Feasibility study of multimodal imaging for redox status and glucose metabolism in tumor.

Understanding the tumor redox status is important for efficient cancer treatment. Here, we noninvasively detected changes in the redox environment of tumors before and after cancer treatment in the same individuals using a novel compact and portable electron paramagnetic resonance imaging (EPRI) device and compared the results with glycolytic information obtained through autoradiography using 2-deoxy-2-[18F]fluoro-d-glucose ([18F]FDG). Human colon cancer HCT116 xenografts were used in the mice. We used 3-carbamoyl-PROXYL (3CP) as a paramagnetic and redox status probe for the EPRI of tumors. The first EPRI was followed by the intraperitoneal administration of buthionine sulfoximine (BSO), an inhibitor of glutathione synthesis, or X-ray irradiation of the tumor. A second EPRI was performed on the following day. Autoradiography was performed after the second EPRI. After imaging, the tumor sections were evaluated by histological analysis and the amount of reducing substances in the tumor was measured. BSO treatment and X-ray irradiation significantly decreased the rate of 3CP reduction in tumors. Redox maps of tumors obtained from EPRI can be compared with tissue sections of approximately the same cross section. BSO treatment reduced glutathione levels in tumors, whereas X-ray irradiation did not alter the levels of any of the reducing substances. Comparison of the redox map with the autoradiography of [18F]FDG revealed that regions with high reducing power in the tumor were active in glucose metabolism; however, this correlation disappeared after X-ray irradiation. These results suggest that the novel compact and portable EPRI device is suitable for multimodal imaging, which can be used to study tumor redox status and therapeutic efficacy in cancer, and for combined analysis with other imaging modalities.

Progression of albuminuria and podocyte injury in focal segmental glomerulosclerosis inhibited by enhanced glycosphingolipid GM3 via valproic acid.

Focal segmental glomerulosclerosis, characterized by decreased numbers of podocytes in glomeruli, is a common cause of refractory nephrotic syndrome. Recently, we showed that enhanced glycosphingolipid GM3 expression after administration of valproic acid, an upregulator of ST3GAL5/St3gal5, was effective in preventing albuminuria and podocyte injury. We also revealed the molecular mechanism for this preventive effect, which involves GM3 directly binding nephrin that then act together in glycolipid-enriched membrane (GEM) fractions under normal conditions and in non-GEM fractions under nephrin injury conditions. Kidney disease is frequently referred to as a "silent killer" because it is often difficult to detect subjective symptoms. Thus, primary treatment for these diseases is initiated after the onset of disease progression. Consequently, the efficacy of enhanced levels of GM3 induced by valproic acid needs to be evaluated after the onset of the disease with severe albuminuria such as focal segmental glomerulosclerosis. Here, we report the therapeutic effect of enhanced GM3 expression induced via administration of valproic acid on albuminuria and podocyte injury after the onset focal segmental glomerulosclerosis in anti-nephrin antibody treated mice. Our findings suggest elevated levels of GM3 following treatment with valproic acid has therapeutic utility for kidney disease associated with severe albuminuria and podocyte injury.

Depression and anxiety symptoms among Vietnamese migrants in Japan during the COVID-19 pandemic.

This study aimed to examine the mental health status and related factors among Vietnamese migrants in Japan during the COVID-19 pandemic. We conducted an online cross-sectional survey between September 21 and October 21, 2021. Along with Patient Health Questionnaire-9 (PHQ-9) and Generalized Anxiety Disorder 7-item (GAD-7) scores, we collected data on demographics, changes in socioeconomic status due to the pandemic, language proficiency, social support, and health conditions. Multivariate logistic regression was performed to identify factors related to symptoms of depression and anxiety. Among 621 participants who completed the questionnaire, moderate-to-severe symptoms of depression (PHQ-9 score ≥ 10 points) and mild-to-severe symptoms of anxiety (GAD-7 score ≥ 5 points) were observed in 203 (32.7%) and 285 (45.9%) individuals, respectively. Factors related to depressive symptoms were age (95% confidence interval [CI]=0.89-0.99), pre-existing health conditions (95% [CI]=1.61-3.76), and a low subjective socioeconomic status (95% [CI]=1.64-3.71). Factors related to anxiety symptoms were being single (95% [CI]=1.01-2.93), having pre-existing health conditions (95% [CI]=1.63-3.88), subjective socioeconomic status (95% [CI]=1.87-3.97), and absence of a partner to discuss one's health with (95% [CI]=1.11-2.47). Vietnamese migrants in Japan experienced a decrease in income, worsening working conditions, and poor mental health status during the COVID-19 pandemic. Further investigations are necessary to find an effective way to increase their social support and mitigate socioeconomic adversities.

