Help Comes from Unexpected Places: How a Tiny Fairy and a Tropical Fish may help us Model Mucopolysaccharidoses

INTRODUCTION

When it comes to disease modeling, countless models are available for Lysosomal Storage Diseases (LSD). Historically, two major approaches are well-established: in vitro assessments are performed in patient fibroblasts, while in vivo pre-clinical studies are performed in mouse models. Still, both platforms have a series of drawbacks. Thus, we implemented two alternative and innovative protocols to mimic a particular sub-group of LSDs, the Mucopolysaccharidoses both in vitro and in vivo.

METHODS

The first one relies on a non-invasive approach using dental pulp stem cells from deciduous teeth (SHEDs). SHEDs are multipotent neuronal precursors that can easily be collected. The second uses a state-of-the-art gene editing technology (CRISPR/Cas9) to generate zebrafish disease models.

RESULTS

Even though this is an ongoing project, we have already established and characterized two MPS II and one MPS VI SHED cell models. These cells self-maintain through several passages and can give rise to a variety of cells including neurons. Furthermore, all MPS-associated sub-cellular phenotypes we have assessed so far are easily observable in these cells. Regarding our zebrafish models, we have successfully knocked down both naglu and hgsnat and the first results we got from the behavioral analysis are promising ones, as we can observe altered activity and sleep patterns in the genetically modified fish. For this particular approach we chose MPS III forms as our target disorders, since their neurological features (hyperactivity, seizures and motor impairment) and lifespan decrease would be easily recognizable in zebrafish.

CONCLUSION

Now that these methods are well-established in our lab, their potential is immense. On one hand, the newly developed models will be of ultimate value to understand the mechanisms underlying MPS sub-cellular pathology, which have to be further elucidated. On the other hand, they will constitute an optimal platform for drug testing in house. Also noteworthy, our models will be published as lab resources and made available for the whole LSD community.

Disruption of zebrafish (Danio rerio) embryonic development after full life-cycle parental exposure to low levels of ethinylestradiol

Exposure of fish to the synthetic estrogen ethinylestradiol (EE2) has been shown to induce a large set of deleterious effects. In addition to the negative impact of EE2 in reproductive endpoints, concern has recently increased on the potential effects of EE2 in fish embryonic development. Therefore, the present study aimed at examining the effects of EE2 on the full embryonic development of zebrafish in order to identify the actual phases where EE2 disrupts this process. Hence, zebrafish were exposed to environmentally relevant low levels of EE2, 0.5, 1 and 2ng/L (actual concentrations of 0.19, 0.24 and 1ng/L, respectively) from egg up to eight months of age (F(1)), and the survival as well as the occurrence of abnormalities in their offsprings (F(2)), per stage of embryonic development, was investigated. A thorough evaluation of reproductive endpoints and transcription of vtg1 gene in the parental generation (F(1)) at adulthood, was performed. No significant differences could be observed for the two lowest EE2 treatments, in comparison with controls, whereas vtg1 transcripts were significantly elevated (40-fold) in the 2ng/L EE2 treatment. In contrast to the findings in the F(1) generation,a significant concentration-dependent increase in egg mortality between 8 and 24hours post-fertilization (hpf) was observed for all EE2 treatments, when compared with controls. The screening of egg and embryo development showed a significant increase in the percentage of abnormalities at 8 hpf for the highest EE2 concentration, a fact that might explain the increased embryo mortality at the 24 hpf time-point observation. Taken together, these findings indicate that the two lowest tested EE2 concentations impact late gastrulation and/or early organogenesis, whereas exposure to 2ng/L EE2 also disrupts development in the blastula phase. After early organogenesis has been completed (24 hpf), no further mortality was observed. These results show that increased embryo mortality occurs at EE2 levels below those inducing reproductive impairment and vtg1 gene induction in the male parental generation, thus suggesting that EE2 may impact some fish populations at levels below those inducing an increase in vtg1 transcripts. Hence, these findings have important implications for environmental risk assessment, strongly supporting the inclusion of embryonic development studies in the screening of endocrine disruption in wild fish populations.

Ligands and therapeutic perspectives of adenosine A(2A) receptors

Adenosine A(2A) receptors are members of the G protein-coupled receptor family and mediate multiple physiological effects of adenosine, both at the central nervous system (CNS) and at peripheral tissues, by activating several pathways or interacting with other receptors or proteins. Increasing evidence relate A(2A) receptors with pharmacological stress testing, neurodegenerative disorders (such as Parkinson's disease) and inflammation, renewing the interest in these receptors, increasingly viewed as promising therapeutic targets. Series of agonists and antagonists have been developed by medicinal chemistry artwork either by structure activity relationship (SAR) or quantitative structure activity relationship (QSAR) studies. These studies have allowed identification of the structural and electrostatic requirements for high affinity A(2A) receptor binding and, therefore, contributing to the rational design of A(2A) receptor ligands. Additional rational chemical modifications of the existing A(2A) receptor ligands may further improve their affinity/selectivity. The purpose of this review is to analize and summarize aspects related to the medicinal chemistry of A(2A) receptor ligands, their present and potencial therapeutic applications by exploring the molecular structure and physiological and pathophysiological roles of A(2A) receptors.