Competitive regulation of alternative splicing and alternative polyadenylation by hnRNP H and CstF64 determines acetylcholinesterase isoforms

Nucleic Acids Res. 2017 Feb 17;45(3):1455-1468. doi: 10.1093/nar/gkw823.

Abstract

Acetylcholinesterase (AChE), encoded by the ACHE gene, hydrolyzes the neurotransmitter acetylcholine to terminate synaptic transmission. Alternative splicing close to the 3΄ end generates three distinct isoforms of AChET, AChEH and AChER. We found that hnRNP H binds to two specific G-runs in exon 5a of human ACHE and activates the distal alternative 3΄ splice site (ss) between exons 5a and 5b to generate AChET. Specific effect of hnRNP H was corroborated by siRNA-mediated knockdown and artificial tethering of hnRNP H. Furthermore, hnRNP H competes for binding of CstF64 to the overlapping binding sites in exon 5a, and suppresses the selection of a cryptic polyadenylation site (PAS), which additionally ensures transcription of the distal 3΄ ss required for the generation of AChET. Expression levels of hnRNP H were positively correlated with the proportions of the AChET isoform in three different cell lines. HnRNP H thus critically generates AChET by enhancing the distal 3΄ ss and by suppressing the cryptic PAS. Global analysis of CLIP-seq and RNA-seq also revealed that hnRNP H competitively regulates alternative 3΄ ss and alternative PAS in other genes. We propose that hnRNP H is an essential factor that competitively regulates alternative splicing and alternative polyadenylation.

MeSH terms

  • Acetylcholinesterase / genetics*
  • Acetylcholinesterase / metabolism*
  • Alternative Splicing*
  • Base Sequence
  • Binding, Competitive
  • Caco-2 Cells
  • Cell Line
  • Cleavage Stimulation Factor
  • Exons
  • GPI-Linked Proteins / genetics
  • GPI-Linked Proteins / metabolism
  • Gene Expression Regulation, Enzymologic
  • Gene Knockdown Techniques
  • HEK293 Cells
  • HeLa Cells
  • Heterogeneous-Nuclear Ribonucleoprotein Group F-H / antagonists & inhibitors
  • Heterogeneous-Nuclear Ribonucleoprotein Group F-H / genetics*
  • Heterogeneous-Nuclear Ribonucleoprotein Group F-H / metabolism*
  • Humans
  • Isoenzymes / genetics
  • Isoenzymes / metabolism
  • Models, Biological
  • Polyadenylation*
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • RNA-Binding Proteins / genetics*
  • RNA-Binding Proteins / metabolism*
  • Regulatory Elements, Transcriptional

Substances

  • CSTF2T protein, human
  • Cleavage Stimulation Factor
  • GPI-Linked Proteins
  • Heterogeneous-Nuclear Ribonucleoprotein Group F-H
  • Isoenzymes
  • RNA, Messenger
  • RNA-Binding Proteins
  • ACHE protein, human
  • Acetylcholinesterase