IMMUNOHISTOCHEMICAL AND IMMUNOCHEMICAL LOCALIZATION OF HEAT-SHOCK PROTEIN 27KD IN THE DEVELOPING RAT RETINA - THE DIFFERENTIAL LOCALIZATIONFROM ALPHA-B-CRYSTALLIN

The localization of two stress proteins, small heat shock protein (HSP 27) and alpha B crystallin, in the developing rat retina were studied immunohistochemically and immunochemically, using the antibodies for H SP27 and alpha B crystallin. At embryonic day 15, the immunoreactivity to alpha B crystallin was observed in some cells in the neural retina and in the pigment epithelium (PE). At postnatal day (P) 5, immunorea ctivity to HSP27 was first observed in the inner limiting membrane (IL M), nerve fiber layer (NFL) and RE. Immunoreactivity to alpha B crysta llin was present in almost the same portions of the retina. At P10, th e differentiating outer segments of the photoreceptor cells (ROS) and PE were intensely immunoreactive to alpha B crystallin, as compared wi th other layers, while the ILM, NFL and some portions of RE were immun oreactive to HSP27. At time progressed, immunoreactivity to HSP27 in t he IPL and alpha B crystallin in the ROS increased. Our enzyme immunoa ssay of the retina revealed that the concentration of HSP27 gradually increased over time. In contrast, the concentration of alpha B crystal lin increased after birth and reached almost to adult level at P30. Th e concentration of HSP27 was much lower as compared to that of alpha B crystallin. The differences in locations and changes in the levels of concentration between HSP27 and alpha B crystallin suggested that the se two stress proteins may have different functions in the developing retina.