A G-rich element forms a G-quadruplex and regulates BACE1 mRNA alternative splicing.
β-Site amyloid precursor protein (APP) cleaving enzyme 1 (BACE1) is the transmembrane aspartyl protease that catalyzes the first cleavage step in the proteolysis of the APP to the amyloid β-protein (Aβ), a process involved in the pathogenesis of Alzheimer disease. BACE1 pre-mRNA undergoes complex alternative splicing, the regulation of which is not well understood. We identified a G-rich sequence within exon 3 of BACE1 involved in controlling splice site selection. Mutation of the G-rich sequence decreased use of the normal 5' splice site of exon 3, which leads to full-length and proteolytically active BACE1, and increased use of an alternative splice site, which leads to a shorter, essentially inactive isoform. Nuclease protection assays, nuclear magnetic resonance, and circular dichroism spectroscopy revealed that this sequence folds into a G-quadruplex structure. Several proteins were identified as capable of binding to the G-rich sequence, and one of these, heterogeneous nuclear ribonucleoprotein H, was found to regulate BACE1 exon 3 alternative splicing and in a manner dependent on the G-rich sequence. Knockdown of heterogeneous nuclear ribonucleoprotein H led to a decrease in the full-length BACE1 mRNA isoform as well as a decrease in Aβ production from APP, suggesting new possibilities for therapeutic approaches to Alzheimer's disease.
Center for Neurologic Diseases, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA.
Jean-François
JF
Fisette
Daniel R
DR
Montagna
Mihaela-Rita
MR
Mihailescu
Michael S
MS
Wolfe
D017398:Alternative Splicing / Q000235:genetics*; D053829:Amyloid Precursor Protein Secretases / Q000235:genetics*; D016564:Amyloid beta-Protein Precursor / Q000235:genetics / Q000378:metabolism; D016282:Aspartic Acid Endopeptidases / Q000235:genetics*; D001483:Base Sequence; D002478:Cells, Cultured; D002942:Circular Dichroism; D004797:Enzyme-Linked Immunosorbent Assay; D005091:Exons / Q000235:genetics; D054856:G-Quadruplexes; D006801:Humans; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary; D012333:RNA, Messenger / Q000235:genetics*; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014162:Transfection
D016564:Amyloid beta-Protein Precursor; D012333:RNA, Messenger; D053829:Amyloid Precursor Protein Secretases; D016282:Aspartic Acid Endopeptidases; C509280:BACE1 protein, human