Sphingomyelin synthase 1 mediates hepatocyte pyroptosis to trigger non-alcoholic steatohepatitis.

OBJECTIVE: Lipotoxic hepatocyte injury is a primary event in non-alcoholic steatohepatitis (NASH), but the mechanisms of lipotoxicity are not fully defined. Sphingolipids and free cholesterol (FC) mediate hepatocyte injury, but their link in NASH has not been explored. We examined the role of free cholesterol and sphingomyelin synthases (SMSs) that generate sphingomyelin (SM) and diacylglycerol (DAG) in hepatocyte pyroptosis, a specific form of programmed cell death associated with inflammasome activation, and NASH. DESIGN: Wild-type C57BL/6J mice were fed a high fat and high cholesterol diet (HFHCD) to induce NASH. Hepatic SMS1 and SMS2 expressions were examined in various mouse models including HFHCD-fed mice and patients with NASH. Pyroptosis was estimated by the generation of the gasdermin-D N-terminal fragment. NASH susceptibility and pyroptosis were examined following knockdown of SMS1, protein kinase Cδ (PKCδ), or the NLR family CARD domain-containing protein 4 (NLRC4). RESULTS: HFHCD increased the hepatic levels of SM and DAG while decreasing the level of phosphatidylcholine. Hepatic expression of Sms1 but not Sms2 was higher in mouse models and patients with NASH. FC in hepatocytes induced Sms1 expression, and Sms1 knockdown prevented HFHCD-induced NASH. DAG produced by SMS1 activated PKCδ and NLRC4 inflammasome to induce hepatocyte pyroptosis. Depletion of Nlrc4 prevented hepatocyte pyroptosis and the development of NASH. Conditioned media from pyroptotic hepatocytes activated the NOD-like receptor family pyrin domain containing 3 inflammasome (NLRP3) in Kupffer cells, but Nlrp3 knockout mice were not protected against HFHCD-induced hepatocyte pyroptosis. CONCLUSION: SMS1 mediates hepatocyte pyroptosis through a novel DAG-PKCδ-NLRC4 axis and holds promise as a therapeutic target for NASH.

Autophagic flux defect in diabetic kidney disease results in megamitochondria formation in podocytes.

Podocyte injury is an important factor in the pathogenesis of diabetic nephropathy. Podocytes are characterized by large numbers of mitochondria. However, mitochondrial dysfunction as it relates to kidney pathology remains poorly understood. The present study found that podocyte mitochondria in different animal models of diabetes mellitus became elongated with the development of albuminuria, suggesting a change in mitochondrial dynamics. We then treated cells with a combination of glucose, fatty acids, and angiotensin II (GFA) to mimic the diabetic milieu. Cultured podocytes exposed to GFA showed megamitochondria formation and decreased autophagosome degradation. We also found that GFA treatment decreased the binding of the autophagosome to the lysosome. Our results suggest that megamitochondria are common in podocytes during diabetic nephropathy and that insufficient autophagy flux may underlie this effect. These findings have expanded our understanding of the pathogenesis of diabetic nephropathy and identified a potential pharmacological target for treatment.

Application of geographically weighted regression models to predict spatial characteristics of nitrate contamination: Implications for an effective groundwater management strategy.

Groundwater nitrate contamination has been the main water quality problem threatening the sustainable utilization of water resources in Jeju Island, South Korea. The spatially varying distribution of nitrate levels associated with complex environmental and anthropogenic factors has been a major challenge restricting improved groundwater management. In this study, we applied ordinary least squares (OLS) regression and geographically weighted regression (GWR) models to determine the relationships between the NO3-N concentration and various parameters (topography, hydrology and land use) across the island. A comparison between the OLS regression and GWR prediction models showed that the GWR models outperformed the OLS regression models, with a higher R2 and a lower corrected Akaike Information Criterion (AICc) value than the OLS regression models. Interestingly, the GWR model was able to provide undiscovered information that was not revealed in the OLS regression models. For example, the GWR model found that orchards (OR) and urban (UR) variables significantly contributed to nitrate enrichment in the certain parts of the island, whereas these variables were ignored as a statistically insignificant factor in the OLS regression model. Our study highlighted that GWR models are a useful tool for investigating spatially varying relationships between groundwater quality and environmental factors; therefore, it can be applied to establish advanced groundwater management plans by reflecting the spatial heterogeneity associated with environmental and anthropogenic conditions.

