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P3‐424: Diet‐induced hyperhomocysteinemia increases amyloid‐beta levels in a mouse model of Alzheimer's disease by modulating the endoplasmatic reticulum stressor response
Author(s) -
Zhuo Jiamin,
Yao Yuemang,
Pratico Domenico
Publication year - 2008
Publication title -
alzheimer's and dementia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.713
H-Index - 118
eISSN - 1552-5279
pISSN - 1552-5260
DOI - 10.1016/j.jalz.2008.05.1995
Subject(s) - hyperhomocysteinemia , endocrinology , medicine , western blot , amyloid (mycology) , homocysteine , chemistry , immunostaining , genetically modified mouse , hippocampus , amyloid precursor protein , biology , alzheimer's disease , biochemistry , transgene , immunohistochemistry , disease , inorganic chemistry , gene
immunoprecipitation and luciferase reporter assays and investigated the regulation of MAPK signaling by LRRK2. Methods: LRRK2 constructs (WT, G2019S, R1441C, kinase dead) were expressed in C. elegans driven by the neuronal specific synaptobrevin promoter. The WT and G2019S lines were integrated, while the other lines were expressed as arrays. C. elegans lines were also crossed to lines carrying GFP driven by the dopamine transporter promoter. For mammalian cell work, epitope tagged LRRK2 constructs were transiently expressed in 293 cells. Results: Expressing LRRK2 strongly potentiated toxicity caused by tunicamycin, heat shock or proteasomal inhibition, which are stresses associated with increased protein misfolding. LRRK2 expression protected C. elegans against agents causing mitochondrial dysfunction, such as rotenone or paraquat, but protection by G2019S LRRK2 was less than protection by wild type LRRK2. In each case, knockdown of lrk-1, the C. elegans homologue of LRRK2 produced the opposite effect. Disease related mutations in LRRK2 specifically increased susceptibility of dopaminergic neurons. Binding studies in mammalian cells indicate that LRRK2 binds to MKK3, 6 and 7, which are upstream kinases regulating the p38 and JNK signaling cascades. LRRK2 appears to act by regulating the subcellular localization of the MKKs. Knockdown of the C. elegans equivalent of p38 or JNK abrogated the actions of LRRK2 in C. elegans. Conclusions: Our data indicate that LRRK2 modulates the p38 and JNK stress kinase cascades through interaction with MKK3, 6 and 7, and this regulation allows LRRK2 to modulate the response of neurons to stresses associated with neurodegenerative disease.