Mechanical stimulation and mitogen-activated protein kinase signaling independently regulate osteogenic differentiation and mineralization by calcifying vascular cells.
Ectopic calcification of vascular tissue is associated with several cardiovascular pathologies and likely involves active regulation by vascular smooth muscle cells and osteoblast-like vascular cells. This process often occurs in sites with altered mechanical environments, suggesting a role for mechanical stimuli in calcification. In this study, we investigated the effect of mechanical stimulation on the proliferation, osteogenic differentiation, calcification, and mitogen-activated protein kinase (MAPK) signaling in calcifying vascular cells (CVCs), a subpopulation of aortic smooth muscle cells putatively involved in vascular calcification. Application of equibiaxial cyclic strain (7%, 0.25 Hz) to CVCs had no effect on cell proliferation, but accelerated alkaline phosphatase expression and significantly increased mineralization by 3.1-fold over unstrained cells. Fluid motion in the absence of strain also enhanced mineralization, but to a lesser degree. Because MAPK pathways mediate mechanically regulated osteoblast differentiation, we tested whether similar signaling was involved in mineralization by CVCs. In static cultures, pharmacological inhibition of the extracellular signal-regulated kinase (ERK1/2), p38 MAPK, and c-Jun N-terminal kinase pathways significantly attenuated mineral production by as much as -94%, compared with uninhibited CVCs. Strikingly, although mechanical stimulation activated each of the MAPK pathways, inhibition of these pathways had no effect on the mechanically induced enhancement of alkaline phosphatase activity or mineralization. These novel data indicate that mechanical signals regulate calcification by CVCs, and although MAPK signaling is critical to CVC osteogenic differentiation and mineralization, it is not involved directly in transduction of mechanical signals to regulate these processes under the conditions utilized in this study.
Simmons
Craig A
CA
Department of Biomedical Engineering, University of Michigan, 1011 N University Avenue, Ann Arbor, MI 48109-1078, USA.
Nikolovski
Janeta
J
Thornton
Amanda J
AJ
Matlis
Sean
S
Mooney
David J
DJ
D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D000873:Anthracenes / Q000494:pharmacology; D002070:Butadienes / Q000494:pharmacology; D002113:Calcification, Physiologic / Q000502:physiology*; D002417:Cattle; D002454:Cell Differentiation / Q000502:physiology; D002460:Cell Line; D049109:Cell Proliferation; D004247:DNA / Q000032:analysis; D004791:Enzyme Inhibitors / Q000494:pharmacology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors / Q000502:physiology*; D007093:Imidazoles / Q000494:pharmacology; D048031:JNK Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000502:physiology*; D009131:Muscle, Smooth, Vascular / Q000201:enzymology*; D009570:Nitriles / Q000494:pharmacology; D010012:Osteogenesis / Q000502:physiology*; D011725:Pyridines / Q000494:pharmacology; D015398:Signal Transduction; D013314:Stress, Mechanical; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000502:physiology*
D000873:Anthracenes; D002070:Butadienes; D004791:Enzyme Inhibitors; D007093:Imidazoles; D009570:Nitriles; D011725:Pyridines; C113580:U 0126; C432165:pyrazolanthrone; D004247:DNA; D048049:Extracellular Signal-Regulated MAP Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D000469:Alkaline Phosphatase; C093642:SB 203580