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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

Increased proliferation in retinas from Bcl-2EC mice.In Panel A, proliferating cells in P14 wild-type and Bcl-2EC mouse retinas were labeled by BrdU and detected using an antibody to BrdU and co-stained with Isolectin-B4-FITC to visualize the vasculature. In Panel B, the data in each bar are the mean number of BrdU+ cells counted in each retina. These experiments were repeated with at least five mice of each genotype. Please note that the number of proliferating cells is higher in retinas from Bcl-2EC mice compared to their wild-type counterparts (****P< 0.0001). Scale bar equals 400 μm.
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pone.0139994.g006: Increased proliferation in retinas from Bcl-2EC mice.In Panel A, proliferating cells in P14 wild-type and Bcl-2EC mouse retinas were labeled by BrdU and detected using an antibody to BrdU and co-stained with Isolectin-B4-FITC to visualize the vasculature. In Panel B, the data in each bar are the mean number of BrdU+ cells counted in each retina. These experiments were repeated with at least five mice of each genotype. Please note that the number of proliferating cells is higher in retinas from Bcl-2EC mice compared to their wild-type counterparts (****P< 0.0001). Scale bar equals 400 μm.

Mentions: Our previous studies in global Bcl–2 knockout mice demonstrated increased apoptosis and proliferation in several organs including the retina [14, 23]. Here, apoptosis was assessed by anti-active capase 3 and proliferation by BrdU staining of wholemount retinas from P14 mice. We observed modest levels of apoptosis in retinas from P14 wild-type mice (Fig 5), while retinas from P14 Bcl-2EC mice demonstrated increased levels of apoptosis compared to their wild-type counterparts. As we had previously seen in global Bcl–2 knockout mice, the level of proliferation in retinas from Bcl-2EC mice was significantly increased compared to their wild-type counterparts (Fig 6). Thus in the absence of Bcl–2, endothelial cell apoptosis and proliferation levels were significantly increased.


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)

Increased proliferation in retinas from Bcl-2EC mice.In Panel A, proliferating cells in P14 wild-type and Bcl-2EC mouse retinas were labeled by BrdU and detected using an antibody to BrdU and co-stained with Isolectin-B4-FITC to visualize the vasculature. In Panel B, the data in each bar are the mean number of BrdU+ cells counted in each retina. These experiments were repeated with at least five mice of each genotype. Please note that the number of proliferating cells is higher in retinas from Bcl-2EC mice compared to their wild-type counterparts (****P< 0.0001). Scale bar equals 400 μm.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0139994.g006: Increased proliferation in retinas from Bcl-2EC mice.In Panel A, proliferating cells in P14 wild-type and Bcl-2EC mouse retinas were labeled by BrdU and detected using an antibody to BrdU and co-stained with Isolectin-B4-FITC to visualize the vasculature. In Panel B, the data in each bar are the mean number of BrdU+ cells counted in each retina. These experiments were repeated with at least five mice of each genotype. Please note that the number of proliferating cells is higher in retinas from Bcl-2EC mice compared to their wild-type counterparts (****P< 0.0001). Scale bar equals 400 μm.
Mentions: Our previous studies in global Bcl–2 knockout mice demonstrated increased apoptosis and proliferation in several organs including the retina [14, 23]. Here, apoptosis was assessed by anti-active capase 3 and proliferation by BrdU staining of wholemount retinas from P14 mice. We observed modest levels of apoptosis in retinas from P14 wild-type mice (Fig 5), while retinas from P14 Bcl-2EC mice demonstrated increased levels of apoptosis compared to their wild-type counterparts. As we had previously seen in global Bcl–2 knockout mice, the level of proliferation in retinas from Bcl-2EC mice was significantly increased compared to their wild-type counterparts (Fig 6). Thus in the absence of Bcl–2, endothelial cell apoptosis and proliferation levels were significantly increased.

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