Protective role of endogenous plasmalogens against hepatic steatosis and steatohepatitis in mice.

Free cholesterol (FC) accumulation in the liver is an important pathogenic mechanism of nonalcoholic steatohepatitis (NASH). Plasmalogens, key structural components of the cell membrane, act as endogenous antioxidants and are primarily synthesized in the liver. However, the role of hepatic plasmalogens in metabolic liver disease is unclear. In this study, we found that hepatic levels of docosahexaenoic acid (DHA)-containing plasmalogens, expression of glyceronephosphate O-acyltransferase (Gnpat; the rate-limiting enzyme in plasmalogen biosynthesis), and expression of Pparα were lower in mice with NASH caused by accumulation of FC in the liver. Cyclodextrin-induced depletion of FC transactivated Δ-6 desaturase by increasing sterol regulatory element-binding protein 2 expression in cultured hepatocytes. DHA, the major product of Δ-6 desaturase activation, activated GNPAT, thereby explaining the association between high hepatic FC and decreased Gnpat expression. Gnpat small interfering RNA treatment significantly decreased peroxisome proliferator-activated receptor α (Pparα) expression in cultured hepatocytes. In addition to GNPAT, DHA activated PPARα and increased expression of Pparα and its target genes, suggesting that DHA in the DHA-containing plasmalogens contributed to activation of PPARα. Accordingly, administration of the plasmalogen precursor, alkyl glycerol (AG), prevented hepatic steatosis and NASH through a PPARα-dependent increase in fatty acid oxidation. Gnpat+/- mice were more susceptible to hepatic lipid accumulation and less responsive to the preventive effect of fluvastatin on NASH development, suggesting that endogenous plasmalogens prevent hepatic steatosis and NASH. CONCLUSION: Increased hepatic FC in animals with NASH decreased plasmalogens, thereby sensitizing animals to hepatocyte injury and NASH. Our findings uncover a novel link between hepatic FC and plasmalogen homeostasis through GNPAT regulation. Further study of AG or other agents that increase hepatic plasmalogen levels may identify novel therapeutic strategies against NASH. (Hepatology 2017;66:416-431).

Association between diabetes and asthma: Evidence from a nationwide Korean study.

BACKGROUND: Type 2 diabetes and asthma share a common pathophysiology: "chronic inflammation." However, it is unclear whether patients with type 2 diabetes are at increased risk of asthma. OBJECTIVE: To investigate the effect of type 2 diabetes on asthma using data from a large population-based study in Korea. METHODS: Data from the Korean National Health Insurance Service identified 13,154,348 participants who underwent regular health checkups from 2005 to 2008. Subjects were classified according to status of diabetes mellitus (DM) and diabetic retinopathy (DR), and followed until the date of asthma development, death, or December 31, 2013. Cox proportional hazard regression analysis was used to evaluate the effect of diabetes, with or without retinopathy, on asthma development. RESULTS: The incidences of asthma in the non-DM, DM without DR, and DR groups were 27.1, 30.1, and 38.4 per 1,000 person-years, respectively. Cox proportional hazard multiple regression models revealed that diabetic patients without retinopathy had a significantly lower risk of developing asthma than non-DM subjects (hazard ratio, 0.943; 95% confidence interval, 0.939-0.948). By contrast, diabetic patients with retinopathy had a higher risk of developing asthma (hazard ratio, 1.067; 95% confidence interval, 1.053-1.081). CONCLUSION: Type 2 diabetes without retinopathy is not a risk factor for asthma development. However, patients with DR are at a greater risk of incident asthma, supporting the notion that the lung is a target organ for diabetic injury. Future studies will address whether proper glycemic control mitigates the risk of asthma.