Prebiotic effect of poly-D-3-hydroxybutyrate prevents dyslipidemia in obese mice.

Obesity is a global health problem caused by genetic, environmental, and psychological factors and is associated with various health disorders. As such, there is a growing focus on the prevention of obesity and related diseases. The gut microbiota plays a crucial role in these diseases and has become a therapeutic target. Prebiotics, such as poly-d-3-hydroxybutyric acid (PHB), have gained attention for their potential to alter the gut microbiota, promote beneficial bacterial growth, and alleviate obesity. In this study, we examined the prebiotic effects of PHB in obese mice. We found that, in C57BL/6N mice, PHB reduced blood lipid levels. Analysis of the intestinal microflora also revealed an increase in short-chain fatty acid-producing bacteria. When PHB was administered to obese mice, subcutaneous fat and dyslipidemia were reduced, and the number of beneficial bacteria in the intestinal microflora increased. Furthermore, fatty degradation and oxidative stress were suppressed in the liver. PHB regulates gut bacterial changes related to obesity and effectively inhibits dyslipidemia, suggesting that it could be a prebiotic agent for curing various obesity-related diseases. In summary, PHB increases the beneficial gut microbiota, leading to an alleviation of obesity-associated dyslipidemia.

Ganglioside GM3 deficiency enhances mast cell sensitivity.

Mast cells are a significant source of cytokines and chemokines that play a role in pathological processes. Gangliosides, which are complex lipids with a sugar chain, are present in all eukaryotic cell membranes and comprise lipid rafts. Ganglioside GM3, the first ganglioside in the synthetic pathway, is a common precursor of the specifying derivatives and is well known for its various functions in biosystems. Mast cells contain high levels of gangliosides; however, the involvement of GM3 in mast cell sensitivity is unclear. Therefore, in this study, we elucidated the role of ganglioside GM3 in mast cells and skin inflammation. GM3 synthase (GM3S)-deficient mast cells showed cytosolic granule topological changes and hyperactivation upon IgE-DNP stimulation without affecting proliferation and differentiation. Additionally, inflammatory cytokine levels increased in GM3S-deficient bone marrow-derived mast cells (BMMC). Furthermore, GM3S-KO mice and GM3S-KO BMMC transplantation showed increased skin allergic reactions. Besides mast cell hypersensitivity caused by GM3S deficiency, membrane integrity decreased and GM3 supplementation rescued this loss of membrane integrity. Additionally, GM3S deficiency increased the phosphorylation of p38 mitogen-activated protein kinase. These results suggest that GM3 increases membrane integrity, leading to the suppression of the p38 signalling pathway in BMMC and contributing to skin allergic reaction.

The novel sustained 3-hydroxybutyrate donor poly-D-3-hydroxybutyric acid prevents inflammatory bowel disease through upregulation of regulatory T-cells.

Inflammatory bowel disease (IBD) is a chronic persistent intestinal disorder, with ulcerative colitis and Crohn's disease being the most common. However, the physio-pathological development of IBD is still unknown. Therefore, research on the etiology and treatment of IBD has been conducted using a variety of approaches. Short-chain fatty acids such as 3-hydroxybutyrate (3-HB) are known to have various physiological activities. In particular, the production of 3-HB by the intestinal microflora is associated with the suppression of various inflammatory diseases. In this study, we investigated whether poly-D-3-hydroxybutyric acid (PHB), a polyester of 3-HB, is degraded by intestinal microbiota and works as a slow-release agent of 3-HB. Further, we examined whether PHB suppresses the pathogenesis of IBD models. As long as a PHB diet increased 3-HB concentrations in the feces and blood, PHB suppressed weight loss and histological inflammation in a dextran sulfate sodium-induced IBD model. Furthermore, PHB increased the accumulation of regulatory T cells in the rectum without affecting T cells in the spleen. These results indicate that PHB has potential applications in treating diseases related to the intestinal microbiota as a sustained 3-HB donor. We show for the first time that biodegradable polyester exhibits intestinal bacteria-mediated bioactivity toward IBD. The use of bioplastics, which are essential materials for sustainable social development, represents a novel approach to diseases related to dysbiosis, including IBD.

