👤 Tatsuki R Kataoka

Notch signaling is a fundamental signal that regulates morphogenesis and cell differentiation during the embryonic period, and it plays a crucial role in macrophage differentiation. Macrophage-mediated inflammation promotes atherosclerosis from the initial lesion formation to acute thrombotic complications in advanced plaques. However, their role in atherosclerosis remains unclear. We herein focused on the Notch ligand Delta-like ligand 1 (Dll1), and examined its role in the pathobiology of atherosclerosis. In Apoe Dll1 blockade suppressed both initial lesion development and plaque vulnerability compared with lesions in mice treated with non-immune IgG. Dll1 Ab decreased lipid accumulation in advanced lesions and increased the collagen content. In ex vivo cultured macrophages, the blockade of Dll1-Notch signaling by Dll1 blocking antibodies suppressed the mRNA expression of Tnf and the release of activated matrix metalloproteinase 9, which increased plaque vulnerability. In contrast, the stimulation of Dll1-Notch by recombinant Dll1 induced Il1b, Il6, and Tnf expression in macrophages, as well as NF-κB activation. An exploratory transcriptome analysis of atherosclerotic arteries suggested that Dll1-Notch signaling regulates the expression of genes associated with inflammation and mitosis. These results indicate that Dll1 promotes the pathobiology of atherosclerosis from the initial lesion development to plaque destabilization in advanced atherosclerotic lesions. Show less

Type 2 diabetic patients exhibited an increased secretion of triglyceride-rich lipoproteins and low high-density lipoprotein cholesterol levels with a greater amount of small dense low-density lipoprotein (LDL). Given that apolipoprotein B (apoB), a proatherogenic lipoprotein, exists at both triglyceride-rich lipoproteins and LDL particles, circulating apoB may associate with diabetic coronary atherosclerosis. The OPTIMAL study was a prospective randomized-controlled study which employed serial near-infrared spectroscopy (NIRS)/intravascular ultrasound (IVUS) imaging to evaluate the efficacy of glycemic control on coronary atherosclerosis in 94 statin-treated type 2 diabetic patients with coronary artery disease (CAD) (UMIN000036721). Of these, 78 patients with both serial apoB levels and NIRS/IVUS images at baseline and week 48 were analyzed. NIRS/IVUS-derived plaque measures were compared in those with and without any reduction of apoB levels. All of the study subjects received a statin, and 60.6% of the study subjects exhibited any reduction of apoB levels. There was no significant difference in the atheroma progression rate between the 2 groups (-0.27 ± 0.15% vs -0.33 ± 0.51%, P = .44). However, patients with any reduction of apoB levels exhibited a greater frequency of change in maximal lipid-core burden index at 4-mm segment (maxLCBI In statin-treated type 2 diabetic patients with CAD, a greater delipidation of coronary atherosclerosis was observed in association with a reduction of apoB levels. The current findings indicate a potential anti-atherosclerotic effect of lowering apoB levels, which may ultimately mitigate future coronary events risk in statin-treated type 2 diabetic patients with CAD. Show less

Addition of the PCSK9 inhibitor, evolocumab, to statin therapy promoted coronary plaque stabilization after an acute coronary syndrome. While apolipoprotein B (ApoB) has been proposed as a goal for lipid-lowering therapy in the prevention of cardiovascular disease, its association with plaque stability has not been studied. The High-Resolution Assessment of Coronary Plaques in a Global Evolocumab Randomized Study (HUYGENS) used serial optical coherence tomography to assess coronary plaque phenotypes in patients with non-ST elevation myocardial infarction treated with evolocumab plus statin or placebo plus statin for 52 weeks. Changes in plaque composition were studied in patients according to achievement of a goal ApoB level <65 mg/dL. Of 112 patients, 67 (59.8 %) achieved the ApoB goal and had lower ApoB values at follow-up compared with those not at goal (37.1 ± 15.0 vs 92.7 ± 19.4 mg/dL, P < 0.001). Patients achieving the ApoB goal demonstrated a greater increase in minimum fibrous cap thickness (+44.6 ± 36.0 vs +24.9 ± 38.1 μm, P = 0.007) and a more pronounced decrease in lipid arc (-57.8 ± 52.8 vs -27.0 ± 59.2°, P = 0.005) at follow-up, compared with those who did not achieve the ApoB goal. At follow-up, thin-cap fibroatheroma (TCFA) was less prevalent among patients achieving the ApoB goal compared with those not at goal (9.0 vs. 40.0 %, P < 0.001). Multivariate analysis demonstrated that achieving an ApoB <65 mg/dL at follow-up independently associated with the absence of TCFA at follow-up (P = 0.004). Lower achieved ApoB levels associated with evidence of greater plaque stabilization even after controlling for low-density lipoprotein cholesterol levels. This highlights the importance of optimizing ApoB levels for the reduction of cardiovascular risk. NCT03570697. Show less

