Plasticity of renal endocrine function

摘要

The kidneys are important endocrine organs.They secrete humoral factors, such as calcitriol, erythropoietin, klotho, and renininto the circulation, and therefore, they are essentially involved in the regulation ofa variety of processes ranging from bone formation to erythropoiesis. The endo-crine functions are established by cells, such as proximal or distal tubular cells,renocortical interstitial cells, or mural cells of afferent arterioles. These endocrinecells are either fixed in number, such as tubular cells, which individually andgradually upregulate or downregulate hormone production, or they belong to a poolof cells, which display a recruitment behavior, such as erythropoietin- and renin-producing cells. In the latter case, regulation of humoral function occurs via(de)recruitment of active endocrine cells. As a consequence renin- and erythropoi-etin-producing cells in the kidney show a high degree of plasticity by reversiblyswitching between distinct cell states. In this review, we will focus on thecharacteristics of renin- and of erythropoietin-producing cells, especially on theirorigin and localization, their reversible transformations, and the mediators, whichare responsible for transformation. Finally, we will discuss a possible interconver-sion of renin and erythropoietin expression.