👤 Masaki Iwasaki

Homozygous familial hypercholesterolemia (HoFH) is a rare genetic disorder characterized by high levels of low-density lipoprotein cholesterol (LDL-C) and increased risk of early onset atherosclerosis. Evinacumab, an angiopoietin-like protein 3 (ANGPTL3)-inhibiting monoclonal antibody, lowers LDL-C independently of LDL receptor activity. However, its effects on other lipid-related markers remain poorly investigated in real-world clinical practice. We herein report a 54-year-old Japanese woman with genetically confirmed compound heterozygous familial hypercholesterolemia (FH) treated with evinacumab in combination with other lipid-lowering agents. Lipoprotein apheresis was continued every two weeks throughout the treatment. Serum sampling before and after evinacumab administration found that, following evinacumab initiation, LDL-C decreased from 324 to 205 mg/dL (reduction of 119 mg/dL, -36.7%) and triglycerides from 155 to 51 mg/dL (reduction of 103 mg/dL, -66.8%). Notably, atherosclerosis-related markers showed substantial reductions, with remnant-like particle cholesterol (RLP-C) decreasing from 10.5 to ＜2.0 mg/dL, small dense LDL-C (sdLDL-C) from 80.2 to 22.1 mg/dL, and malondialdehyde-modified LDL (MDA-LDL) from 105 to 87 mg/dL. Apolipoproteins (ApoB, ApoC2, ApoC3, ApoE, and ApoA5) decreased as well. No significant changes were observed in lipoprotein (a), free fatty acids, interleukin-6, or high-sensitivity C-reactive protein levels. This is the first clinical report to comprehensively evaluate the lipid-modifying effects of evinacumab in a Japanese HoFH patient. In this case, evinacumab was highly efficacious against atherosclerosis-related markers and apolipoproteins, beyond simple LDL-C reduction, suggesting additional cardiovascular benefits. These findings provide mechanistic insights that may inform therapeutic strategies for the management of HoFH. Show less

Methylprednisolone (mPSL) pulse therapy is an essential treatment for systemic lupus erythematosus (SLE); however, it carries a risk of osteonecrosis of the femoral head (ONFH). The pathogenesis of ONFH involves neutrophil extracellular trap (NET)-mediated microcirculation disorders. In BALB/c mice with imiquimod (IMQ)-induced lupus, mPSL pulse elevated serum levels of prenylcysteine oxidase 1 (PCYOX1), an enzyme that produces NET inducers hydrogen peroxide and farnesal, resulting in increased NETs in vivo. Although ischemia was observed in the femoral head, IMQ + mPSL-treated BALB/c mice did not develop ONFH. PCYOX1 is abundant in very-low-density lipoproteins. This study aimed to demonstrate that hyperlipidemia exacerbates NET-mediated microcirculation disorders and leads to ONFH development following mPSL pulse in lupus mice. To address this, ApoE mutant hyperlipidemic and BALB/c mice with IMQ-induced lupus received mPSL pulse. NET-forming neutrophils in peripheral blood were detected by flow cytometry. ONFH was assessed microscopically. As a result, IMQ + mPSL-treated ApoE mutant but not BALB/c mice developed ONFH, exhibiting higher levels of PCYOX1 and NET-forming neutrophils in circulation. In addition, NET-forming neutrophils accumulated in the vessels surrounding the femoral head, accompanied by osteocyte necrosis. This study demonstrated that mPSL pulse in lupus mice with hyperlipidemia enhanced PCYOX1 levels and NET formation, resulting in ONFH development, suggesting that hyperlipidemia may be a risk factor for ONFH following mPSL pulse therapy in SLE. Show less

