Related Experiment Video
Updated: May 8, 2026
Functional Analysis of the Larval Feeding Circuit in Drosophila
Published on: November 19, 2013
Characterization of the structural and functional determinants of MANF/CDNF in Drosophila in vivo model
Riitta Lindström1, Päivi Lindholm, Jukka Kallijärvi
1Department of Biosciences, University of Helsinki, Helsinki, Finland.
Abstract:
Mammalian MANF and CDNF proteins are evolutionarily conserved neurotrophic factors that can protect and repair mammalian dopaminergic neurons in vivo. In Drosophila, the sole MANF protein (DmManf) is needed for the maintenance of dopaminergic neurites and dopamine levels. Although both secreted and intracellular roles for MANF and CDNF have been demonstrated, very little is known about the molecular mechanism of their action. Here, by using a transgenic rescue approach in the DmManf mutant background we show that only full-length MANF containing both the amino-terminal saposin-like and carboxy-terminal SAP-domains can rescue the larval lethality of the DmManf mutant. Independent N- or C-terminal domains of MANF, even when co-expressed together, fail to rescue. Deleting the signal peptide or mutating the CXXC motif in the C-terminal domain destroys the activity of full-length DmManf. Positively charged surface amino acids and the C-terminal endoplasmic reticulum retention signal are necessary for rescue of DmManf mutant lethality when DmManf is expressed in a restricted pattern. Furthermore, rescue experiments with non-ubiquitous expression reveals functional differences between the C-terminal domain of human MANF and CDNF. Finally, DmManf and its C-terminal domain rescue mammalian sympathetic neurons from toxin-induced apoptosis in vitro demonstrating functional similarity of the mammalian and fly proteins. Our study offers further insights into the functional conservation between invertebrate and mammalian MANF/CDNF proteins and reveals the importance of the C-terminal domain for MANF activity in vivo.
Insights
Full-length MANF protein, containing both N- and C-terminal domains, is crucial for rescuing DmManf mutant lethality. Specific domains and motifs are essential for MANF protein activity in vivo.
Area of Science:
- Neuroscience
- Molecular Biology
- Developmental Biology
Background:
- MANF and CDNF are conserved neurotrophic factors with known roles in neuronal protection and repair.
- While secreted and intracellular functions are established, the precise molecular mechanisms of MANF and CDNF remain largely unknown.
- DmManf in Drosophila is vital for dopaminergic neuron maintenance.
Purpose of the Study:
- To elucidate the molecular mechanisms underlying MANF and CDNF protein function.
- To determine the essential domains and motifs for MANF activity in vivo.
- To investigate the functional conservation of MANF/CDNF between invertebrates and mammals.
Main Methods:
- Transgenic rescue experiments in a DmManf mutant Drosophila background.
- Analysis of full-length DmManf, truncated domains, signal peptide deletion, and CXXC motif mutations.
- Rescue experiments with restricted and non-ubiquitous expression patterns.
- In vitro assays using mammalian sympathetic neurons.
Main Results:
- Only full-length DmManf rescues larval lethality; isolated N- or C-terminal domains do not.
- Deletion of the signal peptide or mutation of the CXXC motif abolishes DmManf activity.
- Positively charged surface amino acids and ER retention signal are critical for rescue under restricted expression.
- DmManf and its C-terminal domain protect mammalian neurons in vitro, indicating functional conservation.
Conclusions:
- The full-length structure of MANF, particularly the C-terminal domain, is essential for its in vivo neurotrophic activity.
- Specific molecular features, including the CXXC motif and ER retention signal, are critical for MANF function.
- Significant functional conservation exists between Drosophila and mammalian MANF/CDNF proteins, highlighting evolutionary importance.