A cross-sectional survey of material deprivation and suicide-related ideation among Vietnamese technical interns in Japan.

Background: The economic struggles faced by many technical intern trainees in Japan include the necessity to remit money to their home country, debts owed to intermediaries facilitating their arrival, and reduced working hours due to the COVID-19 pandemic. Furthermore, there is concern that the pandemic may contribute to mental instability resulting from the significant life changes experienced by the trainees. This study examined the experience of material deprivation among Vietnamese intern trainees in Japan and explored the correlation between material deprivation and suicidal ideation. Methods: A cross-sectional study was conducted between September and October 2021, involving 310 Vietnamese technical intern trainees. Data from 200 participants were analyzed. The questionnaire included gender, age, duration of residence in Japan, proficiency in the Japanese language, income changes due to the COVID-19 pandemic, material deprivation status, and suicidal ideation. Suicidal ideation was assessed using the ninth item of the Patient Health Questionnaire-9. Logistic regression analysis was performed to investigate the relationship between material deprivation items and suicidal ideation. Results: The mean age of the respondents was 26.0 ± 5.1 years, with 62.0% (n = 124) being male. Among the material deprivation items, 74.0% (n = 148) reported food deprivation, 59.0% (n = 118) reported cellphone bill deprivation, and 55.0% (n = 110) reported medical expense deprivation. Suicidal ideation was reported by 23.0% (n = 46) of the respondents. The prevalence of suicidal ideation was associated with age (p = 0.031, odds ratio [OR] = 0.889, 95% confidence interval [CI] = 0.799-0.990), deprivation of food expenses (p = 0.003, OR = 3.897, 95% CI = 1.597-9.511), and deprivation of cellphone usage (p = 0.021, OR = 3.671, 95% CI = 1.217-11.075). Conclusion: Vietnamese technical intern trainees in Japan faced various forms of material deprivation, which correlated with a high prevalence of significant psychological issues. Suicidal ideation was influenced by factors such as age, deprivation of food expenses, and inability to pay cellphone bills. The experience of material deprivation could have intensified the mental health challenges faced by Vietnamese trainees, particularly in the demanding circumstances of the COVID-19 pandemic.

Glycosphingolipid GM3 prevents albuminuria and podocytopathy induced by anti-nephrin antibody.

Podocytopathy, which is characterized by injury to podocytes, frequently causes proteinuria or nephrotic syndrome. There is currently a paucity of effective therapeutic drugs to treat proteinuric kidney disease. Recent research suggests the possibility that glycosphingolipid GM3 maintains podocyte function by acting on various molecules including nephrin, but its mechanism of action remains unknown. Here, various analyses were performed to examine the potential relationship between GM3 and nephrin, and the function of GM3 in podocytes using podocytopathy mice, GM3 synthase gene knockout mice, and nephrin injury cells. Reduced amounts of GM3 and nephrin were observed in podocytopathy mice. Intriguingly, this reduction of GM3 and nephrin, as well as albuminuria, were inhibited by administration of valproic acid. However, when the same experiment was performed using GM3 synthase gene knockout mice, valproic acid administration did not inhibit albuminuria. Equivalent results were obtained in model cells. These findings indicate that GM3 acts with nephrin in a collaborative manner in the cell membrane. Taken together, elevated levels of GM3 stabilize nephrin, which is a key molecule of the slit diaphragm, by enhancing the environment of the cell membrane and preventing albuminuria. This study provides novel insight into new drug discovery, which may offer a new therapy for kidney disease with albuminuria.

Sphingomyelin maintains the cutaneous barrier via regulation of the STAT3 pathway.