Dysregulated actions of the bone-derived phosphaturic hormone, fibroblast growth factor-23 (FGF23), underlie the pathophysiology of several diseases. FGF23 is synthesized primarily in osteocytes in response to various endogenous molecules; however, the mechanisms governing FGF23 production are incompletely understood. Glycerol-3-phosphate (G3P), a glycolytic by-product originating from the kidney, critically controls skeletal FGF23 synthesis via its conversion in bone to lysophosphatidic acid (LPA), which stimulates osteocyte FGF23 production. The bioactive vitamin D, 1,25-dihydroxyvitamin D (1,25D), also promotes FGF23 production in osteocytes. We herein demonstrated that LPA requires 1,25D action to raise FGF23 levels in mouse bone explants and mice. RNA sequencing of osteocyte-like Ocy454 cells identified differentially expressed genes (DEGs) uniquely induced by LPA/1,25D co-treatment. These unique DEGs were enriched for the ribosome biogenesis pathway. DEGs concurrently induced by individual LPA and 1,25D treatments were enriched for MAPK signaling, and inhibiting this pathway obliterated LPA/1,25D-induced FGF23 production. DEGs following LPA/1,25D co-treatment were enriched for the cytokine-cytokine receptor interaction pathway. Moreover, LPA/1,25D co-treatment, but not individual LPA and 1,25D treatments, rapidly induced the expression of Il12a, the gene encoding the pro-inflammatory cytokine interleukin-12 alpha-subunit, which responded solely to 1,25D at later times and required MAPK-ERK1/2 signaling. Inhibiting cytokine signaling or knocking down Il12a inhibited, while overexpressing Il12a enhanced LPA/1,25D-induced FGF23 production. However, challenging Ocy454 cells with recombinant bioactive interleukin-12 failed to enhance FGF23 production, suggesting that Il12a plays a noncanonical role. Our results reveal a mechanism of skeletal FGF23 synthesis involving synergistic actions of LPA and 1,25D, advancing our understanding of FGF23 regulation. Show less

A 79-year-old female presented with progressive dyspnea. A bone marrow biopsy revealed hypoplastic marrow with abnormal lymphoid cells. A genetic analysis revealed a MYD88 p.V204F mutation, supporting the diagnosis of lymphoplasmacytic lymphoma/Waldenström's macroglobulinemia (LPL/WM). Additional evaluations established a concomitant diagnosis of aplastic anemia (AA). Treatment prioritized AA with cyclosporine and eltrombopag. Subsequently, the LPL/WM was treated with rituximab monotherapy. This sequential treatment resulted in a symptomatic improvement. Although AA is a diagnosis of exclusion, its coexistence with lymphoma is rare. This case highlights the diagnostic and therapeutic complexity of AA and LPL/WM overlap and suggests that prioritizing the treatment of AA may lead to better outcomes. Show less

Although several retrospective studies have investigated the association of TP53 rs1042522 and ApoB rs693 with the risk of biliary tract cancer (BTC), results have been inconsistent. In this study, to provide evidence from a prospective study, we analyzed the association of these two genetic polymorphisms with BTC risk using data from the Japan Public Health Center-based Prospective Study. We conducted a case-cohort study with 152 BTC cases and 12,159 subcohort subjects and estimated HRs and 95% confidence intervals (CI) using a weighted Cox proportional hazards model. TP53 rs1042522 showed a statistically significant association with the risk of BTC (HR, 1.89; 95% CI, 1.27-2.82, in the recessive genetic model), whereas ApoB rs693 showed no apparent association. Of interest, TP53 rs1042522 seemed to be associated with BTC risk in a recessive model, but not in a dominant model. On comparison of three BTC subtypes, TP53 rs1042522 seemed to be associated with the incidence of gallbladder cancer and extrahepatic bile duct cancer (HR, 2.21; 95% CI, 1.14-4.28 and HR, 1.97; 95% CI, 1.00-3.88, respectively) but showed only a nonsignificant association with intrahepatic bile duct cancer (HR, 1.58; 95% CI, 0.63-3.96). In this prospective case-cohort study, we found evidence to support an association between the TP53 rs1042522 polymorphism and the risk of BTC. The null finding for ApoB rs693 might be due to the extremely low T-allele frequency (4.4%) in the study population. This prospective study highlights the effect of TP53 rs1042522 on BTC risk in Japanese individuals. Identifying carriers of the high-risk CC genotype may facilitate targeted surveillance and early detection strategies, potentially reducing mortality and improving outcomes. Further large-scale studies are required to clarify environmental interactions and optimize prevention. Show less

