Focal contacts organization in osteoblastic cells under microgravity and cyclic deformation conditions.
We compared quantitatively vinculin-related adhesion parameters in osteoblastic cells submitted to opposite mechanical stresses, i.e., low deformation and frequency strain regimens (stretch condition) and microgravity exposure (relaxed condition). Cyclic deformation induced a biphasic response comprising new focal contacts formation followed by their clustering in ROS cells. Microgravity exposure induced a reduction in focal contact number and clustering in ROS cells. We previously demonstrated that 1% cyclic deformations at 0.05 Hz during a daily 10 min episode over 7 days stimulated ROS 17/2.8 growth as compared to static culture whereas relaxed ROS proliferated similarly to static culture (BC). To evaluate whether the proliferation (stretch) or the survival (relaxed) status of ROS cells influences focal contact organization, we inhibited ERKs proliferative-dependent pathway. Inhibition of proliferation by PD98059 was overcome although not fully restored by stretch. Furthermore stretch-induced clustering of vinculin-positive contacts still occurs in the presence of ERKs inhibitor, whereas the increase in focal contact number is abolished. In conclusion, we showed that focal contacts are mechanoeffectors and that hyper-mechanical stimulation could up regulate focal contacts size as compared to hypo-mechanical that down regulate clusterization.
Laboratoire de Biologie du Tissu Osseux (LBTO). Institut National de la Santé et de la Recherche Médicale (INSERM). Saint Etienne Cedex, France.
Alain
A
Guignandon
Omar
O
Akhouayri
Norbert
N
Laroche
Marie-Hélène
MH
Lafage-Proust
Christian
C
Alexandre
Laurence
L
Vico
D000222:Adaptation, Physiological; D000818:Animals; D002448:Cell Adhesion / Q000502:physiology; D002455:Cell Division / Q000502:physiology; D045744:Cell Line, Tumor; D048429:Cell Size; D002470:Cell Survival / Q000502:physiology; D015536:Down-Regulation / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D022001:Focal Adhesions / Q000502:physiology*; D040542:Mechanotransduction, Cellular / Q000502:physiology*; D018613:Microscopy, Confocal; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D010006:Osteoblasts / Q000166:cytology / Q000502:physiology*; D012516:Osteosarcoma; D051381:Rats; D017208:Rats, Wistar; D013026:Space Flight; D013314:Stress, Mechanical; D016596:Vinculin; D014893:Weightlessness
D004791:Enzyme Inhibitors; D016596:Vinculin; D020928:Mitogen-Activated Protein Kinases