Nicotinamide N-methyltransferase expression in SH-SY5Y neuroblastoma and N27 mesencephalic neurones induces changes in cell morphology via ephrin-B2 and Akt signalling

Abstract

Nicotinamide N-methyltransferase (NNMT, E.C. 2.1.1.1) N-methylates nicotinamide to produce 1-methylnicotinamide (MeN). We have previously shown that NNMT expression protected against neurotoxin-mediated cell death by increasing Complex I (CxI) activity, resulting in increased ATP synthesis. This was mediated via protection of the NDUFS3 subunit of CxI from degradation by increased MeN production. In the present study, we have investigated the effects of NNMT expression on neurone morphology and differentiation. Expression of NNMT in SH-SY5Y human neuroblastoma and N27 rat mesencephalic dopaminergic neurones increased neurite branching, synaptophysin expression and dopamine accumulation and release. siRNA gene silencing of ephrin B2 (EFNB2), and inhibition of Akt phosphorylation using LY294002, demonstrated that their sequential activation was responsible for the increases observed. Incubation of SH-SY5Y with increasing concentrations of MeN also increased neurite branching, suggesting that the effects of NNMT may be mediated by MeN. NNMT had no significant effect on the expression of phenotypic and post-mitotic markers, suggesting that NNMT is not involved in determining phenotypic fate or differentiation status. These results demonstrate that NNMT expression regulates neurone morphology in vitro via the sequential activation of the EFNB2 and Akt cellular signalling pathways.

Effects of Nicotinamide N-Methyltransferase on PANC-1 Cells Proliferation, Metastatic Potential and Survival Under Metabolic Stress

“…Furthermore, a recent study showed that NNMT overexpression was associated with increased radioresistance via regulating nicotinamide metabolism [22]. And Parsons et.al have found that NNMT expression reduced cell death by increasing ATP synthesis and complex I activity [23], and was able to induce changes in cell morphology via ephrin-B2 and Akt signaling in human neuroblastoma cells [24]. And very recently, a study found NNMT depletion induced cell apoptosis via mitochondria-mediated pathway in human breast cancer cells [25].…”

“…Win et al [17] observed that NNMT overexpression was positively correlated with Akt phosphorylation and implied worse prognosis in patients with nasopharyngeal carcinoma. Thomas et al [24] found NNMT expression regulated neuron morphology in vitro via the sequential activation of the EFNB2 and Akt cellular signaling pathways. And very recently Zhang et al [25] reported phosphorylation of Akt and ERK 1/2 was decreased in NNMT shRNA treated human breast cancer cells.…”

Nicotinamide metabolism regulates glioblastoma stem cell maintenance

“…In contrast, natural product methyltransferases (NPMTs) comprise a diverse group of enzymes that frequently transfer methyl groups to small molecules from SAM as the methyl donor. Many NPMTs, including NNMT, are specifically expressed in nervous system tissues, and defects in function are associated with neurological disorders (summarized in Supplemental Figure 1A) (36)(37)(38)(39)(40)(41)(42)(43)(44)(45)(46)(47). We interrogated the relative expression levels and prognostic significance of 11 NPMTs in the 2 largest GBM datasets, TCGA and REMBRANDT.…”

Nicotinamide N-methyltransferase increases complex I activity in SH-SY5Y cells via sirtuin 3

“…SH-SY5Y human neuroblastoma, which do not endogenously express NNMT, and S.NNMT.LP human neuroblastoma, comprising SH-SY5Y stably expressing NNMT Cterminally tagged to the V5 epitope (NNMT-V5) and produced as part of our ongoing studies [10,11,20], were cultured as previously described. Although SH-SY5Y do not represent a differentiated neurone-like model, they do exhibit pan-neuronal characteristics, express many neuronal markers such as synaptophysin and are readily amenable to genetic manipulation [10,20].…”