New Insights in the Distribution Profile of TRPC3 and TRPC5 in the Mouse and Human Kidney

Abstract Several reports previously investigated Transient Receptor Potential Canonical subfamily channels 3 and 5 (TRPC3/TRPC5) in the kidney. However, most of the conclusions are based on animal samples or cell cultures leaving the door open for human tissue investigations. Moreover, results often disagreed among investigators. Histological description is lacking since most of these studies focused on functional aspects. Nevertheless, the same reports highlighted the potential differing key-roles of TRPC3 or TRPC5 in various renal disorders. Hence, our interest to investigate the localization of TRPC3 and TRPC5 in human kidneys. For this purpose, both healthy mouse and human kidney samples that were originated from tumor nephrectomies have been prepared for immunohistochemical staining using knockout-tested antibodies. Blocking peptides confirmed antibody specificity. A normalized weighted diaminobenzidine (DAB) area score between 0–3 comparable to a pixelwise H-score was established and employed for semiquantitative analysis. Altogether, our results suggest that glomeruli only express little TRPC3 and TRPC5 compared to several segments of the tubular system. Cortical and medullary proximal tubules are strongly stained. Intermediate tubules, however, are only weakly stained. The distal tubule was studied in three different localizations and depending on species and primary antibody, the staining was marked although slightly varying throughout the different localizations. Finally, the collecting duct was independently of primary antibody more stained in human compared to mouse tissue. We provide evidence that TRPC3 and TRPC5 are differently expressed in various localizations in both mouse and human samples. Especially, the TRPC5 distribution profile, we present here is completely new to our knowledge and raises questions, for instance its physiological relevance in the tubular system. We less verify results of previous studies than propose until now undescribed localizations of TRPC3 and TRPC5 in the mouse but especially and of greater interest in the human kidney. We thereby not only support the translational concept of TRPC channels as key players in physiology and pathophysiology of the human kidney but also present new potential targets to functional analysis.