Calcyclin is an early vasopressin-induced gene in the renal collecting duct - Role in the long term regulation of ion transport

Long-term effects of arginine vasopressin (AVP) in the kidney involve the transcription of unidentified genes. By subtractive hybridization experiments performed on the RCCD1 cortical collecting duct cell line, we identified calcyclin as an early AVP-induced gene (1 h). Calcyclin is a calcium-binding protein involved in the transduction of intracellular signals. In the kidney, calcyclin was localized at the mRNA level. in the glomerulus, all along the collecting duct, and in the epithelium lining the papilla. In RCCD, cells and in m-IMCD3 inner medullary collecting duct cells, calcyclin was evidence in the cytoplasm. Caleyelin mRNA levels were progressively increased by AVP treatment in RCCD1 (1.7-fold at 4 h) and m-IMCD3 (2-fold at 7.5 h) cells. In RCCD1 cells, calcyclin protein levels were increased by 4 h of AVP treatment. In vivo, treatment of genetically vasopressin-deficient Brattleboro rats with AVP for 4 days induced an increase in both calcyclin and aquaporin-2 mRNA expression. Finally, introduction of anti-calcyclin antibodies into RCCD1 cells by permeabilizing the plasma membrane prevented the long-term (but not short-term) increase in short-circuit current induced by AVP. Taken together, these results suggest that calcyclin is an early vasopressin-induced gene that participates in the late phase of the hormone response in transepithelial ion transport.