Calcium inhibits renin gene expression by transcriptional and posttranscriptional mechanisms.
The aim of this study was to investigate the role of cytosolic calcium for renin gene expression in juxtaglomerular cells. For this purpose, we used the immortalized juxtaglomerular mouse cell line As4.1. To increase cytosolic calcium concentration, we treated the cells with thapsigargin and cyclopiazonic acid, inhibitors of the endoplasmatic reticulum Ca- ATPase. Thapsigargin and cyclopiazonic acid inhibited renin gene expression in a characteristic time and concentration-dependent manner. This effect was concentration-dependently blocked by BAPTA-AM, an intracellular Ca2+ chelator. Pharmacological blocking of protein kinase C activity by calphostin, Gö6976, and Gö6983 did not change the effect of thapsigargin on renin gene expression. Experiments with renin1C-promoter-reporter constructs revealed that thapsigargin inhibited renin gene transcription. Analysis of deletion constructs of the renin1C promoter indicated that regulatory elements involved in the calcium-mediated inhibition of renin gene transcription are located in the enhancer region of the renin gene and that > or =3 transcription factor-binding sites are involved in this process. In addition, thapsigargin reduced the renin mRNA half-life from 10 hours (control conditions) to 4 hours. Knockdown studies with small interfering RNA directed to dynamin-1 mRNA revealed that dynamin-1 is likely to be involved in the calcium-mediated destabilization of renin mRNA. These data suggest that calcium inhibits renin gene expression in juxtaglomerular cells via a concerted action of inhibition of renin gene transcription and destabilization of renin mRNA.
Klar
Jürgen
J
Institut für Physiologie, Universität Regensburg, D-93040 Regensburg, Germany. juergen.klar@vkl.uni-regensburg.de
Sigl
Martin
M
Obermayer
Birgit
B
Schweda
Frank
F
Krämer
Bernhard K
BK
Kurtz
Armin
A
D000818:Animals; D002118:Calcium / Q000502:physiology*; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors; D002461:Cell Line, Transformed; D034284:Dynamin I / Q000235:genetics / Q000502:physiology; D004742:Enhancer Elements, Genetic / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015870:Gene Expression / Q000502:physiology*; D006207:Half-Life; D042541:Intracellular Space / Q000378:metabolism; D007606:Juxtaglomerular Apparatus / Q000166:cytology / Q000378:metabolism; D051379:Mice; D009994:Osmolar Concentration; D011499:Protein Processing, Post-Translational; D020871:RNA Stability; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering / Q000494:pharmacology; D012083:Renin / Q000235:genetics*; D019284:Thapsigargin / Q000494:pharmacology; D014158:Transcription, Genetic / Q000187:drug effects / Q000502:physiology; D000092502:Renin Inhibitors
D002118:Calcium; D000252:Calcium-Transporting ATPases; D034284:Dynamin I; D004791:Enzyme Inhibitors; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D012083:Renin; D019284:Thapsigargin; D000092502:Renin Inhibitors