Mitochondrial Activity in Human White Adipocytes Is Regulated by the Ubiquitin Carrier Protein 9/microRNA-30a Axis.

The acquisition of beige adipocyte features by white fat cells corresponds to protection against obesity-induced metabolic diseases in humans and animal models of type 2 diabetes. In adipose tissue, expression of the E2 small ubiquitin-like modifier ligase ubiquitin carrier protein 9 (Ubc9) is positively correlated with markers of insulin resistance and corresponds with impaired browning of human white adipocytes. However, the molecular regulation of Ubc9 expression in adipocytes and other cells remains unclear. In this study, we demonstrate that the mRNA and protein expression of Ubc9 are regulated by the microRNA miRNA-30a (miR-30a) in human subcutaneous adipocytes. Ubc9 and miR-30a exhibit inverse expression in adipose tissue, with miR-30a robustly elevated in brown fat. Depletion of Ubc9 by siRNA or enforced expression of a miR-30a mimic augments mitochondrial volume and respiration in human white adipocytes, reflecting features of brown fat cells. Furthermore, Ubc9 depletion induces a brown fat gene program in human subcutaneous adipocytes. Induction of the beige-selective gene program corresponds to stabilization of the PR domain-containing 16 (PRDM16) protein, an obligate transcriptional regulator of the brown/beige fat metabolic program in white adipocytes that interacts with Ubc9. Taken together, our data demonstrate a previously unappreciated molecular axis that controls browning of human white adipocytes.

Impact of abdominal obesity on the risk of glioma development in patients with diabetes: A nationwide population-based cohort study in Korea.

BACKGROUND: Abdominal obesity has been suggested as a risk factor for glioma; however, it is unclear whether this association applies to people with diabetes. This study examined the association between abdominal obesity and the risk of developing gliomas in diabetic patients. METHODS: We conducted a retrospective cohort study using the National Health Insurance System of South Korea from 2009 to 2012. The primary outcome was the incidence of newly diagnosed gliomas according to waist circumference (WC), and subgroup analyses were performed according to demographic characteristics and diabetes status including disease duration, number of oral hypoglycemic agents, and insulin use. RESULTS: Of a total of 1,893,057 participants, 1,846 (0.10%) cases of gliomas occurred. After adjusting for confounding factors, WC ≥90 cm (men)/85 cm (women) was associated with significantly higher risks of gliomas (adjusted HR [95% CI]; 1.279 [1.053, 1.554], 1.317 [1.048, 1.655], and 1.369 [1.037, 1.807] in the WC <95 cm (men)/90 cm (women) group, WC <100 cm (men)/95 cm (women) group, and WC ≥100 cm (men)/95 cm (women) group, respectively). Subgroup analysis showed that patients with larger WC had a consistently higher incidence of glioma than their lean counterparts, except for insulin users (insulin user vs. nonuser, P for interaction = .03). CONCLUSIONS: Abdominal obesity was associated with the development of gliomas in diabetic patients in a nationwide population-based database. Further study is needed in diabetic patients to stratify the risk for glioma development according to WC and to establish the underlying mechanism of carcinogenesis.

Nitrate sources, timing, and pathways of a permeable volcanic aquifer system with mixed land use in Jeju Island, South Korea.

