GR-KLF15 pathway controls hepatic lipogenesis during fasting.

During periods of fasting, the body undergoes a metabolic shift from carbohydrate utilization to the use of fats and ketones as an energy source, as well as the inhibition of de novo lipogenesis and the initiation of gluconeogenesis in the liver. The transcription factor sterol regulatory element-binding protein-1 (SREBP-1), which plays a critical role in the regulation of lipogenesis, is suppressed during fasting, resulting in the suppression of hepatic lipogenesis. We previously demonstrated that the interaction of fasting-induced Kruppel-like factor 15 (KLF15) with liver X receptor serves as the essential mechanism for the nutritional regulation of SREBP-1 expression. However, the underlying mechanisms of KLF15 induction during fasting remain unclear. In this study, we show that the glucocorticoid receptor (GR) regulates the hepatic expression of KLF15 and, subsequently, lipogenesis through the KLF15-SREBP-1 pathway during fasting. KLF15 is necessary for the suppression of SREBP-1 by GR, as demonstrated through experiments using KLF15 knockout mice. Additionally, we show that GR is involved in the fasting response, with heightened binding to the KLF15 enhancer. It has been widely known that the hypothalamic-pituitary-adrenal (HPA) axis regulates the secretion of glucocorticoids and plays a significant role in the metabolic response to undernutrition. These findings demonstrate the importance of the HPA-axis-regulated GR-KLF15 pathway in the regulation of lipid metabolism in the liver during fasting.

New balance capability index as a screening tool for mild cognitive impairment.

BACKGROUND: Mild cognitive impairment (MCI) is not just a prodrome to dementia, but a very important intervention point to prevent dementia caused by Alzheimer's disease (AD). It has long been known that people with AD have a higher frequency of falls with some gait instability. Recent evidence suggests that vestibular impairment is disproportionately prevalent among individuals with MCI and dementia due to AD. Therefore, we hypothesized that the measurement of balance capability is helpful to identify individuals with MCI. METHODS: First, we developed a useful method to evaluate balance capability as well as vestibular function using Nintendo Wii balance board as a stabilometer and foam rubber on it. Then, 49 healthy volunteers aged from 56 to 75 with no clinically apparent cognitive impairment were recruited and the association between their balance capability and cognitive function was examined. Cognitive functions were assessed by MoCA, MMSE, CDR, and TMT-A and -B tests. RESULTS: The new balance capability indicator, termed visual dependency index of postural stability (VPS), was highly associated with cognitive impairment assessed by MoCA, and the area under the receiver operating characteristic (ROC) curve was more than 0.8, demonstrating high sensitivity and specificity (app. 80% and 60%, respectively). CONCLUSIONS: Early evidence suggests that VPS measured using Nintendo Wii balance board as a stabilometer helps identify individuals with MCI at an early and preclinical stage with high sensitivity, establishing a useful method to screen MCI.

Gender-specific factors contributing to visceral obesity including the sleep-obesity relationship: a large-scale cross-sectional study from East Asia.

Our study aimed to evaluate the relationship between visceral obesity and its associated factors, especially sleep duration in East Asia. We conducted univariate and multivariate analyses using the data of 2538 participants (mean age 56.4 ± 10.8 years) who underwent medical checkups and computed tomography of the abdomen to calculate the visceral fat area from 2008 to 2020. We additionally performed logistic regression analyses using each sleep-duration group (< 5, 5-6, 6-7, 7-8, and ≥ 8 h) and their respective propensity scores as covariates. According to the criteria of visceral obesity(a visceral fat area ≥ 100 cm2), 1147 of 1918 men (59.8%) and 131 of 620 women (21.1%) had visceral obesity. In multivariate analyses, visceral obesity was significantly associated with age, body mass index and triglyceride in both genders, high-density lipoproteins, uric acid levels, and daily alcohol consumption in men; and glycated hemoglobin (HbA1c) in women. In both multivariate and propensity score matching analyses, sleep duration of > 8 h and visceral obestiy showed a positive association in men but a negative association in women with statistical significance. In conclusion, our large-scale cross-sectional study in East Asia identified various gender-specific factors associated with visceral obesity including the long sleep duration.

