ESPE Abstracts

The ‘Developmental Origins of Health and Disease’ (DOHaD) hypothesis encapsulates the relationship between pre- and perinatal exposures causing altered growth and the development of later life disease. Mediators of this relationship have not been fully defined. We have used zebrafish [ZF] (Danio rerio) as a potential model for DOHaD, modifying expression of grb10a, an adapter protein that interacts with the insulin and IGF receptors, to act as a negative regulator of fetal and postnatal growth. We have characterised growth, cardiometabolic status, and the impact on co-ordination of gene expression following morpholino-induced embryonic knockdown (KD) of grb10a expression. This led to a decrease in grb10a expression in the embryo with increased levels of phosphorylated AKT and S6, indicative of increased insulin and IGF-I signalling. Grb10a mRNA levels returned to those seen in control ~10 days post fertilisation (pf). Between 24- and 120-hours pf, KD ZF showed increased growth in body length (+7%), increased glucose uptake (+25%) and decreased heart rate (-50%) compared to control-injected embryos. The transcriptome was assessed between 5- and 30-days pf, coinciding with major changes in ZF maturation and development. The expression of age-related genes in the control fish was characterised by three clusters, while this pattern was markedly disrupted in the KDs. We also modelled transcriptomic networks using hypergraphs and quantified changes to the network structure over time by measuring entropy, a marker of cellular differentiation potential. Entropy of biological pathways differed significantly between the two groups. Thus, grb10a KD results in major functional and organisational changes to the transcriptome. The ZF were followed to 18 months. KD ZF had greater body length and mass than controls. Ventricular muscle in the heart was thicker and the cross-sectional area of muscle fibres was increased in KD. Basal metabolic rate (MR), defined by oxygen consumption, was comparable between KD and control ZF, but maximum MR was higher in KD, resulting in greater aerobic scope. Fasting glucose was higher in KD, while both groups showed a similar glucose response to insulin. This study demonstrates that knockdown of a single gene, grb10a, in ZF embryos results in changes in growth and metabolic phenotype from early life through to 30 days, coincident with major transcriptomic remodelling. In addition, alterations in growth and cardiometabolic function persist in adult KD ZF. Embryonic disruption of gene expression in zebrafish could be a valuable model to identify pathways associated with long-term disruption to health.