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Pre-mRNA splicing imprints mRNA in the nucleus with a novel RNA-binding protein that persists in the cytoplasm
1Howard Hughes Medical Institute and Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, Philadelphia 19104, USA.
Abstract:
We describe a novel RNA binding protein, Y14, a predominantly nuclear nucleocytoplasmic shuttling protein. Interestingly, Y14 associates preferentially with mRNAs produced by splicing but not with pre-mRNAs, introns, or mRNAs produced from intronless cDNAs. Y14 associates with both nuclear mRNAs and newly exported cytoplasmic mRNAs. Splicing of a single intron is sufficient for Y14 association. Y14-containing nuclear complexes are different from general hnRNP complexes. They contain hnRNP proteins and several unique proteins including the mRNA export factor TAP. Thus, Y14 defines novel intermediates in the pathway of gene expression, postsplicing nuclear preexport mRNPs, and newly exported cytoplasmic mRNPs, whose composition is established by splicing. These findings suggest that pre-mRNA splicing imprints mRNA with a unique set of proteins that persists in the cytoplasm and thereby communicates the history of the transcript.
Insights
Researchers identified a new RNA binding protein, Y14, which binds to spliced messenger RNAs (mRNAs). This protein associates with mRNAs after splicing, marking them for export and persisting in the cytoplasm.
Area of Science:
- Molecular Biology
- Gene Expression
- RNA Processing
Background:
- Messenger RNA (mRNA) undergoes significant processing after transcription, including splicing, to become functional.
- The protein complexes associated with mRNA can influence its fate and function.
- Understanding the composition of these complexes is crucial for deciphering gene expression pathways.
Purpose of the Study:
- To identify and characterize novel RNA-binding proteins involved in mRNA processing and export.
- To investigate the association of the identified protein with different RNA species and its localization within the cell.
- To determine the role of this protein in the transition of mRNA from the nucleus to the cytoplasm.
Main Methods:
- Description of a novel RNA binding protein, Y14.
- Analysis of Y14 association with various RNA types (pre-mRNAs, introns, spliced mRNAs, intronless cDNAs).
- Investigation of Y14 localization (nuclear/cytoplasmic) and association with other proteins, including mRNA export factors like TAP.
Main Results:
- Y14 is a nuclear, nucleocytoplasmic shuttling protein.
- Y14 preferentially binds to spliced mRNAs, not pre-mRNAs or introns.
- Splicing of even a single intron triggers Y14 association.
- Y14 forms distinct nuclear complexes containing hnRNP proteins and the mRNA export factor TAP.
- Y14 is found on both nuclear and newly exported cytoplasmic mRNAs.
Conclusions:
- Y14 defines novel messenger ribonucleoprotein (mRNP) intermediates in gene expression: post-splicing nuclear pre-export mRNPs and newly exported cytoplasmic mRNPs.
- The composition of these mRNPs is determined by the splicing process.
- Pre-mRNA splicing imprints mRNA with a specific protein set (including Y14) that is maintained in the cytoplasm, potentially communicating the transcript's history.