Analysis of vanin-1 upregulation and lipid accumulation in hepatocytes in response to a high-fat diet and free fatty acids.

High-fat diet is one of the causes of nonalcoholic fatty liver disease. We have previously demonstrated that high-fat diet induces upregulation of adipose differentiation-related protein mRNA expression accompanied by lipid droplet formation in mouse liver. Vanin-1 is a ubiquitous epithelial ectoenzyme that has pantetheinase activity and produces cysteamine, a potent endogenous antioxidant.

Molecular cloning and functional analysis of scavenger receptor zebrafish CL-P1.

Background: Scavenger receptors are generally expressed in macrophages and vascular endothelial cells and some scavenger receptors are thought to contribute to the development of atherosclerosis.

Methods: We cloned the cDNA of a zebrafish CL-P1 (collectin placenta 1) and performed a knockdown study using its antisense morpholino oligonucleotides (MO).

Results: Zebrafish CL-P1 (zCL-P1) is 51% identical to human CL-P1 in its amino acid sequence.

Comparison of human blood concentrations of collectin kidney 1 and mannan-binding lectin.

Mannan-binding lectin (MBL) was first discovered as a collectin in animal blood, and was shown to have such unique characteristics as a collage-like domain and a carbohydrate recognition domain. We recently identified human collectin kidney 1 (CL-K1, COLEC11) from a human kidney cDNA library. To quantitate the CL-K1 concentration in blood, we developed several polyclonal and monoclonal antibodies using recombinant human CL-K1 in CHO cells and the CL-K1 fragment in Escherichia coli.

Octreotide-treated diabetes accompanied by endogenous hyperinsulinemic hypoglycemia and protein-losing gastroenteropathy.

Occurrence of hypoglycemia in diabetes patients is very rare. We report here a case of frequent hypoglycemic attacks caused by inappropriate endogenous hyperinsulinemia in a female patient with poorly controlled diabetes and protein-losing gastroenteropathy. The blood glucose profiles of the patient were unstable.

Transplanting normal vascular proangiogenic cells to tumor-bearing mice triggers vascular remodeling and reduces hypoxia in tumors.

Blood vessels deliver oxygen and nutrients to tissues, and vascular networks are spatially organized to meet the metabolic needs for maintaining homeostasis. In contrast, the vasculature of tumors is immature and leaky, resulting in insufficient delivery of nutrients and oxygen. Vasculogenic processes occur normally in adult tissues to repair "injured" blood vessels, leading us to hypothesize that bone marrow mononuclear cells (BMMNC) may be able to restore appropriate vessel function in the tumor vasculature.

Thiazolidinediones enhance vascular endothelial growth factor expression and induce cell growth inhibition in non-small-cell lung cancer cells.

Background: It is known that thiazolidinediones are involved in regulating the expression of various genes, including the vascular endothelial growth factor (VEGF) gene via peroxisome proliferator-activated receptor gamma (PPARgamma); VEGF is a prognostic biomarker for non-small-cell lung cancer (NSCLC).

Methods: In this study, we investigated the effects of troglitazone and ciglitazone on the mRNA expression of VEGF and its receptors in human NSCLC cell lines, RERF-LC-AI, SK-MES-1, PC-14, and A549. These mRNA expressions were evaluated by quantitative real-time reverse transcription-polymerase chain reaction (RT-PCR) analysis.

Troglitazone increases expression of E-cadherin and claudin 4 in human pancreatic cancer cells.

We examined the effects of troglitazone on expression of E-cadherin and claudin 4 in human pancreatic cancer cells. Troglitazone dose-dependently increased expression of E-cadherin and claudin 4 mRNA and protein in PK-1 cells. Snail, Slug and ZEB1, mRNAs were not changed by troglitazone, indicating that these three transcriptional repressors would not play a role in the induction of E-cadherin by troglitazone.

A Jak2 inhibitor, AG490, reverses lipin-1 suppression by TNF-alpha in 3T3-L1 adipocytes.