Epidermal tissues play vital roles in maintaining homeostasis and preventing the dysregulation of the cutaneous barrier. Sphingomyelin (SM), a sphingolipid synthesized by sphingomyelin synthase (SMS) 1 and 2, is involved in signal transduction via modulation of lipid-raft functions. Though the implications of SMS on inflammatory diseases have been reported, its role in dermatitis has not been clarified. In this study, we investigated the role of SM in the cutaneous barrier using a dermatitis model established by employing Sgms1 and 2 deficient mice. SM deficiency impaired the cutaneous inflammation and upregulated signal transducer and activator of transcription 3 (STAT3) phosphorylation in epithelial tissues. Furthermore, using mouse embryonic fibroblast cells, the sensitivity of STAT3 to Interleukin-6 stimulation was increased in Sgms-deficient cells. Using tofacitinib, a clinical JAK inhibitor, the study showed that SM deficiency might participate in STAT3 phosphorylation via JAK activation. Overall, these results demonstrate that SM is essential for maintaining the cutaneous barrier via the STAT3 pathway, suggesting SM could be a potential therapeutic target for dermatitis treatment.

Glucosylceramide in T cells regulates the pathology of inflammatory bowel disease.

Inflammatory bowel disease (IBD) is a chronic inflammatory disease in the colon characterized by excessive activation of T cells. Glycosphingolipids (GSLs) are composed of lipid rafts in cellular membranes, and their content is linked to immune cell function. In the present study, we investigated the involvement of GSLs in IBD. Microarray data showed that in IBD patients, the expression of only UDP-glucose ceramide glucosyltransferase (UGCG) decreased among the GSLs synthases. Ad libitum access to dextran sulfate sodium (DSS) resulted in decreased UGCG and glucosylceramide (GlcCer) content in mesenteric lymph nodes and T cells from the spleen. Furthermore, the knockdown of Ugcg in T cells exacerbated the pathogenesis of colitis, which was accompanied by a decrease in Treg levels. Treatment with GlcCer nanoparticles prevented DSS-induced colitis. These results suggested that GlcCer in T cells is involved in the pathogenesis of IBD. Furthermore, GlcCer nanoparticles are a potential efficacious therapeutic target for IBD patients.

Dietary Intake Quality Is Affected by Knowledge and Dietary Intake Frequency among Pregnant Women in Muntinlupa, Philippines: A Cross-Sectional Study.

Improving the nutrition of pregnant women is essential in reducing maternal and child mortality, which is one of the global nutritional goals of 2025. This study evaluated the factors related to the quality of dietary intake among pregnant women in Muntinlupa, Philippines. We conducted a cross-sectional study of 280 pregnant women at a hospital in Muntinlupa from March 2019 to August 2019 using questionnaires. After the primary aggregation, multivariate logistic regression analysis was used to identify factors associated with the quality of dietary intake in pregnant women. Approximately half of the women (46.4%, n = 130) had a low dietary diversity during pregnancy. Less than 30% of the respondents consumed beans, soybean products, and nuts. In the logistic regression analysis, poor maternal knowledge of nutritional sources to prevent anemia (odds ratio (OR) 4.25, 95% confidence interval (CI) 1.47-12.32, p = 0.01) and less frequent meal consumption (OR 2.15, 95% CI 1.08-4.29, p = 0.03) were significantly associated with poor dietary diversity. Our findings are crucial because they suggest that increasing the knowledge of pregnant women about good nutrition and ensuring that dietary intake is frequent and adequate through antenatal care can improve the nutrition of pregnant women.

Endothelial ganglioside GM3 regulates angiogenesis in solid tumors.

Cancer cells require oxygen and nutrients for growth, making angiogenesis one of the essential components of tumor growth. Gangliosides, constituting membrane lipid rafts, regulate intracellular signal transduction and are involved in the malignancy of cancer cells. While endothelial cells, as well as cancer cells, express vast amounts of gangliosides, the precise function of endothelial gangliosides in angiogenesis remains unclear. In this study, we focused on gangliosides of vascular endothelial cells and analyzed their functions on tumor angiogenesis. In human breast cancer, GM3 synthase was highly expressed in vascular endothelial cells as well as immune cells. Angiogenesis increased in GM3S-KO mice. In BAEC, RNA interference of GM3S showed increased cellular invasion and oxidative stress tolerance through activation of ERK. In the breast cancer model, GM3-KO mice showed an increase in tumor growth and angiogenesis. These results suggest that the endothelial ganglioside GM3 regulates tumor angiogenesis by suppressing cellular invasion and oxidative stress tolerance in endothelial cells.

