Expression profile of heat shock protein 108 during retinal development in the chick

In the developing chick retina, heat shock protein 108 (HSP108), which exhibits transferrin binding activity, has been demonstrated at the mRNA level, while transferrin shows two expression peaks. Here, we investigated the expression profile of HSP108 in the developing chick retina at the protein level. The localization of HSP108 in embryonic days 15 (E15), E18, and postnatal day 2 (P2) chick retina was examined immunohistochemically using monoclonal antibody 9G10 specific for chick HSP108, while the expression levels of HSP108 in developing chick retina from E12 to P2 and adult were measured by Western blot analysis. HSP108 was expressed in the ganglion cell layer, inner nuclear layer, outer plexiform layer, outer nuclear layer, inner segments of photoreceptors and retinal pigment epithelium. Two peaks of HSP108 expression were found at around E13 and E18, respectively. Since the two HSP108 peaks appeared to be correlated with the transferrin expression peaks during retinal development, HSP108 may be associated with iron metabolism during the development of the retina.