HnRNP L binds a cis-acting RNA sequence element that enables intron-dependent gene expression

Area of Science:

• Molecular Biology
• Gene Expression Regulation
• RNA Processing

Background:

• Most pre-mRNAs require introns for efficient processing in eukaryotes.
• Intronless genes present challenges for efficient gene expression.
• Understanding cis-acting elements is crucial for intron-independent gene expression.

Purpose of the Study:

• To identify cis-acting RNA sequence elements enabling intron-independent gene expression.
• To investigate the role of specific proteins in this process.
• To explore applications for expressing intron-dependent genes via cDNA.

Main Methods:

• Construction of chimeric genes combining HSV-TK and beta-globin sequences.
• Transient transfection assays to evaluate RNA accumulation.
• RNA UV-cross-linking and protein binding assays.
• Analysis of RNA-protein interactions using hnRNP L.

Main Results:

• A 119-nucleotide HSV-TK sequence element was identified that promotes cytoplasmic accumulation of globin RNA without splicing.
• A 68-kD protein, identified as hnRNP L, specifically binds to this element.
• hnRNP L binding to the RNA element correlates with increased cytoplasmic RNA accumulation.
• This interaction demonstrates sequence-specific RNA-protein involvement in intron-independent expression.

Conclusions:

• hnRNP L binds sequence-specifically to an RNA element that supports intron-independent gene expression.
• Intron-independent pre-mRNA processing and transport involve RNA-protein interactions.
• This identified element may facilitate the expression of cDNA versions of intron-dependent genes.