Adrenomedullin up-regulates osteopontin and attenuates vascular calcification via the cAMP/PKA signaling pathway.
OBJECTIVE
To determine whether adrenomedullin (ADM) attenuates vascular calcification (VC) by inducing osteopontin (OPN) expression.


METHODS
A VC model of rat aorta was induced with vitamin D3 plus nicotine (VDN), and vascular smooth muscle cell (VSMC) calcification was induced with beta-glycerophosphate. Von Kossa staining and alizarin red staining were assessed. Alkaline phosphatase (ALP) activity was measured. Immunohistochemical analysis was used to detect alpha-actin, while RT-PCR and Western blot analysis were used to quantify OPN expression.


RESULTS
Administration of ADM greatly reduced VC in VDN-treated aortas compared with controls, which was confirmed in calcified VSMCs. The decrease in alpha-actin expression was ameliorated by ADM both in vivo and in vitro. Moreover, mRNA and protein expression levels of OPN were significantly up-regulated in calcified aortas, and ADM increased OPN expression in calcified aortas. Furthermore, ADM up-regulated OPN expression in normal aortas and VSMCs. The ADM-mediated effects were similar to that of forskolin, which activates adenylyl cyclase; additionally, while the PKA inhibitor H89 and Ca²(+) chelator Fura-2 blocked the effect of ADM. However, the MEK/ERK inhibitor PD98509 had no effect on ADM induction of OPN mRNA expression. An OPN polyclonal antibody inhibited ADM-mediated attenuation of VC.


CONCLUSIONS
ADM up-regulates OPN expression and thus attenuates VC via PKA. ADM appears to be an endogenous cardiovascular protective peptide and may represent a new therapeutic target for VC treatment.
Cai
Yan
Y
Peking University, Beijing, China.
Teng
Xu
X
Pan
Chun-shui
CS
Duan
Xiao-hui
XH
Tang
Chao-shu
CS
Qi
Yong-fen
YF
D000199:Actins / Q000096:biosynthesis; D000262:Adenylyl Cyclases / Q000378:metabolism; D053607:Adrenomedullin / Q000378:metabolism* / Q000494:pharmacology; D000818:Animals; D001013:Aorta, Thoracic / Q000378:metabolism / Q000473:pathology; D002114:Calcinosis / Q000139:chemically induced / Q000378:metabolism* / Q000473:pathology; D002118:Calcium / Q000502:physiology; D002762:Cholecalciferol; D000242:Cyclic AMP / Q000502:physiology*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D020536:Enzyme Activators / Q000494:pharmacology; D005994:Glycerophosphates; D008297:Male; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000378:metabolism; D009538:Nicotine; D053495:Osteopontin / Q000096:biosynthesis*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction; D015854:Up-Regulation
D000199:Actins; D020536:Enzyme Activators; D005994:Glycerophosphates; D053495:Osteopontin; D053607:Adrenomedullin; D002762:Cholecalciferol; D009538:Nicotine; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D000262:Adenylyl Cyclases; D002118:Calcium; C031463:beta-glycerophosphoric acid
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