A G-rich element forms a G-quadruplex and regulates BACE1 mRNA alternative splicing

Area of Science:

• Molecular Biology
• Neuroscience
• Genetics

Background:

• Alzheimer disease pathogenesis involves amyloid precursor protein (APP) cleavage by BACE1.
• The regulation of BACE1 alternative splicing, crucial for its activity, remains poorly understood.
• BACE1 produces amyloid-beta (Aβ) peptides implicated in Alzheimer disease.

Purpose of the Study:

• To investigate the regulatory mechanisms of BACE1 alternative splicing.
• To identify sequences and proteins involved in controlling BACE1 exon 3 splice site selection.
• To explore potential therapeutic strategies for Alzheimer disease targeting BACE1 regulation.

Main Methods:

• Identification of a G-rich sequence in BACE1 exon 3.
• Site-directed mutagenesis to study the G-rich sequence's function.
• Nuclease protection assays, NMR, and CD spectroscopy to analyze G-quadruplex formation.
• Protein binding assays and RNA immunoprecipitation to identify interacting proteins.
• Heterogeneous nuclear ribonucleoprotein H (hnRNP H) knockdown experiments.

Main Results:

• A G-rich sequence in BACE1 exon 3 was identified as critical for splice site selection.
• This sequence forms a G-quadruplex structure, influencing the ratio of BACE1 mRNA isoforms.
• hnRNP H binds to the G-rich sequence and regulates BACE1 alternative splicing.
• hnRNP H knockdown reduced full-length BACE1 mRNA and decreased Aβ production.

Conclusions:

• The G-quadruplex structure in BACE1 exon 3 is a key regulator of alternative splicing.
• hnRNP H plays a significant role in BACE1 splicing and Aβ production.
• Targeting the BACE1 G-quadruplex or hnRNP H offers novel therapeutic avenues for Alzheimer disease.