Evaluation of energy metabolism and calcium homeostasis in cells affected by Shwachman-Diamond syndrome

Abstract

Isomorphic mutation of the SBDS gene causes Shwachman-Diamond syndrome (SDS). SDS is a rare genetic bone marrow failure and cancer predisposition syndrome. SDS cells have ribosome biogenesis and their protein synthesis altered, which are two high-energy consuming cellular processes. The reported changes in reactive oxygen species production, endoplasmic reticulum stress response and reduced mitochondrial functionality suggest an energy production defect in SDS cells. In our work, we have demonstrated that SDS cells display a Complex IV activity impairment, which causes an oxidative phosphorylation metabolism defect, with a consequent decrease in ATP production. These data were confirmed by an increased glycolytic rate, which compensated for the energetic stress. Moreover, the signalling pathways involved in glycolysis activation also appeared more activated; i.e. we reported AMP-activated protein kinase hyper-phosphorylation. Notably, we also observed an increase in a mammalian target of rapamycin phosphorylation and high intracellular calcium concentration levels ([Ca2+]i), which probably represent new biochemical equilibrium modulation in SDS cells. Finally, the SDS cell response to leucine (Leu) was investigated, suggesting its possible use as a therapeutic adjuvant to be tested in clinical trials.

Mutations in signal recognition particle SRP54 cause syndromic neutropenia with Shwachman-Diamond–like features

“…The deletion of T117 may affect GTP binding through rearrangements of residues 113-116, but this is difficult to predict. 4 0 9 5 jci.org Volume 127 Number 11 November 2017 in 2 cell lines (HeLa and HL60), it had no impact on the expression of 2 other proteins known to be mutated in SDS (i.e., SBDS and DNAJC21) (Supplemental Figure 6) or on the mTOR pathway, which was previously linked to SDS pathophysiology (23,24). Zebrafish model.…”

Why is an energy metabolic defect the common outcome in BMFS?

“…18 To re-establish the correct energetic status, SDS and FA cells augment the glycolysis rate. 16,17 Hence, the return to glycolytic metabolism does not represent a Warburg effect, but the only choice of the cell to produce energy without increasing the accumulation of oxidative damage. However, it is also possible to speculate that this metabolic switch in a differentiated cell represents a precancerous condition that may facilitate tumor transformation.…”

“…18 To re-establish the correct energetic status, SDS and FA cells augment the glycolysis rate. 16,17 Hence, the return to glycolytic metabolism does not represent a Warburg effect, but the only choice of the cell to produce energy without increasing …”

“…16,17 These alterations cause a decrement in ATP production, determining an unbalanced ratio between ATP and AMP. 16 Whatever is the role of FA and SDS, it is important to note that the dysfunction of the OXPHOS machinery determines an increment in oxidative stress production, which induces lipid peroxidation and therefore, an alteration in the mitochondrial membrane, where the OXPHOS machinery resides.…”

“…16 Whatever is the role of FA and SDS, it is important to note that the dysfunction of the OXPHOS machinery determines an increment in oxidative stress production, which induces lipid peroxidation and therefore, an alteration in the mitochondrial membrane, where the OXPHOS machinery resides. 16,17 This triggers a vicious cycle that increases the inefficiency of ATP and oxidative stress production. 18 To re-establish the correct energetic status, SDS and FA cells augment the glycolysis rate.…”