Lipin-1 is a multifunctional metabolic regulator, involving in triacylglycerol and bioactive glycerolipids synthesis as an enzyme, transcriptional regulation as a coactivator, and adipogenesis. In obesity, adipose lipin-1 expression is decreased. Although lipin-1 is implicated in the pathogenesis of obesity, the mechanism is still not clear.

Scavenger receptor collectin placenta 1 (CL-P1) predominantly mediates zymosan phagocytosis by human vascular endothelial cells.

Collectin placenta 1 (CL-P1), a recently discovered scavenger receptor, mediates the uptake of oxidized low density lipoprotein and microbes. In this study, we investigated CL-P1-mediated binding and ingestion of yeast-derived zymosan bioparticles using Chinese hamster ovary (CHO) cells stably expressing human CL-P1 (CHO/CL-P1) and human vascular endothelial cells constitutively expressed CL-P1. The uptake of zymosan by CHO/CL-P1 was dependent upon the level of CL-P1 expressed on the membrane and was inhibited by cytochalasin D and wortmannin.

Lipopolysaccharide induces adipose differentiation-related protein expression and lipid accumulation in the liver through inhibition of fatty acid oxidation in mice.

Background: In the present study, we examined the effect of lipopolysaccharide (LPS) on liver histopathology with special reference to lipid metabolism in mice.

Methods: Mice were injected with LPS intraperitoneally, and its effect on the liver was investigated pathologically and biochemically.

Results: Oil-red O staining and adipose differentiation-related protein (ADRP) immunohistochemistry demonstrated that injection of LPS transiently induced lipid accumulation and ADRP expression in hepatocytes, especially around the portal vein.

Immunolocalization of a novel collectin CL-K1 in murine tissues.

We have recently identified a novel collectin, CL-K1, that may play a role in innate immunity as a member of the collectin family. In this study using mice, we investigated the tissue distribution of CL-K1 for better understanding of its pathophysiological relevance. Real-time PCR analyses demonstrated that CL-K1 mRNA was expressed in all tissues tested.

A diacylglycerol kinase inhibitor, R59022, stimulates glucose transport through a MKK3/6-p38 signaling pathway in skeletal muscle cells.

Diacylglycerol kinase (DGK) is one of lipid-regulating enzymes, catalyzes phosphorylation of diacylglycerol to phosphatidic acid. Because skeletal muscle, a major insulin-target organ for glucose disposal, expresses DGK, we investigated in the present study a role of DGK on glucose transport in skeletal muscle cells. PCR study showed that C2C12 myotubes expressed DGKalpha, delta, epsilon, zeta, or theta isoform mRNA.

Identification and characterization of a novel human collectin CL-K1.

Collectins are a family of C-type lectins with two characteristic structures, collagen like domains and carbohydrate recognition domains. They recognize carbohydrate antigens on microorganisms and act as host-defense. Here we report the cloning and characterization of a novel collectin CL-K1.

Functional role of DMT1 in transferrin-independent iron uptake by human hepatocyte and hepatocellular carcinoma cell, HLF.

Non-transferrin bound iron (NTBI) in serum is cleared rapidly by hepatocytes, although the mechanisms of NTBI uptake by hepatocytes are poorly understood. Dietary iron is transported into intestinal enterocytes by divalent metal transporter 1 (DMT1), which also transports iron from transferrin receptor 1 (TfR1)-mediated recycling endosome to intracytoplasm. We made an antiserum against human DMT1 protein derived from mRNA with the iron responsive element (IRE).

Up-regulation of ADRP in fatty liver in human and liver steatosis in mice fed with high fat diet.

The present study was performed to examine a role of adipose differentiation-related protein (ADRP) in the process of liver steatosis. Immunohistochemical findings indicated that ADRP expression is increased in the hepatocytes in patients with fatty liver when compared with normal liver. ADRP expression is localized in the surface of lipid droplets in the hepatocytes.

