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M Furuse

Publications and source records attributed to M Furuse.

At least 73 records · Page 4Linked to original sources
PubMed1999

Occludin and claudins in tight-junction strands: leading or supporting players?

Tight junctions have attracted much interest from cell biologists, especially electron microscopists, since on freeze-fracture electron microscopy they appear as a well-developed network of continuous, anastomosing intramembranous strands (tight-junction strands). These strands might be directly involved in the 'barrier' as well as 'fence' functions in epithelial and endothelial cell sheets, but until recently little was known of their constituents. This review discusses current understanding of the molecular architecture of tight-junction strands, focusing on the recent discovery of two distinct types of tight-junction-specific integral membrane proteins, occludin and claudins.

Animals↗
PubMed1999

Intracerebroventricular injection of orexins does not stimulate food intake in neonatal chicks.

1. Recently, 2 novel neuropeptides were discovered, both derived from the same precursor by proteolytic processing, which bind and activate 2 closely related orphan G protein-coupled receptors, Named orexin-A and -B (Sakurai et al., 1998). Both stimulate food intake when administered centrally to rats. 2. Our aim was to elucidate whether central injection of mammalian orexin-A or -B stimulates food intake in the chick. 3. Under conditions of free access to food, orexin-A did not alter the food intake of chicks, but cumulative food intake was significantly suppressed by orexin-B. 4. The orexin-B was then administered to chicks deprived of food for 3 h to confirm its suppressive effect. No significant effect of orexin-B on food intake was detected. 5. Central injection of orexin-B did not modify food intake when appetite was stimulated by fasting. 6. Neither of these orexins appears to stimulate feeding in chicks.

Animals↗
PubMed1999

Polymorphism of heat-shock protein gene HSP70-2 in Crohn disease: possible genetic marker for two forms of Crohn disease.

BACKGROUND: Previous reports have shown that heat-shock protein 70 (HSP70) may be associated with Crohn disease. However, genetic analysis of the HSP70 gene in Crohn disease has not been done. The aim of this study is to investigate whether HSP70-2 gene polymorphism is involved in susceptibility to Crohn disease in the Japanese population and whether it correlates with clinical manifestation of the disease. METHODS: A total of 108 genetically unrelated patients with Crohn disease and 108 healthy controls were typed for HSP70-2 PstI polymorphism by restriction fragment length polymorphism analysis (alleles A and B). Patients with Crohn disease were classified into two types: either perforating or non-perforating. RESULTS: Genotype and allele frequency did not differ between patients and controls. In patients with Crohn disease, allele A frequency was significantly higher in the non-perforating than in the perforating type (P = 0.02). When patients with Crohn disease of more than 6.7 years' duration were assessed, the differences in genotype and allele frequency between the two groups became more significant (P < 0.001 and P < 0.001, respectively). CONCLUSIONS: These data suggest that HSP70-2 gene polymorphic allele A is a possible genetic marker of less severe clinical phenotype in Japanese patients with Crohn disease.

Adolescent↗
PubMed1999

Psychosocial factors associated with peptic ulcer in aged persons.

The relationship between psychosocial factors and the occurrence and aggravation of peptic ulcer was studied in elderly people. Thirty-nine (14 male) ulcer patients and 79 (30 male) elderly people aged 65 years and over and living in the community were tested. Information on health status, medication, lifestyle, and psychosocial status was obtained by means of interviews using a questionnaire and from the clinical records of the ulcer patients. The same questionnaire was distributed to the residents. Logistic regression analysis adjusting for age disclosed that peptic ulcer was significantly associated with having an occupation and low exercise practice in men. However, the relationship weakened below statistical significance after adjusting for some physical risk factors besides age. Low education was significant but low instrumental support fell short of statistical significance with peptic ulcer in women even after adjustment for several physical risk factors besides age. Thus, the specific psychosocial factors might be independently associated with the occurrence and aggravation of peptic ulcer in at least elderly women.

Aged↗
PubMed1999

Periarticular calcification in systemic lupus erythematosus.

