Hoffmann, R. A wiki for the life sciences where authorship matters. Nature Genetics (2008)

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Hunter, I. et al.

Hunter, Nixon,

Spatial Compartmentalization of Tumor Necrosis Factor (TNF) Receptor 1-dependent Signaling Pathways in Human Airway Smooth Muscle Cells: LIPID RAFTS ARE ESSENTIAL FOR TNF-{alpha}-MEDIATED ACTIVATION OF RhoA BUT DISPENSABLE FOR THE ACTIVATION OF THE NF-{kappa}B AND MAPK PATHWAYS.

Tumor necrosis factor (TNF)-alpha-induced activation of RhoA, mediated by TNF receptor 1 (TNFR1), is a prerequisite step in a pathway that leads to increased 20-kDa light chain of myosin (MLC(20)) phosphorylation and airway smooth muscle contraction. In this study, we have investigated the proximal events in TNF-alpha- induced RhoA activation. TNFR1 is localized to both lipid raft and nonraft regions of the plasma membrane in primary human airway smooth muscle cells. TNF-alpha engagement of TNFR1 recruited the adaptor proteins TRADD, TRAF-2, and RIP into lipid rafts and activated RhoA, NF-kappaB, and MAPK pathways. Depletion of cholesterol from rafts with methyl-beta-cyclodextrin caused a redistribution of TNFR1 to nonraft plasma membrane and prevented ligand- induced RhoA activation. By contrast, TNF-alpha-induced activation of NF-kappaB and MAPKs was unaffected by methyl-beta-cyclodextrin indicating that, in airway smooth muscle cells, activation of these pathways occurred independently of lipid rafts. Targeted knockdown of caveolin-1 completely abrogated TNF-alpha- induced RhoA activation, identifying this raft-resident protein as a positive regulator of the activation process. The signaling adaptors TRADD and RIP were also found to be necessary for ligand- induced RhoA activation. Taken together, our results suggest that in airway smooth muscle cells, spatial compartmentalization of TNFR1 provides a mechanism for generating distinct signaling outcomes in response to ligand engagement and define a mechanistic role for lipid rafts and caveolin-1 in TNF-alpha- induced activation of RhoA.[1]

References

Spatial Compartmentalization of Tumor Necrosis Factor (TNF) Receptor 1-dependent Signaling Pathways in Human Airway Smooth Muscle Cells: LIPID RAFTS ARE ESSENTIAL FOR TNF-{alpha}-MEDIATED ACTIVATION OF RhoA BUT DISPENSABLE FOR THE ACTIVATION OF THE NF-{kappa}B AND MAPK PATHWAYS. Hunter, I., Nixon, G.F. J. Biol. Chem. (2006) [Pubmed]

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