Lipid-soluble polyphenols from sweet potato exert antitumor activity and enhance chemosensitivity in breast cancer.

Polyphenols are abundant in vegetables and fruit. They have been shown to have various antitumor, antioxidant, and anti-inflammatory effects. Here, we extracted the lipid-soluble fraction of polyphenols from fermented sweet potato (Ipomoea batatas). These lipid-soluble polyphenols mainly contained caffeic acid derivatives with strong antioxidant ability, which we hypothesized to affect diseases for which oxidative stress is a factor, such as cancer. We therefore investigated the antitumor and chemo-sensitizing effects of lipid-soluble polyphenols on E0771 murine breast cancer cells. The lipid-soluble polyphenols accumulated in the cells' cytoplasm due to its high lipophilicity, and reduced reactive oxygen species through its strong antioxidant activity. The lipid-soluble polyphenols also arrested the cell cycle at G0/G1 by suppressing Akt activity, and enhanced the cytotoxicity of anticancer agents. In this model, lipid-soluble polyphenols inhibited tumor growth and enhanced the efficacy of chemotherapy drugs. These results suggest the potential of lipid-soluble polyphenols as a functional food to support cancer therapy.

Volatile Anesthetic Sevoflurane Precursor 1,1,1,3,3,3-Hexafluoro-2-Propanol (HFIP) Exerts an Anti-Prion Activity in Prion-Infected Culture Cells.

Prion disease is a neurodegenerative disorder with progressive neurologic symptoms and accelerated cognitive decline. The causative protein of prion disease is the prion protein (PrP), and structural transition of PrP from the normal helix rich form (PrPC) to the abnormal ß-sheet rich form (PrPSc) occurs in prion disease. While so far numerous therapeutic agents for prion diseases have been developed, none of them are still useful. A fluorinated alcohol, hexafluoro isopropanol (HFIP), is a precursor to the inhalational anesthetic sevoflurane and its metabolites. HFIP is also known as a robust α-helix inducer and is widely used as a solvent for highly aggregated peptides. Here we show that the α-helix-inducing activity of HFIP caused the conformational transformation of the fibrous structure of PrP into amorphous aggregates in vitro. HFIP added to the ScN2a cell medium, which continuously expresses PrPSc, reduced PrPSc protease resistance after 24-h incubation. It was also clarified that ScN2a cells are more susceptible to HFIP than any of the cells being compared. Based on these findings, HFIP is expected to develop as a therapeutic agent for prion disease.

[Pathogenic and Compensatory Mechanisms in Epidermis of Sphingomyelin Synthase 2-Deficient Mice].

Sphingomyelin (SM) is a constituent of cellular membranes, while ceramides (Cer) produced from SM on plasma membranes serve as a lipid mediator that regulates cell proliferation, differentiation, and apoptosis. In the skin, SM also is a precursor of Cer, an important constituent of epidermal permeability barrier. We investigated the role of epidermal SM synthase (SMS)2, an isoform of SMS, which modulates SM and Cer levels on plasma membranes. Although SMS2-knockout (SMS2-KO) mice were not neonatal lethal, an ichthyotic phenotype with epidermal hyperplasia and hyperkeratosis was evident at birth, which persisted until 2 weeks of age. These mice showed abnormal lamellar body morphology and secretion, and abnormal extracellular lamellar membranes in the stratum corneum. These abnormalities were no longer evident by 4 weeks of age in SMS2-KO mice. Our study suggests that (1) exposure to a dry terrestrial environment initiates compensatory responses, thereby normalizing epidermal ichthyotic abnormalities and (2) that a nonlethal gene abnormality can cause an ichthyotic skin phenotype.

DNA damage response in vascular endothelial senescence: Implication for radiation-induced cardiovascular diseases.

