Mario de Bono

Defining function for the neural unknome using genetics and biochemistry
Group Leader page

Project 1: Biochemistry of novel neural protein complexes

Our goal is to understand how nervous systems generate behaviour at molecular, cellular, and circuit levels. Using C. elegans forward genetics we have identified a series of highly conserved proteins that are expressed predominantly in the nervous system, and are associated with behavioural phenotypes, but whose functions are poorly understood in any animal.

The mutant phenotypes of these genes, assessed by behavioural assays, neural imaging, and cell biology, hint at what these proteins do, but biochemistry is required to establish their functions. The goal of this project is to use biochemical approaches to identify and study complexes formed by these proteins.

For example, two proteins form an ER complex required for biogenesis of GPCRs. A different ER protein is required for depolarization of some neurons, suggesting a role in the biogenesis or function of an ion channel. Several are polytopic proteins expressed at the surface of neurons. Others are soluble cytoplasmic proteins previously studied in the context of the mammalian immune responses, but uncharted in the nervous system.

C. elegans is well-known for its powerful genetics, the wiring diagram of its nervous system, and its tractability for in vivo microscopy. Less appreciated are its advantages for biochemistry. Proteins can be rapidly tagged in vivo for immunoprecipitation followed by mass spec analysis; gram quantities of worms can easily be grown in a few days; and efficient protocols to extract protein complexes are available. Biochemistry complements genetics – we expect to find that some neural proteins plug into complexes required for viability that are inaccessible to screens for behavioural phenotypes.

The project envisages an emphasis on biochemistry using C. elegans and tissue culture cells, but experiments will constantly refer back to in vivo analysis, e.g. using CRISPR to knockout interacting proteins and examining their mutant phenotypes using different assays.


References:

Arellano-Carbajal, F., Briseño-Roa, L., Couto, A., Cheung, B.H., Labouesse and M., de Bono, M. (2011)
Macoilin, a conserved nervous system-specific ER membrane protein that regulates neuronal excitability.
PLoS Genet. Mar;7(3):e1001341. doi: 10.1371/journal.pgen.1001341.

Chen, C., Itakura, E., Weber, K.P., Hegde, R.S. and de Bono, M. (2014)
An ER complex of ODR-4 and ODR-8/Ufm1 specific protease 2 promotes GPCR maturation by a Ufm1-independent mechanism.
PLoS Genet. 2014 Mar 6;10(3):e1004082.


Project 2: Genes, circuits, and behaviour

Animals rapidly adopt different states in response to threats or opportunities. These states are coordinated by changes in neurochemistry and physiology that optimise and focus the animal’s response to situations encountered. Hallmarks of such states include arousal, a change in the value of sensory cues, and altered physiology. Examples include states evoked by a potential mate, a predator, or nutritional status.

This project aims to dissect a global state evoked in C. elegans by 21% oxygen. 21% O2 signals to this animal that it is exposed to the surface – a hostile environment. This cue is sensed by tonically signalling neurons that reconfigure the nematode’s physiology and behavioural profile.

Global animal states are complex, but C. elegans offers special opportunities to dissect them: its connectome, including synaptic connections and gap junctions, is defined at the electron microscopy level, and it has powerful genetics.

We recently developed approaches that enable high throughput forward genetic dissection of behaviour, by leveraging next generation sequencing. This project will exploit this pipeline in a series of screens that use sensitised genetic backgrounds to dissect different sub-circuits.

By dissecting an intricate behaviour in this way we expect both to identify new molecular mechanisms that underpin neuron function, and circuitry principles that are conserved.

An ideal candidate will have an interest in combining genetics, behavioural analysis, neural imaging, optogenetics, microscopy, and computer programming. We value individuals who are highly motivated, curious, independent, and fearless.


References

Laurent, P., Soltesz, Z., Nelson, G.M., Chen, C., Arellano-Carbajal, F., Levy, E. and de Bono, M. (2015)
Decoding a neural circuit controlling global animal state in C. elegans.
Elife. 2015 Mar 11;4. doi: 10.7554/eLife.04241.

Busch, K.E., Laurent, P., Soltesz, Z., Murphy, R.J., Faivre, O., Hedwig, B., Thomas, M., Smith, H.L. and de Bono, M. (2012)
Tonic signaling from O₂ sensors sets neural circuit activity and behavioral state.
Nat Neurosci. Mar 4;15(4):581-91. doi: 10.1038/nn.3061.