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Jared Watters, Saptarshi Biswas, Galina Bachay, Dale D. Hunter, William J Brunken; Coordinated Expression of Laminin Chains in Retinal Vascular Basement Membranes. Invest. Ophthalmol. Vis. Sci. 2019;60(9):1630.
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© ARVO (1962-2015); The Authors (2016-present)
Although basement membrane (BM) proteins of the vasculature become disrupted in several retinal diseases, the mechanisms that dictate their spatial and temporal expression patterns remain obscure. Laminins, heterotrimeric glycoproteins, are important in initiating BM formation. Laminin isoforms are myriad, yet the available data suggest that only a limited set of isoforms are expressed in the vascular BM. We hypothesize that the deletion of the Lamb2 gene results in a disruption in the expression of its chain partners rather than compensation by another laminin gene.
Littermate Lamb2-/- and WT retinae were dissected and flat-mounted at P10 and P20. These retinae were stained using chain-specific laminin antibodies (laminin α2: P10 and P20 N=3; laminin α4: P10 N=2, P20 N=3; laminin α5: P10 and P20 N=3; laminin γ3: P20 N=3) and imaged. Laminin-chain expression was measured separately along the vascular tree using the mean fluorescence intensity (MFI). The MFI was compared between mutant and WT littermates by calculating the relative fluorescence intensity (RFI): mutant MFI/WT MFI = RFI; statistical significance was assessed by two-tailed Student's T-test.
The expression of laminin α2 was significantly decreased in Lamb2-/- veins (p=0.001) at P10, and in veins (p=0.011), venules (p=0.004), arteries (p=0.007), and arterioles (p=0.012) at P20. The expression of laminin α5 was significantly decreased in Lamb2-/- arteries (p=0.004) at P10, and in veins (p=0.005), venules (p=0.014), arteries (p=0.004), arterioles (p=0.001), the intermediate vascular plexus (IVP) (p=0.011), and the deep vascular plexus (DVP) (p=0.014) at P20. In contrast, the expression of laminin α4 was largely unaltered in Lamb2-/- vessels. The expression of laminin γ3 was significantly decreased in Lamb2-/- veins (p=0.001), venules (p=0.001), the IVP (p=0.013), and the DVP (p=0.012) at P20.
Our results demonstrate that there is coordinated expression among laminin chains within the retinal vascular membrane. Moreover, laminin expression pattern and coordinated expression of chain partners is both temporally and spatially regulated over the vascular tree. This is the first conclusive demonstration of coordinated expression of laminin chains in any developing system.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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