Prevalence of and factors associated with physical restraint use in the intensive care unit: a multicenter prospective observational study in Japan.

Physical restraint is widely used in the intensive care unit (ICU) to ensure patient safety despite its ethical implications. We performed a prospective observational study in six ICUs in Japan to determine the prevalence of and factors associated with physical restraint use in the ICU, a phenomenon that has not yet been reported on in Japan. Data were collected on 10 random days between November 2018 and February 2019. We evaluated physical restraint use in ICU patients aged ≥ 20 years during the data collection days. Among the 787 observations, the prevalence of physical restraint use was 32.9%; however, it was 41.5% in patients receiving invasive mechanical ventilation (IMV). The average age of patients was 68.5 years, and the average Acute Physiologic Assessment and Chronic Health Evaluation (APACHE) II score was 19.4. Among the included patients, 52.1% received IMV, and 17.2% were diagnosed with delirium. Logistic regression analysis revealed that the independent factors [odds ratio (95% confidence interval)] associated with physical restraint use were age [1.02 (1.00-1.05)], APACHE II score [1.05 (1.01-1.09)], IMV [2.15 (1.16-4.01)], central venous catheter indwelling [2.66 (1.46-4.85)], sedative medication [2.98 (1.72-5.17)], agitation [7.83 (2.96-20.8)], and delirium [4.16 (2.37-7.29)]. Approximately one-third of the ICU patients required physical restraint in Japan. In addition, physical restraint use was influenced by disease severity, mental condition, and the medical apparatus used. Based on these findings, further investigations are imperative to develop strategies to reduce physical restraint use.

High protein diet-induced metabolic changes are transcriptionally regulated via KLF15-dependent and independent pathways.

High protein diet (HPD) is an affordable and positive approach in prevention and treatment of many diseases. It is believed that transcriptional regulation is responsible for adaptation after HPD feeding and Kruppel-like factor 15 (KLF15), a zinc finger transcription factor that has been proved to perform transcriptional regulation over amino acid, lipid and glucose metabolism, is known to be involved at least in part in this HPD response. To gain more insight into molecular mechanisms by which HPD controls expressions of genes involved in amino acid metabolism in the liver, we performed RNA-seq analysis of mice fed HPD for a short period (3 days). Compared to a low protein diet, HPD feeding significantly increased hepatic expressions of enzymes involved in the breakdown of all the 20 amino acids. Moreover, using KLF15 knockout mice and in vivo Ad-luc analytical system, we were able to identify Cth (cystathionine gamma-lyase) as a new target gene of KLF15 transcription as well as Ast (aspartate aminotransferase) as an example of KLF15-independent gene despite its remarkable responsiveness to HPD. These findings provide us with a clue to elucidate the entire transcriptional regulatory mechanisms of amino acid metabolic pathways.

FoxO-KLF15 pathway switches the flow of macronutrients under the control of insulin.

KLF15 is a transcription factor that plays an important role in the activation of gluconeogenesis from amino acids as well as the suppression of lipogenesis from glucose. Here we identified the transcription start site of liver-specific KLF15 transcript and showed that FoxO1/3 transcriptionally regulates Klf15 gene expression by directly binding to the liver-specific Klf15 promoter. To achieve this, we performed a precise in vivo promoter analysis combined with the genome-wide transcription-factor-screening method "TFEL scan", using our original Transcription Factor Expression Library (TFEL), which covers nearly all the transcription factors in the mouse genome. Hepatic Klf15 expression is significantly increased via FoxOs by attenuating insulin signaling. Furthermore, FoxOs elevate the expression levels of amino acid catabolic enzymes and suppress SREBP-1c via KLF15, resulting in accelerated amino acid breakdown and suppressed lipogenesis during fasting. Thus, the FoxO-KLF15 pathway contributes to switching the macronutrient flow in the liver under the control of insulin.

Insulin- and Lipopolysaccharide-Mediated Signaling in Adipose Tissue Macrophages Regulates Postprandial Glycemia through Akt-mTOR Activation.

