Induction of peroxisomal lipid metabolism in mice fed a high-fat diet.

Peroxisomes catalyze a range of essential metabolic functions, mainly related to lipid metabolism. However, their roles in obesity have yet to be clarified. The aim of this study was to investigate the correlation between obesity and peroxisomal lipid metabolism, particularly very long-chain fatty acid (VLCFA) metabolism, gene expression of peroxisomal ß-oxidation enzymes, peroxisomal ATP-binding cassette (ABC) transporter adrenoleukodystrophy (ABCD1) gene and its related gene, ABCD2, the elongation of the VLCFA (ELOVL) gene family and the transcriptional factors involved in the regulation of these genes, including peroxisome proliferator-activated receptor α (PPARα) and sterol regulatory element-binding protein. These factors were analyzed in livers from mice fed a high-fat diet (HFD) or a regular diet (RD) for 20 weeks. Furthermore, the amounts of plasma saturated and unsaturated fatty acids, including VLCFAs, were measured. A HFD induced hepatic gene expression of not only hydroxysteroid 17-ß dehydrogenase 4 (HSD17b4) and sterol carrier protein 2 (SCP2) in peroxisomal ß-oxidation enzymes but also of ELOVL1, 2, 5 and 6, which are involved in the elongation of saturated and unsaturated VLCFAs. Furthermore, ABCD2 mRNA prominently increased in the HFD mice. The transcriptional regulator of these genes, PPARα, was also up-regulated in the HFD mice. VLCFA ratios including C24:0/C22:0, C25:0/C22:0 and C26:0/C22:0 are the most significant diagnostic markers of inherited peroxisomal diseases. These ratios were found to be low in the plasma of the HFD mice compared with the RD mice. The results suggest that HFD activates hepatic peroxisomal VLCFA metabolism, and may provide useful fundamental information to explain the role of peroxisomal function in obesity and lifestyle-related diseases.

X-linked adrenoleukodystrophy: diagnostic and follow-up system in Japan.

X-linked adrenoleukodystrophy (ALD) is an intractable neurodegenerative disease associated with the accumulation of very long-chain saturated fatty acids (VLCFA) in tissues and body fluids. We have established a Japanese referral center for the diagnosis of ALD, using VLCFA measurements and mutation analysis of the ABCD1 gene, and have identified 60 kinds of mutations in 69 Japanese ALD families, which included 38 missense mutations, 6 nonsense mutations, 8 frame-shift mutations, 3 amino acid deletions, 2 exon-skip mutations and 3 large deletions. A total of 24 kinds of mutations (40%) were identified only in Japanese patients by referring to the current worldwide ALD mutation database. There was no clear correlation between these mutations and phenotypes of 81 male patients in these 69 families. About 12% of the individuals with ALD had de novo mutations by mutation analysis in the male probands and their mothers, which should be helpful data for genetic counseling. The only effective therapy for the cerebral form of ALD should be hematopoietic stem cell transplantation at the early stages of the cerebral symptoms, therefore, we performed presymptomatic diagnosis of ALD by extended familial screening of the probands with careful genetic counseling, and established a long follow-up system for these patients to prevent the progression of brain involvement and to monitor the adrenocortical insufficiency. Further elucidation of pathology in ALD, especially concerning the mechanisms of the onset of brain involvement, is expected.

Pericellular matrix of decidua-derived mesenchymal cells: a potent human-derived substrate for the maintenance culture of human ES cells.

In routine culture, human embryonic stem (hES) cells are maintained on either feeder cells or special culture substrates such as Matrigel. However, to expand hES cells for clinical applications, it is desirable to minimize animal-derived materials in the culture for safety reasons. In this report, we show that the pericellular matrix prepared from human decidua-derived mesenchymal cells (PCM-DM) is a potent substrate material that supports the growth and pluripotency of hES cells as efficiently as Matrigel does. This supporting activity of PCM-DM is stable and can be preserved for several months in the refrigerator. PCM-DM-based culture is compatible with non-conditioned commercial defined medium, and with the maintenance of dissociated hES cells in the presence of ROCK inhibitor. Since decidual mesenchymal cells can be prepared and expanded in a large quantity, PCM-DM is a practical human-derived substitute for the animal-derived substrates for use in clinical-grade culture of hES cells.

