Alternative exon definition events control the choice between nuclear retention and cytoplasmic export of U11/U12-65K...

Area of Science:

• Molecular Biology
• Cell Biology
• RNA Biology

Background:

• Cellular homeostasis relies on precise regulation of gene expression.
• The minor spliceosome, crucial for U12-type introns, requires specific protein components.
• Dysregulation of spliceosome components can impact cellular function and development.

Purpose of the Study:

• To elucidate the regulatory mechanisms controlling the abundance of U11/U12-65K, a key component of the minor spliceosome.
• To investigate the role of mRNA 3' untranslated region (3'UTR) length in regulating U11/U12-65K expression.
• To understand how alternative splicing and mRNA processing events influence spliceosome component levels.

Main Methods:

• Analysis of mRNA isoforms with varying 3'UTR lengths.
• Investigation of U11 snRNP interactions with target mRNAs.
• Study of nuclear retention and splicing of non-productive mRNA isoforms.
• Examination of alternative terminal exon definition and polyadenylation signals.

Main Results:

• A negative feedback loop regulates U11-48K and U11/U12-65K mRNA levels via alternative 3'UTR lengths.
• A binary switch between short (productive) and long (non-productive) 3'UTR isoforms is dynamically regulated.
• Nuclear retention of long 3'UTR isoforms is mediated by U11 snRNP binding.
• Alternative splicing and polyadenylation signals dictate the choice between mRNA isoforms.

Conclusions:

• The intricate molecular circuitry involving alternative mRNA processing controls the abundance of a key spliceosomal protein.
• This mechanism dynamically regulates spliceosome component levels in developing neurons and other cell types.
• The findings provide new insights into the nuclear export regulation of non-productively spliced mRNAs.