ABSTRACT
Title
Deregulation of calcium signaling in hippocampal astrocytes in TAT-PRO model of Alzheimer’s disease
Authors
D. Lim1, A. Grolla1, E. Marcello2, F. Gardoni2, M. Di Luca2, P. Canonico1, A.A. Genazzani1.
1 DISCAFF, University of Oriental Piedmont "Amedeo Avogadro", via Bovio 6, 28100 Novara, Italy
2Institute of Pharmacological Sciences, School of Pharmacy, University of Milan, via Balzaretti 9, 20133 Milan, Italy
1 DISCAFF, University of Oriental Piedmont "Amedeo Avogadro", via Bovio 6, 28100 Novara, Italy
2Institute of Pharmacological Sciences, School of Pharmacy, University of Milan, via Balzaretti 9, 20133 Milan, Italy
Abstract
The hallmark of Alzheimer’s disease are extracellular depositions of aggregates of beta amyloid (Ab) called senile plaques and intracellular accumulation of neurofiblillary tangles composed of hyperfosforylated microtubule-associated protein tau. Ab is formed by the aberrant processing of amyloid precursor protein (APP) which is cleaved by a concerted action of two proteases, beta-secretase (BACE) and gamma-secretase complex. Mutations of several genes including APP, presenilin (PS) 1/2, ApoE4 and SORL1 favor the activity of BACE which shifts the APP processing to the production of highly fibrillogenic Abeta(1-42) species. Physiologically, Ab production is counteracted by the activity of the alpha-secretase ADAM10, which directs the APP processing to a non-amyloidogenic pathway which gives rise to soluble APPalpha and membrane-bound C-terminal fragment alpha (CTFalpha).
Calcium is an ubiquitous and potent carrier of signal in cell, that, depending on its modality, can be both beneficial and detrimental for cell survival (Carafoli, 2004). According to the “calcium hypothesis” of AD, long lasting overload of the cytoplasm and the endoplasmic reticulum (ER) with Ca2+, somehow induced by the amyloidogenic APP processing, represent one of the starting points for the cascade of events leading to neuronal death, although the mechanisms of the Ca2+ deregulation in AD are poorly understood (for recent reviews see Berridge, 2010; Supnet and Bezprozvanny, 2010),.
Recently, Marcello with collaborators (Marcello et. al., 2007) developed a model of AD in which TAT-driven peptide corresponding to the prolin-reach domain of ADAM10 competitively disrupts interaction of ADAM10 with partner proteins thereby shifting the APP processing towards the pathway that produce toxic Abeta(1-42) species. Here we used the TAT-PRO AD in vitro model to study in depth the Abeta-related alterations of calcium homeostasis in neuronal and glial hippocampal primary cultures. Our data demonstrate that Tat-Pro deregulates Ca2+ homeostasis mainly in astroglial cells. In particular, Ab potentiated DHPG-induced Ca2+ transients specifically in astrocytes. This appeared to correlate with an increased expression of two key components of Ca2+ signaling, mGluR5 and IP3R1.
Calcium is an ubiquitous and potent carrier of signal in cell, that, depending on its modality, can be both beneficial and detrimental for cell survival (Carafoli, 2004). According to the “calcium hypothesis” of AD, long lasting overload of the cytoplasm and the endoplasmic reticulum (ER) with Ca2+, somehow induced by the amyloidogenic APP processing, represent one of the starting points for the cascade of events leading to neuronal death, although the mechanisms of the Ca2+ deregulation in AD are poorly understood (for recent reviews see Berridge, 2010; Supnet and Bezprozvanny, 2010),.
Recently, Marcello with collaborators (Marcello et. al., 2007) developed a model of AD in which TAT-driven peptide corresponding to the prolin-reach domain of ADAM10 competitively disrupts interaction of ADAM10 with partner proteins thereby shifting the APP processing towards the pathway that produce toxic Abeta(1-42) species. Here we used the TAT-PRO AD in vitro model to study in depth the Abeta-related alterations of calcium homeostasis in neuronal and glial hippocampal primary cultures. Our data demonstrate that Tat-Pro deregulates Ca2+ homeostasis mainly in astroglial cells. In particular, Ab potentiated DHPG-induced Ca2+ transients specifically in astrocytes. This appeared to correlate with an increased expression of two key components of Ca2+ signaling, mGluR5 and IP3R1.