Bridging the gap from frog research to human therapy: a tale of neural differentiation in Xenopus animal caps and human pluripotent cells.

Over the last decade, much progress has been made toward an understanding of the mechanism of regulation of neural differentiation. In this article, following a brief overview of neural induction research, I would like to discuss the potential contribution of basic embryological research to the progress of human therapeutic development in the present and future, focusing on the medical application of in vitro differentiation of neural tissues. This kind of linkage between basic and medical research will probably be strengthened even more by the recent emergence of human induced pluripotent stem cells. Human pluripotent stem cells are powerful tools for bridging the gap from our accumulated knowledge of embryology to regenerative medicine, as well as to a wide spectrum of medical and pharmaceutical research and development. In this commentary, I describe these issues with a particular emphasis on the contributions made by Japanese scientists.

Calcitonin gene-related peptide mediates acid-induced lung injury in mice.

BACKGROUND AND OBJECTIVE: Acid-induced lung injury from aspiration is one of the most important causes of ARDS. Calcitonin gene-related peptide (CGRP) is a neuropeptide that has various biological actions. The current study investigated whether CGRP might have pathophysiological roles in acid-induced lung injury. METHODS: The investigations employed CGRP gene-disrupted mice--mutant mice (CGRP(-/-)) and their littermate controls (CGRP(+/+)). Anaesthetized and mechanically ventilated mice received 2 mL/kg HCl (pH = 1.5) intratracheally. Lung wet-to-dry weight ratios were calculated to assess pulmonary oedema, total and differential cell counts of the BALF were determined, and measurements of myeloperoxidase activity were performed. RESULTS: Acid-induced lung injury was characterized by an increase in lung permeability and respiratory failure. Disruption of the CGRP gene significantly attenuated acid-induced injury, oedema and respiratory failure. CONCLUSIONS: This study suggests that CGRP is involved in the pathogenesis of acute lung injury caused by acid aspiration and CGRP mutant mice may provide an appropriate model to study molecular mechanisms in this context.

Adrenomedullin insufficiency increases allergen-induced airway hyperresponsiveness in mice.

Adrenomedullin (ADM), a newly identified vasodilating peptide, is reported to be expressed in lungs and have a bronchodilating effect. We hypothesized whether ADM could be involved in the pathogenesis of bronchial asthma. We examined the role of ADM in airway responsiveness using heterozygous ADM-deficient mice (AM+/-) and their littermate control (AM+/+). Here, we show that airway responsiveness is enhanced in ADM mutant mice after sensitization and challenge with ovalbumin (OVA). The immunoreactive ADM level in the lung tissue after methacholine challenge was significantly greater in the wild-type mice than that in the mutant. However, the impairment of ADM gene function did not affect immunoglobulins (OVA-specific IgE and IgG1), T helper 1 and 2 cytokines, and leukotrenes. Thus the conventional mechanism of allergen-induced airway responsiveness is not relevant to this model. Furthermore, morphometric analysis revealed that eosinophilia and airway hypersecretion were similarly found in both the OVA-treated ADM mutant mice and the OVA-treated wild-type mice. On the other hand, the area of the airway smooth muscle layer of the OVA-treated mutant mice was significantly greater than that of the OVA-treated wild-type mice. These results suggest that ADM gene disruption may be associated with airway smooth muscle hyperplasia as well as enhanced airway hyperresponsiveness. ADM mutant mice might provide novel insights to study the pathophysiological role of ADM in vivo.

Neuroradiologic findings in Sotos syndrome.

Sotos syndrome is a well-known anomaly syndrome characterized by overgrowth, characteristic facial gestalt, and developmental delay, and haploinsufficiency of the NSD1 gene has been revealed as one of the major genetic causes. However, there have been only a few reports on neuroradiologic findings by computed tomography (CT) or magnetic resonance imaging (MRI), and functional examination of the brain has not been reported. We examined three cases with typical Sotos syndrome, which also were confirmed by genetic analysis with a specific probe for the NSD1 gene. The results of MRI showed the characteristic features that have been reported previously. The findings obtained by using single-photon emission computed tomography and magnetic resonance spectroscopy suggested an association between mental delay and behavioral tendency in Sotos syndrome and immaturity in frontal brain function.

Aberrant peroxisome morphology in peroxisomal beta-oxidation enzyme deficiencies.

