Takao Kaji

Enhanced expression of cancer testis antigen genes in glioma stem cells

Cancer stem cells are an important target for effective therapy, since they show tumorigenicity, chemoresistance, and radioresistance. We isolated cancer stem cells from glioma cell lines and tissues and examined the expression of cancer testis antigen (CTA) genes as potential target molecules for cancer vaccine therapy. CTA genes were highly and frequently expressed in cancer stem cells compared with differentiated cells. In addition, histone acetylation levels in the promoter regions of CTA genes were high in cancer stem cells and low in differentiated cells, while DNA methylation analysis of the promoter regions revealed hypomethylation in cancer stem cells. This epigenetic difference between cells leads to heterogeneous expression of CTA genes in the tumor mass, which consists of cells at various levels of differentiation. Moreover, the expression level of HLA class I antigens was not affected by the differentiation status, suggesting that CTA genes may present as surface antigens in cancer stem cells. Taken together, these findings suggest that CTA genes may be attractive candidates for targeted vaccine therapy against cancer stem cells in glioma patients.

Serotonin 5-HT2C receptor-independent expression of hypothalamic NOR1, a novel modulator of food intake and energy balance, in mice

NOR1, Nur77 and Nurr1 are orphan nuclear receptors and members of the NR4A subfamily. Here, we report that the expression of hypothalamic NOR1 was remarkably decreased in mildly obese beta-endorphin-deficient mice and obese db/db mice with the leptin receptor mutation, compared with age-matched wild-type mice, whereas there were no genotypic differences in the expression of hypothalamic Nur77 or Nurr1 in these animals. The injection of NOR1 siRNA oligonucleotide into the third cerebral ventricle significantly suppressed food intake and body weight in mice. On the other hand, the decreases in hypothalamic NOR1 expression were not found in non-obese 5-HT2C receptor-deficient mice. Moreover, systemic administration of m-chlorophenylpiperazine (mCPP), a 5-HT2C/1B receptor agonist, had no effect on hypothalamic NOR1 expression, while suppressing food intake in beta-endorphin-deficient mice. These findings suggest that 5-HT2C receptor-independent proopiomelanocortin-derived peptides regulate the expression of hypothalamic NOR1, which is a novel modulator of feeding behavior and energy balance.

Amphioxus mouth after dorso-ventral inversion.

IntroductionDeuterostomes (animals with ‘secondary mouths’) are generally accepted to develop the mouth independently of the blastopore. However, it remains largely unknown whether mouths are homologous among all deuterostome groups. Unlike other bilaterians, in amphioxus the mouth initially opens on the left lateral side. This peculiar morphology has not been fully explained in the evolutionary developmental context. We studied the developmental process of the amphioxus mouth to understand whether amphioxus acquired a new mouth, and if so, how it is related to or differs from mouths in other deuterostomes.ResultsThe left first somite in amphioxus produces a coelomic vesicle between the epidermis and pharynx that plays a crucial role in the mouth opening. The vesicle develops in association with the amphioxus-specific Hatschek nephridium, and first opens into the pharynx and then into the exterior as a mouth. This asymmetrical development of the anterior-most somites depends on the Nodal-Pitx signaling unit, and the perturbation of laterality-determining Nodal signaling led to the disappearance of the vesicle, producing a symmetric pair of anterior-most somites that resulted in larvae lacking orobranchial structures. The vesicle expressed bmp2/4, as seen in ambulacrarian coelomic pore-canals, and the mouth did not open when Bmp2/4 signaling was blocked.ConclusionsWe conclude that the amphioxus mouth, which uniquely involves a mesodermal coelomic vesicle, shares its evolutionary origins with the ambulacrarian coelomic pore-canal. Our observations suggest that there are at least three types of mouths in deuterostomes, and that the new acquisition of chordate mouths was likely related to the dorso-ventral inversion that occurred in the last common ancestor of chordates.

