Regulación de la homeostasis de Ca2+ y viabilidad celular por STIM1 en la línea de neuroblastoma SH-SY5Y

Abstract

The role of STIM1, one of the main mediators of the extracelular entry of Ca²⁺ (SOCE), in the regulation of Ca²⁺ homeostasis and cell viability of the SH-SY5Y neuroblastoma line, has been described in this Doctoral Thesis. To carry out this study, a STIM1 knock-out and therefore a SOCE-defective cell line has been generated using the CRISPR/Cas9 genomic editing system. Our results show that STIM1 is not essential for SH-SY5Y cell differentiation. However, a loss of cell viability is observed during differentiation of STIM1- deficient cells. In this regard, our results indicate that STIM1-KO cells show a greater expression and Ca²⁺ entry through the Caᵥ1.2 channel, which leads to an alteration of the intracellular Ca²⁺ homeostasis, triggering a loss of mitochondrial functionality and an increase in cell death. Gene silencing of the Caᵥ1.2 channel normalised mitochondrial viability and functionality, confirming that the upregulation of Caᵥ1.2 is the main cause of cell death observed in STIM1-KO cells. On the other hand, our results indicate that STIM1 is a key regulator in the transfer of Ca²⁺ between the endoplasmic reticulum and the mitochondria, a role mediated by the IP3 type 3 receptor. All this allows us to conclude that STIM1 shows a key role in the maintenance of intracellular Ca²⁺ homeostasis and that STIM1-KO cells constitute a useful in vitro model to understand the role of STIM1 and intracellular Ca²⁺ signalling in neurodegeneration.