Parathyroid hormone-related protein as a renal regulating factor - From vessels to glomeruli and tubular epithelium

Parathyroid hormone (PTH) and PTH-related protein (PTHrP) produce similar b iological effects through the PTH/PTHrP receptor. Less is known about the p hysiological role of PTHrP, which was first identified as the agent of the humoral hypercalcemia of malignancy. Despite the widespread production of P THrP in healthy individuals, the concentration of the protein is below the detectable limit of current assays, suggesting that PTHrP normally function s locally in an autocrine or paracrine manner. Thus, some differences in th eir biological activities have been described and they may be related to th e presence of different receptors. In this regard, a second receptor that b inds selectively to PTH has also been found. Recent studies have demonstrat ed the expression of both PTH/PTHrP receptor and protein in the renal glome ruli. Moreover, there are convincing data that support a direct role of PTH and PTHrP in modulating renal blood flow and glomerular filtration rate. T his multifunctional protein, PSHrP, also has a proliferative effect on both glomerular mesangial cells and tubular epithelial cells. Increases in the expression of PTHrP have been observed in several experimental models of ne phropathies, suggesting that PTHrP upregulation is a common event associate d with the mechanism of renal injury and repair. Copyright (C) 2001 S. Karg er AG, Basel.