Implications of RASAL3 gene mutations in autoimmune diseases

Autoimmune diseases result from the breakdown of self-tolerance, often due to mutations affecting key immune regulatory genes. The dysregulation of Ras- MAPK is a hallmark of several autoimmune disorders as it is implicated in crucial T and B lymphocyte functions such as proliferation, differentiation, motility, apoptosis and senescence. Mutations of interest in the RASAL3 gene were identified in five patients suffering from either pediatric auto-immune hepatitis (AIH) or Evans syndrome using whole exome sequencing and subsequently confirmed by Sanger sequencing and segregation analysis. RASAL3 encodes a RasGAP protein that negatively regulates the Ras-MAPK pathway, which is essential in BCR/TCR-mediated lymphocyte homeostasis and activation. Given its role in modulating T cell responses, alterations in RASAL3 could lead to aberrant immune activation and autoimmunity. To investigate this hypothesis, a cellular model was established using Jurkat T cells and B-LCLs to monitor pERK induction following TCR- and BCR-mediated activation of the Ras pathway. Additionally, HEK cells were employed to explore the signaling context of RASAL3 through the generation of expression plasmids harboring mutant RASAL3 sequences and the optimization of Ras pathway stimulation conditions.