The physiological role of immune cells in the regulation of postprandial glucose metabolism has not been fully elucidated. We have found that adipose tissue macrophages produce interleukin-10 (IL-10) upon feeding, which suppresses hepatic glucose production in cooperation with insulin. Both elevated insulin and gut-microbiome-derived lipopolysaccharide in response to feeding are required for IL-10 production via the Akt/mammalian target of rapamycin (mTOR) pathway. Indeed, myeloid-specific knockout of the insulin receptor or bone marrow transplantation of mutant TLR4 marrow cells results in increased expression of gluconeogenic genes and impaired glucose tolerance. Furthermore, myeloid-specific Akt1 and Akt2 knockout results in similar phenotypes that are rescued by additional knockout of TSC2, an inhibitor of mTOR. In obesity, IL-10 production is impaired due to insulin resistance in macrophages, whereas adenovirus-mediated expression of IL-10 ameliorates postprandial hyperglycemia. Thus, the orchestrated response of the endogenous hormone and gut environment to feeding is a key regulator of postprandial glycemia.

Glucocorticoid receptor suppresses gene expression of Rev-erbα (Nr1d1) through interaction with the CLOCK complex.

Glucocorticoids have various medical uses but are accompanied by side effects. The glucocorticoid receptor (GR) has been reported to regulate the clock genes, but the underlying mechanisms are incompletely understood. In this study, we focused on the suppressive effect of the GR on the expression of Rev-erbα (Nr1d1), an important component of the clock regulatory circuits. Here we show that the GR suppresses Rev-erbα expression via the formation of a complex with CLOCK and BMAL1, which binds to the E-boxes in the Nr1d1 promoter. In this GR-CLOCK-BMAL1 complex, the GR does not directly bind to DNA, which is referred to as tethering. These findings provide new insights into the role of the GR in the control of circadian rhythm.

Acquired partial lipoatrophy as graft-versus-host disease and treatment with metreleptin: two case reports.

INTRODUCTION: Acquired partial lipoatrophy has been reported after bone marrow transplantation during childhood; however, no adult cases have previously been reported. We herein report two adult cases of acquired partial lipoatrophy after transplantation. CASE PRESENTATION: A 28-year-old Japanese woman developed diabetic ketoacidosis and received insulin therapy after bone marrow transplantation. She manifested partial lipoatrophy of the extremities, prominent insulin resistance, hyperglycemia, hypertriglyceridemia, and fatty liver. A 40-year-old Japanese woman underwent liver transplantation from a living donor for alcoholic liver disease after abstinence from alcohol. She newly developed non-alcoholic steatohepatitis and diabetes. Non-alcoholic steatohepatitis progressed to liver failure, and a second liver transplantation from a brain-dead donor was performed at 42 years of age. She demonstrated loss of subdermal fat of the upper and lower extremities, prominent insulin resistance, hyperglycemia, and hypertriglyceridemia. In both cases, the injection of recombinant methionyl human leptin reversed all of the metabolic abnormalities. CONCLUSIONS: Acquired partial lipoatrophy after transplantation is a manifestation of chronic graft-versus-host disease in adults. This entity is associated with diabetes with prominent insulin resistance and severe hypertriglycemia and can be successfully treated with metreleptin for the long term.

A candidate functional SNP rs7074440 in TCF7L2 alters gene expression through C-FOS in hepatocytes.

The SNP rs7903146 at the transcription factor 7-like 2 (TCF7L2) locus is established as the strongest known genetic marker for type 2 diabetes via genome-wide association studies. However, the functional SNPs regulating TCF7L2 expression remain unclear. Here, we show that the SNP rs7074440 is a candidate functional SNP highly linked with rs7903146. A reporter plasmid with rs7074440 normal allele sequence exhibited 15-fold higher luciferase activity compared with risk allele sequence in hepatocytes, demonstrating a strong enhancer activity at rs7074440. Additionally, we identified C-FOS as an activator binding to the rs7074440 enhancer using a TFEL genome-wide screen method. Consistently, knockdown of C-FOS significantly reduced TCF7L2 expression in hepatocytes. Collectively, a novel enhancer regulating TCF7L2 expression was revealed through searching for functional SNPs.

Effect of sodium-glucose cotransporter 2 (SGLT2) inhibition on weight loss is partly mediated by liver-brain-adipose neurocircuitry.