OBJECTIVE: To describe the radiologic manifestations of periarticular calcification in patients with systemic lupus erythematosus (SLE) and to investigate clinical variables associated with its occurrence. METHODS: Hand radiographs and clinical records of 52 patients who had 4 or more features of the 1982 revised criteria for classifying SLE and who had no other collagen vascular diseases were analyzed retrospectively. RESULTS: Periarticular calcifications were found in 7 patients (13.5%) near the distal and proximal interphalangeal (DIP and PIP) joints and metacarpophalangeal (MCP) joints. No significant association with calcification was noted for the following variables: age at disease onset, duration of the disease, sex, the maximum value of the serum calcium, organic phosphate, and uric acid, Raynaud's phenomenon, lupus nephritis, femoral avascular necrosis, central nervous system lupus, proteinuria, or the use of drugs such as corticosteroids, synthetic vitamin D, and nonsteroidal antiinflammatory drugs. However, a significant association was noted with the use of furosemide (p < 0.01 by chi-square). In 5 patients periarticular calcification was observed during or just after hyperuricemia had developed while taking diuretics. CONCLUSION: Periarticular calcification in patients with SLE was seen in the DIP, PIP, and MCP joints, and appeared to be associated with the use of diuretics. If patients with SLE are prescribed a diuretic regimen, crystal associated arthritis should be considered as a possibility when diagnosing oligoarthritis.

Adult↗
PubMed1999

[Trigeminal neuralgia with the offending artery transfixing the trigeminal nerve: a case report].

We report a rare case of a patient manifesting trigeminal neuralgia with the offending artery transfixing the trigeminal nerve. A 67-year-old woman was admitted with typical episodes of trigeminal neuralgia on the right side. Magnetic resonance angiograms revealed the right superior cerebellar artery (SCA) compressing the nerve. Through a retromastoid suboccipital craniotomy on the right side, the right SCA was found to compress the root entry zone (REZ) and then penetrate the portio major of the trigeminal nerve. The nerve was dissected parallel to the axis, 7 mm distally from the transfixing point to facilitate transposition of the SCA. In addition to anchoring the distal portion of the SCA to the tentrium, a prosthesis was interposed between the proximal portion and the pons to secure the decompression. The pain was completely relieved immediately after operation with no neurological deficit. Procedures, such as the longitudinal rhizotomy employed in this case, must be carried out for microcompression, in response to individual anatomical variations in neurovascular structures.

Aged↗
PubMed1998

Distinct roles of two separable in vitro activities of yeast Mre11 in mitotic and meiotic recombination.

UNLABELLED: In Saccharomyces cerevisiae, Mre11 protein is involved in both double-strand DNA break (DSB) repair and meiotic DSB formation. Here, we report the correlation of nuclease and DNA-binding activities of Mre11 with its functions in DNA repair and meiotic DSB formation. Purified Mre11 bound to DNA efficiently and was shown to have Mn2+-dependent nuclease activities. A point mutation in the N-terminal phosphoesterase motif (Mre11D16A) resulted in the abolition of nuclease activities but had no significant effect on DNA binding. The wild-type level of nuclease activity was detected in a C-terminal truncated protein (Mre11DeltaC49), although it had reduced DNA-binding activity. Phenotypes of the corresponding mutations were also analyzed. The mre11D16A mutation conferred methyl methanesulfonate-sensitivity to mitotic cells and caused the accumulation of unprocessed meiotic DSBs. The mre11DeltaC49 mutant exhibited almost wild-type phenotypes in mitosis. However, in meiosis, no DSB formation could be detected and an aberrant chromatin configuration was observed at DSB sites in the mre11DeltaC49 mutant. These results indicate that Mre11 has two separable functional domains: the N-terminal nuclease domain required for DSB repair, and the C-terminal dsDNA-binding domain essential to its meiotic functions such as chromatin modification and DSB formation. KEYWORDS: DNA binding/double-strand break repair/DSB formation/Mre11/nuclease

Bacteriophage M13↗
PubMed1998

A single gene product, claudin-1 or -2, reconstitutes tight junction strands and recruits occludin in fibroblasts.

Three integral membrane proteins, clau- din-1, -2, and occludin, are known to be components of tight junction (TJ) strands. To examine their ability to form TJ strands, their cDNAs were introduced into mouse L fibroblasts lacking TJs. Immunofluorescence microscopy revealed that both FLAG-tagged claudin-1 and -2 were highly concentrated at cell contact sites as planes through a homophilic interaction. In freeze-fracture replicas of these contact sites, well-developed networks of strands were identified that were similar to TJ strand networks in situ and were specifically labeled with anti-FLAG mAb. In glutaraldehyde-fixed samples, claudin-1-induced strands were largely associated with the protoplasmic (P) face as mostly continuous structures, whereas claudin-2-induced strands were discontinuous at the P face with complementary grooves at the extracellular (E) face which were occupied by chains of particles. Although occludin was also concentrated at cell contact sites as dots through its homophilic interaction, freeze-fracture replicas identified only a small number of short strands that were labeled with anti-occludin mAb. However, when occludin was cotransfected with claudin-1, it was concentrated at cell contact sites as planes to be incorporated into well- developed claudin-1-based strands. These findings suggested that claudin-1 and -2 are mainly responsible for TJ strand formation, and that occludin is an accessory protein in some function of TJ strands.

