The effect of cyclic mechanical strain on the expression of adhesion-related genes by periodontal ligament cells in two-dimensional culture.
OBJECTIVE
Cell adhesion plays important roles in maintaining the structural integrity of connective tissues and sensing changes in the biomechanical environment of cells. The objective of the present investigation was to extend our understanding of the effect of cyclic mechanical strain on the expression of adhesion-related genes by human periodontal ligament cells.


METHODS
Cultured periodontal ligament cells were subjected to a cyclic in-plane tensile deformation of 12% for 5 s (0.2 Hz) every 90 s for 6-24 h in a Flexercell FX-4000 Strain Unit. The following parameters were measured: (i) cell viability by the MTT assay; (ii) caspase-3 and -7 activity; and (iii) the expression of 84 genes encoding adhesion-related molecules using real-time RT-PCR microarrays.


RESULTS
Mechanical stress reduced the metabolic activity of deformed cells at 6 h, and caspase-3 and -7 activity at 6 and 12 h. Seventy-three genes were detected at critical threshold values < 35. Fifteen showed a significant change in relative expression: five cell adhesion molecules (ICAM1, ITGA3, ITGA6, ITGA8 and NCAM1), three collagen α-chains (COL6A1, COL8A1 and COL11A1), four MMPs (ADAMTS1, MMP8, MMP11 and MMP15), plus CTGF, SPP1 and VTN. Four genes were upregulated (ADAMTS1, CTGF, ICAM1 and SPP1) and 11 downregulated, with the range extending from a 1.76-fold induction of SPP1 at 12 h to a 2.49-fold downregulation of COL11A1 at 24 h.


CONCLUSIONS
The study has identified several mechanoresponsive adhesion-related genes, and shown that onset of mechanical stress was followed by a transient reduction in overall cellular activity, including the expression of two apoptosis 'executioner' caspases.
Faculty of Dentistry, National University of Singapore, Singapore.
A
A
Saminathan
K J
KJ
Vinoth
D C
DC
Wescott
M N
MN
Pinkerton
T J
TJ
Milne
T
T
Cao
M C
MC
Meikle
D051722:ADAM Proteins / Q000032:analysis; D000071097:ADAMTS1 Protein; D001696:Biomechanical Phenomena; D019002:CD56 Antigen / Q000032:analysis; D053148:Caspase 3 / Q000032:analysis; D053179:Caspase 7 / Q000032:analysis; D002448:Cell Adhesion / Q000235:genetics; D018929:Cell Culture Techniques; D048430:Cell Shape / Q000235:genetics; D002470:Cell Survival / Q000235:genetics; D024142:Collagen Type VI / Q000032:analysis; D024102:Collagen Type VIII / Q000032:analysis; D024161:Collagen Type XI / Q000032:analysis; D055513:Connective Tissue Growth Factor / Q000032:analysis; D020869:Gene Expression Profiling / Q000379:methods*; D005786:Gene Expression Regulation / Q000235:genetics; D006801:Humans; D039001:Integrin alpha Chains / Q000032:analysis; D039422:Integrin alpha3 / Q000032:analysis; D039503:Integrin alpha6 / Q000032:analysis; D018799:Intercellular Adhesion Molecule-1 / Q000032:analysis; D053507:Matrix Metalloproteinase 11 / Q000032:analysis; D053517:Matrix Metalloproteinase 15 / Q000032:analysis; D020784:Matrix Metalloproteinase 8 / Q000032:analysis; D053495:Osteopontin / Q000032:analysis; D010513:Periodontal Ligament / Q000166:cytology*; D013314:Stress, Mechanical; D013997:Time Factors; D019096:Vitronectin / Q000032:analysis
C526317:CCN2 protein, human; D019002:CD56 Antigen; C553839:Col6a1 protein, human; D024142:Collagen Type VI; D024102:Collagen Type VIII; D024161:Collagen Type XI; D039001:Integrin alpha Chains; D039422:Integrin alpha3; D039503:Integrin alpha6; C507098:MMP15 protein, human; C522918:NCAM1 protein, human; C506895:SPP1 protein, human; D019096:Vitronectin; C093856:integrin alpha8; D053495:Osteopontin; D018799:Intercellular Adhesion Molecule-1; D055513:Connective Tissue Growth Factor; D053148:Caspase 3; D053179:Caspase 7; D051722:ADAM Proteins; D000071097:ADAMTS1 Protein; C103859:ADAMTS1 protein, human; C511771:MMP11 protein, human; D053507:Matrix Metalloproteinase 11; D053517:Matrix Metalloproteinase 15; C488762:MMP8 protein, human; D020784:Matrix Metalloproteinase 8