Familial hypercholesterolemia (FH) causes corneal arcus (CA) and xanthomas via lipid particle deposition. Lipoprotein(a) [Lp(a)] consists of an apolipoproteinB100 and apolipoprotein(a). As apolipoprotein(a) accumulates within extracellular connective tissues, it may associate with CA and tendon xanthoma. To elucidate the association between elevated Lp(a) and FH-related physical features and evaluate their independent and joint prognostic utility on cardiovascular risk. We retrospectively analyzed 484 clinically diagnosed FH patients, evaluating both Lp(a) and physical features. Physical features were compared in individuals with and without Lp(a) ≥ 30 mg/dL. The occurrence of major adverse cardiovascular events (MACE = cardiovascular death + acute coronary syndrome + ischemic stroke) was compared in those stratified according to Lp(a) ≥ 30 mg/dL and physical features. The median value of Lp(a) was 18.4 mg/dL; subjects with Lp(a) ≥ 30 mg/dL were more likely to exhibit CA and greater Achilles tendon thickness (ATT). Receiver operating characteristic analysis suggested 14.0 mm as an optimal cut-off value of ATT predicting Lp(a) ≥ 30 mg/dL (C-statistic = 0.58). Even after adjusting for age, sex, untreated low-density lipoprotein cholesterol level, and FH-related pathogenic variants, the co-existence of CA and ATT ≥ 14.0 mm was independently associated with Lp(a) ≥30 mg/dL (odds ratio = 2.31; 95% CI = 1.22-4.38; P = .010). During a 15-year observational period (median = 1835 days), MACE occurred more frequently in subjects with Lp(a) ≥ 30 mg/dL (log-rank P = .026). This Lp(a)-associated cardiovascular risk was further elevated among those with both CA and ATT ≥ 14.0 mm (log-rank P = .042), whereas the presence of physical stigmata did not worsen cardiovascular outcome when Lp(a) was < 30 mg/dL. Assessment of CA and ATT in FH identifies those more likely to have higher Lp(a) levels. The presence of these triads is associated with the highest risk of MACE and potentially guides intensification of antiatherosclerotic therapies. Show less

The Hey family (also known as Chf, Herp, Hesr, and Hrt) is a set of Hairy/Enhancer of Split-related basic helix-loop-helix type transcription factors. Hey1, Hey2, and HeyL have been identified in mammals. Although Hey proteins are known to regulate cardiovascular development, muscle homeostasis, osteogenesis, neurogenesis, and oncogenesis, their roles in tooth development have been largely obscure. Therefore, this study aimed to clarify detailed spatiotemporal expression patterns of Hey1 and Hey2 in developing molars and incisors of mice by section in situ hybridization. Hey1 and Hey2 were not significantly expressed in tooth germs at epithelial thickening, bud, and cap stages during molar development. In the dental epithelium in molars at the bell stage and incisors, Hey2 transcripts were restricted to the undifferentiated inner enamel epithelium and down-regulated in preameloblasts and ameloblasts. On the other hand, Hey1 was mainly expressed in preameloblasts and down-regulated in differentiated ameloblasts. Both genes were not significantly expressed in other dental epithelial tissues, including the outer enamel epithelium, stellate reticulum, and stratum intermedium cells. In the dental mesenchyme, Hey1 was intensely transcribed in the subodontoblastic layer of the dental pulp in both molars and incisors, whereas Hey2 was barely detectable in mesenchymal components. Our data implied that Hey2 function is restricted to transient amplifying cells of the ameloblast cell lineage and that Hey1 plays a role in the composition of the subodontoblastic layer, in addition to ameloblast differentiation. These findings provide novel clues for the better understanding of tooth development. Show less

