Peroxynitrite supports a metabolic reprogramming in merlin-deficient Schwann cells and promotes cell survival

Abstract

Neurofibromatosis type 2 (NF2) is an autosomal-dominant disorder characterized by the development of bilateral vestibular schwannomas. The NF2 gene encodes the tumor suppressor merlin, and loss of merlin activity promotes tumorigenesis and causes NF2. Cellular redox signaling has been implicated in different stages of tumor development. Among reactive nitrogen species, peroxynitrite is the most powerful oxidant produced by cells. We recently showed that peroxynitrite-mediated tyrosine nitration down-regulates mitochondrial metabolism in tumor cells. However, whether peroxynitrite supports a metabolic shift that could be exploited for therapeutic development is unknown. Here, we show that vestibular schwannomas from NF2 patients and human, merlin-deficient (MD) Schwann cells have high levels of endogenous tyrosine nitration, indicating production of peroxynitrite. Furthermore, scavenging or inhibiting peroxynitrite formation significantly and selectively decreased survival of human and mouse MD-Schwann cells. Using multiple complementary methods, we also found that merlin deficiency leads to a reprogramming of energy metabolism characterized by a peroxynitrite-dependent decrease of oxidative phosphorylation and increased glycolysis and glutaminolysis. In MD-Schwann cells, scavenging of peroxynitrite increased mitochondrial oxygen consumption and membrane potential, mediated by the up-regulation of the levels and activity of mitochondrial complex IV. This increase in mitochondrial activity correlated with a decrease in the glycolytic rate and glutamine dependence. This is the first demonstration of a peroxynitrite-dependent reprogramming of energy metabolism in tumor cells. Oxidized proteins constitute a novel target for therapeutic development not only for the treatment of NF2 schwannomas but also other tumors in which peroxynitrite plays a regulatory role.

CuATSM effectively ameliorates ALS patient astrocyte‐mediated motor neuron toxicity in human in vitro models of amyotrophic lateral sclerosis

“…Oxygen consumption rate was measured in adherent cells by extracellular flux analysis using a Seahorse XF24 or Seahorse XFe96 analyzer (Seahorse, Agilent). The oxygen consumption rate was measured in basal conditions and after the sequential addition of oligomycin (2 μM), trifluoromethoxy carbonylcyanide phenylhydrazone (FCCP, 5 μM) and antimycin A (10 μM) as previously described (Pestoni et al, 2019 ). For every test conducted, three baseline reads were taken prior to start of injections with an additional three measurements taken between injections.…”

Regulatory Phenomena in the Glutathione Peroxidase Superfamily

“…However, for some decades already, H 2 O 2 is recognized to be an important signaling molecule (51,54), and even peroxynitrite, which is also a GPx substrate, has recently been shown to be a signal for proliferation in schwannomas (137). Therefore, a regulatory role of GPx1 can no longer be disregarded.…”

Maternal exposure to hyperbaric oxygen at the preimplantation stages increases apoptosis and ectopic Cdx2 expression and decreases Oct4 expression in mouse blastocysts via Nrf2‐Notch1 upregulation and Nf2 downregulation

“…22,23,[28][29][30][31] On the other hand, studies involving cultured breast cancer and Schwann cells in vitro, as well as knockout mouse models in vivo, have revealed that the deficiency of Nf2/Merlin resulted in a notable increase in the expression of prooxidant genes and levels of ROS, while simultaneously leading to a decrease in the expression of antioxidant genes. [32][33][34] These results indicate a positive correlation between oxidative stress and the Hippo-Nf2 signaling.…”