👤 Risa Mitsumori

Late-onset Alzheimer's disease (LOAD) is the most common form of dementia in the elderly, yet no curative treatments are available. Although genome-wide association studies (GWASs) have identified numerous genetic risk factors, these factors often differ among ethnic groups, and the mechanisms driving LOAD onset remain poorly understood. Most GWASs of LOAD have been conducted in European populations; the expansion of future studies to non-European populations should uncover novel genetic factors underlying LOAD pathogenesis. To identify novel LOAD-susceptible genes, we conducted whole-genome sequencing data analysis on 1928 Japanese individuals including 325 patients with LOAD and 1603 cognitively normal elderly controls. A GWAS for common variants identified a statistically significant association signal in rs429358, within the apolipoprotein E gene (APOE), which defines the APOE Show less

Argyrophilic grain (AG) is a common neurodegenerative accumulation of 4 repeat tau in dendritic spine. Dementia with grain (DG) is defined as AGs with a sole pathological basis for cognitive decline. As with other multifactorial diseases, DG could result from interactions of environmental and genetic factors. However, the genetic basis of DG is largely unknown. To clarify the genetic architecture of DG pathogenesis, we conducted a genome-wide association study (GWAS) with 214 DG cases versus 12,405 controls. We have identified a candidate locus associated with the risk of DG, the SVIL locus on chromosome 10, with genome-wide significance (rs11595141, P = 4.86 Show less

Adenosine monophosphate-activated protein kinase (AMPK) is a sensor for cellular energy status. When the cellular energy level is decreased, AMPK is activated and functions to suppress energy-consuming processes, including protein synthesis. Recently, AMPK has received attention as an attractive molecular target for cancer therapy. Several studies have revealed that the activation of AMPK by chemical stimulators, such as metformin, induces apoptosis in a variety of hematologic malignant cells. From another perspective, these results suggest that the function of AMPK is impaired in hematologic tumor cells. However, the precise mechanisms by which this impairment occurs are not well understood. In melanoma cells, oncogenic BRAF constitutively activates the extracellular signal-regulated kinase (ERK) pathway and phosphorylates liver kinase B1, an upstream activator of 5' adenosine monophosphate-activated protein kinase (AMPK), resulting in the inactivation of liver kinase B1 and AMPK. In this study, we analyzed whether ERK is involved in the suppression of AMPK activity using established and primary human leukemia cells. We found an inverse correlation between the intensity of ERK activity and the degree of AMPK activation after stimulation with either glucose deprivation or metformin. We also found that the inhibition of ERK activity by U0126 restored AMPK activation after metformin treatment. Furthermore, a combined treatment with metformin and U0126 enhanced the antileukemic activity of metformin. Importantly, metformin induced ERK activation by suppressing the protein levels of dual specificity phosphatase 6, a negative regulator of ERK. This crosstalk between AMPK and ERK could diminish the antileukemic activity of metformin. Taken together, our present observations suggest a novel therapeutic strategy for improving the efficacy of metformin in treating leukemia. Show less