Purchase this article with an account.
Saptarshi Biswas, Galina Bachay, Dale D Hunter, William J Brunken; γ3-Containing Laminins Regulate Retinal Arterial Morphogenesis via Dystroglycan. Invest. Ophthalmol. Vis. Sci. 2017;58(8):2446.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Deletion of the laminin γ3-gene (Lamc3) leads to arterial dys-morphogenesis and down-regulated Dll4 expression. In this study, we asked whether developmental defects in the Lamc3-/- retinal arteries persist under pathological stress, and identify how γ3-containing laminins regulate arterial Dll4 expression.
For oxygen induced retinopathy (OIR) studies, P7 litters and dams were placed in 75% O2 until P12; then returned to normoxia until P15. Vascular phenotypes, arterial expression of dystroglycan (DG) and specific integrin subunits were measured by immunohistochemistry (IHC). For studies of DII4 regulation, human aortic endothelial cells (HAECs) were grown to confluence (3 days); DG function-blocking antibody was added to disrupt laminin-DG signaling. Dll4 expression levels in the HAECs were measured with IHC. To assess the effect of DG deletion in vivo, arterial branching and Dll4 expression were measured by IHC in endothelial cell (EC)-specific DG knockout retinas.
Lamc3-/- retinas have hyper-branched arteries with reduced pruning and smooth muscle coverage. Under hypoxis stress P12 Lamc3-/- mice showed significantly less vaso-obliteration (22%), hyper-branched arteries (~67%) and reduced arterial smooth muscle coverage (~16%), suggesting that developmental defects in the Lamc3-/- retinal arteries persist in pathological condition. At P15, OIR Lamc3-/- mice showed increased neo-vascular tuft formation relative to WT retina. Arterial expression levels of integrin subunits (α2/3/6 and β1) were unaffected in the Lamc3-/- retina, consistent with the inability of γ3-containing laminins to bind integrins. Interestingly, we observed that DG expression level was significantly down-regulated (α-DG: ~57%; β-DG: ~35%) in Lamc3-/- retinal arteries. EC-specific deletion of DG led to significant increase in arterial branching (~86%) and reduced Dll4 expression (~30%), phenocopying Lamc3 deletion. Finally, blocking laminin-DG binding in vitro significantly down-regulated Dll4 expression (~45%) in the HAECs, suggesting that laminin-DG signaling can directly induce endothelial Dll4 expression.
Our results suggest that γ3-containing laminins in the arterial BM signal through DG to regulate arterial morphogenesis by inducing arterial Dll4 expression in the retina.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
This PDF is available to Subscribers Only