👤 Koji Oida

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by selective motor neuron cell death. A GGGGCC hexanucleotide repeat expansion (HRE) within the chromosome 9 open reading frame 72 (C9orf72) gene is a major causative factor in ALS. This abnormal HRE triggers five types of dipeptide repeat protein (DPR), each composed of two alternating amino acid expressions. Among the DPRs, arginine-rich Poly-PR localizes predominantly to the nucleus, exerting particularly strong toxicity on motor and cortical neurons. Several mechanisms have been proposed for poly-PR-induced neurotoxicity. In this study, poly-PR-expressing NSC34 motor neuron-like cells showed an increase in oxidative stress. Fibroblast growth factor receptor 1 (FGFR1) is known to promote neurogenesis and inhibit apoptosis in neurons. However, its neuroprotective effects against DPR-induced toxicity have not been previously reported. Here, we demonstrated that FGFR1 activation reduced oxidative stress by upregulating nuclear factor erythroid 2-related factor 2 (NRF2) expression. Furthermore, we propose that the increase in NRF2 through FGFR1 activation may result from the alleviation of protein translation impairment. Overall, these findings suggest that FGFR1 activation provides neuroprotection against poly-PR toxicity and may represent a potential therapeutic strategy for ALS. Show less

A GGGGCC hexanucleotide repeat expansion (HRE) within the C9orf72 gene is a major causative factor in amyotrophic lateral sclerosis (ALS). This aberrant HRE results in the generation of five distinct dipeptide repeat proteins (DPRs). Among the DPRs, poly-PR accumulates in the nucleus and exhibits particularly strong toxicity to motor and cortical neurons. Fibroblast growth factor receptor 1 (FGFR1) is known to promote neurogenesis and inhibit apoptosis in neurons. Nevertheless, there has been no previous report of its neuroprotective effects against poly-PR toxicity. The objective of this study was to investigate the neuroprotective effects of FGFR1 activation in poly-PR-expressing NSC34 motor neuron-like cells. RT-qPCR analysis in NSC34 cells showed that Fgfr1 was the most highly expressed member of the Fgfr family in NSC34 cells. The activation of FGFR1 by FGF2, a common ligand for all FGFRs, exerted neuroprotective effects against the toxicity of poly-PR. Additionally, FGFR1 activation was observed to enhance cell viability through the PI3K-AKT pathway, while the contribution of the MEK-ERK pathway was found to be limited. Furthermore, FGFR1 activation suppressed the accumulation of p53 protein and promoted its degradation through increased murine double minute 2 (MDM2), an E3 ubiquitin ligase that targets p53. The neuroprotective effects were attenuated by PD173074, a selective FGFR1 inhibitor or Nutlin-3a, an inhibitor of the p53-MDM2 interaction. Overall, these findings suggest that FGFR1 activation provides neuroprotection against poly-PR toxicity. Consequently, this study suggests the potential utility of FGFR1 activation as a therapeutic strategy for ALS. Show less

Statins decrease cholesteryl ester transfer protein (CETP) levels, which have been positively associated with hepatic lipid content as well as serum low density lipoproteins-cholesterol (LDL-C) levels. However, the relationship between the CETP status and statin-induced reductions in LDL-C levels has not yet been elucidated in detail. We herein examined the influence of the CETP status on the lipid-reducing effects of pitavastatin in hypercholesterolemic patients with type 2 diabetes mellitus as well as the molecular mechanism underlying pitavastatin-induced modifications in CETP levels. Fifty-three patients were treated with 2 mg of pitavastatin for 3 months. Serum levels of LDL-C, small dense (sd) LDL-C, and CETP were measured before and after the pitavastatin treatment. The effects of pitavastatin, T0901317, a specific agonist for liver X receptor (LXR) that reflects hepatic cholesterol contents, and LXR silencing on CETP mRNA expression in HepG2 cells were also examined by a real-time PCR assay. The pitavastatin treatment decreased LDL-C, sdLDL-C, and CETP levels by 39, 42, and 23%, respectively. Despite the absence of a significant association between CETP and LDL-C levels at baseline, baseline CETP levels and its percentage change were an independent positive determinant for the changes observed in LDL-C and sdLDL-C levels. The LXR activation with T0901317 (0.5 μM), an in vitro condition analogous to hepatic cholesterol accumulation, increased CETP mRNA levels in HepG2 cells by approximately 220%, while LXR silencing markedly diminished the increased expression of CETP. Pitavastatin (5 μM) decreased basal CETP mRNA levels by 21%, and this was completely reversed by T0901317. Baseline CETP levels may predict the lipid-reducing effects of pitavastatin. Pitavastatin-induced CETP reductions may be partially attributed to decreased LXR activity, predictable by the ensuing decline in hepatic cholesterol synthesis. UMIN Clinical Trials Registry ID UMIN000019020. Show less