The occurrence of various N-related human activities increases the difficulty in distinguishing the major sources of NO3- contamination in groundwater, especially in areas with mixed land uses. In addition, the estimation of the timing and pathways of NO3- is necessary to better understand the processes of NO3- contamination in the subsurface aquifer system. This study applied environmental tracers, such as stable isotopes and age tracers (δ15N and δ18O of NO3-, δ11B, chlorofluorocarbons, and 3H), to elucidate the sources, timing, and pathways of NO3- contamination in the groundwaters of the Hanrim area, which has suffered from illegal disposal of livestock wastes since the 1980s, and also characterizes them based on mixed N-contaminant sources such as chemical fertilizers and sewage. The combined use of δ15N and δ11B overcame the limitation of using only NO3- isotopes for the identification of overlapping sources of N and successfully identified the major source of N as livestock wastes. The lumped parameter model (LPM) estimated the binary mixing of the young (age: 23-40 years, NO3-N: 2.55-15.10 mg/L) and old (age: >60 years, NO3-N: <3 mg/L) groundwaters, and explained their age mixing behaviors. The young groundwater was highly affected by livestock-derived N loading during 1987-1998, which coincides with the period of improper dumping of livestock wastes. Furthermore, the young groundwater with elevated NO3-N followed the historical NO3-N curves with younger ages (6 and 16 years) than those derived from the LPM, suggesting the possibility of faster inflows of livestock wastes through the permeable volcanic structures. This study demonstrated that a comprehensive understanding of NO3- contamination processes can be achieved using environmental tracer methods, which enables the efficient management of groundwater resources in areas with multiple N sources.

Hydrogeochemistry and isotopic tracing of nitrate contamination of two aquifer systems on Jeju Island, Korea.

The groundwater of Jeju Island (Republic of Korea) is vulnerable to contamination because its aquifers are mainly composed of highly permeable geological units and its agricultural fields are often exposed to excessive use of predominantly synthetic fertilizers. In the Gosan area of Jeju Island, we investigated nitrate contamination in both a perched aquifer above an impermeable clay bed and the regional groundwater beneath this aquitard. The δO and δD values indicate that the perched groundwater is recharged by local precipitation, whereas the regional groundwater is recharged mainly by regional flow from an adjacent mountainous region. The perched groundwater contained very high NO-N concentrations of up to 87 mg/L. The isotopic composition of nitrate in the perched groundwater showed that synthetic fertilizers applied in high excesses of crop N needs were the main cause of aquifer pollution. Elevated nitrate concentrations were also observed in the regional groundwater especially after precipitation events. Concentration and isotopic data revealed that the inflow of shallow perched groundwater along the poorly cemented or uncemented annulus of regional groundwater wells was one of the main reasons for the nitrate contamination observed in the regional groundwater. In both aquifers, δN and δO values showed that the sources of nitrate were derived from synthetic fertilizers that had been recycled in the soil zone by nitrification and in some portions of the perched aquifer (dissolved oxygen concentrations <2 mg/L) indicated that denitrification occurred locally.

Integrated application of a Bayesian mixing model, numerical model, and environmental tracers to characterize groundwater recharge sources in a mountainous area.

In this study, the combined use of a Bayesian mixing model (BMM), numerical model (random walk particle tracking-RWPT), and environmental tracers (δ18O-δD, 3H, and CFC) was applied to elucidate the probabilistic contribution of the recharge sources, flow path, and residence time of groundwater across the mountainous area of Jeju Island, South Korea. Especially, the BMM ability to estimate the variable recharge contributions to the aquifer by different elevations and seasons was investigated. The δ18O-δD isotopes showed that groundwater in the study area was primarily fed by precipitation during the wet season, and the BMM estimated that wet season recharge contributed to approximately 64% of the total. The BMM-based probabilistic estimation of recharge sources revealed a mixed contribution of source waters from different elevations. A notable difference in recharge flow path was observed between highland (>450 masl) and lowland (<400 masl) wells, where the inflow of source water from the regional flow was dominant in the former and both regional and local recharges served as significant groundwater sources in the latter. Evidence from age tracers (3H and CFC-12) also supported different recharge mechanisms between highland and lowland wells. A reasonable match between the BMM- and RWPT-derived recharge contributions (RMSE 0.02-0.06) was achieved within the uncertainty ranges, with RWPT being particularly useful for capturing different flow paths between highland and lowland wells. The dynamics revealed here provide important information for establishing an improved and informed groundwater management plan for the mountainous area of Jeju Island. Ultimately, this study highlights the advantageous integrated analysis of BMM, RWPT, and environmental tracer analyses to enhance the reliability of recharge area estimation and increase the collective understanding of complex hydrogeological systems in mountainous areas.