Ovarian carcinosarcoma (OCS) is a rare and aggressive tumor, and the development of its sarcomatous component is believed to be due to epithelial-mesenchymal transition (EMT). The SWIch/sucrose nonfermentable chromatin remodeling factor (CRF) is closely related to EMT; however, the relationship between CRF and EMT in OCS remains unclear. In this study, we analyzed the protein expression of CRFs, including ARID1A and SMARCA4, and their downstream mRNA expression in 28 OCS cases, two fallopian tube CS cases, and one peritoneal CS case. ARID1A and SMARCA4 exhibited a histological type-specific loss of protein expression in 5 of 11 (45%) endometrioid cases and all 5 serous/homologous OCS cases, respectively. The mRNA analysis suggested that sarcomatogenesis is induced by the transforming growth factor-β and Hippo signaling pathways, both of which regulate YAP1. Immunostaining for YAP1 suggested YAP1-associated sarcomatogenesis in the CRF-retained group, whereas YAP1-unassociated sarcomatogenesis was suggested in the CRF-reduced group. High-grade serous carcinoma cell line experiments showed that the transcriptome of the SMARCA4-knockdown group showed lower expression of the epithelial gene CDH1 and higher expression of mesenchymal genes such as VIM, ZEB1, and SNAI1 than the control group. Moreover, cell adhesion disappeared and cell morphology changed to a spindle shape, indicating sarcomatogenesis. In conclusion, this study reveals a mechanism for sarcoma development in OCS and provides novel therapeutic possibilities. Show less

In a series of studies on blood-brain barrier transportable peptides, a soybean dipeptide, Tyr-Pro, penetrated the mouse brain parenchyma after oral intake and improved short and long memory impairment in acute Alzheimer's model mice. Here, we aimed to clarify the anti-dementia effects of this peptide administered to SAMP8 mice prior to dementia onset. At the end of the 25-week protocol in 16-week-old SAMP8 mice, Tyr-Pro (10 mg/kg/day) significantly improved the reduced spatial learning ability compared with that in the control and amino acid (Tyr + Pro) groups as indicated by the results of Morris water maze tests conducted for five consecutive days. The hippocampus and cortex regions of SAMP8 harvested after the test showed lower amyloid ß (Aß) accumulation in the Tyr-Pro group than those in the control and amino acid groups. Consistent with the lower level of Aß, decreased expression of ß-secretase (BACE1) and markedly increased expression (4-times higher) of insulin degrading enzyme (IDE) were obtained compared to those in the control group. Collectively, we demonstrated that long-term daily intake of the dipeptide Tyr-Pro in SAMP8 mice may be sufficient for maintaining cognitive ability by preventing excess Aß accumulation through downregulated BACE1 and particularly upregulated IDE. Show less

Low-grade epilepsy-associated tumors are the second most common histopathological diagnoses in cases of drug-resistant focal epilepsy. However, the connection between neuroimaging features and genetic alterations in these tumors is unclear, prompting an investigation into genotype-relevant neuroimaging characteristics. This study retrospectively analyzed neuroimaging and surgical specimens from 46 epilepsy patients with low-grade epilepsy-associated neuroepithelial tumors that had genetic mutations identified through panel sequencing to investigate their relationship to genotypes. Three distinct neuroimaging groups were established: Group 1 had indistinct borders and iso T1-weighted and slightly high or high T2-weighted signal intensities without a diffuse mass effect, associated with 93.8% sensitivity and 100% specificity to These findings suggest that tumor genotype may be predicted by neuroimaging before surgery, providing insights for personalized treatment approaches. Show less

Lung adenocarcinoma is the most common type of lung cancer. Known risk variants explain only a small fraction of lung adenocarcinoma heritability. Here, we conducted a two-stage genome-wide association study of lung adenocarcinoma of East Asian ancestry (21,658 cases and 150,676 controls; 54.5% never-smokers) and identified 12 novel susceptibility variants, bringing the total number to 28 at 25 independent loci. Transcriptome-wide association analyses together with colocalization studies using a Taiwanese lung expression quantitative trait loci dataset (n = 115) identified novel candidate genes, including FADS1 at 11q12 and ELF5 at 11p13. In a multi-ancestry meta-analysis of East Asian and European studies, four loci were identified at 2p11, 4q32, 16q23, and 18q12. At the same time, most of our findings in East Asian populations showed no evidence of association in European populations. In our studies drawn from East Asian populations, a polygenic risk score based on the 25 loci had a stronger association in never-smokers vs. individuals with a history of smoking (P Show less

