BackgroundWe established a community-based cohort study to assess the long-term impact of the Great East Japan Earthquake on disaster victims and gene-environmental interactions on the incidence of major diseases such as cancer and cardiovascular diseases.MethodsWe asked participants to join our cohort in the health check-up settings and assessment center based settings. Inclusion criteria was aged 20 years or over and living in Miyagi or Iwate Prefecture. We obtained information on lifestyle, effect of disaster, blood, and urine information (Type 1 survey), and some detailed measurements (Type 2 survey), for example, carotid echography, calcaneal ultrasound bone mineral density, and so on. All participants agreed to measure genome information and to distribute their information widely.ResultsAs a result, 87,865 gave their informed consent to join our study. Participation rate at health check-up site was about 70%. The participants with Type 1 survey were more likely to have psychological distress than those of Type 2 survey, and women were more likely to have psychological distress than men. Additionally, coastal residents were more likely to have higher degrees of psychological distress than inland residents regardless of sex.ConclusionThis cohort comprised large sample size and it contains information on disaster, genome information, and metabolome information. This cohort also had several detailed measurements. Using this cohort enabled us to clarify the long-term effect of disaster and also to establish personalized prevention based on genome, metabolome, and other omics information.

Gaucher disease is caused by defective acid β-glucosidase (GCase) function. Saposin C is a lysosomal protein needed for optimal GCase activity. To test the in vivo effects of saposin C on GCase, saposin C deficient mice (C−/−) were backcrossed to point mutated GCase (V394L/V394L) mice. The resultant mice (4L;C*) began to exhibit CNS abnormalities ∼30 days: first as hindlimb paresis, then progressive tremor and ataxia. Death occurred ∼48 days due to neurological deficits. Axonal degeneration was evident in brain stem, spinal cord and white matter of cerebellum accompanied by increasing infiltration of the brain stem, cortex and thalamus by CD68 positive microglial cells and activation of astrocytes. Electron microscopy showed inclusion bodies in neuronal processes and degenerating cells. Accumulation of p62 and Lamp2 were prominent in the brain suggesting the impairment of autophagosome/lysosome function. This phenotype was different from either V394L/V394L or C−/− alone. Relative to V394L/V394L mice, 4L;C* mice had diminished GCase protein and activity. Marked increases (20- to 30-fold) of glucosylsphingosine (GS) and moderate elevation (1.5- to 3-fold) of glucosylceramide (GC) were in 4L;C* brains. Visceral tissues had increases of GS and GC, but no storage cells were found. Neuronal cells in thick hippocampal slices from 4L;C* mice had significantly attenuated long-term potentiation, presumably resulting from substrate accumulation. The 4L;C* mouse mimics the CNS phenotype and biochemistry of some type 3 (neuronopathic) variants of Gaucher disease and is a unique model suitable for testing pharmacological chaperone and substrate reduction therapies, and investigating the mechanisms of neuronopathic Gaucher disease.

Mammalian ceramide synthases 1 to 6 (CerS1-6) generate Cer in an acyl-CoA-dependent manner, and expression of individual CerS has been shown to enhance the synthesis of ceramides with particular acyl chain lengths. However, the contribution of each CerS to steady-state levels of specific Cer species has not been evaluated. We investigated the knockdown of individual CerS in the MCF-7 human breast adenocarcinoma cell line by using small-interfering RNA (siRNA). We found that siRNA-induced downregulation of each CerS resulted in counter-regulation of nontargeted CerS. Additionally, each CerS knockdown produced unique effects on the levels of multiple sphingolipid species. For example, downregulation of CerS2 decreased very long-chain Cer but increased levels of CerS4, CerS5, and CerS6 expression and upregulated long-chain and medium-long-chain sphingolipids. Conversely, CerS6 knockdown decreased C16:0-Cer but increased CerS5 expression and caused non-C16:0 sphingolipids to be upregulated. Knockdown of individual CerS failed to decrease total sphingolipids or upregulate sphingoid bases. Treatment with siRNAs targeting combined CerS, CerS2, CerS5, and CerS6, did not change overall Cer or sphingomyelin mass but caused upregulation of dihydroceramide and hexosyl-ceramide and promoted endoplasmic reticulum stress. These data suggest that sphingolipid metabolism is robustly regulated by both redundancy in CerS-mediated Cer synthesis and counter-regulation of CerS expression.

The role of “sphingolipid rheostat” by ceramide and sphingosine 1-phosphate (S1P) in the regulation of autophagy remains unclear. In human leukemia HL-60 cells, amino acid deprivation (AA(−)) caused autophagy with an increase in acid sphingomyleinase (SMase) activity and ceramide, which serves as an autophagy inducing lipid. Knockdown of acid SMase significantly suppressed the autophagy induction. S1P treatment counteracted autophagy induction by AA(−) or C₂-ceramide. AA(−) treatment promoted mammalian target of rapamycin (mTOR) dephosphorylation/inactivation, inducing autophagy. S1P treatment suppressed mTOR inactivation and autophagy induction by AA(−). S1P exerts biological actions via cell surface receptors, and S1P₃ among five S1P receptors was predominantly expressed in HL-60 cells. We evaluated the involvement of S1P₃ in suppressing autophagy induction. S1P treatment of CHO cells had no effects on mTOR inactivation and autophagy induction by AA(−) or C₂-ceramide. Whereas S1P treatment of S1P₃ overexpressing CHO cells resulted in activation of the mTOR pathway, preventing cells from undergoing autophagy induced by AA(−) or C₂-ceramide. These results indicate that S1P-S1P₃ plays a role in counteracting ceramide signals that mediate mTOR-controlled autophagy. In addition, we evaluated the involvement of ceramide-activated protein phosphatases (CAPPs) in ceramide-dependent inactivation of the mTOR pathway. Inhibition of CAPP by okadaic acid in AA(−)- or C₂-ceramide-treated cells suppressed dephosphorylation/inactivation of mTOR, autophagy induction, and autophagy-associated cell death, indicating a novel role of ceramide-CAPPs in autophagy induction. Moreover, S1P₃ engagement by S1P counteracted cell death. Taken together, these results indicated that sphingolipid rheostat in ceramide-CAPPs and S1P-S1P₃ signaling modulates autophagy and its associated cell death through regulation of the mTOR pathway.