 -/- mice displayed attenuated retinal vascular development and neovascularization. In vitro studies indicated that in addition to modulating apoptosis, Bcl-2 expression also impacts endothelial and epithelial cell adhesion, migration and extracellular matrix production. However, studies delineating the cell autonomous role Bcl-2 expression plays in the endothelium during vascular development, pruning and remodeling, and neovascularization are lacking. Here we generated mice carrying a conditional Bcl-2 allele (Bcl-2Flox/Flox) and VE-cadherin-cre (Bcl-2EC mice). Bcl-2EC mice were of normal stature and lifespan and displayed some but not all of the retinal vascular defects previously observed in global Bcl-2 deficient mice. Bcl-2EC mice had decreased numbers of endothelial cells, decreased retinal arteries and premature primary branching of the retinal vasculature, but unlike the global knockout mice, spreading of the retinal superficial vascular layer proceeded normally. Choroidal neovascularization was attenuated in Bcl-2EC mice, although retinal neovascularization accompanying oxygen-induced ischemic retinopathy was not. Thus, Bcl-2 expression in the endothelium plays a significant role during postnatal retinal vascularization, and pathological choroidal but not retinal neovascularization, suggesting vascular bed specific Bcl-2 function in the endothelium.

No MeSH data available.


Related in: MedlinePlus

Decreased endothelial cell number in retinas from Bcl-2EC mice.Retinas from P21 and P42 Wild-type (WT) and Bcl-2EC mice were prepared by trypsin digest and HE/PAS staining. Endothelial cells (arrow) and pericytes (arrowhead) were then quantitated per x400 field of view. Scale bar = 100 μm. Experiments were repeated with eyes from >5 mice with similar results. The quantitative assessment of this data is summarized in Table 1.
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pone.0139994.g001: Decreased endothelial cell number in retinas from Bcl-2EC mice.Retinas from P21 and P42 Wild-type (WT) and Bcl-2EC mice were prepared by trypsin digest and HE/PAS staining. Endothelial cells (arrow) and pericytes (arrowhead) were then quantitated per x400 field of view. Scale bar = 100 μm. Experiments were repeated with eyes from >5 mice with similar results. The quantitative assessment of this data is summarized in Table 1.

Mentions: Although vascularization of the mouse retina is complete by postnatal day 21 (P21), remodeling and pruning of unnecessary vessels occurs until P42 [22]. To assess the impact endothelial Bcl–2 expression has on retinal vascular development, retinal endothelial cell and pericyte numbers were calculated from retinal trypsin digest preparations from P21 and P42 wild-type (WT) and Bcl-2EC mice. On trypsin digest preparations, endothelial cell nuclei appear large, oval, and weakly stained within the vessel wall (arrow), while pericyte nuclei are darkly stained, small, round, and protrude laterally from the vessel wall (arrowhead) (Fig 1). Bcl-2EC mice demonstrated decreased numbers of endothelial cells in trypsin digest preparations compared to their wild-type counterparts (Table 1 and Fig 1). Here we show that retinal endothelial cell numbers in both wild-type and Bcl-2EC mice decreased by P42 suggesting that pruning and remodeling may occur independent of Bcl–2 expression. Although, pericyte numbers were similar in P21 wild-type and Bcl-2EC mice (Table 1), only wild-type mice demonstrated a decrease in pericyte number at P42 due to remodeling and pruning. Perhaps maintaining pericyte numbers during retinal vascular remodeling in Bcl-2EC mice protected the vasculature from even more vascular cell loss during this process.


Endothelium Expression of Bcl-2 Is Essential for Normal and Pathological Ocular Vascularization.

