Expression of BMP-4 in the murine retina

Purpose. Bone morphogenetic proteins (BMPs), closely related members of the transforming growth factor-beta superfamily of intercellular signaling molecules, were initially identified on the basis of their ability to induce bone and cartilage formation in ectopic extraskeletal sites when implanted into animals. In differential screening analysis of genes which are preferentially expressed in the retina and retinal pigment epithelium (RPE), we detected expression of BMP-4. In order to analyze the cellular expression pattern of BMP-4 within the retina and RPE, in situ hybridization was performed. Methods. Using digoxigenin-labeled anti-sense and sense RNA probes made from the murine BMP-4 cDNA, in situ hybridization of sectioned adult mouse eyes was carried out using standard techniques. Results. Staining of the adult mouse retina was observed with the BMP-4 anti-sense probe. Differential staining with the anti-sense BMP-4 probe was demonstrated in the inner nuclear, outer nuclear, and ganglion cell layers of the retina. Developmental expression of BMP-4 and other BMPs in the embryonic eye is currently being investigated. Conclusion: BMP-4 expression has now been localized in the adult mouse retina. Delineation of the spatial and temporal developmental pattern of expression of BMPs in the retina may provide insight into the role of this family of molecules in retinal development.