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Biomedical subjects

Atsushi Utani

Publications and source records attributed to Atsushi Utani.

25 records · Page 2Linked to original sources
PubMed2003

Activation of p38 MAPK suppresses matrix metalloproteinase-1 gene expression induced by platelet-derived growth factor.

p38 mitogen-activated protein kinase (MAPK) regulates matrix metalloproteinase-1 (MMP-1) gene expression bidirectionally depending on the induction. We sought to determine whether cytokines related to the regulation of extracellular matrix could activate p38 MAPK in dermal fibroblasts. We determined p38 MAPK phosphorylation/activation in dermal fibroblasts stimulated with platelet-derived growth factor-BB (PDGF-BB), transforming growth factor-beta or interleukin-4. Induction of MMP-1 mRNA by PDGF-BB was enhanced in the presence of a specific inhibitor of p38 MAPK, suggesting that p38 MAPK would function as a negative regulator of the MMP-1 mRNA level. We then determined which isoforms of p38 MAPK expressed in dermal fibroblasts were responsible for the downregulation of the MMP-1 mRNA level. Overexpression of p38beta2, but not of p38alpha, significantly decreased PDGF-BB-induced MMP-1 promoter activity, although PDGF-BB activated signaling pathways to both p38alpha and p38beta2. Taken together, the results of this study indicate that p38beta2 can function as a negative regulator of MMP-1 induced by PDGF-BB in vitro, suggesting that activation of p38beta2 might contribute to the pathogenesis of cutaneous fibrosis.

Animals↗
PubMed2002

Identification of neurite outgrowth promoting sites on the laminin alpha 3 chain G domain.

Laminins are expressed in specific tissues and are involved in various biological activities including promoting cell adhesion, growth, migration, neurite outgrowth, and differentiation. The laminin alpha3 chain is mainly located in the skin and is also expressed in the floor plate of the developing neural tube. Previously, we showed that the human laminin alpha3 chain LG4 module binds to syndecan-2/4, a membrane-associated proteoglycan, and promotes human fibroblast adhesion. Here, we have evaluated the neurite outgrowth activity of the laminin alpha3 chain LG4 and LG5 modules. Three overlapping recombinant proteins, which contained LG4 and/or LG5 modules of the human laminin alpha3 chain, were prepared using a mammalian cell expression system. Two proteins, rec-alpha3LG4-5 and rec-alpha3LG4, promoted cell attachment and neurite outgrowth of rat pheochromocytoma PC12 cells, but rec-alpha3LG5 was inactive. Twenty-two peptides covering the entire LG4 module were synthesized and tested for cell attachment and neurite outgrowth activity to identify active sites of the LG4 module. A3G75 (KNSFMALYLSKG, alpha3 chain 1411-1422) and A3G83 (GNSTISIRAPVY, alpha3 chain 1476-1487) promoted PC12 cell attachment and neurite outgrowth. Additionally, A3G75 and A3G83 inhibited PC12 cell attachment to rec-alpha3LG4. These results suggest that the A3G75 and A3G83 sites are important for PC12 cell attachment and neurite outgrowth in the laminin alpha3 chain LG4 module. We also conjugated the A3G75 and A3G83 peptides on chitosan membranes to test their potential as bio-materials. These peptide-conjugated chitosan membranes were more active for neurite outgrowth than the peptide-coated plates. These results suggest that the A3G75- and A3G83-conjugated chitosan membranes are applicable as bio-medical materials for neural tissue repair and engineering.

Amino Acid Sequence↗
PubMed2002

Essential role of p38 mitogen-activated protein kinase in contact hypersensitivity.