Peroxisomes are ubiquitous organelles in eukaryotic cells and surrounded by a single membrane, and undergo considerable changes in size, shape and number. Peroxisomal disorders are classified into two categories: peroxisome biogenesis disorders (PBDs) and single-enzyme deficiencies (SEDs). Morphologically aberrant peroxisomes called 'peroxisomal ghosts' in PBDs are well known, however, a morphological approach to the study of peroxisomes in SEDs has been rarely reported. Here, we investigated the morphology of peroxisomes in cultured fibroblasts from patients lacking peroxisomal beta-oxidation enzymes, including acyl-CoA oxidase (AOX) or D-3-hydroxyacyl-CoA dehydratase/D-3-hydroxyacyl-CoA dehydrogenase bifunctional protein (D-BP). Morphological analysis by immunofluorescence examination using an antibody against catalase revealed a smaller number of large peroxisomes in fibroblasts from these patients. Moreover, immunoelectron microscopy using an antibody against the 70-kDa peroxisomal membrane protein (PMP70) showed large peroxisomes with various horseshoe-shaped membrane structures. These results give an important clue to elucidating the division of peroxisomes and how peroxisomes change in size, shape, number and position within cells, which are subjects for future study.

Molecular mechanism of a temperature-sensitive phenotype in peroxisomal biogenesis disorder.

Peroxisomal biogenesis disorders include Zellweger syndrome and milder phenotypes, such as neonatal adrenoleukodystrophy (NALD). Our previous study of a NALD patient with a marked deterioration by a fever revealed a mutation (Ile326Thr) within a SH3 domain of PEX13 protein (Pex13p), showing a temperature-sensitive (TS) phenotype in peroxisomal biogenesis. Clinical TS phenotypes also have been reported in several genetic diseases, but the molecular mechanisms still remain to be clarified. The immunofluorescent staining with anti-Pex13p antibody also revealed TS phenotype of the I326T mutant protein itself in the patient cells. Protease digestion of the recombinant Pex13p-SH3 domain showed an increase of protease susceptibility, suggesting a problem of mutant protein fold. Conformational analyses against urea denaturation using urea gradient gel electrophoresis or fluorescence emission from tryptophan residue revealed that the mutant protein should be easily unfolded. Far-UV circular dichroism (CD) spectra demonstrated that both wild-type and the mutant protein have antiparallel beta-sheets as their secondary structure with slightly different extent. The thermal unfolding profiles measured by CD showed a marked lower melting temperature for I326T protein compared with that of wild-type protein. Analysis of the protein 3D-structure indicated that the Ile326 should be a core residue for folding kinetics and the substitution of Ile326 by threonine should directly alter the kinetic equilibrium, suggesting a marked increase of the unfolded molecules when the patient had a high fever. Structural analyses of the protein in the other genetic diseases could provide an avenue for better understanding of genotype-phenotype correlations.

Molecular and neurologic findings of peroxisome biogenesis disorders.

Peroxisomal disorders, an expanding group of genetic disorders in humans, can be grouped into three categories: peroxisome biogenesis disorders, single peroxisomal enzyme deficiencies, and contiguous gene syndrome. At present, 13 complementation groups of peroxisome biogenesis disorders and their responsible genes have been identified, including our newly identified group with a PEX14 defect. We describe neuronal abnormalities related to deficiencies in peroxisomes and the phenotype-genotype relationship in peroxisome biogenesis disorders. We also identified 32 Japanese patients with peroxisome biogenesis disorders, subdivided into six complementation groups. Our institution acts as the only diagnostic center for studies on peroxisomal disorders in Japan.

Identification of a new complementation group of the peroxisome biogenesis disorders and PEX14 as the mutated gene.

Peroxisome biogenesis disorders (PBD) are lethal hereditary diseases caused by abnormalities in the biogenesis of peroxisomes. At present, 12 different complementation groups have been identified and to date, all genes responsible for each of these complementation groups have been identified. The peroxisomal membrane protein PEX14 is a key component of the peroxisomal import machinery and may be the initial docking site for the two import receptors PEX5 and PEX7. Although PEX14 mutants have been identified in yeasts and CHO-cells, human PEX14 deficiency has apparently not been documented. We now report the identification of a new complementation group of the peroxisome biogenesis disorders with PEX14 as the defective gene. Indeed, human PEX14 rescues the import of a PTS1-dependent as well as a PTS2-dependent protein into the peroxisomes in fibroblasts from a patient with Zellweger syndrome belonging to the new complementation group. This patient was homozygous for a nonsense mutation in a putative coiled-coil region of PEX14, c.553C>T (p.Q185X). Furthermore, we showed that the patient's fibroblasts lacked PEX14 as determined by immunocytochemical analysis. These findings indicate that there are 13 genotypes in PBD and that the role of PEX14 is also essential in humans.

