Differences in susceptibility to nutrient‐induced cell death between primary and immortalized Leigh Syndrome French Canadian type (LSFC) patient fibroblasts

Abstract

LSFC is a monogenic metabolic disease resulting from a mutation in the leucine‐rich pentatricopeptide repeat‐containing (LRPPRC) gene. It is characterized by cytochrome c oxidase (COX) deficiency and episodes of lactic acidosis leading to death at an early age. Recently, we reported that primary (P) LSFC fibroblasts were more susceptible than controls to necrosis induced by nutrient overload (palmitate 1 mM and lactate 10 mM), an effect associated with a lower [ATP] (FASEB J 2011 25:722.15). In this study, we compared P and immortalized (I) LSFC and control fibroblasts. Under basal conditions, control P and I cells displayed similar characteristics regarding (i) LRPPRC localization (immunocytochemistry) and content (Western) as well as (ii) COX activity. Both these parameters showed the expected decrease in LSFC P and I cells. However, compared to P cells, I cells from both groups had higher citrate synthase activity (~25%) and lower [ATP] (~40%). Accordingly, during nutrient overload, I cells were more susceptible than P cells to both necrosis and apoptosis. While this was observed for control and LSFC cells, LSFC I cells remain more susceptible to necrosis compared to their control counterpart. Collectively, our results highlight differences between P and I cells that ought to be considered for data interpretation and study design. (Supported by: Association de l'acidose lactique and CIHR Emerging Team Grant)