title: Modulation of collagen gel compaction by extracellular ATP is MAPK and NF-kappaB pathways dependent.
abstract: Understanding the mechanisms that regulate mechanosensitivity in osteoblasts is important for controlling bone homeostasis and the development of new drugs to combat bone loss. It is believed that prestress or force generation (the tensile stress within the cell body) plays an important role in regulating cellular mechanosensitivity. In the present study, a three-dimensional (3D) collagen culture was used to monitor the change in prestress of the osteoblast-like cells. Collagen hydrogel compaction has been used as an indicator of the change in the degree of cell prestress. Previous results in this model demonstrated that extracellular ATP reduced the mechanosensitivity of osteoblasts by reducing cellular prestress. To elucidate the potential mechanisms involved in this process, the signaling pathways downstream of P2 purinoceptors involved in regulating the compaction of type I collagen gels were investigated. By using specific inhibitors to these signaling pathways, we found that ATP-induced reduction in collagen gel compaction rate is dependent on mitogen-activated protein kinase (MAKP) and NF-kappaB pathways. However, blocking protein kinase C with GF109203X did not change the compaction kinetics in the presence of ATPgammaS. Moreover, blocking cyclic AMP (cAMP), phosphatidylinositol-3 kinase (PI3K), calmodulin (CaM) or L-type voltage sensitive calcium channels did not affect ATP's ability to reduce collagen gel compaction. The results from the present and previous studies indicate that extracellular ATP may act as a negative feedback modulator in the mechanotransduction system since mechanical stimuli increase ATP release from stimulated cells.
authors.affiliation: Flexcell International Corporation, 437 Dimmocks Mill Rd., Suite 28, Hillsborough, NC 27278, USA. jie@flexcellint.com
authors.forename: Jie
authors.initials: J
authors.lastname: Qi
authors.forename: Liqun
authors.initials: L
authors.lastname: Chi
authors.forename: Jian
authors.initials: J
authors.lastname: Wang
authors.forename: Ruwan
authors.initials: R
authors.lastname: Sumanasinghe
authors.forename: Michelle
authors.initials: M
authors.lastname: Wall
authors.forename: Mari
authors.initials: M
authors.lastname: Tsuzaki
authors.forename: Albert J
authors.initials: AJ
authors.lastname: Banes
mesh_terms: D016475:3T3 Cells; D000255:Adenosine Triphosphate / Q000378:metabolism* / Q000494:pharmacology; D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D001483:Base Sequence; D002147:Calmodulin / Q000378:metabolism; D003094:Collagen / Q000235:genetics / Q000378:metabolism*; D017931:DNA Primers / Q000235:genetics; D045604:Extracellular Fluid / Q000378:metabolism; D005782:Gels; D015870:Gene Expression / Q000187:drug effects; D007700:Kinetics; D020935:MAP Kinase Signaling System; D040542:Mechanotransduction, Cellular; D051379:Mice; D008954:Models, Biological; D009219:Myosin-Light-Chain Kinase / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism*; D010006:Osteoblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D018048:Receptors, Purinergic P2 / Q000378:metabolism; D013314:Stress, Mechanical
chemical_list: D002147:Calmodulin; D017931:DNA Primers; D005782:Gels; D016328:NF-kappa B; D018048:Receptors, Purinergic P2; D000255:Adenosine Triphosphate; D003094:Collagen; D019869:Phosphatidylinositol 3-Kinases; D009219:Myosin-Light-Chain Kinase; D000262:Adenylyl Cyclases