Osteochondromatosis is a benign proliferative disorder characterized by cartilage-capped bony protuberances. In humans and most mammals, variants in the EXT1 or EXT2 gene are strongly correlated with the etiology of osteochondromatosis. However, in cats, osteochondromatosis has only been associated with feline leukemia virus infection. In this study, to explore other factors involved in the etiology of feline osteochondromatosis, we examined the EXT1 and EXT2 genes in a feline leukemia virus-negative cat with osteochondromatosis. Genetic analysis revealed a heterozygous single base pair duplication in exon 6 of the EXT1 gene (XM₀₂₃₂₄₈₇₆₂.2:c.1468dupC), leading to a premature stop codon in the EXT1 protein. Notably, this frameshift variant is recognized as one of the most common pathogenic variants in human osteochondromatosis. Our data suggest for the first time that genetic variants can have etiologic roles in osteochondromatosis in cats, as in humans and other animals. Show less

cAMP responsive element-binding protein 3 like 3 (CREB3L3) is a membrane-bound transcription factor involved in the maintenance of lipid metabolism in the liver and small intestine. CREB3L3 controls hepatic triglyceride and glucose metabolism by activating plasma fibroblast growth factor 21 (FGF21) and lipoprotein lipase. In this study, we intended to clarify its effect on atherosclerosis. CREB3L3-deficifient, liver-specific CREB3L3 knockout, intestine-specific CREB3L3 knockout, both liver- and intestine-specific CREB3L3 knockout, and liver CREB3L3 transgenic mice were crossed with LDLR CREB3L3 ablation in LDLR CREB3L3 has multi-potent protective effects against atherosclerosis owing to new mechanistic interaction between CREB3L3 and SREBPs under atherogenic conditions. Show less

Mitochondrial pathophysiology is implicated in the development of Alzheimer's disease (AD). An integrative database of gene dysregulation suggests that the mitochondrial ubiquitin ligase MITOL/MARCH5, a fine-tuner of mitochondrial dynamics and functions, is downregulated in patients with AD. Here, we report that the perturbation of mitochondrial dynamics by MITOL deletion triggers mitochondrial impairments and exacerbates cognitive decline in a mouse model with AD-related Aβ pathology. Notably, MITOL deletion in the brain enhanced the seeding effect of Aβ fibrils, but not the spontaneous formation of Aβ fibrils and plaques, leading to excessive secondary generation of toxic and dispersible Aβ oligomers. Consistent with this, MITOL-deficient mice with Aβ etiology exhibited worsening cognitive decline depending on Aβ oligomers rather than Aβ plaques themselves. Our findings suggest that alteration in mitochondrial morphology might be a key factor in AD due to directing the production of Aβ form, oligomers or plaques, responsible for disease development. Show less

Gastric inhibitory polypeptide receptor (GIPR) directly induces energy accumulation in adipose tissue in vitro. However, the importance of the direct effect of GIPR signaling on adipose tissue in vivo remains unclear. In the current study, we generated adipose tissue-specific GIPR knockout (GIPR Show less

Angiopoietin-like protein 4 (ANGPTL4) is a multifunctional protein, playing roles in glucose and lipid metabolism, inflammation, angiogenesis, and tumorigenesis. Recent research suggests that ANGPTL4 is induced by hypoxia and is a useful diagnostic or prognostic marker for various cancers. However, it remains unclear whether ANGPTL4 expression influences prostate cancer. Here we examined the biological and clinical relevance of ANGPTL4 expression in prostate cancer. Firstly we examined ANGPTL4 expression in the prostate cancer cell lines LNCaP and LNCaP/CH incubated at 1% O2 for at least 6 months. We compared cellular proliferation, migration, and ANGPTL4 secretion in a culture medium between these cell lines. In addition, we investigated the effect of various concentrations of recombinant ANGPTL4 protein (rANGPTL4) on cellular proliferation and intracellular signaling pathways. Moreover, we used ANGPTL4 knockdown by RNA interference to investigate the influence of ANGPTL4 expression on these cell lines. Finally, we investigated the correlation between ANGPTL4 expression in prostate cancer specimens and clinicopathological parameters using immunohistochemistry. Our data suggested that the expression of ANGPTL4 in hypoxic conditions was 14.4-fold higher than that in normoxic condition. ANGPTL4 secretion in the culture medium increased 7.0-fold. In addition, rANGPTL4 increased cellular proliferation 1.72-fold via Akt activation. Moreover, ANGPTL4 knockdown decreased cell growth and its secretion by 25.7 and 41.4%, respectively, compared with the control. A multivariate analysis showed that positive ANGPTL4 expression in the resected specimens was an independent prognostic indicator of biochemical recurrence (P=0.03, hazard ratio = 2.02). Our results show that ANGPTL4 is induced by hypoxia and promotes cancer progression via the activated PI3K/Akt pathway. Moreover, ANGPTL4 can be used as a prognostic marker for prostate cancer patients undergoing radical prostatectomy. Show less