A post-exposure cohort study in Hiroshima and Nagasaki reported that low-dose exposure to radiation heightened the risk of cardiovascular diseases (CVD), such as stroke and myocardial infarction, by 14-18% per Gy. Moreover, the risk of atherosclerosis in the coronary arteries reportedly increases with radiation therapy of the chest, including breast and lung cancer treatment. Cellular senescence of vascular endothelial cells (ECs) is believed to play an important role in radiation-induced CVDs. The molecular mechanism of age-related cellular senescence is believed to involve genomic instability and DNA damage response (DDR); the chronic inflammation associated with senescence causes cardiovascular damage. Therefore, vascular endothelial cell senescence is believed to induce the pathogenesis of CVDs after radiation exposure. The findings of several prior studies have revealed that ionizing radiation (IR) induces cellular senescence as well as cell death in ECs. We have previously reported that DDR activates endothelial nitric oxide (NO) synthase, and NO production promotes endothelial senescence. Endothelial NO synthase (eNOS) is a major isoform expressed in ECs that maintains cardiovascular homeostasis. Therefore, radiation-induced NO production, a component of the DDR in ECs, may be involved in CVDs after radiation exposure. In this article, we describe the pathology of radiation-induced CVD and the unique radio-response to radiation exposure in ECs.

Maternal Knowledge Associated with the Prevalence of Iron and Folic Acid Supplementation Among Pregnant Women in Muntinlupa, Philippines: A Cross-Sectional Study.

PURPOSE: The World Health Organization advocates that all pregnant women in areas where anemia is prevalent receive supplements of iron and folic acid. However, owing to a myriad of factors, the uptake of iron and folic acid supplementation (IFAS) is still low in many countries. Therefore, this study was conducted to assess the prevalence of IFAS and its associated factors among pregnant women. PATIENTS AND METHODS: A cross-sectional study was conducted at a hospital in Muntinlupa, Philippines, between March and August 2019 among 280 pregnant women. A systematic random sampling technique was used to select participants. Data were collected using interviewer-administered questionnaires. Multivariable logistic regression analyses were employed to identify factors associated with the prevalence of IFAS among pregnant women. RESULTS: Among 280 pregnant women, a majority (85.6%, n= 238) took IFAS during pregnancy. Among the respondents, 128 (45.9%) women had knowledge about signs and symptoms of anemia, 126 (45.3%) had knowledge of the benefits associated with IFAS, and 42 (15.4%) had knowledge about side effects associated with IFAS. The main sources of information about IFAS were health care providers (41.8%), followed by community health workers (CHWs) (14.6%). Maternal knowledge concerning IFAS benefits (OR = 2.50, CI = 1.04-5.97, p=0.04) was positively associated with the prevalence of IFAS. CONCLUSION: Maternal knowledge about the benefits of taking IFAS was significantly associated with the prevalence of IFAS among pregnant women in Muntinlupa, Philippines. There is a pressing need to improve health education on the benefits of IFAS among pregnant women to increase its prevalence. This emphasizes the necessity of increased involvement of health care providers and CHWs to increase women's knowledge of IFAS benefits and support them through pregnancy.

Tumor hypoxia regulates ganglioside GM3 synthase, which contributes to oxidative stress resistance in malignant melanoma.

BACKGROUND: Tumor hypoxia drastically changes cancer phenotypes, including angiogenesis, invasion, and cell death. Gangliosides are sialic acid-containing glycosphingolipids that are ubiquitously distributed on plasma membranes and are involved in many biological processes, such as the endoplasmic reticulum stress response and apoptosis. In this study, we investigated the regulation and function of glycosphingolipids, which associate with lipid raft on mammalian plasma membranes under hypoxic condition. METHODS: B16F10 melanoma cells were subjected to chemical hypoxia and low pO2 condition, and the effect of hypoxia on expression of GM3 synthase were analyzed. Cellular resistance to oxidative stress was analyzed in GM3S-KO B16F10 cells. RESULTS: Hypoxia treatment decreased the expression of ganglioside GM3 synthase (GM3S; ST3GAL5), which synthesizes the common substrate of ganglioside biosynthesis. RNA interference of hypoxia inducible factor 1 subunit alpha (HIF-1α) inhibited hypoxia-induced GM3S suppression. Additionally, GM3S deficiency increased cellular resistance to oxidative stress and radiation therapy via upregulation of ERK. CONCLUSIONS: Altered synthesis of glycosphingolipids downstream of HIF-1α signaling increased the resistance of melanoma cells to oxidative stress. Furthermore, GM3 has important role on cellular adaptive response to hypoxia. GENERAL SIGNIFICANCE: This study indicates that tumor hypoxia regulates therapy-resistance via modulation of ganglioside synthesis.

