Endoplasmic Reticulum Calcium Mediates Drosophila Wing Development

Area of Science:

• Developmental Biology
• Cell Signaling
• Ion Channel Physiology

Background:

• Temporal dynamics of morphogen presentation are crucial for tissue patterning, but mechanisms controlling morphogen release remain unclear.
• Inwardly rectifying potassium (Irk) channels influence intracellular calcium and bone morphogenetic protein (BMP/Dpp) release in Drosophila wing development.
• Irk channels modulate calcium signaling in various cell types, suggesting a conserved role in secretion.

Purpose of the Study:

• To investigate the role of endoplasmic reticulum (ER) calcium regulation in BMP/Dpp release and Drosophila wing development.
• To test the hypothesis that electrical activity controls ER calcium release, impacting BMP release.

Main Methods:

• RNA interference (RNAi) was used to reduce expression of key ER calcium regulators (Stim, Orai, SERCA, SK, Best2).
• Live imaging tracked calcium and Dpp release in Drosophila wing discs and pupal wings.
• Immunohistochemistry assessed SMAD phosphorylation, a downstream marker of BMP/Dpp signaling.

Main Results:

• Reduced Stromal interaction molecule 1 (Stim) and SarcoEndoplasmic Reticulum Calcium ATPase (SERCA) function led to decreased calcium transient amplitude and frequency.
• Knockdown of Stim and SERCA resulted in diminished BMP/Dpp release.
• These changes correlated with disrupted wing morphology.

Conclusions:

• ER calcium homeostasis is critical for regulating BMP/Dpp release.
• Proper BMP/Dpp signaling, controlled by ER calcium dynamics, is essential for Drosophila wing development.