The transcription factor cyclic AMP-responsive element-binding protein H (CREBH, encoded by To investigate the influence of intestinal CREBH on cholesterol metabolism, we compared plasma, bile, fecal, and tissue cholesterol levels between wild-type (WT) mice and mice overexpressing active human CREBH mainly in the small intestine (CREBH Tg mice) under different dietary conditions. Plasma cholesterol, hepatic lipid, and cholesterol crystal formation in the gallbladder were lower in CREBH Tg mice fed a lithogenic diet (LD) than in LD-fed WTs, while fecal cholesterol output was higher in the former. These results suggest that intestinal CREBH overexpression suppresses cholesterol absorption, leading to reduced plasma cholesterol, limited hepatic supply, and greater excretion. The expression of Niemann-Pick C1-like 1 ( Intestinal CREBH regulates dietary cholesterol flow from the small intestine by controlling the expression of multiple intestinal transporters. We propose that intestinal CREBH could be a therapeutic target for hypercholesterolemia. Show less

Canonical Wnt signals, transduced by stabilized β-catenin, play similar roles across animals in maintaining stem cell pluripotency, regulating cell differentiation, and instructing normal embryonic development. Dysregulated Wnt/β-catenin signaling causes diseases and birth defects, and a variety of regulatory processes control this pathway to ensure its proper function and integration with other signaling systems. We previously identified GTP-binding protein 2 (Gtpbp2) as a novel regulator of BMP signaling, however further exploration revealed that Gtpbp2 can also affect Wnt signaling, which is a novel finding reported here. Knockdown of Gtpbp2 in Xenopus embryos causes severe axial defects and reduces expression of Spemann-Mangold organizer genes. Gtpbp2 knockdown blocks responses to ectopic Wnt8 ligand, such as organizer gene induction in ectodermal tissue explants and induction of secondary axes in whole embryos. However, organizer gene induction by ectopic Nodal2 is unaffected by Gtpbp2 knockdown. Epistasis tests, conducted by activating Wnt signal transduction at sequential points in the canonical pathway, demonstrate that Gtpbp2 is required downstream of Dishevelled and Gsk3β but upstream of β-catenin, which is similar to the previously reported effects of Axin1 overexpression in Xenopus embryos. Focusing on Axin in Xenopus embryos, we find that knockdown of Gtpbp2 elevates endogenous or exogenous Axin protein levels. Furthermore, Gtpbp2 fusion proteins co-localize with Dishevelled and co-immunoprecipitate with Axin and Gsk3b. We conclude that Gtpbp2 is required for canonical Wnt/β-catenin signaling in Xenopus embryos. Our data suggest a model in which Gtpbp2 suppresses the accumulation of Axin protein, a rate-limiting component of the β-catenin destruction complex, such that Axin protein levels negatively correlate with Gtpbp2 levels. This model is supported by the similarity of our Gtpbp2-Wnt epistasis results and previously reported effects of Axin overexpression, the physical interactions of Gtpbp2 with Axin, and the correlation between elevated Axin protein levels and lost Wnt responsiveness upon Gtpbp2 knockdown. A wide variety of cancer-causing Wnt pathway mutations require low Axin levels, so development of Gtpbp2 inhibitors may provide a new therapeutic strategy to elevate Axin and suppress aberrant β-catenin signaling in cancer and other Wnt-related diseases. Show less

