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Regulation of acetylcholine receptor transcript expression during development in Xenopus laevis
T J Baldwin1, C M Yoshihara, K Blackmer
1Biology Department, Massachusetts Institute of Technology, Cambridge 02139.
The Journal of Cell Biology
|February 1, 1988
Summary
Researchers studied acetylcholine receptor (AChR) transcript levels in developing Xenopus embryos. They found that while initially coordinated, gamma subunit transcript levels are regulated differently later, independent of muscle activity.
Area of Science:
- Developmental Biology
- Neuroscience
- Molecular Biology
Background:
- The skeletal muscle acetylcholine receptor (AChR) is crucial for neuromuscular transmission.
- Understanding the regulation of AChR subunit gene expression during embryonic development is essential for characterizing neuromuscular junction formation.
Purpose of the Study:
- To investigate the expression patterns of acetylcholine receptor (AChR) subunit transcripts during embryonic development in Xenopus laevis.
- To determine if electrical activity influences AChR transcript levels in developing myotomal muscle cells.
Main Methods:
- Isolation of Xenopus AChR cDNAs (alpha, gamma, delta subunits) using Torpedo AChR cDNAs as probes.
- Northern blot analysis to identify transcript sizes for each subunit.
- RNase protection assays to quantify transcript levels and assess coordinate expression with muscle-specific actin mRNA.
Main Results:
- Xenopus AChR cDNAs showed significant homology to Torpedo counterparts and hybridized to somite-specific transcripts.
- Transcripts for alpha, gamma, and delta subunits were coordinately expressed at late gastrula and increased with actin mRNA.
- Post-muscle activity, alpha and delta transcripts decreased fourfold, and gamma transcripts decreased over 50-fold per somite, even when muscle activity was blocked by anesthetic.
Conclusions:
- AChR transcripts are initially coordinately expressed during Xenopus embryonic development.
- Gamma subunit transcript levels are regulated differently from alpha and delta subunits at later developmental stages.
- AChR transcript levels in Xenopus myotomal muscle are not regulated by electrical activity, suggesting alternative regulatory mechanisms are involved.