Association between organochlorine pesticides and nonalcoholic fatty liver disease in the National Health and Nutrition Examination Survey 2003-2004.

While endocrine disruptors are emerging as a cause of nonalcoholic fatty liver disease (NAFLD), little is known about the link between NAFLD and organochlorine pesticides (OCPs), one of the endocrine disruptors. We retrospectively analyzed the U.S. National Health and Nutrition Examination Survey 2003-2004 and compared the baseline demographics in individuals according to the presence of NAFLD (fatty liver index [FLI] ≥ 60). Logistic regression analysis was performed to determine whether OCP concentration affected NAFLD prevalence and subgroup analyses regarding NAFLD-related variables and advanced hepatic fibrosis (FIB-4 ≥ 2.67) were performed. Of the 1515 individuals, 579 (38.2%) had NAFLD. Oxychlordane showed concentration-dependent risk for NAFLD (OR 3.471 in fourth quartile [Q4]; 95% CI 1.865-6.458; P = 0.007). p,p'-DDE and trans-nonachlor showed similar trends without statistical significance. Conversely, mirex showed the lowest risk for NAFLD in the highest concentration quartile (OR 0.29 in Q4; 95% CI 0.175-0.483; P < 0.001). Oxychlordane showed the most pronounced association with the levels of each component of FLI and liver enzymes. None of the OCPs were significantly associated with advanced fibrosis. In conclusion, among OCPs, exposure to oxychlordane showed the most prominent impact associated with NAFLD.

Sphingosine 1-Phosphate Receptor 4 Promotes Nonalcoholic Steatohepatitis by Activating NLRP3 Inflammasome.

BACKGROUND & AIMS: Sphingosine 1-phosphate receptors (S1PRs) are a group of G-protein-coupled receptors that confer a broad range of functional effects in chronic inflammatory and metabolic diseases. S1PRs also may mediate the development of nonalcoholic steatohepatitis (NASH), but the specific subtypes involved and the mechanism of action are unclear. METHODS: We investigated which type of S1PR isoforms is activated in various murine models of NASH. The mechanism of action of S1PR4 was examined in hepatic macrophages isolated from high-fat, high-cholesterol diet (HFHCD)-fed mice. We developed a selective S1PR4 functional antagonist by screening the fingolimod (2-amino-2-[2-(4- n -octylphenyl)ethyl]-1,3- propanediol hydrochloride)-like sphingolipid-focused library. RESULTS: The livers of various mouse models of NASH as well as hepatic macrophages showed high expression of S1pr4. Moreover, in a cohort of NASH patients, expression of S1PR4 was 6-fold higher than those of healthy controls. S1pr4+/- mice were protected from HFHCD-induced NASH and hepatic fibrosis without changes in steatosis. S1pr4 depletion in hepatic macrophages inhibited lipopolysaccharide-mediated Ca++ release and deactivated the Nod-like receptor pyrin domain-containning protein 3 (NLRP3) inflammasome. S1P increased the expression of S1pr4 in hepatic macrophages and activated NLRP3 inflammasome through inositol trisphosphate/inositol trisphosphate-receptor-dependent [Ca++] signaling. To further clarify the biological function of S1PR4, we developed SLB736, a novel selective functional antagonist of SIPR4. Similar to S1pr4+/- mice, administration of SLB736 to HFHCD-fed mice prevented the development of NASH and hepatic fibrosis, but not steatosis, by deactivating the NLRP3 inflammasome. CONCLUSIONS: S1PR4 may be a new therapeutic target for NASH that mediates the activation of NLRP3 inflammasome in hepatic macrophages.

Serum gamma-glutamyltransferase is associated with arterial stiffness in healthy individuals.