We propose Langerhans cell histiocytosis (LCH) is an inflammatory process that is prolonged by mutations. We hypothesize that Merkel cell polyomavirus (MCPyV) infection triggers an interleukin-1 (IL-1) activation loop that underlies the pathogenesis of LCH. Langerhans cells (LCs) are antigen presenting cells in the skin. When LCs encounter exogenous antigens, they migrate from the epidermis into draining lymphoid tissues to initiate T-cell activity. It has been proposed that LC migration-related factors, including E-cadherin, matrix metalloproteinase, and Notch ligand induce LCH activity. We found that the tyrosine phosphatase SHP-1, which binds IL-1 receptor-associated kinase 1, is expressed at a significantly higher level in LCH affecting multiple organ systems (MS-LCH) than in LCH affecting a single organ system (SS-LCH). IL-1 stimulates T helper 17 cells and their signature cytokine IL-17 had been a matter of controversy. We detected higher levels of IL-17A receptor expression in MS-LCH than in SS-LCH and proposed an IL-17 endocrine model that could settle the controversy. IL-1 is the first cytokine secreted in response to sensitizers and promotes LC migration from sentinel tissues. Myeloid differentiation primary response 88 (MyD88), downstream of the IL-1 receptor, has functions in both RAS signaling and inflammation, leading to human cell transformation. In 2010, an activating mutation in the B-rapidly accelerated fibrosarcoma gene (BRAF) V600E was found in LCH. This BRAF mutation induces phosphorylation of the extracellular signal-regulated kinase (ERK) that may play an important role with MyD88 in LCH pathogenesis. However, phosphorylated ERK (pERK) is rapidly dephosphorylated by dual specificity phosphatase 6 (DUSP6), and limited proliferation is predicted in BRAF mutant cells. MyD88 binds pERK via its D-domain, thereby preventing pERK-DUSP6 interaction and maintaining ERK in an active, phosphorylated state. We detected MCPyV-DNA in the peripheral blood cells of two out of three patients with LCH in high-risk organs but not in those of patients with LCH in non-high-risk organs (0/12; P = .029). MCPyV infection can trigger precursor LCH cells with BRAF mutation to produce IL-1; the IL-1 loop is amplified in all LCH subclasses. Our model indicates both BRAF mutation and IL-1 loop regulation as potential therapeutic targets. Show less

Mammalian tribbles homolog 1 (TRIB1) regulates hepatic lipogenesis and is genetically associated with plasma triglyceride (TG) levels and cholesterol, but the molecular mechanisms remain obscure. We explored these mechanisms in mouse livers transfected with a TRIB1 overexpression, a shRNA template or a control (LacZ) adenovirus vector. The overexpression of TRIB1 reduced, whereas induction of the shRNA template increased, plasma glucose, TG, and cholesterol and simultaneously hepatic TG and glycogen levels. The involvement of TRIB1 in hepatic lipid accumulation was supported by the findings of a human SNP association study. A TRIB1 SNP, rs6982502, was identified in an enhancer sequence, modulated enhancer activity in reporter gene assays, and was significantly (P=9.39 × 10(-7)) associated with ultrasonographically diagnosed non-alcoholic fatty liver disease in a population of 5570 individuals. Transcriptome analyses of mouse livers revealed significant modulation of the gene sets involved in glycogenolysis and lipogenesis. Enforced TRIB1 expression abolished CCAAT/enhancer binding protein A (CEBPA), CEBPB, and MLXIPL proteins, whereas knockdown increased the protein level. Levels of TRIB1 expression simultaneously affected MKK4 (MAP2K4), MEK1 (MAP2K1), and ERK1/2 (MAPK1/3) protein levels and the phosphorylation of JNK, but not of ERK1/2. Pull-down and mammalian two-hybrid analyses revealed novel molecular interaction between TRIB1 and a hepatic lipogenic master regulator, MLXIPL. Co-expression of TRIB1 and CEBPA or MLXIPL reduced their protein levels and proteasome inhibitors attenuated the reduction. These data suggested that the modulation of TRIB1 expression affects hepatic lipogenesis and glycogenesis through multiple molecular interactions. Show less

The activity of 6-phosphofructo-1-kinase is strictly controlled by fructose-2,6-bisphosphate, the level of which is regulated by another enzyme, 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFK2/FBP2). PFK2/FBP2 is a bifunctional enzyme, having kinase and phosphatase activities, and regulates both glycolysis and gluconeogenesis. Here, we examined the hormonal regulation of the PFK2/FBP2 gene in vitro using the reporter assay, the electromobility shift assay (EMSA), and the chromatin immunoprecipitation (ChIP) assay in HuH7 cells and also using the mouse liver in vivo. We found that the transcriptional activity of the PFK2/FBP2 gene was stimulated by insulin and inhibited by cAMP and glucocorticoid. Liver X receptor (LXR) α showed a potent and specific stimulatory effect on PFK2/FBP2 gene transcription. Deletion and mutagenesis analyses identified the LXR response element (LXRE) in the 5'-promoter region of the PFK2/FBP2 gene. Binding of LXRα was confirmed by the EMSA and ChIP assay. Endogenous PFK2/FBP2 mRNA in the mouse liver was increased in the fasting/refeeding state compared with the fasting state. Altogether, PFK2/FBP2 gene transcription is found to be regulated in a way that is more similar to other glycolytic enzyme genes than to gluconeogenic genes. Furthermore, our data strongly suggest that LXRα is one of the key regulators of PFK2/FBP2 gene transcription. Show less

