Study of pathway alterations in Gaucher disease by induced pluripotent stem cell models

Gaucher disease (GD) is a lysosomal storage disorder characterized by β-glucocerebrosidase enzyme deficiency, due to mutations in the GBA1 gene. GD patients, even if affected by a monogenic disease, exhibit a wide range of symptoms, ranging from very mild hematological and visceral phenotypes, to severe neurological involvement. The absence of a clear genotype-phenotype correlation supports the idea that other players act together with GBA1 mutations to give rise to the final clinical picture. To identify new pathway alterations occurring in the pathological condition, GD patient derived induced pluripotent stem cell (iPSC) lines have been generated, characterized and isogenic gene corrected in the mutation site. iPSC differentiation towards the macrophage fate has been employed to investigate the hematopoietic compartment. While GD iPSCs are able to efficiently give rise to CD43+/CD45+ progenitors and mature CD14+/CD163+ monocyte/macrophages, they showed a decreased proliferative potential compared to healthy donor cells. The activation of necroptosis pathway, emerged in both pluripotent and differentiated GD cells, that showed a significant upregulation of the effectors, RIPK3 and MLKL. To dissect brain inflammatory mechanisms, iPSC have been differentiated to neural precursor cells (NPC) and dopaminergic neurons. GD cells presented also at the NPC state both a growth deficit and an increased cell death rate. Since the Hippo pathway is involved in the control of many cellular mechanisms as proliferation, differentiation and cell death, we evaluated its activation in GD lines. Interestingly, many of the pathway transcriptional targets were downregulated in GD neurons and the nuclear localization of YAP, the main pathway effector, resulted reduced, suggesting that the Hippo pathway core is highly activated in the pathogenic context. The identification of altered signalling pathways that may contribute to the cellular metabolism imbalance, are instrumental in the development of new pharmacological approaches to GD that are especially required for neuronopathic patients.