Neuropeptide function during embryonic development in sea urchins S. purpuratus

Lead Research Organisation: University College London
Department Name: Structural Molecular Biology


Strategic Research priority: World Class Underpinning Bioscience
Neuropeptides are important regulators of physiological processes and behaviour in animals. Much of what we know about neuropeptide function is based upon studies on adult animals and little is known about the roles of neuropeptide signalling systems during embryonic/larval stages of development. In this project the sea urchin Strongylocentrotus purpuratus will be used a model system to address this issue, building upon data recently obtained by the supervisors in a new collaboration. The successful applicant will have a unique opportunity to pioneer a new field of research, supported by the complementary expertise of Elphick (neurobiologist) and Oliveri (systems developmental biologist).

Neuropeptides are ancient neuronal signalling molecules that exert effects by binding to receptor proteins on target cells regulate many physiological processes and behaviours. Comparative genomics/transcriptomics has enabled reconstruction of the evolutionary history of neuropeptide signalling systems and discovery of neuropeptides in an increasingly wide range of species. Thus, sequencing of the genome of the sea Strongylocentrotus purpuratus enabled Elphick to obtain the first insights into the diversity of neuropeptide systems in an echinoderm. In collaboration with Oliveri, a development biologist using genome wide approaches in the sea urchin system, it was discovered that many of the neuropeptides that are expressed in the adult nervous system are also expressed during embryonic/larval development in the sea urchin. This has provided the basis for the project proposed here, which will investigate for the first time the development roles of neuropeptide signalling at molecular, cellular and organismal level, using the sea urchin as model system.
The first focus is on the characterisation of these neuropeptide precursor in S. purpuratus. QPCR and transcriptome data was used to map the temporal expression of these genes, revealing that almost of all of these genes are expressed in the late larval stage, when neuronal cells differentiate. Using fluorescence mRNA in situ hybridisation and immunocytochemistry, expression of the neuropeptides precursor genes was mapped throughout development, from egg to larva. Localisation of many neuropeptide precursor genes revealed distinct sub-populations of peptidergic neurons and showed that the sea urchin larval nervous system is far more complex than previously thought ( Interestingly, we also discovered that many neuropeptides precursor genes are also expressed during embryogenesis, before neuronal cells differentiate, suggesting that some of these genes have a developmental role as well as a conserved neurosecretory role.
The second focus is on the TRH signalling system. The TRH gene is expressed during early sea urchin embryogenesis. Using mRNA in situ hybridisation and immunocytochemistry, expression of the TRH precursor peptide has been mapped throughout development, from egg to larva, in comparison with the TRH receptor. A deorphanisation assay was done to prove that this Sp-TRH peptide is the ligand that binds to the Sp-TRH receptor. Morpholino-mediated knockdowns, coupled with CRISPR/Cas9 of Trh and Trh Receptor gene expression was used to determine the developmental roles of Trh, revealing a role of Trh signalling system in larval skeleton growth. Taken together, the Trh signalling system likely has a conserved role in growth throughout bilateria.


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Studentship Projects

Project Reference Relationship Related To Start End Student Name
BB/M009513/1 01/10/2015 31/03/2024
1618888 Studentship BB/M009513/1 01/10/2015 30/09/2019 Natalie Wood
Description We revealed distinct combinations of neuropeptides expressed in the larval sea urchin nervous system.

We discovered the neuropeptide Thyrotropin-releasing hormone (TRH) has a role in skeleton growth in the sea urchin larvae, and showed the involvement of canonical signalling pathways VEGF and FGF signalling in mediating TRH signalling to affect skeleton growth. By making comparisons with other animals (Mammals and nematodes) we hypothesis that TRH has a evolutionary conserved role in growth across bilaterian animals.

We troubleshooted CRISPR/Cas9 technology in the sea urchin and revealed CRISPR/Cas9 works but is variably efficient. Additional research is needed to further optimise the technology in sea urchin.
Exploitation Route Our research opens up new research questions into the roles of other neuropeptides in the invertebrate deuterostome sea urchin, the roles of TRH in other animals and the wider use of CRISPR/Cas9 technology in sea urchins.
Sectors Other