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Biomedical subjects

Minoru Fukuda

Publications and source records attributed to Minoru Fukuda.

81 records · Page 5Linked to original sources
PubMed2002

Biosynthesis of HNK-1 glycans on O-linked oligosaccharides attached to the neural cell adhesion molecule (NCAM): the requirement for core 2 beta 1,6-N-acetylglucosaminyltransferase and the muscle-specific domain in NCAM.

The HNK-1 glycan, sulfo-->3GlcAbeta1-->3Galbeta1-->4GlcNAcbeta1-->R, is highly expressed in neuronal cells and apparently plays critical roles in neuronal cell migration and axonal extension. The HNK-1 glycan synthesis is initiated by the addition of beta1,3-linked GlcA to N-acetyllactosamine followed by sulfation of the C-3 position of GlcA. The cDNAs encoding beta1,3-glucuronyltransferase (GlcAT-P) and HNK-1 sulfotransferase (HNK-1ST) have been recently cloned. Among various adhesion molecules, the neural cell adhesion molecule (NCAM) was shown to contain HNK-1 glycan on N-glycans. In the present study, we first demonstrated that NCAM also bears HNK-1 glycan attached to O-glycans when NCAM contains the O-glycan attachment scaffold, muscle-specific domain, and is synthesized in the presence of core 2 beta1,6-N-acetylglucosaminyltransferase, GlcAT-P, and HNK-1ST. Structural analysis of the HNK-1 glycan revealed that the HNK-1 glycan is attached on core 2 branched O-glycans, sulfo-->3GlcAbeta1-->3Galbeta1-->4GlcNAcbeta1-->6(Galbeta1-->3)GalNAc. Using synthetic oligosaccharides as acceptors, we found that GlcAT-P and HNK-1ST almost equally act on oligosaccharides, mimicking N- and O-glycans. By contrast, HNK-1 glycan was much more efficiently added to N-glycans than O-glycans when NCAM was used as an acceptor. These results are consistent with our results showing that HNK-1 glycan is minimally attached to O-glycans of NCAM in fetal brain, heart, and the myoblast cell line, C2C12. These results combined together indicate that HNK-1 glycan can be synthesized on core 2 branched O-glycans but that the HNK-1 glycan is preferentially added on N-glycans over O-glycans of NCAM, probably because N-glycans are extended further than O-glycans attached to NCAM containing the muscle-specific domain.

Animals↗
PubMed2002

Influences of the lysosomal associated membrane proteins (Lamp-1, Lamp-2) and Mac-2 binding protein (Mac-2-BP) on the prognosis of pancreatic carcinoma.

BACKGROUND: Lamps and Mac-2-BP are ligands of galectin-3, and they were suggested to influence tumor proliferation and metastasis formation. The authors studied the expression of Lamp-1, Lamp-2, and Mac-2-BP in pancreatic carcinoma and evaluated their influence on patient prognosis. METHODS: Northern blot analysis, in situ hybridization, and immunohistochemistry were performed in 12 normal and 28 pancreatic carcinoma tissue samples and in pancreatic carcinoma cell lines. The molecular findings in the tumor samples were correlated with the prognosis and histopathologic tumor characteristics. In addition, in Lamp-1 transfected CAPAN-1 pancreatic carcinoma cells, cell proliferation was analyzed. RESULTS: Lamp-1, Lamp-2, and Mac-2-BP were overexpressed in 61% (1.6-fold increase, not significant), 71% (3.0-fold increase, P < 0.01), and 93% (5.6-fold increase, P < 0.01) of the pancreatic carcinoma samples. Lamp-1 and Lamp-2 immunoreactivity was present at the luminal side of the ductal carcinoma cells whereas Mac-2-BP immunoreactivity was diffusely spread over the whole cytoplasm and the nucleolus of ductal carcinoma cells. Correlation of the molecular data with clinical patient parameters revealed that patients whose tumors exhibited high Lamp-1 mRNA expression lived significantly longer (median, 17 months) after tumor resection than patients whose tumors exhibited low to moderate Lamp-1 mRNA levels (median, 8 months; P < 0.02). No relation between Lamp-2 and Mac-2-BP mRNA expression and any of the histopathologic parameters was found. Lamp-1 transfected CAPAN-1 cells showed decreased cell growth compared with the nontransfected cells. CONCLUSIONS: Lamp-1 might influence local tumor progression rather than the formation of tumor metastasis in pancreatic carcinoma, whereas Mac-2-BP and Lamp-2 seem to have little influence on these parameters in pancreatic carcinoma.

