EXPRESSION AND LOCALIZATION OF INHIBIN ALPHA-SUBUNIT IN RAT RETINAL PHOTORECEPTOR CELLS

To determine whether rat retinal photoreceptor cells produce inhibin, a molecule closely related to activin, a multifunctional growth factor in the transforming growth factor beta superfamily (TGF beta), we hav e conducted immunohistochemistry using specific antibodies for inhibin which were raised against a synthetic N-terminal fragment of the alph a-subunit of inhibin. The mature inhibin molecule was identified at bo th the inner and outer segments of photoreceptor cells. To determine i f messenger RNA for the alpha-subunit of inhibin is expressed in the r etinal cells, both in situ hybridization with a specific probe and the reverse transcription-polymerase chain reaction (RT-PCR) technique wi th primers specific for the alpha-subunit of inhibin were used. Messen ger RNA expression of the alpha-subunit of inhibin was detected by RT- PCR and localized in the photoreceptor cells as determined by in situ hybridization. In addition, the identity of the cDNA product of RT-PCR was verified with Southern analysis and DNA sequencing. The localizat ion of mature inhibin protein and its corresponding message to photore ceptor cells suggest that inhibin may have a paracrine function in the retina, perhaps in the photoreceptor cells themselves.