Zaitoun IS, Johnson RP, Jamali N, Almomani R, Wang S, Sheibani N, Sorenson CM - PLoS ONE (2015)

Decreased endothelial cell number in retinas from Bcl-2EC mice.Retinas from P21 and P42 Wild-type (WT) and Bcl-2EC mice were prepared by trypsin digest and HE/PAS staining. Endothelial cells (arrow) and pericytes (arrowhead) were then quantitated per x400 field of view. Scale bar = 100 μm. Experiments were repeated with eyes from >5 mice with similar results. The quantitative assessment of this data is summarized in Table 1.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4622043&req=5

pone.0139994.g001: Decreased endothelial cell number in retinas from Bcl-2EC mice.Retinas from P21 and P42 Wild-type (WT) and Bcl-2EC mice were prepared by trypsin digest and HE/PAS staining. Endothelial cells (arrow) and pericytes (arrowhead) were then quantitated per x400 field of view. Scale bar = 100 μm. Experiments were repeated with eyes from >5 mice with similar results. The quantitative assessment of this data is summarized in Table 1.
Mentions: Although vascularization of the mouse retina is complete by postnatal day 21 (P21), remodeling and pruning of unnecessary vessels occurs until P42 [22]. To assess the impact endothelial Bcl–2 expression has on retinal vascular development, retinal endothelial cell and pericyte numbers were calculated from retinal trypsin digest preparations from P21 and P42 wild-type (WT) and Bcl-2EC mice. On trypsin digest preparations, endothelial cell nuclei appear large, oval, and weakly stained within the vessel wall (arrow), while pericyte nuclei are darkly stained, small, round, and protrude laterally from the vessel wall (arrowhead) (Fig 1). Bcl-2EC mice demonstrated decreased numbers of endothelial cells in trypsin digest preparations compared to their wild-type counterparts (Table 1 and Fig 1). Here we show that retinal endothelial cell numbers in both wild-type and Bcl-2EC mice decreased by P42 suggesting that pruning and remodeling may occur independent of Bcl–2 expression. Although, pericyte numbers were similar in P21 wild-type and Bcl-2EC mice (Table 1), only wild-type mice demonstrated a decrease in pericyte number at P42 due to remodeling and pruning. Perhaps maintaining pericyte numbers during retinal vascular remodeling in Bcl-2EC mice protected the vasculature from even more vascular cell loss during this process.

Bottom Line: In vitro studies indicated that in addition to modulating apoptosis, Bcl-2 expression also impacts endothelial and epithelial cell adhesion, migration and extracellular matrix production.However, studies delineating the cell autonomous role Bcl-2 expression plays in the endothelium during vascular development, pruning and remodeling, and neovascularization are lacking.Thus, Bcl-2 expression in the endothelium plays a significant role during postnatal retinal vascularization, and pathological choroidal but not retinal neovascularization, suggesting vascular bed specific Bcl-2 function in the endothelium.

View Article: PubMed Central - PubMed

Affiliation: Department of Ophthalmology and Visual Sciences, University of Wisconsin, Madison, WI, 53705, United States of America.

ABSTRACT
Bcl-2 is an anti-apoptotic protein with important roles in vascular homeostasis and angiogenesis. Mice globally lacking Bcl-2 (Bcl-2 -/-) are small in stature and succumb to renal failure shortly after weaning as a result of renal hypoplasia/cystic dysplasia. We have shown that Bcl-2 -/- mice displayed attenuated retinal vascular development and neovascularization. In vitro studies indicated that in addition to modulating apoptosis, Bcl-2 expression also impacts endothelial and epithelial cell adhesion, migration and extracellular matrix production. However, studies delineating the cell autonomous role Bcl-2 expression plays in the endothelium during vascular development, pruning and remodeling, and neovascularization are lacking. Here we generated mice carrying a conditional Bcl-2 allele (Bcl-2Flox/Flox) and VE-cadherin-cre (Bcl-2EC mice). Bcl-2EC mice were of normal stature and lifespan and displayed some but not all of the retinal vascular defects previously observed in global Bcl-2 deficient mice. Bcl-2EC mice had decreased numbers of endothelial cells, decreased retinal arteries and premature primary branching of the retinal vasculature, but unlike the global knockout mice, spreading of the retinal superficial vascular layer proceeded normally. Choroidal neovascularization was attenuated in Bcl-2EC mice, although retinal neovascularization accompanying oxygen-induced ischemic retinopathy was not. Thus, Bcl-2 expression in the endothelium plays a significant role during postnatal retinal vascularization, and pathological choroidal but not retinal neovascularization, suggesting vascular bed specific Bcl-2 function in the endothelium.

No MeSH data available.


Related in: MedlinePlus