Calcium signaling in the developing Xenopus myotome

Area of Science:

• Developmental Biology
• Cellular Physiology
• Molecular Biology

Background:

• Embryonic Xenopus myocytes display spontaneous calcium (Ca2+) transients during in vitro differentiation.
• These Ca2+ transients are essential for myofibril organization and sarcomere formation via a known signal transduction pathway.
• Given their role in myocyte polarization and migration in culture, a potential in vivo function during tissue formation was hypothesized.

Purpose of the Study:

• To investigate the role of Ca2+ dynamics in the intact Xenopus paraxial mesoderm during myotome development.
• To characterize Ca2+ transients in vivo and their correlation with somitogenesis and myocyte maturation.

Main Methods:

• Examined Ca2+ dynamics in the intact Xenopus paraxial mesoderm.
• Investigated the role of intracellular Ca2+ stores by using caged inositol trisphosphate (IP3) and caffeine to elicit Ca2+ elevations.
• Blocked ryanodine receptors (RyRs) to assess their involvement in somite maturation.

Main Results:

• Ca2+ transients in the developing myotome share characteristics with those observed in cultured myocytes.
• In vivo Ca2+ transients correlate with both somitogenesis and myocyte maturation.
• Ca2+ transients in vivo depend on Ca2+ release from ryanodine receptor (RyR) stores, similar to cultured myocytes.

Conclusions:

• Calcium transients play a significant role in the development of the Xenopus myotome.
• Ryanodine receptor (RyR) mediated Ca2+ release is critical for somite maturation during embryonic development.
• These findings highlight the importance of intracellular calcium signaling in muscle tissue formation in vivo.