Motoneurons regulate myoblast proliferation and patterning in Drosophila

Area of Science:

• Developmental biology
• Neurobiology
• Muscle development

Background:

• Motoneurons influence muscle fiber differentiation and receptor development.
• The role of motoneurons in earlier muscle patterning events is less understood.
• In Drosophila, denervation of flight muscles leads to reduced muscle size or absence.

Purpose of the Study:

• To investigate whether motoneurons control myoblast number through cell division, apoptosis, or migration.
• To determine the role of motoneurons in the patterning of de novo arising dorso-ventral muscles (DVMs).
• To elucidate the underlying mechanisms of neuron-dependent muscle patterning.

Main Methods:

• Studied the effects of denervation on myoblast proliferation using BrdU incorporation.
• Assessed myoblast apoptosis frequency post-denervation.
• Utilized time-lapse imaging of GFP-expressing myoblasts in vivo.
• Examined the expression of the founder-cell marker Dumbfounded/Kirre (Duf).

Main Results:

• Denervation reduced the rate of myoblast cell division but did not affect apoptosis.
• Myoblast migration and localization remained unchanged after denervation.
• Denervation disrupted the segregation of myoblasts into DVMs and abolished Duf-positive cells.
• Muscle patterning was severely disrupted in the absence of innervation.

Conclusions:

• Motoneurons regulate myoblast proliferation and are crucial for proper muscle patterning.
• Nerve-dependent control involves the regulation of specific founder cells that prefigure adult muscle fibers.
• This study reveals a novel role for motoneurons in establishing muscle pattern through founder cell regulation.