title: Polypyrimidine tract binding protein (PTB) associates with intronic and exonic domains to squelch nuclear export of unspliced RNA.
abstract: Retention of unspliced pre-messenger RNA (pre-mRNA) in the nucleus is essential for cell survival. Available nuclear factors must recognize and discern between diverse export signals present in pre-mRNA to establish an export inhibitory complex. We found that polypyrimidine domains present in both intron and exon were important for export inhibition of a minigene transcript based on hepatitis B virus pregenomic RNA. Overexpression of PTB drastically reduced export and presence of RRM4 domain seemed critical. This inhibitory network overrode stimulation from an exonic export-facilitating element. We posit that binding of PTB to multiple loci on pre-mRNA regulates nuclear retention.
authors.affiliation: Department of Microbiology, University of Calcutta, University College of Science and Technology, 35 Ballygunge Circular Road, Kolkata 700 019, India.
authors.forename: Dipika
authors.initials: D
authors.lastname: Roy
authors.forename: Joydip
authors.initials: J
authors.lastname: Bhanja Chowdhury
authors.forename: Sagarmoy
authors.initials: S
authors.lastname: Ghosh
mesh_terms: D021581:Active Transport, Cell Nucleus; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism*; D005091:Exons; D006515:Hepatitis B virus / Q000378:metabolism; D006801:Humans; D007438:Introns; D038941:Polypyrimidine Tract-Binding Protein / Q000378:metabolism*; D011485:Protein Binding; D012322:RNA Precursors / Q000378:metabolism*; D012326:RNA Splicing; D012333:RNA, Messenger / Q000378:metabolism*
chemical_list: D012322:RNA Precursors; D012333:RNA, Messenger; D038941:Polypyrimidine Tract-Binding Protein
keywords: HBV; Nuclear retention; PRE; PTB; Pre-mRNA export