Generation and morpho-functional characterization of zebrafish models of piga deficiency: new tools to investigate the molecular underpinnings of MCAHS2 and explore potential rescue strategies.

The PIGA gene is fundamental for the synthesis of GPI within the endoplasmic reticulum, subsequently transferred to numerous proteins to allow the attachment to the membrane and proper functioning. Alterations in the function of PIGA determine the onset of a severe pathological picture, with symptoms such as delayed psychomotor development, epilepsy, dysmorphism and congenital anomalies. Understanding the biochemical/biological alterations induced by GPI deficiency is essential to develop therapeutic approaches that can mitigate, if not correct, the clinical picture, pending the development of targeted gene therapies. The experimental models used so far have shown significant limitations, either for early lethality found in knock-out (KO) mice, or for the difficult translation to the context of tissues and organs, and in particular to the nervous system, of the data obtained from cellular models. For various reasons, including the external development of embryos and their transparency, zebrafish has the potential to overcome the obstacles encountered so far. The project involves the generation of zebrafish models with complete and partial elimination of piga activity and their initial morpho-functional characterization. These models will allow to identify phenotypes and molecular processes related to GPI-AP deficiency in embryos and adults, thanks to the use of complementary techniques such as in-situ hybridization, immune-mediated imaging, large-scale differential gene expression analysis and the use of transgenic lines with reporter genes for different signal transduction pathways. These studies will lay the foundations for the identification of phenotypic-rescue strategies, a necessary step to progress towards the search for therapeutic options.