Abstract
Abstract: :
Purpose: Bone morphogenic proteins (BMPs) are members of the transforming growth factor-beta superfamily of intracellular signaling molecules. BMP-4 expression has previously been demonstrated in the adult retina and the retinal pigmented epithelium. Additionally, retinal BMP4 expression is known to be attenuated in mice with ischemic retinopathy. This study was designed to determine if BMP-4 is expressed in cultured rat Müller cells and to test whether its expression is altered by hypoxia. Methods: A well-characterized rat Müller cell line, rMC-1, was used in these experiments. Total RNA was isolated from Müller cells exposed to either control or hypoxic conditions. RT-PCR was performed on RNA isolated from control and hypoxic samples using primers for rat BMP-4 and GAPDH, the internal control. The resultant PCR products were run on agarose gels and the gels were analyzed and quantified using optical density measurement of the BMP-4 band relative to GAPDH band. Results: Bands of appropriate size for BMP-4 (300 bp) and GAPDH (703 bp) were found by PCR. DNA Sequencing of BMP-4 band established that the PCR product was homologous to the published sequence for rat BMP-4. Optical density analysis of the bands in three separate experiments showed a 2.5 fold reduction in BMP-4 expression in the Müller cells grown in hypoxia. Conclusions: BMP-4 mRNA is markedly decreased in rat Müller cells exposed to hypoxia. This raises the possibility that alterations in BMP-4 levels in Müller cells play a role in the retina's response to hypoxia, which may have implications in the pathogenesis and treatment of ischemic retinopathy.
Keywords: Muller cells • hypoxia • growth factors/growth factor receptors