Srp20 regulates TrkB pre-mRNA splicing to generate TrkB-Shc transcripts with implications for Alzheimer's disease.
Previously, we reported elevated levels of the neuron-specific tropomyosin receptor kinase B (TrkB) transcript, TrkB- sarc homology containing (Shc) in the hippocampus of Alzheimer's disease (AD) brains. In this study, we determined how TrkB-Shc transcripts are increased in AD. Utilizing a TrkB minigene transiently transfected into SHSY5Y cells, we found increased exon 19 inclusion in TrkB minigene transcripts (to generate TrkB-Shc) following cellular exposure to amyloid beta 1-42 (Αβ(42)). As this suggested altered TrkB pre-mRNA splicing in AD, we conducted an in silico screening for putative splice regulatory protein-binding sites in the intron/exon splice regulatory regions of exons 18 and 19 of the TrkB gene and then assessed their gene expression profiles using a microarray database of control/AD post-mortem human hippocampal brain tissue. We found significant changes in serine/arginine protein 20 (Srp20) gene expression in AD cases and confirmed this using a second cohort of control/AD. In vitro, we found increased Srp20 mRNA levels in SHSY5Y cells treated with Αβ(42) fibrils. Moreover, Srp20 over-expression was found to increase exon 19 inclusion in TrkB minigene transcripts and ratio of endogenous TrkB-Shc:TrkB-TK+ mRNA expression. Conversely, Srp20 expression knockdown produced the opposite effects. Our findings suggest that dysregulation of factors regulating TrkB pre-mRNA splicing may contribute to gene expression changes that occur in AD.
Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, NSW, Australia. jwong@uow.edu.au
Jenny
J
Wong
Brett
B
Garner
Glenda M
GM
Halliday
John B J
JB
Kwok
D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000235:genetics / Q000473:pathology; D016229:Amyloid beta-Peptides / Q000494:pharmacology; D000704:Analysis of Variance; D001665:Binding Sites / Q000235:genetics; D001921:Brain / Q000378:metabolism* / Q000473:pathology; D045744:Cell Line, Tumor; D005091:Exons / Q000187:drug effects / Q000235:genetics; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D006801:Humans; D008297:Male; D046228:Microarray Analysis; D009447:Neuroblastoma / Q000473:pathology; D010446:Peptide Fragments / Q000494:pharmacology; D011485:Protein Binding; D020033:Protein Isoforms; D012322:RNA Precursors / Q000235:genetics / Q000378:metabolism; D012326:RNA Splicing / Q000187:drug effects / Q000235:genetics*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics / Q000494:pharmacology; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D020813:Receptor, trkB / Q000235:genetics / Q000378:metabolism*; D000068103:Serine-Arginine Splicing Factors; D059467:Transcriptome
D016229:Amyloid beta-Peptides; D010446:Peptide Fragments; D020033:Protein Isoforms; D012322:RNA Precursors; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D016601:RNA-Binding Proteins; C491388:SRSF3 protein, human; C075222:amyloid beta-protein (1-42); D000068103:Serine-Arginine Splicing Factors; D020813:Receptor, trkB