Animals↗
PubMed1998

Effects of various N-terminal fragments of glucagon-like peptide-1(7-36) on food intake in the neonatal chick.

Recently, the suppressive effect on food intake by the central administration of glucagon-like peptide-1 (GLP-1) has been confirmed in both rats and chicks. The importance of the N-terminal amino acid, histidine, for the bioactivity of GLP-1(7-36) in the central nervous system was suggested, though the role for C-terminal amino acids in the central nervous system has not been reported. The present study was done to elucidate the central effect of N-terminal fragments of GLP-1(7-36) on food intake of the neonatal chick. Intracerebroventricular (i.c.v.) administration of mammalian GLP-1(7-36) inhibited food intake of chicks, but the fragments of GLP-1(7-16) and GLP-1(7-26) did not show the suppressive effect on food intake. Furthermore, the extended fragments, GLP-1(7-30) and GLP-1(7-33), also had no effects on food intake. It is concluded that C-terminal amino acids of GLP-1(7-36) have an important role for the bioactivity in the central nervous system with special reference to feeding behavior.

Amino Acid Sequence↗
PubMed1998

Claudin-1 and -2: novel integral membrane proteins localizing at tight junctions with no sequence similarity to occludin.

Occludin is the only known integral membrane protein localizing at tight junctions (TJ), but recent targeted disruption analysis of the occludin gene indicated the existence of as yet unidentified integral membrane proteins in TJ. We therefore re-examined the isolated junction fraction from chicken liver, from which occludin was first identified. Among numerous components of this fraction, only a broad silver-stained band approximately 22 kD was detected with the occludin band through 4 M guanidine-HCl extraction as well as sonication followed by stepwise sucrose density gradient centrifugation. Two distinct peptide sequences were obtained from the lower and upper halves of the broad band, and similarity searches of databases allowed us to isolate two full-length cDNAs encoding related mouse 22-kD proteins consisting of 211 and 230 amino acids, respectively. Hydrophilicity analysis suggested that both bore four transmembrane domains, although they did not show any sequence similarity to occludin. Immunofluorescence and immunoelectron microscopy revealed that both proteins tagged with FLAG or GFP were targeted to and incorporated into the TJ strand itself. We designated them as "claudin-1" and "claudin-2", respectively. Although the precise structure/function relationship of the claudins to TJ still remains elusive, these findings indicated that multiple integral membrane proteins with four putative transmembrane domains, occludin and claudins, constitute TJ strands.

Amino Acid Sequence↗
PubMed1998

Occludin-deficient embryonic stem cells can differentiate into polarized epithelial cells bearing tight junctions.

Occludin is the only known integral membrane protein of tight junctions (TJs), and is now believed to be directly involved in the barrier and fence functions of TJs. Occludin-deficient embryonic stem (ES) cells were generated by targeted disruption of both alleles of the occludin gene. When these cells were subjected to suspension culture, they aggregated to form simple, and then cystic embryoid bodies (EBs) with the same time course as EB formation from wild-type ES cells. Immunofluorescence microscopy and ultrathin section electron microscopy revealed that polarized epithelial (visceral endoderm-like) cells were differentiated to delineate EBs not only from wild-type but also from occludin-deficient ES cells. Freeze fracture analyses indicated no significant differences in number or morphology of TJ strands between wild-type and occludin-deficient epithelial cells. Furthermore, zonula occludens (ZO)-1, a TJ-associated peripheral membrane protein, was still exclusively concentrated at TJ in occludin-deficient epithelial cells. In good agreement with these morphological observations, TJ in occludin-deficient epithelial cells functioned as a primary barrier to the diffusion of a low molecular mass tracer through the paracellular pathway. These findings indicate that there are as yet unidentified TJ integral membrane protein(s) which can form strand structures, recruit ZO-1, and function as a barrier without occludin.

Animals↗
PubMed1998

MHC class I bound peptides of a colon carcinoma cell line, a Ki-ras gene-targeted progeny cell line and a B cell line.

MHC class I associated peptides on cancer cells represent potential targets for CD8+ cytotoxic T cell activity against tumor cells. We eluted the naturally bound MHC class I peptides of a colon carcinoma cell line and compared them to peptides isolated from a B cell line and a slow-growing activated Ki-ras-disrupted colon cancer cell line. While we failed to detect any significant differences in class I associated peptides due to the presence or absence of activated Ki-ras in colon cancer cell lines, the colon cancer cell lines and B cell line presented vastly different peptide repertoires in the context of HLA-A*0201 molecules.

B-Lymphocytes↗
PubMed1998

Mutations in the MRE11, RAD50, XRS2, and MRE2 genes alter chromatin configuration at meiotic DNA double-stranded break sites in premeiotic and meiotic cells.

