CALL FOR PAPERS Integrative and Translational Physiology: Integrative Aspects of Energy Homeostasis and Metabolic Diseases Plasticity of renal endocrine function

Kurt B, Kurtz A. Plasticity of renal endocrine function. Am J Physiol Regul Integr Comp Physiol 308: R455–R466, 2015. First published January 21, 2015; doi:10.1152/ajpregu.00568.2013.—The kidneys are important endocrine organs. They secrete humoral factors, such as calcitriol, erythropoietin, klotho, and renin into the circulation, and therefore, they are essentially involved in the regulation of a variety of processes ranging from bone formation to erythropoiesis. The endocrine functions are established by cells, such as proximal or distal tubular cells, renocortical interstitial cells, or mural cells of afferent arterioles. These endocrine cells are either fixed in number, such as tubular cells, which individually and gradually upregulate or downregulate hormone production, or they belong to a pool of cells, which display a recruitment behavior, such as erythropoietinand reninproducing cells. In the latter case, regulation of humoral function occurs via (de)recruitment of active endocrine cells. As a consequence reninand erythropoietin-producing cells in the kidney show a high degree of plasticity by reversibly switching between distinct cell states. In this review, we will focus on the characteristics of reninand of erythropoietin-producing cells, especially on their origin and localization, their reversible transformations, and the mediators, which are responsible for transformation. Finally, we will discuss a possible interconversion of renin and erythropoietin expression.