Sodium-glucose cotransporter 2 (SGLT2) inhibitors have both anti-diabetic and anti-obesity effects. However, the precise mechanism of the anti-obesity effect remains unclear. We previously demonstrated that the glycogen depletion signal triggers lipolysis in adipose tissue via liver-brain-adipose neurocircuitry. In this study, therefore, we investigated whether the anti-obesity mechanism of SGLT2 inhibitor is mediated by this mechanism. Diet-induced obese mice were subjected to hepatic vagotomy (HVx) or sham operation and loaded with high fat diet containing 0.015% tofogliflozin (TOFO), a highly selective SGLT2 inhibitor, for 3 weeks. TOFO-treated mice showed a decrease in fat mass and the effect of TOFO was attenuated in HVx group. Although both HVx and sham mice showed a similar level of reduction in hepatic glycogen by TOFO treatment, HVx mice exhibited an attenuated response in protein phosphorylation by protein kinase A (PKA) in white adipose tissue compared with the sham group. As PKA pathway is known to act as an effector of the liver-brain-adipose axis and activate triglyceride lipases in adipocytes, these results indicated that SGLT2 inhibition triggered glycogen depletion signal and actuated liver-brain-adipose axis, resulting in PKA activation in adipocytes. Taken together, it was concluded that the effect of SGLT2 inhibition on weight loss is in part mediated via the liver-brain-adipose neurocircuitry.

A key role of nuclear factor Y in the refeeding response of fatty acid synthase in adipocytes.

Fatty acid synthase (Fasn) is a key component of energy metabolism that is dynamically induced by food intake. Although extensive studies have revealed a number of transcription factors involved in the fasting/refeeding transition of Fasn expression in hepatocytes, much less evidence is available for adipocytes. Using the in vivo Ad-luc analytical system, we identified the inverted CCAAT element (ICE) around -100 nucleotides in the Fasn promoter as a critical cis-element for the refeeding response in adipocytes. Electrophoretic mobility shift assays and chromatin immunoprecipitation show that nuclear factor Y (NF-Y) binds to ICE specifically in refeeding states. Notably, the NF-Y binding to ICE is differently regulated between adipocytes and hepatocytes. These findings provide insights into the specific mechanisms controlling energy metabolism in adipocytes.

KLF15 Enables Rapid Switching between Lipogenesis and Gluconeogenesis during Fasting.

Hepatic lipogenesis is nutritionally regulated (i.e., downregulated during fasting and upregulated during the postprandial state) as an adaptation to the nutritional environment. While alterations in the expression level of the transcription factor SREBP-1c are known to be critical for nutritionally regulated lipogenesis, upstream mechanisms governing Srebf1 expression remain unclear. Here, we show that the fasting-induced transcription factor KLF15, a key regulator of gluconeogenesis, forms a complex with LXR/RXR, specifically on the Srebf1 promoter. This complex recruits the corepressor RIP140 instead of the coactivator SRC1, resulting in reduced Srebf1 and thus downstream lipogenic enzyme expression during the early and euglycemic period of fasting prior to hypoglycemia and PKA activation. Through this mechanism, KLF15 overexpression specifically ameliorates hypertriglyceridemia without affecting LXR-mediated cholesterol metabolism. These findings reveal a key molecular link between glucose and lipid metabolism and have therapeutic implications for the treatment of hyperlipidemia.

Identification of human ELOVL5 enhancer regions controlled by SREBP.

Fatty acid elongase 5 (ELOVL5) is an enzyme involved in the synthesis of polyunsaturated fatty acids. Sterol Regulatory Element-binding Protein (SREBP)-1 activates ELOVL5 and increases polyunsaturated fatty acid synthesis, which in turn negatively affects SREBP-1 expression. Thus, ELOVL5 has been established as an SREBP-1 target gene and an important component of the negative feedback loop of de novo lipogenesis. However, the human ELOVL5 promoter/enhancer has not been fully analyzed and the location of SREBP biding sites around the ELOVL5 gene has yet to be defined. Here we performed a detailed promoter/enhancer analysis of human ELOVL5 gene, and identified two new SREBP binding sites, one in the 10 kb upstream region and one in the exon 1. These two SRE motifs are conserved among mammals and the mechanism found in the present study by which SREBP activates ELOVL5 is considered to be common in mammals. Through these findings, we clarified the molecular mechanism how SREBP activates ELOVL5, an important regulator of de novo lipogenesis.

