Calcimimetics increase CaSR expression and reduce mineralization in vascular smooth muscle cells: mechanisms of action.
OBJECTIVE
Vascular calcification (VC) contributes to morbidity and mortality in patients with chronic kidney disease (CKD). Allosteric modulators of the calcium (Ca)-sensing receptor (CaSR) may slow the progression of VC in CKD patients either by reducing serum parathyroid hormone (PTH), Ca, and phosphate levels or by a direct effect on the vessel wall. The aim of this study was to examine the effects of calcimimetics on CaSR expression, cell phenotype, and mineral deposition in human vascular smooth muscle cells (h-VSMCs).


RESULTS
Primary h-VSMCs were exposed for 14 days to increasing concentrations of Ca(2+) (from 1.8 to 5 mmol/L) in the presence or absence of calcimimetics R-568 or AMG 641 (0.1 μmol/L). Mineralization was detected by Alizarin red staining, and the cell phenotype was assessed using immunocytochemistry and qRT-PCR. CaSR expression was evaluated using flow cytometry. Short- and long-term exposure (1 day to 14 days) of h-VSMCs to calcimimetics promoted CaSR protein transport from the endoplasmic reticulum to the plasma membrane with enhanced CaSR expression on the cell surface, together with an increase in total cell CaSR expression due to enhanced biosynthesis. In pro-mineralizing conditions, exposure to calcimimetics counteracted the Ca(2+)-dependent reduction of CaSR expression, decreased matrix collagen secretion, and mineral deposition by ~90%. These effects involved CaSR activation since it could be inhibited by CaSR siRNA, but not scrambled siRNA.


CONCLUSIONS
The calcimimetic-dependent increase in biosynthesis and activation of the CaSR in h-VSMCs probably play a key role in the protection against calcium-induced VC.
Inserm Unit 1088, University of Picardie Jules Verne, 1 rue des Louvels, 80037 Amiens, France.
Lucie
L
Hénaut
Cédric
C
Boudot
Ziad A
ZA
Massy
Irene
I
Lopez-Fernandez
Sebastien
S
Dupont
Aurélien
A
Mary
Tilman B
TB
Drüeke
Saïd
S
Kamel
Michel
M
Brazier
Romuald
R
Mentaverri
D000814:Aniline Compounds / Q000494:pharmacology*; D001713:Biphenyl Compounds / Q000494:pharmacology*; D057966:Calcimimetic Agents / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002478:Cells, Cultured; D024042:Collagen Type I / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000378:metabolism; D032389:Myocytes, Smooth Muscle / Q000187:drug effects* / Q000378:metabolism; D010627:Phenethylamines / Q000494:pharmacology*; D010641:Phenotype; D011437:Propylamines; D021381:Protein Transport; D034622:RNA Interference; D044169:Receptors, Calcium-Sensing / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D013997:Time Factors; D014162:Transfection; D015854:Up-Regulation; D061205:Vascular Calcification / Q000235:genetics / Q000378:metabolism / Q000517:prevention & control*
D000814:Aniline Compounds; D001713:Biphenyl Compounds; C095550:CASR protein, human; D057966:Calcimimetic Agents; D024042:Collagen Type I; C544316:N-((6-(methyloxy)-4'-(trifluoromethyl)-3-biphenylyl)methyl)-1-phenylethanamine; C107873:N-(2-chlorophenylpropyl)-1-(3-methoxyphenyl)ethylamine; D010627:Phenethylamines; D011437:Propylamines; D044169:Receptors, Calcium-Sensing; D002118:Calcium
Calcimimetics; Calcium-sensing receptor (CaSR); Human vascular smooth muscle cells (h-VSMCs); Vascular calcification