TRANSCRIPTION AND TRANSLATION OF GP600 AND RECEPTOR-ASSOCIATED PROTEIN (RAP) IN ACTIVE HEYMANN NEPHRITIS

Active Heymann nephritis (HN) of rat, an autoimmmune glomerular diseas e, is a model for human membranous glomerulonephropathy. The autoantig en of HN is a glycoprotein of similar to 600 kd that is present in bot h rat and human kidneys. Another kidney protein of 39-45 hd called rec eptor-associated protein (RAP) is associated with gp600. In normal kid ney very little gp600 and RAP can be detected in glomeruli. This study was undertaken to determine whether the synthesis of gp600 and RAP wo uld increase after development of active HN. Kidneys from normal (n = 5) and active (n = 11) NN rats were studied for expression of gp600 an d RAP and their mRNAs by immunofluorescence and in situ hybridization. In all HN kidneys in contrast to normal kidneys both the transcriptio n and translation of gp600 were markedly increased in glomeruli and pr oximal tubules. Transcription and translation of RAP were also increas ed but less so than gp600. The site of increased transcription of gp60 0 and RAP in glomeruli was clearly localized to the visceral glomerula r epithelial cells. Conclusions: This is the first study to show incre ased transcription of gp600 and RAP ill active HN and the first study to identify the visceral glomerular epithelial cell as the cell for th e increased transcription.