Enhanced caffeine-induced Ca2+ release in the 3xTg-AD mouse model of Alzheimer's disease.
Alzheimer's disease (AD) is the most prevalent form of dementia among the elderly and is a complex disorder that involves altered proteolysis, oxidative stress and disruption of ion homeostasis. Animal models have proven useful in studying the impact of mutant AD-related genes on other cellular signaling pathways, such as Ca2+ signaling. Along these lines, disturbances of intracellular Ca2+ ([Ca2+]i) homeostasis are an early event in the pathogenesis of AD. Here, we have employed microfluorimetric measurements of [Ca2+]i to investigate disturbances in Ca2+ homeostasis in primary cortical neurons from a triple transgenic mouse model of Alzheimer's disease (3xTg-AD). Application of caffeine to mutant presenilin-1 knock-in neurons (PS1KI) and 3xTg-AD neurons evoked a peak rise of [Ca2+]i that was significantly greater than those observed in non-transgenic neurons, although all groups had similar decay rates of their Ca2+ transient. This finding suggests that Ca2+ stores are greater in both PS1KI and 3xTg-AD neurons as calculated by the integral of the caffeine-induced Ca2+ transient signal. Western blot analysis failed to identify changes in the levels of several Ca2+ binding proteins (SERCA-2B, calbindin, calsenilin and calreticulin) implicated in the pathogenesis of AD. However, ryanodine receptor expression in both PS1KI and 3xTg-AD cortex was significantly increased. Our results suggest that the enhanced Ca2+ response to caffeine observed in both PS1KI and 3xTg-AD neurons may not be attributable to an alteration of endoplasmic reticulum store size, but to the increased steady-state levels of the ryanodine receptor.
Smith
Ian F
IF
Department of Neurobiology and Behavior, University of California, Irvine, California 92697-4545, USA.
Hitt
Brian
B
Green
Kim N
KN
Oddo
Salvatore
S
LaFerla
Frank M
FM
D000544:Alzheimer Disease / Q000235:genetics / Q000378:metabolism* / Q000503:physiopathology; D000818:Animals; D001921:Brain / Q000187:drug effects / Q000378:metabolism* / Q000503:physiopathology; D002110:Caffeine / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D002135:Calcium-Binding Proteins / Q000187:drug effects / Q000378:metabolism; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism; D004195:Disease Models, Animal; D006706:Homeostasis / Q000187:drug effects / Q000502:physiology; D008565:Membrane Proteins / Q000235:genetics; D051379:Mice; D008822:Mice, Transgenic; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D053764:Presenilin-1; D019837:Ryanodine Receptor Calcium Release Channel / Q000187:drug effects / Q000378:metabolism*; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology
D002135:Calcium-Binding Proteins; D008565:Membrane Proteins; D010726:Phosphodiesterase Inhibitors; D053764:Presenilin-1; D019837:Ryanodine Receptor Calcium Release Channel; D002110:Caffeine; D002118:Calcium