title: Increased expression of the gamma-secretase components presenilin-1 and nicastrin in activated astrocytes and microglia following traumatic brain injury.
abstract: Gamma-secretase is an aspartyl protease composed of four proteins: presenilin (PS), nicastrin (Nct), APH1, and PEN2. These proteins assemble into a membrane complex that cleaves a variety of substrates within the transmembrane domain. The gamma-secretase cleavage products play an important role in various biological processes such as embryonic development and Alzheimer's disease (AD). The major role of gamma-secretase in brain pathology has been linked to AD and to the production of the amyloid beta-peptide. However, little is known about the possible role of gamma-secretase following acute brain insult. Here we examined by immunostaining the expression patterns of two gamma-secretase components, PS1 and Nct, in three paradigms of brain insult in mice: closed head injury, intracerebroventricular injection of LPS, and brain stabbing. Our results show that in naïve and sham-injured brains expression of PS1 and Nct is restricted mainly to neurons. However, following insult, the expression of both proteins is also observed in nonneuronal cells, consisting of activated astrocytes and microglia. Furthermore, the proteins are coexpressed within the same astrocytes and microglia, implying that these cells exhibit an enhanced gamma-secretase activity following brain damage. In view of the important role played by astrocytes and microglia in brain disorders, our findings suggest that gamma-secretase may participate in brain damage and repair processes by regulating astrocyte and microglia activation and/or function.
authors.affiliation: Department of Neurobiochemistry, George S Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv, Tel Aviv, Israel.
authors.forename: Yasmine
authors.initials: Y
authors.lastname: Nadler
authors.forename: Alexander
authors.initials: A
authors.lastname: Alexandrovich
authors.forename: Nikolaos
authors.initials: N
authors.lastname: Grigoriadis
authors.forename: Tobias
authors.initials: T
authors.lastname: Hartmann
authors.forename: Kosagi S Jagannatha
authors.initials: KS
authors.lastname: Rao
authors.forename: Esther
authors.initials: E
authors.lastname: Shohami
authors.forename: Reuven
authors.initials: R
authors.lastname: Stein
mesh_terms: D053829:Amyloid Precursor Protein Secretases / Q000378:metabolism*; D000818:Animals; D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism*; D001930:Brain Injuries / Q000139:chemically induced / Q000473:pathology*; D004195:Disease Models, Animal; D037502:Galectin 3 / Q000378:metabolism; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D008070:Lipopolysaccharides; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D017628:Microglia / Q000187:drug effects / Q000378:metabolism*; D010751:Phosphopyruvate Hydratase / Q000378:metabolism; D053764:Presenilin-1 / Q000378:metabolism*; D013997:Time Factors; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology*
chemical_list: D037502:Galectin 3; D005904:Glial Fibrillary Acidic Protein; D008070:Lipopolysaccharides; D008562:Membrane Glycoproteins; D053764:Presenilin-1; C413604:nicastrin protein; D053829:Amyloid Precursor Protein Secretases; D010751:Phosphopyruvate Hydratase