OBJECTIVE: Gamma-glutamyltransferase (GGT) has been reported to be useful in predicting cardiovascular disease. Arterial stiffness measured by brachial-ankle pulse wave velocity (baPWV) is not only a marker of vascular damage but a significant predictor of cardiovascular events. Gender difference has been reported in the association between GGT and baPWV. We assessed, therefore, the association between GGT and baPWV in a large population and determined whether there was gender difference. DESIGN: This cross-sectional study was conducted at the Asan Medical Centre, Seoul, Republic of Korea. SUBJECTS AND MEASUREMENTS: Serum GGT, baPWV and conventional risk factors were measured in 10 988 apparently healthy subjects (7248 men, 3740 women) who participated in a routine health screening examination. RESULTS: In both men and women, we observed positive linearity between GGT quartiles and body mass index, waist circumference, systolic blood pressure, diastolic blood pressure, fasting plasma glucose, total cholesterol, LDL cholesterol, triglycerides, uric acid, high-sensitive C-reactive protein (hsCRP) and homeostatic model assessment of insulin resistance (HOMA-IR) score (P for trends < 0·001). The proportion of individuals with diabetes, hypertension increased as the GGT quartile increased (P for trends < 0·001). Age-adjusted mean baPWV increased gradually in both males and females according to GGT quartiles (P for trends < 0·001 in both genders). The odds for higher baPWV (i.e. >75th percentile in each sex) were significantly higher in the highest compared with the lowest GGT quartiles, after adjustment for confounding variables, in both men [odds ratio (OR) = 1·63, 95% CI = 1·21-2·20] and women (OR = 1·56, 95% CI = 1·08-2·27). CONCLUSIONS: These results suggest that GGT is independently associated with the increased level of arterial stiffness both in men and in women and the association between them appears to be stronger in men compared to women.

Peroxisome proliferator-activated receptor-gamma coactivator 1-alpha overexpression prevents endothelial apoptosis by increasing ATP/ADP translocase activity.

OBJECTIVE: Fatty acids increase reactive oxygen species generation and cell apoptosis in endothelial cells. The peroxisome proliferator-activated receptor-gamma coactivator 1-alpha (PGC-1alpha) is a transcriptional coactivator that increases mitochondrial biogenesis and fatty acid oxidation in various cells. This study was undertaken to investigate the possible preventive effect of PGC-1alpha on endothelial apoptosis and its molecular mechanism. METHODS AND RESULTS: Treatment with linoleic acid in cultured human aortic endothelial cells increased reactive oxygen species generation and cell apoptosis. These effects appeared to be mediated by increases in cytosolic fat metabolites, ie, fatty acyl CoA, diacylglycerol, and ceramide, and consequent decreases in ATP/ADP translocase activity of adenine nucleotide translocator. Adenoviral overexpression of PGC-1alpha prevented linoleic acid-induced increases in reactive oxygen species generation and cell apoptosis in human aortic endothelial cells by increasing fatty acid oxidation, decreasing diacylglycerol and ceramide, and increasing ATP/ADP translocase activity. In isolated aorta, PGC-1alpha overexpression prevented linoleic acid-induced decrease in endothelium-dependent vasorelaxation, and this effect was abolished by adenine nucleotide translocator1 shRNA. CONCLUSIONS: PGC-1alpha regulates reactive oxygen species generation and apoptosis in endothelial cells by increasing fatty acid oxidation and enhancing ATP/ADP translocase activity. Measures to increase PGC-1alpha expression or ATP/ADP translocase activity in vascular cells may aid in the prevention or treatment of atherosclerosis.

Insulin Resistance Increases Serum Immunoglobulin E Sensitization in Premenopausal Women.

Background: Although studies have shown that obesity is associated with aeroallergen sensitization (atopy), controversy still exists. We aimed to investigate the association between metabolic status, obesity, and atopy stratified by sex and menopausal status. Methods: A total of 1,700 adults from the 2010 Korean National Health and Nutrition Examination Survey were classified into metabolically healthy nonobese (MHNO), metabolically unhealthy nonobese (MUNO), metabolically healthy obese (MHO), and metabolically unhealthy obese (MUO) by body mass index and insulin resistance. Atopy was defined as a positive response to at least one aeroallergen. Multiple regression analysis was used to evaluate the risk of immunoglobulin E (IgE) elevation or atopy in relation to the degree of metabolic abnormality and obesity. Results: In premenopausal women, total IgE was positively correlated with obesity and insulin resistance. MUNO participants had a higher risk of having elevated total IgE compared to MHNO participants (odds ratio [OR], 2.271; 95% confidence interval [CI], 1.201 to 4.294), while MHO participants did not show a significant difference (OR, 1.435; 95% CI, 0.656 to 3.137) in premenopausal women. MUNO, but not MHO was also associated with atopy (OR, 2.157; 95% CI, 1.284 to 3.625). In men and postmenopausal women, there was no significant difference between metabolic status, obesity, and atopy among groups. Conclusion: Increased insulin resistance is associated with total IgE and atopy in premenopausal women but not in postmenopausal women or men.