In the yeast Saccharomyces cerevisiae, meiotic recombination is initiated by DNA double-stranded breaks (DSBs) occurring in micrococcal nuclease (MNase)-hypersensitive regions of the chromatin. MNase-sensitive sites also undergo meiosis-specific alterations in chromatin structure prior to the appearance of DSBs. DSB formation requires the products of numerous genes. Herein we have examined the effects of mutations in four such genes, MRE11, RAD50, XRS2, and MRE2, on MNase sensitivity at DSB sites in premeiotic and meiotic cells. Disruption mutations in each of four genes confer greater than wild-type levels of MNase sensitivity in premeiotic cells. In meiotic prophase, all of these mutations affect MNase sensitivity at DSB sites and fall into two distinct phenotypic classes. The type 1 mutations (mre2 and mre11) confer a reduction in MNase sensitivity relative to the wild-type level. The type 2 mutations (rad50 and xrs2) permit a meiotic increase in the MNase sensitivity to reach a final level higher than that observed in wild-type cells. An mre11 disruption mutation (type 1) is epistatic to a rad50 null mutation (type 2) with respect to its meiotic effects on MNase sensitivity, suggesting that the events observed in the type 2 mutants during meiosis are dependent upon type 1 functions. One interpretation of these results is that Mre11, Rad50, Xrs2, and possibly Mer2 (whose splicing is Mre2-dependent) form a complex at recombination hot spots and establish a chromatin/DNA configuration favorable for the induction of DSBs.

Chromatin↗
PubMed1998

Air bubbles in the subclavian or internal jugular veins: a common finding on contrast-enhanced CT.

We investigated the frequency of air bubbles in the subclavian (SCV) or internal jugular (IJV) vein in 200 patients who underwent contrast-enhanced CT of the head and neck. Half the patients were reviewed retrospectively (group 1), while the other half were investigated prospectively after the radiologists who administered the contrast medium were instructed to be careful not to inject even a single air bubble during the procedure (group 2). Air bubbles were observed in the SCV or IJV in 15 of the 100 patients in group 1, while in group 2, there were 4 such patients. Air injection, a common "complication", can be reduced by care during the procedure.

Air↗
PubMed1998

Overcoming barriers in the study of tight junction functions: from occludin to claudin.

Tight junctions (TJs) are essential structures for the physiological functions of epithelial and endothelial cells, and have been suggested to have both barrier and fence functions. Tight junctions create a primary barrier to the diffusion of solutes through the paracellular pathway, and also function as a fence between apical and basolateral membrane domains, to create and maintain cell polarity of epithelial and endothelial cells. Several peripheral membrane proteins have been shown to be concentrated at the cytoplasmic surface of TJs. However, TJ-specific integral membrane proteins had not been identified until recently, and the lack of information concerning TJ-specific integral membrane proteins has hampered a more direct assessment of the function of TJs at the molecular level. Here, we present an overview of current progress in the identification of TJ-specific integral membrane proteins.

Animals↗
PubMed1998

Subcellular distribution of tight junction-associated proteins (occludin, ZO-1, ZO-2) in rodent skin.

Occludin is an integral membrane protein that is concentrated at tight junctions (zonulae occludentes) in simple epithelial cells. ZO-1 and ZO-2 are peripheral membrane proteins that are localized at tight junctions in simple epithelial cells and at cadherin-based adherens junctions in nonepithelial cells. In this study, we investigated the expression and subcellular distribution of occludin, ZO-1, and ZO-2 in rodent skin. Immunoblotting detected all of these molecules in isolated epidermis, but the occludin/ZO-1 (or occludin/ZO-2) ratio was significantly lower than that in cultured simple epithelial cells. In the epidermis of adult skin, occludin was concentrated at cell-cell borders only in the most superficial zone of the granular cell layer, whereas ZO-1 and ZO-2 were distributed in a much broader zone from the spinous to the granular layers. During mouse skin development, this peculiar distribution of occludin in the epidermis appeared when the periderm, a simple epithelium bearing typical occludin-based tight junctions, was sloughed off at embryonic day 16.5 of gestation. Freeze-fracture electron microscopy identified the so-called focal strands or maculae occludentes, i.e., spot tight junction-like structures, between adjacent granular cells, and anti-occludin monoclonal antibody exclusively labeled these focal strands. In hair follicles, occludin and ZO-1 were colocalized at cell-cell borders in Henle's layer and the cornifying cuticle of the inner root sheath. In addition, ZO-1 but not occludin were localized weakly at the outer root sheath and intensely at the hair cortex/matrix.

Animals↗