Effect of tension-force on plasminogen activator activity from human periodontal ligament cells.
The plasminogen activator (PA)-plasmin proteolytic system has recently received considerable attention because of its participation in a wide variety of biological activities and in pathological conditions involving tissue destruction. Excessive mechanical stress such as occlusal trauma is associated with alveolar bone loss in severe periodontitis. Therefore, mechanical stress may involve degradation of the extracellular matrix by occlusal trauma through activation of the PA-plasmin proteolytic system. We examined the effects of mechanical stress on PA activity, gene expressions of tissue type (t) PA, urokinase type (u) PA and PA inhibitor-1 (PAI-1) in human PDL cells. Human PDL cells were cultured on flexible-bottomed culture plates and placed on a Flexercell Strain Unit. The cells were flexed at 6 cycles (5 s strain, 5 s relaxation) at 9% and 18% elongation for 5 d. Application of tension-force induced significantly higher PA activity in stressed PDL cells than in non-stressed controls, and did so in a time- and magnitude-dependent manner (p < 0.001, ANOVA). Western-blot analysis revealed that the high level of activity was due to tPA and not uPA. Gene expression of tPA mRNA in stressed PDL cells, as examined by RT-PCR, increased on d 5. These findings suggest that tPA may be involved in periodontal metabolism in response to mechanical stress.
Yamaguchi
M
M
Department of Biochemistry, Nihon University School of Dentistry at Matsudo, Chiba, Japan.
Shimizu
N
N
Ozawa
Y
Y
Saito
K
K
Miura
S
S
Takiguchi
H
H
Iwasawa
T
T
Abiko
Y
Y
D000704:Analysis of Variance; D015153:Blotting, Western; D002478:Cells, Cultured; D003799:Dental Stress Analysis; D004789:Enzyme Activation; D005347:Fibroblasts / Q000378:metabolism; D015870:Gene Expression; D006801:Humans; D010513:Periodontal Ligament / Q000166:cytology / Q000201:enzymology*; D017395:Plasminogen Activator Inhibitor 1 / Q000096:biosynthesis; D016133:Polymerase Chain Reaction; D015842:Serine Proteinase Inhibitors / Q000096:biosynthesis; D013314:Stress, Mechanical; D010959:Tissue Plasminogen Activator / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D014568:Urokinase-Type Plasminogen Activator / Q000037:antagonists & inhibitors / Q000096:biosynthesis
D017395:Plasminogen Activator Inhibitor 1; D015842:Serine Proteinase Inhibitors; D010959:Tissue Plasminogen Activator; D014568:Urokinase-Type Plasminogen Activator