Abstract
Abstract: :
The p27 cyclin kinase inhibitor is expressed in mitotic retinal progenitor cells and mature Müller glia of the mouse and primate retina. Previously, we have shown that proliferation associated with glial cell activation following retinal injury is regulated by p27. Early reactive gliosis during development combined with hyperproliferation of retinal progenitor cells leads to retinal dysplasia. This dysplasia is even more severe when another cyclin kinase inhibitor (p19) is disrupted in combination with p27. We propose that this is due to the increase in cell number due to hyperproliferation rather than a direct effect on Müller glia. Interestingly, p53 inactivation rescues the retinal dysplasia in p27–/–;p19–/– mice.Purpose: Using a combination of genetic approaches, we have sought to determine if p53 is required cell–autonomously for glial cell activation. Methods:To analyze the role of p53 in Müller glial cell reactive gliosis and retinal dysplasia, we have analyzed triple knockout mice (p27–/–;p19–/–;p53–/–) and conditional knockout p53–lox mice combined with various Cre–transgenic mouse lines and Cre–expressing retroviruses. Analysis includes immunofluorescence with 36 different antibodies to cell type specific proteins, proliferation analysis with BrdU, apoptosis analysis with TUNEL, and microarray hybridization with our RET13K retinal cDNA microarray. Results: Considering that proliferation is deregulated during retinal development due to the absence of p27 and p19, we were surprised to find that most of the cell types are generated in the correct proportion and are organized appropriately. The only exception is glial cell activation and disruption of the outer limiting membrane. Conclusions: Based on our data, we propose that p53 is an important regulator of the stress response of Müller glia in the retina following retinal injury.
Keywords: Muller cells • genetics • proliferation