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Updated: Jul 12, 2025
Detection of In Situ Protein-protein Complexes at the Drosophila Larval Neuromuscular Junction Using Proximity Ligation Assay
Published on: January 20, 2015
hkb is required for DIP-α expression and target recognition in the Drosophila neuromuscular circuit
Yupu Wang1,2,3,4, Rio Salazar1,2,5,4, Luciano Simonetta1,2,6
1Department of Molecular Genetics and Cellular Biology, University of Chicago, Chicago, IL 60637.
Insights
The transcription factor huckebein (hkb) regulates cell surface protein DIP-α expression in Drosophila motor neurons. This regulation is specific to dorsal motor neurons, involving even-skipped (eve) and impacting neural connectivity.
Area of Science:
- Neuroscience
- Developmental Biology
- Genetics
Background:
- Cell surface proteins (CSPs) mediate neuronal connections, but their regulation is poorly understood.
- Dpr and DIP proteins in Drosophila instruct synaptic connectivity, growth, and survival.
- DIP-α is expressed in specific motor neuron subtypes in the Drosophila larval neuromuscular system.
Approach:
- Conducted an F1 dominant modifier genetic screen to identify regulators of Dpr and DIP proteins.
- Investigated the role of the transcription factor huckebein (hkb) in DIP-α expression and motor neuron targeting.
- Utilized genetic interactions to elucidate the downstream pathway involving even-skipped (eve).
Key Points:
- Huckebein (hkb) genetically interacts with DIP-α and is crucial for dorsal Is motor neuron target recognition.
- Loss of hkb results in the complete absence of DIP-α expression in dorsal Is motor neurons.
- Even-skipped (eve) acts downstream of hkb and is specifically involved in regulating dorsal Is motor neuron connectivity.
Conclusions:
- Identified huckebein (hkb) as a key transcriptional regulator of DIP-α in Drosophila motor neurons.
- Demonstrated that hkb and even-skipped (eve) function in the same pathway to control dorsal Is motor neuron connectivity.
- Revealed distinct transcriptional regulatory mechanisms for the same cell surface protein (DIP-α) in different neuronal subtypes.
Abstract:
Our nervous system contains billions of neurons that form precise connections with each other through interactions between cell surface proteins (CSPs). In Drosophila, the Dpr and DIP immunoglobulin protein subfamilies form homophilic or heterophilic interactions to instruct synaptic connectivity, synaptic growth and cell survival. However, the upstream regulation and downstream signaling mechanisms of Dprs and DIPs are not clear. In the Drosophila larval neuromuscular system, DIP-α is expressed in the dorsal and ventral type-Is motor neurons (MNs). We conducted an F1 dominant modifier genetic screen to identify regulators of Dprs and DIPs. We found that the transcription factor, huckebein (hkb), genetically interacts with DIP-α and is important for target recognition specifically in the dorsal Is MN, but not the ventral Is MN. Loss of hkb led to complete removal of DIP-α expression. We then confirmed that this specificity is through the dorsal Is MN specific transcription factor, even-skipped (eve), which acts downstream of hkb. Genetic interaction between hkb and eve revealed that they act in the same pathway to regulate dorsal Is MN connectivity. Our study provides insight into the transcriptional regulation of DIP-α and suggests that distinct regulatory mechanisms exist for the same CSP in different neurons.
