Calcitonin stimulates amino acid incorporation into plasminogen activator by cultured renal tubular cells

Abstract

Received 30 July 1981 1. Introduction A cultured epithelial cell line (LLC-PK1) derived from porcine kidney has receptors for calcitonins and responds to these hormones with an increase in the cellular content of CAMP [ 1,2] and activation of a CAMP-dependent protein kinase [3]. The LLC-PK1 cells had been selected and maintained in (41 because of their ability to produce large amounts of plasmin- ogen activator. The synthesis and secretion of this enzyme in several other cell systems is modulated by specific hormones, some of which act by increasing cellular levels of CAMP [5,6]. Calcitonin also markedly stimulates plasminogen activator production by LLC- PK1 cells and decreases their replication [7]. Here, we show that calcitonin increases amino acid incorpora- tion into proteins secreted by LLC-PK1 cells. The increased incorporation is mainly into a protein which on polyacrylamide gel electrophoresis has an estimated M, of m 45 000 and has plasminogen activator activity. 2. Materials and methods 2.1.