Increased expression of PPARgamma in high fat diet-induced liver steatosis in mice.

The present study was performed to examine a hypothesis that peroxisome proliferator-activated receptor gamma (PPARgamma) is implicated in high fat diet-induced liver steatosis. Mice were fed with control or high fat diet containing approximately 10% or 80% cholesterol, respectively. Macroscopic and microscopic findings demonstrated that lipid accumulation in the liver was observed as early as 2 weeks after high fat diet and that high fat diet for 12 weeks developed a fatty liver phenotype, establishing a novel model of diet-induced liver steatosis.

Involvement of MEK-ERK signaling pathway in the inhibition of cell growth by troglitazone in human pancreatic cancer cells.

In the present study, we examined a role of mitogen-activated protein kinases (MAPKs), extracellular signal-related kinase (ERK), c-Jun N-terminal protein kinase, and p38 MAPK in troglitazone-induced inhibition of cell growth in human pancreatic cancer cells. Among the three kinases, troglitazone specifically inhibited the phosphorylation of ERK1/2 in a dose- and time-dependent manner. Troglitazone also down-regulated the protein expression of mitogen-activated protein kinase kinase (MEK)1/2, an upstream molecule that regulates ERK phosphorylation.

Inhibition of cell invasion and morphological change by troglitazone in human pancreatic cancer cells.

Background: We have recently demonstrated that peroxisome proliferator activated receptor (PPAR) gamma activation by its selective ligand, troglitazone, potently inhibited cell proliferation in human pancreatic cancer cells. The present study was performed to clarify the role of PPARgamma in cell invasion/motility in human pancreatic cancer cells.

Methods: Cell invasive activity was assessed by an in vitro invasion assay, using a Transwell chamber, and by a wound-healing assay, in the human pancreatic cancer cell lines, PK-1 and PK-9.

Growth arrest by troglitazone is mediated by p27Kip1 accumulation, which results from dual inhibition of proteasome activity and Skp2 expression in human hepatocellular carcinoma cells.

In our study, we examined whether human hepatocellular carcinoma (HCC) expresses peroxisome proliferator-activated receptor gamma (PPARgamma) and the effects of PPAR gamma activation by its selective ligands on cell growth and cell invasion in HCC cells. RT-PCR and Western blot analysis revealed that HCC-derived cell lines, HepG2 and HLF, express PPARgamma mRNA and protein. Luciferase assay in HLF cells showed that troglitazone, a selective ligand for PPAR gamma, transactivated the transcription of a peroxisome proliferator response element-driven promoter in a dose-dependent manner, suggesting that the expressed PPARgamma functions as a transcriptional factor.

PPAR gamma ligand-induced apoptosis through a p53-dependent mechanism in human gastric cancer cells.

We have recently demonstrated that the PPAR gamma ligand troglitazone induced cell growth arrest and evoked apoptosis in a gastric cancer cell line, MKN-45. Since in general, p53 plays an important role in the induction of apoptosis and growth inhibition, we tried to clarify whether or not p53 mediates troglitazone-induced apoptosis and growth arrest in gastric cancer cells. Troglitazone increased the number of apoptoic cells in MKN-28, MKN-45 and MKN-74, but not in KATO-III cells.

Troglitazone induces G1 arrest by p27(Kip1) induction that is mediated by inhibition of proteasome in human gastric cancer cells.

We examined in the present study whether human gastric cancer cells express peroxisome proliferator-activated receptor gamma (PPARgamma), the effect of PPARgamma activation by troglitazone, a selective ligand, on cellular growth, and the mechanism of the growth arrest by troglitazone in gastric cancer cells. RT-PCR, northern blot and western blot analysis demonstrated that all four tested human gastric cancer cell lines, MKN-28, MKN-45, MKN-74 and KATO-III, expressed PPARgamma mRNA and protein. WST-1 assay and flow cytometric analysis revealed that troglitazone inhibited the growth and induced G1 arrest in all four gastric cancer cell lines.