Vasopressin-induced heat shock protein expression in renal tubular cells

Heat shock proteins (HSPs), which have been shown to be induced in the kidney by a variety of stress conditions, including ischemia, inflammation, oxidative stress, and toxin exposure, are believed to protect the cells from injury. In the present study, we demonstrated that administration of vasopressin i.v. to Wistar rats leads to HSP70 induction in the kidney. The effect was specific to the kidney (i.e., absent in brain, heart, lung, muscle, etc.) and selective for the HSP70 gene family (HSP27, HSP60, and HSP90 were not induced). Western blot analysis demonstrated that HSP70 protein expression peaked between 6 and 12 hours after vasopressin administration. Immunohistochemical staining revealed that induction was localized to renal tubule lining cells, with no expression seen in glomerular or interstitial regions. The elevated protein levels were preceded by the induction of HSP70 mRNA within 30 minutes after vasopression injection. The induction of HSP70 mRNA was associated with the activation of heat shock transcription factor 1 (HSF1), suggesting that the response was regulated at the level of transcription. This HSP70 expression was completely blocked in the presence of both a general vasopressin receptor antagonist (V1 and V2 receptors) and an antidiuretic antagonist (V2), but not in the presence of a vasopressor antagonist (V1). These observations could be significant for understanding the possible involvement of HSP70 in physiological processes of the kidney, as well as pathophysiologic conditions associated with either elevated or deficient levels of vasopressin.