Upregulation of IGF2 expression during vascular calcification.
The process of vascular calcification shares many similarities with that of skeletal mineralisation and involves the deposition of hydroxyapatite crystals in arteries and cardiac valves. However, the cellular mechanisms responsible have yet to be fully elucidated. In this study, we employed microarray analysis to demonstrate the upregulation of more than >9000 genes during the calcification of murine vascular smooth muscle cells (VSMCs), of which the most significantly, differentially expressed gene was Igf2. Following the validation of increased IGF2 expression by RT-qPCR and immunoblotting in calcifying murine VSMCs, IGF2 expression was further demonstrated in the calcified aorta of the Enpp1(-/-) mouse model of medial aortic calcification. Having confirmed that IGF1R and IGF2R were expressed in cultured murine VSMCs, cell-signalling studies in these cells revealed that IGF2 (50 ng/ml) significantly stimulated the phosphorylation of Akt and Erk1/2 (P<0.05). These results potentially indicate that IGF2 may mediate VSMC calcification via the stimulation of Erk1/2 and Akt signalling. This study suggests that the increased IGF2 expression in calcifying VSMCs may reflect the well-established prenatal role of IGF2, particularly as the osteogenic phenotypic transition of VSMCs in a calcified environment recapitulates many of the events occurring during embryonic development. A full understanding of the importance of IGF2 in this pathological process will lead to a better understanding of the aetiology of vascular calcification.
The Roslin Institute and Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Easter Bush, Roslin, Midlothian, EH25 9RG Scotland, UK Sanford-Burnham Medical Research Institute, Sanford Children's Health Research Center, La Jolla, California 92037, USA.
Dongxing
D
Zhu
Neil C W
NC
Mackenzie
Jose Luis
JL
Millan
Colin
C
Farquharson
Vicky E
VE
Macrae
D000818:Animals; D001011:Aorta / Q000473:pathology; D004195:Disease Models, Animal; D004789:Enzyme Activation; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D020869:Gene Expression Profiling; D007335:Insulin-Like Growth Factor II / Q000235:genetics* / Q000378:metabolism; D020935:MAP Kinase Signaling System; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009131:Muscle, Smooth, Vascular / Q000473:pathology; D032389:Myocytes, Smooth Muscle / Q000201:enzymology / Q000473:pathology; D010727:Phosphoric Diester Hydrolases / Q000172:deficiency / Q000378:metabolism; D011494:Protein Kinases / Q000378:metabolism; D011755:Pyrophosphatases / Q000172:deficiency / Q000378:metabolism; D059467:Transcriptome / Q000235:genetics; D015854:Up-Regulation / Q000235:genetics*; D061205:Vascular Calcification / Q000235:genetics* / Q000473:pathology
D007335:Insulin-Like Growth Factor II; D011494:Protein Kinases; D048049:Extracellular Signal-Regulated MAP Kinases; D010727:Phosphoric Diester Hydrolases; C065962:ectonucleotide pyrophosphatase phosphodiesterase 1; D011755:Pyrophosphatases
IGF2; NPP1; VSMC; vascular calcification