The present study was designed to elucidate the role of p38 mitogen-activated protein kinase (p38) in the pathogenesis of inflammation, using a mouse contact hypersensitivity (CHS) model induced by 2,4-dinitro-1-fluorobenzene (DNFB). Ear swelling was induced by challenge with DNFB, accompanied by infiltration of mononuclear cells, neutrophils, and eosinophils and a marked increase in mRNA levels of cytokines such as interleukin (IL)-2, interferon (IFN)-gamma, IL-4, IL-5, IL-1beta, IL-18, and tumor necrosis factor-alpha in the challenged ear skin. Both ear swelling and the number of infiltrated cells in DNFB-challenged ear skin were significantly inhibited by treatment with SB202190, a p38 inhibitor. Furthermore, the DNFB-induced expression of all cytokines except IL-4 was significantly inhibited by treatment with SB202190. Ribonuclease protection assay revealed that the mRNA levels of chemokines such as IP-10 and MCP-1 in ear skin were markedly increased at 24 h after challenge with DNFB. The induction of these chemokines was significantly inhibited by treatment with SB202190. In p38alpha +/- mice, both ear swelling and infiltration of cells induced by DNFB were reduced compared with those in wild-type mice. However, induction of cytokines by DNFB was also observed in p38alpha +/- mice, although the induction of IFN-gamma, IL-5, and IL-18 was typically reduced compared with that in wild-type mice. Challenge with DNFB slightly induced IP-10 and MCP-1 mRNA in p38alpha +/- mice, with weaker signals than those in SB202190-treated wild-type mice. These results suggest that p38 plays a key role in CHS and is an important target for the treatment of CHS.

Allergens↗
PubMed2002

Identification of biologically active sequences in the laminin alpha 4 chain G domain.

Laminins are a family of trimeric extracellular matrix proteins consisting of alpha, beta, and gamma chains. So far five different laminin alpha chains have been identified. The laminin alpha 4 chain, which is present in laminin-8/9, is expressed in cells of mesenchymal origin, such as endothelial cells and adipocytes. Previously, we identified heparin-binding sites in the C-terminal globular domain (G domain) of the laminin alpha 4 chain. Here we have focused on the biological functions of the laminin alpha 4 chain G domain and screened active sites using a recombinant protein and synthetic peptides. The rec-alpha 4G protein, comprising the entire G domain, promoted cell attachment activity. The cell attachment activity of rec-alpha 4G was completely blocked by heparin and partially inhibited by EDTA. We synthesized 116 overlapping peptides covering the entire G domain and tested their cell attachment activity. Twenty peptides showed cell attachment activity, and 16 bound to heparin. We further tested the effect of the 20 active peptides in competition assays for cell attachment and heparin binding to rec-alpha 4G protein. A4G6 (LAIKNDNLVYVY), A4G20 (DVISLYNFKHIY), A4G82 (TLFLAHGRLVFM), and A4G83 (LVFMFNVGHKKL), which promoted cell attachment and heparin binding, significantly inhibited both cell attachment and heparin binding to rec-alpha 4G. These results suggest that the four active sites are involved in the biological functions of the laminin alpha 4 chain G domain. Furthermore, rec-alpha 4G, A4G6, and A4G20 were found to interact with syndecan-4. These active peptides may be useful for defining of the molecular mechanism laminin-receptor interactions and laminin-mediated cellular signaling pathways.

Amino Acid Sequence↗
PubMed2002

Targeted disruption of dermatopontin causes abnormal collagen fibrillogenesis.

Gene targeting of a member of small leucine-rich repeat proteoglycans demonstrates that collagen fibrillogenesis is mediated by a set of extracellular matrix components, which interact with collagen. Collagen-associated protein dermatopontin knockout mice were generated in order to analyze the biologic involvement of dermatopontin in the formation of collagen fibrils. Although dermatopontin-null mice did not exhibit any obvious anatomical abnormality, skin elasticity was increased. Skin tensile tests revealed that the initial elastic modulus was 57% lower in dermatopontin-null mice than in wild-type mice, and that maximum tensile strength was similar. Remarkably, light microscopy study showed a significant decrease in the relative thickness of the dermis in dermatopontin-null mice compared with wild-type mice (45.2 +/- 3.09% and 57.8 +/- 4.25%, respectively). The skin collagen content was 40% lower in dermatopontin-null than in wild-type mice. Collagen fibrils in dermatopontin-null mice showed a great variety in diameter and irregular contours under the electron microscope. These data indicate that dermatopontin plays a critical role in elasticity of skin and collagen accumulation attributed to collagen fibrillogenesis in vivo.

Animals↗