Metals accelerate production of the aberrant splicing isoform of the presenilin-2.
Oxidative stress is a major risk factor for Alzheimer's disease (AD) and other neurodegenerative disorders. Metals are known to be one of the factors that contribute to oxidative stress. Recently, we reported that the aberrant splicing isoform (PS2V) generated by skipping exon5 of the presenilin-2 (PS2) gene is a diagnostic feature of sporadic AD (SAD). PS2V is inducible by exposure of human neuroblastoma to hypoxia. We examined whether this aberrant splicing was caused by metal-induced oxidative stress, such as exposure to aluminum. As a result, we demonstrated that exposure to aluminum accelerated PS2V production induced by hypoxia. This acceleration of the production of PS2V to hypoxia was caused by chronic aluminum exposure, but was not related to the intracellular content of aluminum. HMGA1a is a mediator of PS2V production, and it was induced by aluminum as well as by hypoxia. Induction of HMGA1a was increased by chronic exposure to aluminum, and a nuclear extract containing HMGA1a bound to a specific sequence on exon5 of PS2 pre-mRNA, as reported previously. Finally, the acceleration of PS2V production induced by aluminum under hypoxic conditions reflected, but has not yet been directly shown to cause, vulnerability to endoplasmic reticulum stress. These results suggest that exposure to some metals can accelerate and enhance PS2V generation, and that hypoxia plus chronic exposure to metals may promote the development of AD.
Department of Anatomy and Neuroscience, Osaka University Graduate School of Medicine, Osaka, Japan.
Shinsuke
S
Matsuzaki
Takayuki
T
Manabe
Taiichi
T
Katayama
Atsuko
A
Nishikawa
Takeshi
T
Yanagita
Hiroaki
H
Okuda
Yuichi
Y
Yasuda
Shingo
S
Miyata
Shunsuke
S
Meshitsuka
Masaya
M
Tohyama
D017398:Alternative Splicing / Q000187:drug effects*; D017607:Aluminum Compounds / Q000494:pharmacology; D000544:Alzheimer Disease / Q000209:etiology; D000998:Antiviral Agents / Q000494:pharmacology; D016923:Cell Death / Q000187:drug effects; D015687:Cell Hypoxia / Q000187:drug effects / Q000502:physiology; D045744:Cell Line, Tumor; D003300:Copper / Q000494:pharmacology; D019327:Copper Sulfate / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004721:Endoplasmic Reticulum / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D025741:HMGA1a Protein / Q000235:genetics / Q000378:metabolism; D006801:Humans; D058085:Iron Compounds / Q000494:pharmacology; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008670:Metals / Q000494:pharmacology*; D009447:Neuroblastoma / Q000188:drug therapy / Q000378:metabolism*; D009942:Organometallic Compounds / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology; D053766:Presenilin-2; D011753:Pyrones / Q000494:pharmacology; D013997:Time Factors; D014415:Tunicamycin / Q000494:pharmacology
D017607:Aluminum Compounds; D000998:Antiviral Agents; D058085:Iron Compounds; D008565:Membrane Proteins; D008670:Metals; D009942:Organometallic Compounds; C508861:PSEN2 protein, human; D053766:Presenilin-2; D011753:Pyrones; D014415:Tunicamycin; D025741:HMGA1a Protein; C067527:aluminum maltolate; D003300:Copper; D019327:Copper Sulfate; C029892:cupric chloride