Drosophila based screening to replace mammalian systems to identify the functional role of candidate genes in controlling muscle dyadic architecture

Scientific and clinical background:
Diseases of the heart (cardiomyopathies) remain a leading cause of morbidity and mortality for which additional treatment strategies are needed. An emerging and consistent finding across a range of cardiomyopathies is that there is ultrastructural remodelling in cardiac myocytes consisting of loss and disorganisation of surface membrane structures known as transverse (t-) tubules. This loss of t-tubules is a key causal factor of perturbed cellular calcium homeostasis which contributes to the two leading causes of morbidity and mortality; contractile failure and arrhythmias. Importantly the t-tubule network is highly plastic and it can be restored, albeit in a disordered manner, following some therapeutic interventions and this is associated with improved cardiac function. However, the factors (genes) that control the formation and organisation of the t-tubule network and consequently impact on dyadic architecture and cellular calcium homeostasis are very poorly understood and are not advanced rapidly with traditional animal-based experimental methodologies. 

Scientific aims:
This PhD seeks to use a novel to the field, albeit proven, interdisciplinary approach to identify genes that regulate the t-tubule network. We will achieve this by combining bioinformatic methodology, functional and ultrastructural assessments using the Drosophila somatic muscle paradigm and validation in human induced pluripotent stem cell derived cardiac myocytes (hiPSC-CMs). 

The Drosophila somatic muscle paradigm is a powerful tool in this context as the somatic muscles of Drosophila share structural and functional homology with mammalian cardiac muscle. Additionally, Drosophila shares considerable genetic homology with humans and what little we understand already about mammalian cardiac t-tubule regulators was founded on work originally performed in Drosophila. These factors, in combination with the available powerful Drosophila genetic tools, enable a rapid screen with functional and structural assessment of putative t-tubule regulatory genes.

3Rs aims:
The programme of work principally provides a Replacement strategy whereby the model organism Drosophila melanogaster is used as a rapid and comprehensive screening tool to evaluate a bioinformatically informed panel of candidate genes for their t-tubule regulatory role. Notably, in addition to identifying which genes have t-tubule regulatory roles, the functional and ultrastructural methodology that we will employ will also provide additional information on the role of these genes in controlling dyadic structure and function.

Using the proposed strategy, we anticipate that over the course of five-years, our own group will completely replace the need to use ~ 1,000 mice for the generation conditionally targeted allele founders. Additionally, based on conservative criteria and a sample of published work using genetically altered mice to study t-tubules in the heart, our approach has the potential to replace the use of several thousand mice each year worldwide.

3Rs legacy:
Two key determinants leading to a long-lasting legacy from our proposed approach are demonstration of feasibility and wider applicability and training in the methodology. That Drosophila is suited to addressing a wider array of clinically or scientifically driven questions is undeniably supported by the high degree of conservation between the human and Drosophila protein coding genomes and that the vast majority of human disease-causing genes have Drosophila homologs. 

In addition to fully open access sharing of the interdisciplinary methodology that we develop, we have an extensive track record in providing tailored training in Drosophila techniques that we will lever to promote widespread adoption of the use of Drosophila across a broad portfolio of research disciplines locally, nationally and internationally via engagement workshops, conferences and engagement events.

This Studentship was co-awarded with the British Heart Foundation (BHF).