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PubMed2002

Changes in the proliferative activity of epidermal melanocytes in serum-free primary culture during the development of ultraviolet radiation B-induced pigmented spots in hairless mice.

Long-term exposure to ultraviolet radiation B (UVB) induced pigmented spots in the dorsal skin of hairless mice of strain (HR-1 X HR/De)F1. To clarify the cellular mechanism for the development of these UVB-induced pigmented spots, we investigated changes in the proliferative activity of epidermal melanoblasts and melanocytes in the dorsal skin at various weeks after UVB irradiation. Epidermal cell suspensions from the dorsal skin of hairless mice were cultured in a serum-free medium supplemented with dibutyryl adenosine 3':5'-cyclic monophosphate (DBcAMP) and basic fibroblast growth factor (bFGF). The suspensions were prepared from dorsal skins of mice exposed to UVB for 4 weeks (the stage of hyperpigmentation). Suspensions were also prepared from mice at 3 (the stage of depigmentation), 8 (the stage of appearance of pigmented spots), 20 (the stage of development of small-sized pigmented spots) and 37 (the stage of development of medium-sized pigmented spots) weeks after the cessation of 8-week UVB exposure. At the stage of hyperpigmentation the proliferative activity of melanoblasts and melanocytes was suppressed. With the development of pigmented spots, the proliferative activity of undifferentiated melanoblasts gradually increased, and then followed the increase in the proliferative activity of differentiated melanocytes. These results suggest that the proliferative activity of epidermal melanoblasts and melanocytes in UVB-irradiated skin increases with the development of pigmented spots.

Animals↗
PubMed2002

Keratinocytes control the proliferation and differentiation of cultured epidermal melanocytes from ultraviolet radiation B-induced pigmented spots in the dorsal skin of hairless mice.

Long-term exposure of ultraviolet radiation B (UVB)-induced pigmented spots in the dorsal skin of hairless mice of Hos:(HR-1 X HR//De) F1. Previous study showed that the proliferative and differentiative activities of cultured epidermal melanoblasts/melanocytes from UVB-induced pigmented spots increased with the development of the pigmented spots. To determine whether the increase in the proliferative and differentiative activities of epidermal melanoblasts/melanocytes was brought about by direct changes in melanocytes, or by indirect changes in surrounding keratinocytes, pure cultured melanoblasts/melanocytes and keratinocytes were prepared and co-cultured in combination with control and irradiated mice in a serum-free culture medium. Keratinocytes from irradiated mice stimulated the proliferation and differentiation of both neonatal and adult non-irradiated melanoblasts/melanocytes more greatly than those from non-irradiated mice. In contrast, both non-irradiated and irradiated adult melanocytes proliferated and differentiated similarly when they were co-cultured with irradiated adult keratinocytes. These results suggest that the increased proliferative and differentiative activities of mouse epidermal melanocytes from UVB-induced pigmented spots are regulated by keratinocytes, rather than melanocytes.

Animals↗
PubMed2002

The cytosolic and transmembrane domains of the beta 1,6 N-acetylglucosaminyltransferase (C2GnT) function as a cis to medial/Golgi-targeting determinant.

The beta 1,6 N-acetylglucosaminyltransferase (C2GnT) has been recently mapped to the cis/medial-Golgi compartment. To analyze the Golgi-targeting determinants of C2GnT, we constructed various deletion mutants of the enzyme fused to the enhanced green fluorescent protein (EGFP) and localized these proteins by fluorescence microscopy in living cells. We found that the N-terminal peptide encompassing amino acids 1 to 32 represents the minimal Golgi-targeting signal sufficient to localize EGFP to the same compartment as the full-length C2GnT. This peptide makes up the cytoplasmic and the transmembrane domains of the enzyme and was referred to as CTd (cytoplasmic and transmembrane domains). We compared the Golgi-targeting efficiency of the C2GnT-derived CTd with its homologous domains from other glycosyltransferases, including the H-type alpha(1,2)-fucosyltransferase (FucTI), the polypeptide N-acetylgalactosaminyltransferase-I (GalNAcT-I), the alpha(1,3)-fucosyltransferase VII (FucTVII), and the alpha(2,6)-sialyltransferase (ST6Gal-I) and found that the Golgi-targeting determinants of these glycosyltransferases were also composed of their cytosolic and transmembrane domains. To investigate whether the CTd of C2GnT could serve as a cis to medial Golgi-specific signal, we tested its ability to mislocalize two late-Golgi acting glycosyltransferases FucTI and FucTVII. We show that fusing the C2GnT-derived CTd with the catalytic domain of FucTVII resulted in a complete mislocalization of the enzyme to the C2GnT compartment, with a parallel alteration of sialyl-Lewis x synthesis and P-selectin binding. The intracellular distribution and activity of FucTI, however, were not affected. Thus, CTds of either early or late-Golgi acting glycosyltransferases represent the Golgi-targeting domains of these enzymes. In addition, we show that C2GnT-derived CTd can function as a cis/medial Golgi-targeting determinant.