Peroxisomal localization in the developing mouse cerebellum: implications for neuronal abnormalities related to deficiencies in peroxisomes.

In subjects with Zellweger syndrome, the most severe phenotype of peroxisomal biogenesis disorder, brain abnormalities include cortical dysplasia, neuronal heterotopia, and dysmyelination. To clarify the relationship between the lack of peroxisomes and neuronal abnormalities, we investigated peroxisomal localization in the mouse cerebellum, using double immunofluorescent staining for peroxisomal proteins. On immunostaining for peroxisomal matrix protein, while there are few peroxisomes in Purkinje cells, many locate in astroglia, especially soma of Bergmann glia. Clusters of peroxisomes were seen on the inferior side of the Purkinje cell layer in mice on postnatal days 3-5, and with time there was a shift to the superior side. The peroxisomal punctate pattern was seen to be radial and co-localized with Bergmann glial fibers. In cultured cells from the mouse cerebellum, peroxisomes were few in Purkinje cells, whereas many were evident in glial fibrillary acidic protein-positive cells. On the other hand, on immunostaining for peroxisomal membrane protein Pex14p, many particles were seen in Purkinje cells during all developmental stages, which means Purkinje cells possessed empty peroxisomal structures similar to findings of fibroblasts from the Zellweger patients. As peroxisomes in glial cells may control the development of neurons, the neuron-glial interaction and mechanisms of developing central nervous systems deserve ongoing attention.

Genetic heterogeneity of peroxisome biogenesis disorders among Japanese patients: evidence for a founder haplotype for the most common PEX10 gene mutation.

We, as the only diagnostic center for peroxisome biogenesis disorders (PBD) in Japan, identified a total of 31 Japanese patients with PBD during the last 20 years. They were 27 patients with Zellweger syndrome (ZS), including two sib cases, three with neonatal adrenoleukodystrophy (NALD) and one with rhizomelic type chondrodysplasia punctata (RCDP). No patient with infantile Refsum disease has been detected. These patients were genetically subdivided into complementation group A (five ZS and one NALD), B (11 ZS), C (four ZS), E (five ZS and two NALD), F (two ZS), and R (one RCDP). They were subjected to mutation analysis of PEX1, PEX2, PEX6, PEX7, and PEX10. All the 11 ZS patients with group-B PBD had a common mutation, i.e., a homozygous 2-base-pair deletion in PEX10. To determine whether this highly frequent mutation is due to a founder effect, we analyzed single nucleotide polymorphisms within PEX10 among patients and Japanese controls. The mutation apparently arose once on an ancestral chromosome in the Japanese population. Based on the value of 24 PBD patients identified during the last 10 years, we estimated the prevalence of PBD in Japan to be approximately one in 500,000 births.

A potent inhibitor of cytosolic phospholipase A2, arachidonyl trifluoromethyl ketone, attenuates LPS-induced lung injury in mice.

Acute respiratory distress syndrome (ARDS) is an acute lung injury of high mortality rate, and sepsis syndrome is one of the most frequent causes of ARDS. Metabolites of arachidonic acid, including thromboxanes and leukotrienes, are proinflammatory mediators and potentially involved in the development of ARDS. A key enzyme for the production of these inflammatory mediators is cytosolic phospholipase A(2) (cPLA(2)). Recently, it has been reported that arachidonyl trifluoromethyl ketone (ATK) is a potent inhibitor of cPLA(2). In the present study, we hypothesized that pharmacological intervention of cPLA(2) could affect acute lung injury. To test this hypothesis, we examined the effects of ATK in a murine model of acute lung injury induced by septic syndrome. The treatment with ATK significantly attenuated lung injury, polymorphonuclear neutrophil sequestration, and deterioration of gas exchange caused by lipopolysaccharide and zymosan administration. The current observations suggest that pharmacological intervention of cPLA(2) could be a novel therapeutic approach to acute lung injury caused by sepsis syndrome.

