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Structurally distinct elements mediate internal ribosome entry within the 5'-noncoding region of a voltage-gated

Gwendolyn M Jang1, Louis E-C Leong, Lily T Hoang

  • 1Department of Microbiology and Molecular Genetics, College of Medicine, University of California, Irvine, California 92697, USA.

The Journal of Biological Chemistry
|September 2, 2004
PubMed

Insights

The 5' untranslated region of mouse Kv1.4 mRNA facilitates internal ribosome entry, crucial for gene expression in brain, heart, and muscle tissues. This region

Area of Science:

  • Molecular Biology
  • Neuroscience
  • Cardiology

Background:

  • Kv1.4 is a voltage-gated potassium channel crucial for neuronal and cardiac function.
  • The 5'-noncoding region (5'-NCR) of mRNA plays a significant role in regulating gene expression.
  • Understanding Kv1.4 mRNA regulation is vital for studying channelopathies and neurological disorders.

Purpose of the Study:

  • To investigate the role of the Kv1.4 5'-NCR in mediating internal ribosome entry.
  • To identify specific RNA elements within the 5'-NCR responsible for regulating Kv1.4 expression.
  • To elucidate the structural and functional interplay of RNA elements within the Kv1.4 5'-NCR.

Main Methods:

  • Internal ribosome entry assays in various cell types.
  • Enzymatic structure probing to predict RNA secondary structures.
  • Systematic deletion analysis of the Kv1.4 5'-NCR.
  • RNase cleavage assays to assess RNA structural integrity.

Main Results:

  • The 1.2-kb Kv1.4 5'-NCR mediates internal ribosome entry in brain, heart, and skeletal muscle cells.
  • Both upstream (1.0 kb) and downstream (0.2 kb) regions of the 5'-NCR independently support internal ribosome entry, with combined regions showing enhanced efficiency.
  • The 3'-most 0.2 kb forms stem-loop structures (X, Y, Z) and single-stranded regions (Psi, Omega), with stem-loop X potentially interacting with a polypyrimidine tract.
  • Deletions in the 3'-most 0.2 kb altered expression and RNase cleavage patterns within stem-loop X, indicating its integral role.

Conclusions:

  • The Kv1.4 5'-NCR is a key regulator of Kv1.4 expression through internal ribosome entry.
  • Kv1.4 expression is controlled by a complex interplay of multiple RNA elements and structural features within its 5'-NCR.
  • These findings provide insights into the post-transcriptional regulation of voltage-gated potassium channels.

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