Search tips
Search criteria

Results 1-5 (5)

Clipboard (0)

Select a Filter Below

more »
Year of Publication
Document Types
1.  Regulation of A Disintegrin And Metalloprotease-33 Expression by Transforming Growth Factor-β 
The asthma susceptibility gene, a disintegrin and metalloprotease-33 (ADAM33), is selectively expressed in mesenchymal cells, and the activity of soluble ADAM33 has been linked to angiogenesis and airway remodeling. Transforming growth factor (TGF)-β is a profibrogenic growth factor, the expression of which is increased in asthma, and recent studies show that it enhances shedding of soluble ADAM33. In this study, we hypothesized that TGF-β also affects ADAM33 expression in bronchial fibroblasts in asthma. Primary fibroblasts were grown from bronchial biopsies from donors with and those without asthma, and treated with TGF-β2 to induce myofibroblast differentiation. ADAM33 expression was assessed using quantitative RT-PCR and Western blotting. To examine the mechanisms whereby TGF-β2 affected ADAM33 expression, quantitative methylation-sensitive PCR, chromatin immunoprecipitation, and nuclear accessibility assays were conducted on the ADAM33 promoter. We found that TGF-β2 caused a time- and concentration-dependent reduction in ADAM33 mRNA expression in normal and asthmatic fibroblasts, affecting levels of splice variants similarly. TGF-β2 also induced ADAM33 protein turnover and appearance of a cell-associated C-terminal fragment. TGF-β2 down-regulated ADAM33 mRNA expression by causing chromatin condensation around the ADAM33 promoter with deacetylation of histone H3, demethylation of H3 on lysine-4, and hypermethylation of H3 on lysine-9. However, the methylation status of the ADAM33 promoter did not change. Together, these data suggest that TGF-β2 suppresses expression of ADAM33 mRNA in normal or asthmatic fibroblasts. This occurs by altering chromatin structure, rather than by gene silencing through DNA methylation as in epithelial cells. This may provide a mechanism for fine regulation of levels of ADAM33 expression in fibroblasts, and may self-limit TGF-β2–induced ectodomain shedding of ADAM33.
PMCID: PMC3359905  PMID: 22227561
a disintegrin and metalloprotease-33; myofibroblast; transforming growth factor-β; histone modification
2.  Echoviruses Bind Heparan Sulfate at the Cell Surface 
Journal of Virology  2001;75(10):4918-4921.
Some echoviruses (EV) that bind decay-accelerating factor (DAF) also bind cells of human and murine origins in a DAF-independent manner. Pretreatment of cells with heparinase 1 or heparin blocks the binding of radiolabeled virus to the cell surface, and heparin prevents infection of rhabdomyosarcoma cells by certain EV, including several low-passage clinical isolates of EV 6 and some EV that do not bind DAF. These studies suggest that heparan sulfate may be of in vivo relevance as an attachment molecule for EV.
PMCID: PMC114248  PMID: 11312365
3.  Fatty Acid-Depleted Albumin Induces the Formation of Echovirus A Particles 
Journal of Virology  2000;74(7):3410-3412.
Picornavirus infection requires virus uncoating, associated with the production of 135S “A” particles and 80S empty particles from 160S mature virions, to release the RNA genome into the cell cytoplasm. Normal albumin inhibits this process. We now show that when depleted of fatty acids, albumin induces the formation of echovirus A particles.
PMCID: PMC111843  PMID: 10708459
4.  Role for β2-Microglobulin in Echovirus Infection of Rhabdomyosarcoma Cells 
Journal of Virology  1998;72(7):5360-5365.
A monoclonal antibody (MAb) that blocks most echoviruses (EVs) from infecting rhabdomyosarcoma (RD) cells has been isolated. By using the CELICS cloning method (T. Ward, P. A. Pipkin, N. A. Clarkson, D. M. Stone, P. D. Minor, and J. W. Almond, EMBO J. 13:5070–5074, 1994), the ligand for this antibody has been identified as β2-microglobulin (β2m), the 12-kDa protein that associates with class I heavy chains to form class I HLA complexes. A commercial MAb (MAb 1350) against β2m was also found to block EV7 infection without affecting binding to its receptor, DAF, or replication of EV7 viral RNA inside cells. Entry of EV7 into cells was reduced by only 30% by antibody and cytochalasin D, an inhibitor of endocytosis mediated by caveolae and clathrin-coated pits, but was not significantly reduced by sodium azide. The block to virus entry by cytochalasin D was additive to the block induced by antibody. We suggest that EV7 rapidly enters into a multicomponent receptor complex prior to entry into cells and that this initial entry event requires β2m or class I HLA for infection to proceed.
PMCID: PMC110159  PMID: 9620989

Results 1-5 (5)