Glycogen shortage during fasting triggers liver-brain-adipose neurocircuitry to facilitate fat utilization.

During fasting, animals maintain their energy balance by shifting their energy source from carbohydrates to triglycerides. However, the trigger for this switch has not yet been entirely elucidated. Here we show that a selective hepatic vagotomy slows the speed of fat consumption by attenuating sympathetic nerve-mediated lipolysis in adipose tissue. Hepatic glycogen pre-loading by the adenoviral overexpression of glycogen synthase or the transcription factor TFE3 abolished this liver-brain-adipose axis activation. Moreover, the blockade of glycogenolysis [corrected] through the knockdown of the glycogen phosphorylase gene and the resulting elevation in the glycogen content abolished the lipolytic signal from the liver, indicating that glycogen is the key to triggering this neurocircuitry. These results demonstrate that liver glycogen shortage activates a liver-brain-adipose neural axis that has an important role in switching the fuel source from glycogen to triglycerides under prolonged fasting conditions.

Apolipoprotein C-II deficiency with no rare variant in the APOC2 gene.

AIM: Familial apolipoprotein C-II (apoC-II) deficiency is a rare autosomal recessive disorder with marked hypertriglyceridemia resulting from impaired activation of lipoprotein lipase. In most cases of apoC-II deficiency, causative mutations have been found in the protein-coding region of APOC2; however, several atypical cases of apoC-II deficiency were reported to have markedly reduced, but detectable levels of plasma apoC-II protein (hereafter referred to as hypoapoC-II), which resulted from decreased promoter activity or improper splicing of apoC-II mRNA due to homozygous mutations in APOC2. Here we aim to dissect the molecular bases of a new case of hypoapoC-II. METHODS: We performed detailed biochemical/genetic analyses of our new case of hypoapoC-II, manifesting severe hypertriglyceridemia (plasma triglycerides, 3235 mg·dL(-1)) with markedly reduced levels of plasma apoC-II (0.6 mg·dL(-1)). RESULTS: We took advantage of a monocyte/macrophage culture system to prove that transcription of apoC-II mRNA was decreased in the patient's cells, which is compatible with the reported features of hypoapoC-II. Concomitantly, transcriptional activity of the minigene reporter construct of the patient's APOC2 gene was decreased; however, no rare variant was detected in the patient's APOC2 gene. Fifty single nucleotide variants were detected in the patient's APOC2, but all were common variants (allele frequencies ＞35%) that are supposedly not causative. CONCLUSIONS: A case of apoC-II deficiency was found that is phenotypically identical to hypoapoC-II but with no causative mutations in APOC2, implying that other genes regulate apoC-II levels. The clinical entity of hypoapoC-II is discussed.

Ability of water-soluble biosubstances to eliminate hydroxyl and superoxide radicals examined by spin-trapping ESR measurements: two-dimensional presentation of antioxidative ability.

The hydroxyl- and superoxide-radical-eliminating ability of water-soluble biosubstances was examined by ESR combined with the spin-trapping method, indicating a median inhibitory dose, ID(h)(50) (mM) and id(h)(50) (mg/mL) for the hydroxyl radical, and ID(s)(50) (mM) and id(s)(50) (mg/mL) for the superoxide radical. Both the 1/[ID(h)(50) (mM)] and 1/[ID(s)(50) (mM)] values of selected biosubstances were linearly related to the second-order rate constant, k(2) (M(-1) s(-1)), defined for the reaction between biosubstances and the radicals in a logarithmic presentation. The result indicates that ID(h)(50) (mM) and ID(s)(50) (mM) are suitable parameters for both types of radical-eliminating ability. The obtained results are depicted two-dimensionally, taking id(h)(50) (mg/mL) as the abscissa and id(s)(50) (mg/mL) as the ordinate in the ROS inhibitory diagram. The biosubstances tested were assigned to five separate areas characterized by their functional groups on the diagram. The obtained ROS inhibitory diagram indicates the possibility for screening appropriate antioxidants.