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Creatine kinase transcript accumulation: effect of nerve during muscle development

C H Washabaugh1, M P Ontell, J A Kant

  • 1Department of Cell Biology and Physiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261, USA.

Developmental Dynamics : an Official Publication of the American Association of Anatomists
|July 27, 1999
PubMed

Insights

Nerve absence affects muscle-specific creatine kinase (CK) mRNA accumulation in developing mouse hindlegs. While the developmental switch to muscle CK (MCK) mRNA is nerve-independent, MCK mRNA levels decrease without innervation.

Area of Science:

  • Developmental Biology
  • Neuroscience
  • Molecular Biology

Background:

  • Cytoplasmic creatine kinase (CK) plays a crucial role in cellular energy homeostasis.
  • The differential expression of CK isoforms, specifically muscle CK (MCK) and brain CK (BCK), is critical during muscle development.
  • The influence of neural regulation on the accumulation of CK mRNAs during fetal development is not fully understood.

Purpose of the Study:

  • To investigate the role of nerve supply in regulating the accumulation of cytoplasmic creatine kinase (CK) mRNAs in developing mouse hindleg muscles.
  • To determine if the developmental switch from BCK to MCK mRNA is nerve-dependent.
  • To assess the impact of denervation on MCK and BCK mRNA levels during fetal development.

Main Methods:

  • Laser ablation of the lumbosacral spinal cord in embryonic day 14 (E14) mouse fetuses to create aneural hindleg muscles.
  • In situ hybridization to evaluate the accumulation of MCK and BCK mRNAs in hindleg muscles prior to birth.
  • Competitive PCR to quantify the number of MCK and BCK transcripts per nanogram of total RNA in soleus and extensor digitorum longus (EDL) muscles.

Main Results:

  • The developmental switch from BCK to MCK mRNA dominance occurs between E14 and E16.5 in both innervated and aneural leg muscles, indicating it is nerve-independent.
  • Absence of innervation does not affect BCK mRNA accumulation.
  • While MCK mRNA levels increase in aneural muscles, they are progressively lower than in innervated muscles from E16.5 to E19.5, suggesting innervation positively influences MCK mRNA accumulation.

Conclusions:

  • The developmental switch in cytoplasmic CK mRNA dominance is not regulated by nerve input.
  • Innervation is crucial for the optimal accumulation of muscle-specific CK (MCK) mRNA during late fetal development.
  • The absence of innervation specifically impacts the accumulation of MCK transcripts, not BCK transcripts, in developing hindleg muscles.

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