Segmental expression of somatostatin receptor subtypes sst1 and sst2 in tubules and glomeruli of human kidney

Abstract

Somatostatin is known to modulate mesangial and tubular cell function and growth, but the somatostatin receptor (sst) subtypes responsible for these effects have not been defined. There are at least five different sst receptor subtypes (sst1-sst5). We used RT-PCR to demonstrate that normal human kidney consistently expresses mRNA for sst1 and sst2 (9 of 9 donors). Some donors expressed sst4 or sst5mRNA, but none expressed sst3 mRNA. Expression of sst1 and sst2 was further assessed by staining serial sections of normal human kidney with sst1 and sst2 antisera, Arachis hypogaea (AH) lectin (to define distal tubule/collecting duct cells), Phaseolus vulgaris lectin (proximal tubules), and Tamm-Horsfall protein (THP) antiserum (thick ascending limb of the loop of Henle). Specificity of antisera was demonstrated by transfection and absorption studies. Sst2, but not sst1, was expressed in glomeruli. Intense sst1 and sst2 staining localized exclusively to AH+ and THP+ tubules. Thus sst1 and sst2 subtype-selective analogs may be useful to beneficially modulate renal cell function in pathological conditions.