Elongation factor-1 alpha mRNA is selectively translated following mitogenic stimulation

Area of Science:

• Molecular Biology
• Cell Biology
• Biochemistry

Background:

• Cell proliferation requires precise regulation of protein synthesis.
• Elongation factor eEF-1 alpha is crucial for protein synthesis.
• Understanding mRNA regulation is key to controlling cell growth.

Purpose of the Study:

• To investigate the regulation of protein synthesis elongation factor eEF-1 alpha during cell proliferation.
• To determine if increased synthesis of eEF-1 alpha is due to new mRNA or existing transcripts.
• To examine the localization and translation status of eEF-1 alpha mRNA in quiescent and stimulated cells.

Main Methods:

• Northern blot analysis to assess mRNA levels.
• Solution hybridization protection assays for transcript quantification.
• Cellular fractionation and polysome profiling to localize transcripts.
• Salt-shift and translational runoff assays to evaluate translational activity.

Main Results:

• Serum stimulation selectively increased eEF-1 alpha synthesis sixfold.
• eEF-1 alpha mRNA levels remained constant, indicating translation of pre-existing mRNA.
• eEF-1 alpha transcripts redistributed from stored particles and monosomes/disomes to large polysomes.
• Transcripts in monosomes/disomes of quiescent cells were associated with actively translating ribosomes.

Conclusions:

• Increased eEF-1 alpha synthesis during cell proliferation is regulated post-transcriptionally, via translation of pre-existing mRNA.
• Specific mRNA transcripts can dynamically shift within the polysome profile based on translational apparatus affinity.
• This dynamic mRNA movement plays a role in selective protein synthesis during mitogenic stimulation.