Delineation of groundwater quality locations suitable for target end-use purposes through deep neural network models.

Groundwater is the main source of water for beverages, and its quality varies depending on extraction location; this is particularly the case in regions with complex geology, topography, and multiple forms of land use. Thus, it is important to determine a suitable groundwater extraction location based on intended water use and the related water quality standards. In this study, deep neural network (DNN) models and GIS data relating to groundwater quality were applied to estimate potential maps of Gangwon Province in South Korea, where groundwater is frequently extracted for drinking purposes. These maps specify areas where the groundwater quality is conducive for being used as mineral water and water for brewing coffee (hereafter referred as "coffee water"). Sensitivity analysis identified how inputs were sensitive to model estimation and showed that land-use variables were the most sensitive. The importance of each variable quantified how good or bad its region is for the desired groundwater. The overall features of importance were similar between mineral water and coffee water. However, with differences in hydrogeological units, carbonate rock was a variable of high positive importance for mineral water; metamorphic rock was its equivalent for coffee water. Our results offer a potential map of desired groundwater quality in the absence of a detailed understanding of the underlying hydrochemical processes governing groundwater quality. Additionally, the development of such a potential mapping model can help to determine the appropriate development area of groundwater for their respective purposes.

Perilipin 5 is a novel target of nuclear receptor LRH-1 to regulate hepatic triglycerides metabolism.

Liver receptor homolog-1 (LRH-1) has emerged as a regulator of hepatic glucose, bile acid, and mitochondrial metabolism. However, the functional mechanism underlying the effect of LRH-1 on lipid mobilization has not been addressed. This study investigated the regulatory function of LRH-1 in lipid metabolism in maintaining a normal liver physiological state during fasting. The Lrh-1f/f and LRH-1 liver-specific knockout (Lrh-1LKO) mice were either fed or fasted for 24 h, and the liver and serum were isolated. The livers were used for qPCR, western blot, and histological analysis. Primary hepatocytes were isolated for immunocytochemistry assessments of lipids. During fasting, the Lrh-1LKO mice showed increased accumulation of triglycerides in the liver compared to that in Lrh-1f/f mice. Interestingly, in the Lrh-1LKO liver, decreases in perilipin 5 (PLIN5) expression and genes involved in ß-oxidation were observed. In addition, the LRH-1 agonist dialauroylphosphatidylcholine also enhanced PLIN5 expression in human cultured HepG2 cells. To identify new target genes of LRH-1, these findings directed us to analyze the Plin5 promoter sequence, which revealed -1620/-1614 to be a putative binding site for LRH-1. This was confirmed by promoter activity and chromatin immunoprecipitation assays. Additionally, fasted Lrh-1f/f primary hepatocytes showed increased co-localization of PLIN5 in lipid droplets (LDs) compared to that in fasted Lrh-1LKO primary hepatocytes. Overall, these findings suggest that PLIN5 might be a novel target of LRH-1 to mobilize LDs, protect the liver from lipid overload, and manage the cellular needs during fasting. [BMB Reports 2021; 54(9): 476-481].

Differentiation of natural and anthropogenic contaminant sources using isotopic and microbial signatures in a heavily cultivated coastal area.

