Â-AMYLOID-MEDIATED INDUCTION AND ACTIVATION OF P19INK4D INVOLVES CALCIUM-DEPENDENT SIGNALING

MARÍA F. OGARA; PABLO F. SIRKIN; NICOLÁS PREGI; EDUARDO T. CÁNEPA

Villa Carlos Paz - Córdoba

Congreso; XLIV Reunión Anual de la Sociedad Argentina de Investigacion en Bioquímica y Biologia Molecular; 2008

Sociedad Argentina de Investigacion en Bioquímica y Biologia Molecular

Â-AMYLOID-MEDIATED INDUCTION AND ACTIVATION OF P19INK4D INVOLVES CALCIUM-DEPENDENT SIGNALING Ogara|||MF; Sirkin|||PF; Pregi|||N; Cánepa|||ET Laboratorio de Biología Molecular-Departamento de Química Biológica-FCEN-UBA-Buenos Aires E-mail: flopyogara@qb.fcen.uba.ar â-amyloid,a key player in neurodegenerative diseases and the main component of senile plaques, acts by causing oxidative stress: lipid and protein oxidation and DNA damage. In response to genotoxic stress, p19INK4d, a member of the INK4 family of cell cycle inhibitors, becomes transcriptionally induced and phosphorylated. p19 improves DNA repair and reduces apoptosis. However, the mechanism leading to p19 induction and activation in response to â-amyloid remains unknown. Our working hypothesis is that â-amyloid, by increasing intracellular Ca2+ levels, activates calpains, which convert CDK5 regulatory subunit p35 to its active form, p25. We show that p19 is phosphorylated by CDKs. We used SH-SY5Y cells differentiated with retinoic acid as a neuronal model. By Northern blot and metabolic labeling with 32P, â-amyloid treatment of both differentiated and undifferentiated cells induced the expression and phosphorylation of p19 in a dose-dependent manner, as well as the expression of p35. Similar results were obtained with A23187, a Ca2+ ionophore. Antisense downregulation of CDKs prevented the â-amyloid induced phosphorylation of p19. Our results show that Ca2+-dependent signaling becomes activated upon â-amyloid treatment and appears to be involved in the induction and activation of p19INK4d.. Â-AMYLOID-MEDIATED INDUCTION AND ACTIVATION OF P19INK4D INVOLVES CALCIUM-DEPENDENT SIGNALING Ogara|||MF; Sirkin|||PF; Pregi|||N; Cánepa|||ET Laboratorio de Biología Molecular-Departamento de Química Biológica-FCEN-UBA-Buenos Aires E-mail: flopyogara@qb.fcen.uba.ar â-amyloid,a key player in neurodegenerative diseases and the main component of senile plaques, acts by causing oxidative stress: lipid and protein oxidation and DNA damage. In response to genotoxic stress, p19INK4d, a member of the INK4 family of cell cycle inhibitors, becomes transcriptionally induced and phosphorylated. p19 improves DNA repair and reduces apoptosis. However, the mechanism leading to p19 induction and activation in response to â-amyloid remains unknown. Our working hypothesis is that â-amyloid, by increasing intracellular Ca2+ levels, activates calpains, which convert CDK5 regulatory subunit p35 to its active form, p25. We show that p19 is phosphorylated by CDKs. We used SH-SY5Y cells differentiated with retinoic acid as a neuronal model. By Northern blot and metabolic labeling with 32P, â-amyloid treatment of both differentiated and undifferentiated cells induced the expression and phosphorylation of p19 in a dose-dependent manner, as well as the expression of p35. Similar results were obtained with A23187, a Ca2+ ionophore. Antisense downregulation of CDKs prevented the â-amyloid induced phosphorylation of p19. Our results show that Ca2+-dependent signaling becomes activated upon â-amyloid treatment and appears to be involved in the induction and activation of p19INK4d..