Attenuation of antigen-induced airway hyperresponsiveness in CGRP-deficient mice.

Bronchial hyperresponsiveness and eosinophilia are major characteristics of asthma. Calcitonin gene-related peptide (CGRP) is a neuropeptide that has various biological actions. In the present study, we questioned whether CGRP might have pathophysiological roles in airway hyperresponsiveness and eosinophilia in asthma. To determine the exact roles of endogenous CGRP in vivo, we chose to study antigen-induced airway responses using CGRP gene-disrupted mice. After ovalbumin sensitization and antigen challenge, we assessed airway responsiveness and measured proinflammatory mediators. In the sensitized CGRP gene-disrupted mice, antigen-induced bronchial hyperresponsiveness was significantly attenuated compared with the sensitized wild-type mice. Antigen challenge induced eosinophil infiltration in bronchoalveolar lavage fluid, whereas no differences were observed between the wild-type and CGRP-mutant mice. Antigen-induced increases in cysteinyl leukotriene production in the lung were significantly reduced in the CGRP-disrupted mice. These findings suggest that CGRP could be involved in the antigen-induced airway hyperresponsiveness, but not eosinophil infiltration, in mice. The CGRP-mutant mice may provide appropriate models to study molecular mechanisms underlying CGRP-related diseases.

[Evaluation before and after pranlukast administration with the QOL questionnaire (revised version 2001) for pediatric patients with bronchial asthma and their parents or caregivers].

We conducted a longitudinal investigation with the QOL questionnaire (revised version 2001) before and after the 4-week-administration of a leukotriene receptor antagonist pranlukast. A significant improvement in the < 4 yrs group was observed at week 1, and that in > or = 4 yrs group at week 2. Under these conditions, the overall QOL score, physical domains and mental domains, significantly improved in both the < 4 yrs group and the > or = 4 yrs group. Overall, a slight correlation was observed between ratio changes in QOL scores and differences in symptom scores. However, no correlation was found in part of patients, suggesting that the QOL questionnaire allows measurement of mental changes in the patients themselves and their parents or caregivers for therapeutic effects which cannot be determined with ordinary physical findings only. In "event present" group, a significant difference in physical and mental domains was revealed by the comparison of QOL scores before and after administration. And furthermore in "event absence" group, the p-value for physical domain and mental domain was 0.0505 and 0.0912 in the < 4 yrs group, respectively, 0.0101 and 0.0446 in the > or = 4 yrs group, respectively. The above results led us to consider the QOL questionnaire (revised version 2001) useful for routine medical care. Furthermore, pranlukast was considered useful for improvement not only of physical symptoms of bronchial asthma but also of the patient's QOL, although the placebo effects in this open trial must be considered.

A novel aberrant splicing mutation of the PEX16 gene in two patients with Zellweger syndrome.

Human Pex16p, a peroxisomal membrane protein composed of 336 amino acids, plays a central role in peroxisomal membrane biogenesis. A nonsense mutation (R176ter) in the PEX16 gene has been reported in the case of only one patient (D-01) belonging to complementation group D of the peroxisome biogenesis disorders. We have now identified two patients belonging to group D (D-02 and D-03) whose fibroblasts were found to contain no peroxisomal membrane structure ghosts. Molecular analysis of the PEX16 gene revealed aberrant cDNA species lacking 65 bp, corresponding to exon 10 skipping caused by a splice site mutation (IVS10 + 2T -->C). Both patients, although unrelated, were homozygous for this mutation. This mutation changes the amino acid sequence starting from codon 298 and introduces a termination codon at codon 336. As a consequence, the cell's ability to membrane synthesis and protein import is disrupted, which implies that the changed C terminus of the Pex16p in these patients likely affects its function.

Ictal and interictal single photon emission computed tomography in a patient with benign familial infantile convulsions.

Ictal and interictal single photon emission computed tomography (SPECT) and ictal electroencephalography (EEG) were studied in a 3-month-old girl with benign familial infantile convulsions (BFIC) to reveal the epileptic focus. There was bilateral diffuse propagation from a left frontal lobe focus on the ictal EEG. Perfusion in the left frontal region was increased on ictal SPECT and decreased on interictal SPECT. Epileptic foci of BFIC showed the same characteristics as foci of symptomatic partial epilepsy.