Hydrogeochemical and multiple isotope data for groundwater samples were obtained and interpreted to discriminate anthropogenic and natural contaminant sources in a coastal aquifer underlying a heavily cultivated watershed in Hwaseong, South Korea. The local aquifers are vulnerable to contamination, due to high anthropogenic N inputs and the location close to the ocean facilitating seawater intrusion. Thus, to effectively control the groundwater quality in the study area, it is necessary to differentiate between anthropogenic and natural contaminant sources. The concentrations of NO3-N in the groundwater ranged between 0.14 and 45.6 mg/L in August 2015 and 0.2-39.6 mg/L in March 2016. High concentrations of Cl- (388-1107 mg/L) and a high electrical conductivity (1027-2715 µS/cm) were observed in the study area, suggesting that the groundwater was affected by seawater intrusion. Furthermore, δ15N-NO3-, δ34S-SO42- values and 87Sr/86Sr of groundwater were determined to reveal the origins of the natural and anthropogenic contaminants and the groundwater mean residence times (MRT) and 87Sr/86Sr ratios were used to assess the hydrogeochemical processes along the flow path in the study area. Young groundwater was affected by an anthropogenic contamination source with contributions of 26-46% adding nitrate to the aquifer, whereas old groundwater was impacted by mixing with seawater with contributions of 10-20% with low concentrations of NO3-N, but elevated concentrations of chloride and sulfate. Recently recharged uncontaminated groundwater showed oxic conditions with a diverse microbial community structure, whereas young groundwater contaminated by anthropogenic sources showed a less diverse microbial community structure. The results of this study suggest that multiple isotopes combined with groundwater MRT and microbial data can be applied to distinguish natural and anthropogenic contaminant sources in a groundwater system.

Hepatic MIR20B promotes nonalcoholic fatty liver disease by suppressing PPARA.

Background: Non-alcoholic fatty liver disease (NAFLD) is characterized by excessive lipid accumulation and imbalances in lipid metabolism in the liver. Although nuclear receptors (NRs) play a crucial role in hepatic lipid metabolism, the underlying mechanisms of NR regulation in NAFLD remain largely unclear. Methods: Using network analysis and RNA-seq to determine the correlation between NRs and microRNA in human NAFLD patients, we revealed that MIR20B specifically targets PPARA. MIR20B mimic and anti-MIR20B were administered to human HepG2 and Huh-7 cells and mouse primary hepatocytes as well as high-fat diet (HFD)- or methionine-deficient diet (MCD)-fed mice to verify the specific function of MIR20B in NAFLD. We tested the inhibition of the therapeutic effect of a PPARα agonist, fenofibrate, by Mir20b and the synergic effect of combination of fenofibrate with anti-Mir20b in NAFLD mouse model. Results: We revealed that MIR20B specifically targets PPARA through miRNA regulatory network analysis of nuclear receptor genes in NAFLD. The expression of MIR20B was upregulated in free fatty acid (FA)-treated hepatocytes and the livers of both obesity-induced mice and NAFLD patients. Overexpression of MIR20B significantly increased hepatic lipid accumulation and triglyceride levels. Furthermore, MIR20B significantly reduced FA oxidation and mitochondrial biogenesis by targeting PPARA. In Mir20b-introduced mice, the effect of fenofibrate to ameliorate hepatic steatosis was significantly suppressed. Finally, inhibition of Mir20b significantly increased FA oxidation and uptake, resulting in improved insulin sensitivity and a decrease in NAFLD progression. Moreover, combination of fenofibrate and anti-Mir20b exhibited the synergic effect on improvement of NAFLD in MCD-fed mice. Conclusions: Taken together, our results demonstrate that the novel MIR20B targets PPARA, plays a significant role in hepatic lipid metabolism, and present an opportunity for the development of novel therapeutics for NAFLD. Funding: This research was funded by Korea Mouse Phenotyping Project (2016M3A9D5A01952411), the National Research Foundation of Korea (NRF) grant funded by the Korea government (2020R1F1A1061267, 2018R1A5A1024340, NRF-2021R1I1A2041463, 2020R1I1A1A01074940, 2016M3C9A394589324), and the Future-leading Project Research Fund (1.210034.01) of UNIST.