Hypothalamic orexin and pro-opiomelanocortin activities are essential for the anorexic effects of m-chlorophenylpiperazine in mice

Hypothalamic pro-opiomelanocortin (POMC) activity is reportedly essential for satiety signalling downstream of serotonin (5-HT). Here we show that food-restricted wild-type mice, which exhibited decreased hypothalamic POMC expression and increased hypothalamic orexin expression, were responsive to m-chlorophenylpiperazine (m-CPP), a 5-HT(2C/1B) receptor agonist, leading to anorexia, whereas food-restricted A(y) mice with decreased hypothalamic POMC and orexin expression, were not. Injection of POMC small interfering RNA (siRNA) oligonucleotide+orexin siRNA oligonucleotide into the third cerebral ventricle was unresponsive to mCPP-induced anorexia, whereas a single injection of POMC or orexin siRNA oligonucleotides elicited a response. The injection of POMC siRNA oligonucleotides suppressed the anorexic effects of sibutramine, a serotonin and noradrenaline re-uptake inhibitor. The injection of orexin siRNA oligonucleotides suppressed the hyperphagia induced by the injection of POMC siRNA oligonucleotides. These findings suggest that functional hypothalamic POMC and orexin activity has a critical role in satiety signalling of mCPP in mice.

Dynamic Modification of Oral Innervation During Metamorphosis in Branchiostoma belcheri, the Oriental Lancelet

The oral apparatus in lancelets undergoes a remarkable modification during larval development, especially during metamorphosis, when the oral innervation is radically altered. The larval mouth opens on the left side at the early larval stage, and a peripheral nerve network, the oral nerve ring (ONR), develops around it. The ONR enlarges as the mouth expands caudally, eventually receiving fibers from nerves as far back as the tenth on the left side. The mouth shrinks during metamorphosis, and with this change the ONR regresses; the posterior sixth to tenth nerves become freed from the connection with the ONR, whereas the fourth and fifth nerves retain their connections. This modification is the basis for the asymmetric innervation to the velum. There is no mesodermal or mesenchymal restriction for guiding nerve patterning as typically found in vertebrate cranial nerves. Rather, it seems to be the ONR, which has no counterpart in vertebrates, that plays pivotal roles for patterning the nervous system in the oral region. The oral innervation pattern in lancelets represents a derived character state that may be related to the asymmetry of the ancestral body and head.

The acute anorexic effect of liraglutide, a GLP-1 receptor agonist, does not require functional leptin receptor, serotonin, and hypothalamic POMC and CART activities in mice.

The acute anorexic effect of liraglutide, a GLP-1 receptor agonist, did not require functional leptin receptor, serotonin, and hypothalamic proopiomelanocortin and cocaine amphetamine regulated transcript activities in mice, although decrease in functional hypothalamic orexin activity might be involved in the acute anorexic effect of liraglutide.

α1-Adrenergic receptor downregulates hepatic FGF21 production and circulating FGF21 levels in mice.

Fibroblast growth factor 21 (FGF21) is primarily secreted by the liver as an endocrine hormone and is suggested as a promising target for the treatment of metabolic diseases. FGF21 acts centrally to exert its effects on energy expenditure and body weight via the sympathetic nervous system in mice. Here we show that intraperitoneal injection of phentolamine (an α-adrenergic receptor antagonist, 5mg/kg) significantly increased plasma FGF21 levels compared with the saline controls in C57BL6J mice, whereas alprenolol (a β-adrenergic receptor antagonist, 6mg/kg) had no effect. In addition, intraperitoneal injection of prazosin (an α1-adrenergic receptor antagonist, 5mg/kg) significantly increased plasma FGF21 levels compared with the controls, whereas yohimbine (an α2-adrenergic receptor antagonist, 5mg/kg) had no effect. Moreover, the treatment with prazosin significantly increased the expression of hepatic FGF21, while having no effect on the expression of hepatic PPARα and PPARγ. After a 5-h fast, intraperitoneal injection of prazosin significantly increased plasma FGF21 levels and impaired glucose tolerance compared with controls. These findings suggest that α1-adrenergic receptor downregulates the expression of hepatic FGF21 and plasma FGF21 levels independently of feeding and hepatic PPARα and PPARγ expression in mice, and that the increases in circulating FGF21 levels might be related to impaired glucose tolerance.

