Mechanical tension alters semaphorin expression in the periodontium.
BACKGROUND
Periodontal remodeling requires coordinated cell movement. Semaphorins are cell-surface signals that regulate cell migration and may be differentially regulated by periodontal cells. Mechanical tension can regulate periodontal ligament (PDL) remodeling. We predicted that mechanical tension alters the expression of the subset of semaphorins in the periodontium likely to be most involved with regulating the remodeling of this tissue.


METHODS
PDL and gingival cells were exposed to mechanical tension, and their attachment and movement on collagen matrices were evaluated. Alterations in extracellular matrix and semaphorin transcript expression were monitored by semiquantitative reverse transcription-polymerase chain reaction.


RESULTS
Mechanical tension induced osteoclast regulatory transcripts in the PDL cells to a greater extent than gingival fibroblasts, increasing the expression of osteoprotegerin and decreasing receptor activator of nuclear factor-kappa B ligand. These mechanical forces reduced PDL cell mingling, without altering cell attachment or motility. Concurrently, these forces induced dynamic changes in several semaphorin molecules in PDL cells, increasing semaphorin 3D and 5B and decreasing semaphorin 7A. In addition, plexin transcript expression was altered, decreasing plexin A1 and increasing plexin C1. These changes were different than those observed in gingival fibroblasts.


CONCLUSIONS
These data suggest that a subset of semaphorins and plexins are dynamically regulated in the PDL. Because these molecules may be involved in cell guidance, changes in semaphorins may play a pivotal role in periodontal remodeling, affecting angiogenesis or PDL cell invasion into sites of injury.
Spencer
Amber Y
AY
Department of Cell Biology and Anatomy, Center of Excellence in Oral and Craniofacial Biology, School of Dentistry, Louisiana State University Health Science Center, New Orleans, LA 70119, USA.
Lallier
Thomas E
TE
D015703:Antigens, CD / Q000032:analysis; D001696:Biomechanical Phenomena; D002448:Cell Adhesion; D002465:Cell Movement; D002478:Cells, Cultured; D024042:Collagen Type I; D003470:Culture Media; D005109:Extracellular Matrix / Q000737:chemistry; D005347:Fibroblasts / Q000378:metabolism; D058851:GPI-Linked Proteins; D005881:Gingiva / Q000166:cytology / Q000378:metabolism; D006801:Humans; D008562:Membrane Glycoproteins / Q000032:analysis; D009419:Nerve Tissue Proteins / Q000032:analysis; D010006:Osteoblasts / Q000378:metabolism; D053244:Osteoprotegerin / Q000032:analysis; D010513:Periodontal Ligament / Q000166:cytology / Q000378:metabolism*; D053245:RANK Ligand / Q000032:analysis; D011956:Receptors, Cell Surface / Q000032:analysis; D011991:Receptors, Virus / Q000032:analysis; D039961:Semaphorins / Q000032:analysis*; D013314:Stress, Mechanical
D015703:Antigens, CD; D024042:Collagen Type I; D003470:Culture Media; D058851:GPI-Linked Proteins; D008562:Membrane Glycoproteins; D009419:Nerve Tissue Proteins; D053244:Osteoprotegerin; C492116:PLXNA1 protein, human; D053245:RANK Ligand; D011956:Receptors, Cell Surface; D011991:Receptors, Virus; C409766:SEMA3B protein, human; C118753:SEMA7A protein, human; D039961:Semaphorins; C112038:VESPR semaphorin receptor