title: Akt-mediated anti-apoptotic effects of substance P in Anti-Fas-induced apoptosis of human tenocytes.
abstract: Substance P (SP) and its receptor, the neurokinin-1 receptor (NK-1 R), are expressed by human tenocytes, and they are both up-regulated in cases of tendinosis, a condition associated with excessive apoptosis. It is known that SP can phosphorylate/activate the protein kinase Akt, which has anti-apoptotic effects. This mechanism has not been studied for tenocytes. The aims of this study were to investigate if Anti-Fas treatment is a good apoptosis model for human tenocytes in vitro, if SP protects from Anti-Fas-induced apoptosis, and by which mechanisms SP mediates an anti-apoptotic response. Anti-Fas treatment resulted in a time- and dose-dependent release of lactate dehydrogenase (LDH), i.e. induction of cell death, and SP dose-dependently reduced the Anti-Fas-induced cell death through a NK-1 R specific pathway. The same trend was seen for the TUNEL assay, i.e. SP reduced Anti-Fas-induced apoptosis via NK-1 R. In addition, it was shown that SP reduces Anti-Fas-induced decrease in cell viability as shown with crystal violet assay. Protein analysis using Western blot confirmed that Anti-Fas induces cleavage/activation of caspase-3 and cleavage of PARP; both of which were inhibited by SP via NK-1 R. Finally, SP treatment resulted in phosphorylation/activation of Akt as shown with Western blot, and it was confirmed that the anti-apoptotic effect of SP was, at least partly, induced through the Akt-dependent pathway. In conclusion, we show that SP reduces Anti-Fas-induced apoptosis in human tenocytes and that this anti-apoptotic effect of SP is mediated through NK-1 R and Akt-specific pathways.
authors.affiliation: Department of Integrative Medical Biology, Anatomy, Umeå University, Umeå, Sweden.
authors.forename: Ludvig J
authors.initials: LJ
authors.lastname: Backman
authors.forename: Patrik
authors.initials: P
authors.lastname: Danielson
mesh_terms: D000125:Achilles Tendon / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D000906:Antibodies / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3 / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D010766:Phosphorylation; D011065:Poly(ADP-ribose) Polymerases / Q000235:genetics / Q000378:metabolism; D061251:Primary Cell Culture; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics* / Q000378:metabolism; D018040:Receptors, Neurokinin-1 / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D013373:Substance P / Q000494:pharmacology / Q000502:physiology*; D019014:fas Receptor / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism
chemical_list: D000906:Antibodies; C491901:FAS protein, human; D018040:Receptors, Neurokinin-1; D019014:fas Receptor; D013373:Substance P; D007770:L-Lactate Dehydrogenase; D011065:Poly(ADP-ribose) Polymerases; D051057:Proto-Oncogene Proteins c-akt; D053148:Caspase 3