Ingestion of eicosapentaenoic acid in the early stage of social isolation reduces a fibroblast growth factor 21 resistant state independently of body weight in KKA(y) mice.

Fibroblast growth factor (FGF) 21 is a mediator of glucose and lipid metabolism. Although exogenous administration of FGF21 exerts beneficial effects on glucose and lipid metabolism, circulating FGF21 levels are elevated in ob/ob and db/db mice, diet-induced obese mice and obese human. Here we show that ingestion of eicosapentaenoic acid (EPA) for 6 days after individually-housing significantly suppressed the hyperglycemia and hypertriglyceridemia associated with decreases in plasma insulin and FGF21 levels in KKA(y) mice while having no effects on food intake, body weight or plasma active GLP-1 levels. The ingestion of EPA had no significant effects on the expression of FGF21 in the liver, epididymal white adipose tissue and skeletal muscle. Moreover, the ingestion of EPA significantly decreased the expression of hepatic peroxisome sterol regulatory element-binding protein (SREBP1c), carbohydrate response element-binding protein (ChREBP), stearoyl-CoA deaturase and periostin, which are involved in hepatic lipogenesis and hepatosteaotosis, in KKA(y) mice. On the other hand, the ingestion of EPA had no significant effects on expression of hepatic gp78, Notch, forkhead box protein O1 or glucose-6-phosphatase. These findings suggest that EPA ingestion in the early stage of social isolation suppresses hyperglycemia and hypertriglyceridemia associated with reduced FGF21 and insulin resistance without altering food intake and body weight, and that the EPA ingestion suppresses hepatic lipogenesis by suppressing Notch- and gp78-independent SEREBP1c and ChREBP pathways in KKA(y) mice.

Pharmacologic stimulation of central GLP-1 receptors has opposite effects on the alterations of plasma FGF21 levels induced by feeding and fasting.

Fibroblast growth factor 21 (FGF21) functions as an endocrine hormone to regulate energy metabolism. Circulating FGF21 is derived from the liver and is produced in response to alterations of nutritional status. Here we show the effects of liraglutide, a human glucagon-like-peptide-1 (GLP-1) receptor agonist, injected into the third cerebral ventricle on body weight and plasma FGF21 levels in free-feeding mice, food-deprived mice, and mice provided 1g after the injection. In free-feeding mice, liraglutide (5-100μg/kg) injected into the third cerebral ventricle suppressed food intake and body weight after 24h in a dose-dependent manner. Liraglutide (50 and 100μg/kg) significantly increased plasma FGF21 levels and hepatic FGF21 expression, whereas smaller doses (5 and 10μg/kg) had no effect. In food-deprived mice, body weight did not differ significantly between the saline control and liraglutide-treated groups, but liraglutide (100μg/kg) significantly decreased plasma FGF21 levels at 24h compared with the saline control. In mice provided 1g food, body weight did not differ significantly between the saline control and liraglutide-treated groups, but liraglutide (50μg/kg) significantly decreased plasma FGF21 levels at 24h compared with the saline control. These findings suggest that intracerebral injection of liraglutide decreases body weight by inhibiting food intake and increases plasma FGF21 levels in free-feeding mice, whereas it suppresses the elevations of plasma FGF21 levels induced by fasting or the restricted feeding. Thus, pharmacologic stimulation of central GLP-1 receptors has opposite effects on the alterations of plasma FGF21 levels induced by feeding and fasting.

Mosapride, a selective serotonin 5-HT4 receptor agonist, and alogliptin, a selective dipeptidyl peptidase-4 inhibitor, exert synergic effects on plasma active GLP-1 levels and glucose tolerance in mice.

Pharmacologic stimulation of serotonin 5-HT4 receptors increased plasma active glucagon-like-peptide-1 (GLP-1) levels independent of feeding, and that pharmacologic stimulation of 5-HT4 receptors and pharmacologic inhibition of dipeptidyl peptidase-4 exerted synergic effects on plasma active GLP-1 levels and glucose tolerance in mice.