PrP (122-139) is a covert mitochondrial targeting signal of prion protein and it specifically triggers the perinuclear clustering of mitochondria in neuronal culture cells.

In many neurodegenerative diseases, mitochondria are actively involved in the onset and/or progression of diseases because the energy depletion of the neuronal cells directly leads to the dysfunction and degeneration of cells. In the case of prion diseases, mitochondrial involvement has been reported recently and evidence that prion protein (PrP) is localized in mitochondria is increasing. Despite these findings, the precise molecular mechanism by which PrP targets mitochondria remains unclear. PrP is a secretory protein and does not have a pre-sequence that targets the mitochondria, therefore, we thought that there was a covert signal in the amino acid sequence of PrP. To find the sequence, we constructed various GFP-fused PrP-truncations and colocalization with mitochondria was verified by live-cell imaging. Consequently, we found that 18 amino acids, PrP (122-139), are indispensable for the mitochondrial targeting of PrP. In addition, fluorescent microscopy observation revealed that PrP-localized mitochondria were accumulated at the perinuclear region in neuronal cells such as mouse neuroblastoma Neuro2a (N2a) and prion persistent infection N2a strain (ScN2a), anterograde movement of the mitochondria toward the cell membrane was completely inhibited because of the stacking of PrP on the outer membrane. The cristae formation of perinuclear accumulated mitochondria was disappeared indicating the reduced mitochondrial activity. Surprisingly, PrP-dependent mitochondrial perinuclear accumulation was specifically occurred on neuronal cells, whereas in epithelial HeLa cells and fibroblast COS-7 cells, no perinuclear accumulation observed even after the mitochondrial targeting of PrP.

Flower isoforms promote competitive growth in cancer.

In humans, the adaptive immune system uses the exchange of information between cells to detect and eliminate foreign or damaged cells; however, the removal of unwanted cells does not always require an adaptive immune system1,2. For example, cell selection in Drosophila uses a cell selection mechanism based on 'fitness fingerprints', which allow it to delay ageing3, prevent developmental malformations3,4 and replace old tissues during regeneration5. At the molecular level, these fitness fingerprints consist of combinations of Flower membrane proteins3,4,6. Proteins that indicate reduced fitness are called Flower-Lose, because they are expressed in cells marked to be eliminated6. However, the presence of Flower-Lose isoforms at a cell's membrane does not always lead to elimination, because if neighbouring cells have similar levels of Lose proteins, the cell will not be killed4,6,7. Humans could benefit from the capability to recognize unfit cells, because accumulation of damaged but viable cells during development and ageing causes organ dysfunction and disease8-17. However, in Drosophila this mechanism is hijacked by premalignant cells to gain a competitive growth advantage18. This would be undesirable for humans because it might make tumours more aggressive19-21. It is unknown whether a similar mechanism of cell-fitness comparison is present in humans. Here we show that two human Flower isoforms (hFWE1 and hFWE3) behave as Flower-Lose proteins, whereas the other two isoforms (hFWE2 and hFWE4) behave as Flower-Win proteins. The latter give cells a competitive advantage over cells expressing Lose isoforms, but Lose-expressing cells are not eliminated if their neighbours express similar levels of Lose isoforms; these proteins therefore act as fitness fingerprints. Moreover, human cancer cells show increased Win isoform expression and proliferate in the presence of Lose-expressing stroma, which confers a competitive growth advantage on the cancer cells. Inhibition of the expression of Flower proteins reduces tumour growth and metastasis, and induces sensitivity to chemotherapy. Our results show that ancient mechanisms of cell recognition and selection are active in humans and affect oncogenic growth.