Centromeric DNA forms two structures on the mitotic chromosome: the kinetochore, which interacts with kinetochore microtubules, and the inner centromere, which connects sister kinetochores. The assembly of the inner centromere is poorly understood. In this study, we show that the human Mis14 (hMis14; also called hNsl1 and DC8) subunit of the heterotetrameric hMis12 complex is involved in inner centromere architecture through a direct interaction with HP1 (heterochromatin protein 1), mediated via a PXVXL motif and a chromoshadow domain. We present evidence that the mitotic function of hMis14 and HP1 requires their functional association at interphase. Alterations in the hMis14 interaction with HP1 disrupt the inner centromere, characterized by the absence of hSgo1 (Shugoshin-like 1) and aurora B. The assembly of HP1 in the inner centromere and the localization of hMis14 at the kinetochore are mutually dependent in human chromosomes. hMis14, which contains a tripartite-binding domain for HP1 and two other kinetochore proteins, hMis13 and blinkin, is a cornerstone for the assembly of the inner centromere and kinetochore. Show less

Both glucocorticoid and insulin are known to have an anabolic effect on lipogenesis. Acetyl-CoA, an intermediate product of glycolysis, is supplied for fatty acid synthesis when carbohydrate intake is sufficient. Acetyl-CoA carboxylase (ACC), consisting of two isoenzymes ACC1 and ACC2, mediates the conversion from acetyl-CoA to malonyl-CoA, and thus plays a key role for the regulation of lipogenesis. In this study, we surveyed the effects of glucocorticoid and insulin on the transcriptional activity of the alternative promoters of ACCs (PI-PIII for ACC1, and PI and PII for ACC2) using the HepG2 human hepatocyte cell line in vitro. We also examined the roles of the insulin and/or glucose-regulated transcriptional factor(s) such as SREBP1c, LXRalpha/beta, and ChREBP on each promoter of the ACC genes. We found that both insulin and glucocorticoid had potent positive effects on all the promoters examined, and additive effects of both hormones were recognized in ACC1 PI and ACC2 PI. Furthermore, a representative insulin-responsive transcription factor SREBP1c showed significant stimulatory effects on all the promoters of ACC genes, among which those on ACC1 PIII and ACC2 PI were most prominent. On the other hand, the effect of LXRalpha was rather selective; it showed a marked stimulatory effect only on ACC1 PII. LXRbeta and ChREBP had minimal, if any, effects on some of the promoters. Altogether, our data suggest that insulin and glucocorticoid have positive effects on both ACC1 and ACC2 gene transcription. SREBP1c might be a master regulator of the expression of both genes regardless of the promoter utilized, whereas LXRalpha seems to play a promoter-specific role. Since ACC1 facilitates lipogenesis by stimulating fatty acid synthesis and ACC2 inhibits lipolysis, both insulin and glucocorticoid seem to play an important role in the pathogenesis of obesity and/or hepatic steatosis. Show less

Apolipoprotein A-V (apoA-V) is a recently discovered apolipoprotein that appears to have a role in plasma triglyceride (TG) transport. We have developed an ELISA for apoA-V using monoclonal antibodies that has a lower limit of detection of 0.3 ng/ml and linearity up to 20 ng/ml. The ELISA was then used to quantify plasma apoA-V in 196 healthy subjects and 106 patients with insulin-resistant diabetes mellitus. In the healthy subjects, total apoA-V concentration was 179.2 +/- 74.8 ng/ml, and it was greater in females than in males (P < 0.005). It was correlated positively with the plasma HDL cholesterol (r = 0.32, P < 0.0001), apoA-I (r = 0.27, P = 0.0001), and apoE (r = 0.18, P = 0.011) concentrations and negatively with plasma TG concentration (r = -0.22, P = 0.021). In relation to single nucleotide polymorphism 3 (-1131C/T) of the apoA-V gene, apoA-V concentration was higher in the T/T type than in the C/C type (P < 0.01). Plasma TG concentration was lower in the T/T type than in the C/C or C/T type (P < 0.05). ApoA-V concentration was lower in the diabetic patients (69.4 +/- 44.3 ng/ml; P < 0.01) than in the healthy controls. Show less