The hepatocyte paraffin 1 (Hep Par 1) antibody is widely used as a hepatocyte marker, recognizing carbamoyl phosphate synthetase 1 (CPS1), an essential component of the urea cycle. Various missense, nonsense, and frameshift mutations occur in the CPS1 gene. In neonatal patients with homozygous CPS1 deficiency (CPS1D), urea cycle defects with resulting severe hyperammonemia can be fatal, though liver transplantation provides a complete cure for CPS1D. We performed Hep Par 1 immunostaining in the explanted livers of 10 liver transplant patients with CPS1D. Seven were negative for Hep Par 1 in the hepatocytes and the other three showed normal diffuse granular cytoplasmic staining. As expected, all three Hep Par 1-positive patients had at least one missense mutation, and all four patients who had only nonsense or frameshift mutations were Hep Par 1-negative. The other three patients were unexpectedly negative for Hep Par 1, even though each had one missense mutation. These results suggest that CPS1D can be related to the loss of Hep Par 1 reactivity due to the loss of protein production, a one amino acid substitution resulting in an abortive protein product, or both. Hep Par 1 immunohistochemistry can be used as a simple method to confirm CPS1D. Show less

Although high brain and acute leukemia, cytoplasmic (BAALC) expression is a well-characterized poor prognostic factor in acute myeloid leukemia (AML), neither the exact mechanisms by which BAALC drives leukemogenesis and drug resistance nor therapeutic approaches against BAALC-high AML have been properly elucidated. In this study, we found that BAALC induced cell-cycle progression of leukemia cells by sustaining extracellular signal-regulated kinase (ERK) activity through an interaction with a scaffold protein MEK kinase-1 (MEKK1), which inhibits the interaction between ERK and MAP kinase phosphatase 3 (MKP3/DUSP6). BAALC conferred chemoresistance in AML cells by upregulating ATP-binding cassette proteins in an ERK-dependent manner, which can be therapeutically targeted by MEK inhibitor. We also demonstrated that BAALC blocks ERK-mediated monocytic differentiation of AML cells by trapping Krüppel-like factor 4 (KLF4) in the cytoplasm and inhibiting its function in the nucleus. Consequently, MEK inhibition therapy synergizes with KLF4 induction and is highly effective against BAALC-high AML cells both in vitro and in vivo. Our data provide a molecular basis for the role of BAALC in regulating proliferation and differentiation of AML cells and highlight the unique dual function of BAALC as an attractive therapeutic target against BAALC-high AML. Show less

Cellular migration is a fundamental process linked to cancer metastasis. Growing evidence indicates that the receptor for advanced glycation end products (RAGE) plays a pivotal role in this process. With regard to downstream signal transducers of RAGE, diaphanous-1 and activated small guanine nucleotide triphosphatases, Rac1 and Cdc42, have been identified. To obtain precise insight into the direct downstream signaling mechanism of RAGE, we screened for proteins interacting with the cytoplasmic domain of RAGE employing an immunoprecipitation-liquid chromatography coupled with an electrospray tandem mass spectrometry system. In the present study, we found that the cytoplasmic domain of RAGE interacted with an atypical DOCK180-related guanine nucleotide exchange factor, dedicator of cytokinesis protein 7 (DOCK7). DOCK7 bound to the RAGE cytoplasmic domain and transduced a signal to Cdc42, resulting in the formation of abundant highly branched filopodia-like protrusions, dendritic pseudopodia. Blocking of the function of DOCK7 greatly abrogated the formation of dendritic pseudopodia and suppressed cellular migration. These results indicate that DOCK7 functions as an essential and downstream regulator of RAGE-mediated cellular migration through the formation of dendritic pseudopodia. Show less