Animals↗
PubMedDate not supplied

Unusual posterior hyaloid strand in a young child with optic disc pit maculopathy: intraoperative and histopathological findings.

BACKGROUND: The mechanism responsible for optic disc pit maculopathy is unclear, but abnormal vitreous structures, including the anomalous Cloquet's canal at the optic disc pit, have been suggested as important factors. CASE: We report the intraoperative and ultrastructural findings of an unusual posterior vitreous strand in the eye of an 8-year-old girl with optic disc pit maculopathy. OBSERVATIONS: The patient presented with decreased vision in the left eye. Examination of the left eye revealed a best-corrected visual acuity (VA) of 0.08 and a macular detachment associated with an optic disc pit. Vitrectomy was performed with the adjunctive use of triamcinolone acetonide intraoperatively. The presence of an unusual posterior hyaloid strand tightly attached to the margin of the optic disc pit was noted. An unusual movement of this strand was observed during the surgery. The strand was excised, and fluid-gas exchange was performed using gas tamponade with 20% SF(6). After 12 months, a complete macular reattachment was obtained, with the VA improving to 1.2. Electron microscopic examination of the removed strand revealed abundant thick collagen fibrils with a frame of fine fibrils. CONCLUSION: The unusual posterior vitreous strand connected to the optic disc pit may have contributed to the pathogenesis of maculopathy in this young child.

Child↗
PubMedDate not supplied

Polysialyltransferases: major players in polysialic acid synthesis on the neural cell adhesion molecule.

Polysialic acid is a unique carbohydrate composed of a linear homopolymer of alpha2,8-linked sialic acid, and is mainly attached to the fifth immunoglobulin-like domain of the neural cell adhesion molecule (NCAM) via a typical N-linked glycan in vertebrate neural system. Polysialic acid plays critical roles in neural development by modulating adhesive property of NCAM such as neural cell migration, neurite outgrowth, neural pathfinding, and synaptogenesis. The expression of polysialic acid is temporally and spatially regulated during neural development. Polysialylation of NCAM is catalyzed by two polysialyltransferases, ST8Sia II (STX) and ST8Sia IV (PST), which belong to the family of six genes encoding alpha 2,8-sialyltransferases. ST8Sia II and IV are expressed differentially in tissue-specific and cell-specific manners, and they apparently have distinct roles in development and organogenesis. The presence of polysialic acid is always associated with expression of ST8Sia II and/or IV, suggesting that ST8Sia II and IV are the key enzymes that control the expression of polysialic acid. Both ST8Sia II and IV can transfer multiple alpha 2,8-linked sialic acid residues to an acceptor N-glycan containing a NeuNAc alpha 2-->3 (or 6) Gal beta 1-->4GlcNAc beta 1-->R structure without participation of other enzymes. The two enzymes differently but cooperatively act on NCAM and the amount of polysialic acid synthesized by both enzymes together is greater than that synthesized by either enzyme alone. The polysialyltransferases are thus important regulators in polysialic acid synthesis and contribute to neural development in the vertebrate.

Amino Acid Sequence↗
PubMedDate not supplied

Both bronchial and vascular stenting followed by chemoradiotherapy for locally advanced non-small cell lung cancer.

Airway and vascular constrictions are expected problems for lung cancer patients. The clinical course of a patient in whom stents were inserted in 3 constriction regions is reported. A 72-year-old man with advanced primary lung cancer (squamous cell carcinoma stage IIIB) developed suffocating constriction of the trachea and showed superior vena cava (SVC) syndrome. Self-expandable metal stents were inserted into the trachea, SVC and left subclavian vein and the patient was treated by radiotherapy and weekly irinotecan. Within 5 months of treatment, complete local control was achieved and there was no reconstriction. Both endobronchial and endovascular stenting prior to antitumor therapy may be beneficial in the treatment of locally advanced cases of lung cancer.

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