title: Advanced glycation end products induce apoptosis in fibroblasts through activation of ROS, MAP kinases, and the FOXO1 transcription factor.
abstract: Advanced glycation end products (AGEs) are elevated in aged and diabetic individuals and are associated with pathological changes associated with both. Previously we demonstrated that the AGE N(epsilon)-(carboxymethyl)lysine (CML)-collagen induced fibroblast apoptosis through the cytoplasmic and mitochondrial pathways and the global induction of proapoptotic genes. In the present study we investigated upstream mechanisms of CML-collagen-induced apoptosis. CML-collagen induced activation of the proapoptotic transcription factor FOXO1 compared with unmodified collagen. When FOXO1 was silenced, CML-collagen-stimulated apoptosis was reduced by approximately 75% compared with fibroblasts incubated with nonsilencing small interfering RNA, demonstrating the functional significance of FOXO1 activation (P < 0.05). CML-collagen but not control collagen also induced a 3.3-fold increase in p38 and a 5.6-fold increase in JNK(1/2) activity (P < 0.05). With the use of specific inhibitors, activation of p38 and JNK was shown to play an important role in CML-collagen-induced activation of FOXO1 and caspase-3. Moreover, inhibition of p38 and JNK reduced CML-collagen-stimulated apoptosis by 48 and 57%, respectively, and by 89% when used together (P < 0.05). In contrast, inhibition of the phosphatidylinositol 3-kinase/Akt pathway enhanced FOXO1 activation. p38 and JNK stimulation by CML-collagen was almost entirely blocked when formation of ROS was inhibited and was partially reduced by NO and ceramide inhibitors. These inhibitors also reduced apoptosis to a similar extent. Together these data support a model in which AGE-induced apoptosis involves the formation of ROS, NO, and ceramide and leads to p38 and JNK MAP kinase activation, which in turn induces FOXO1 and caspase-3.
authors.affiliation: Dept. of Periodontology and Oral Biology, Boston Univ. School of Dental Medicine, Boston, MA 02118, USA.
authors.forename: Mani
authors.initials: M
authors.lastname: Alikhani
authors.forename: Christine M
authors.initials: CM
authors.lastname: Maclellan
authors.forename: Markos
authors.initials: M
authors.lastname: Raptis
authors.forename: Siddarth
authors.initials: S
authors.lastname: Vora
authors.forename: Philip C
authors.initials: PC
authors.lastname: Trackman
authors.forename: Dana T
authors.initials: DT
authors.lastname: Graves
mesh_terms: D000818:Animals; D017209:Apoptosis; D053148:Caspase 3 / Q000378:metabolism; D002417:Cattle; D002478:Cells, Cultured; D002518:Ceramides / Q000494:pharmacology; D003094:Collagen / Q000502:physiology; D004789:Enzyme Activation; D005347:Fibroblasts / Q000378:metabolism*; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors / Q000378:metabolism*; D017127:Glycation End Products, Advanced / Q000502:physiology*; D006801:Humans; D020935:MAP Kinase Signaling System / Q000502:physiology*; D009569:Nitric Oxide / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D053148:Caspase 3; D002518:Ceramides; D003094:Collagen; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors; D017127:Glycation End Products, Advanced; D009569:Nitric Oxide; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D047428:Protein Kinase Inhibitors; D017382:Reactive Oxygen Species; C085126:FOXO1 protein, human