A loss of balance between cell membrane-associated proteases and their inhibitors may underlie cancer invasion and metastasis. We analysed the roles of a membrane- associated serine protease inhibitor, HAI-1, in oral squamous cell carcinoma (OSCC). While membranous HAI-1 was widely observed in cancer cells of human OSCC tissues, this was significantly reduced at the infiltrative invasion front. In vitro, HAI-1 was detected in all eight OSCC cell lines examined, in which its cognate membrane protease, matriptase was also expressed. HAI-1 expression knock-down (KD) in OSCC lines, SAS and HSC-3, reduced the growth of both lines in vitro but significantly enhanced SAS tumourigenicity in vivo, which was accompanied by histological changes suggestive of the epithelial-mesenchymal transition. Both HAI-1-KD lines also exhibited significantly enhanced migratory capability, and membrane-associated but not truncated HAI-1 was required to rescue this phenotype. Other OSCC lines (HSC-2, Sa3, Ca9-22) also showed enhanced migration in response to HAI-1 KD. The enhanced migration is partly attributed to dysregulation of matriptase, as simultaneous matriptase KD alleviated the migration of HAI-1-KD cells. HAI-1 deficiency also altered the expression of CD24, S100A4, CCND2 and DUSP6, all of which are involved in tumour progression. While matriptase was involved in the increased CD24 expression associated with HAI-1 deficiency, the protease appeared to be not responsible for the altered expression of other genes. Therefore, a matriptase-independent mechanism for the invasiveness associated with HAI-1 KD is also present. Together, these observations suggest that HAI-1 has a crucial suppressive role in OSCC cell invasiveness. Show less

Clinical studies have shown a close association between nonalcoholic fatty liver disease and adult-onset GH deficiency, but the relevant molecular mechanisms are still unclear. No mouse model has been suitable to study the etiological relationship of human nonalcoholic fatty liver disease and human adult-onset GH deficiency under conditions similar to the human liver in vivo. We generated human (h-)hepatocyte chimeric mice with livers that were predominantly repopulated with h-hepatocytes in a h-GH-deficient state. The chimeric mouse liver was mostly repopulated with h-hepatocytes about 50 d after transplantation and spontaneously became fatty in the h-hepatocyte regions after about 70 d. Infusion of the chimeric mouse with h-GH drastically decreased steatosis, showing the direct cause of h-GH deficiency in the generation of hepatic steatosis. Using microarray profiles aided by real-time quantitative RT-PCR, comparison between h-hepatocytes from h-GH-untreated and -treated mice identified 14 GH-up-regulated and four GH-down-regulated genes, including IGF-I, SOCS2, NNMT, IGFLS, P4AH1, SLC16A1, SRD5A1, FADS1, and AKR1B10, respectively. These GH-up- and -down-regulated genes were expressed in the chimeric mouse liver at lower and higher levels than in human livers, respectively. Treatment of the chimeric mice with h-GH ameliorated their altered expression. h-Hepatocytes were separated from chimeric mouse livers for testing in vitro effects of h-GH or h-IGF-I on gene expression, and results showed that GH directly regulated the expression of IGF-I, SOCS2, NNMT, IGFALS, P4AH1, FADS1, and AKR1B10. In conclusion, the chimeric mouse is a novel h-GH-deficient animal model for studying in vivo h-GH-dependent human liver dysfunctions. Show less

Both cyclin D1 and c-myc are key molecules in breast cancer carcinogenesis, and their transcriptional level and stability are regulated through several signaling pathways, including the Wnt signaling pathway. We performed immunohistochemical and mutational analyses of Wnt signaling components to investigate the association of Wnt signaling alterations with breast cancer carcinogenesis using 49 surgically resected primary breast cancer samples. Positive staining of cyclin D1 and c-myc was observed in 55.1% and 30.6% of the 49 breast cancer samples, respectively. Aberrant cytoplasmic expression of beta-catenin, which indicates the existence of alterations in the Wnt signaling pathway, was observed in 38.8% of breast cancer samples, though no mutation was found in the beta-catenin and Axin 1 genes. Reduced expression of APC was observed in 34.7% of samples. Statistical analysis revealed strong correlations between overexpression of beta-catenin and that of cyclin D1 and c-myc (p=0.0001 and 0.0117, respectively). Furthermore, overexpression of beta-catenin was significantly correlated with reduced expression of APC (p=0.0127). Wnt signaling alterations were frequently observed in breast cancer from the results of beta-catenin immunohistochemistry, although no mutation in the components of the Wnt signaling pathway was found in the present study. Based on the statistical analyses, we speculated that reduced expression of APC leads to overexpression of beta-catenin, and aberrant expression of cyclin D1 and c-myc mainly depends on alterations in the Wnt signaling pathway in breast cancer. Show less