Cytokine-induced autophagy promotes long-term VCAM-1 but not ICAM-1 expression by degrading late-phase IκBα.

Pro-inflammatory cytokines are known to induce endothelial cell autophagy, but the role of autophagy in regulating the expression of pro-inflammatory molecules has not been characterized. We hypothesized that autophagy facilitates expression of endothelial adhesion molecules. TNFα and IL-1β induced autophagy markers in human umbilical vein endothelial cells and inhibition of autophagy by 3-methyladenine (3-MA) blocked adhesion of Jurkat lymphocytes.

Inhibition of cancer cell epithelial mesenchymal transition by normal fibroblasts via production of 5-methoxytryptophan.

We reported previously that human fibroblasts release 5-methoxytryptophan (5-MTP) which inhibits cancer cell COX-2 overexpression and suppresses cancer cell migration and metastasis. To determine whether fibroblasts block cancer cell epithelial mesenchymal transition (EMT) via 5-MTP, we evaluated the effect of Hs68 fibroblasts (HsFb) on A549 cancer cell EMT in a two-chamber system. Co-incubation of A549 with HsFb prevented TGF-β1-induced reduction of E-cadherin and increase in Snail and N-cadherin.

Endothelium-Derived 5-Methoxytryptophan Protects Endothelial Barrier Function by Blocking p38 MAPK Activation.

The endothelial junction is tightly controlled to restrict the passage of blood cells and solutes. Disruption of endothelial barrier function by bacterial endotoxins, cytokines or growth factors results in inflammation and vascular damage leading to vascular diseases. We have identified 5-methoxytryptophan (5-MTP) as an anti-inflammatory factor by metabolomic analysis of conditioned medium of human fibroblasts.

Prostacyclin protects vascular integrity via PPAR/14-3-3 pathway.

Vascular integrity is protected by the lining endothelial cells (ECs) through structural and molecular protective mechanisms. In response to external stresses, ECs are dynamic in producing protective molecules such as prostacyclin (PGI2). PGI2 is known to inhibit platelet aggregation and controls smooth muscle cell contraction via IP receptors.

Quiescent and proliferative fibroblasts exhibit differential p300 HAT activation through control of 5-methoxytryptophan production.

Quiescent fibroblasts possess unique genetic program and exhibit high metabolic activity distinct from proliferative fibroblasts. In response to inflammatory stimulation, quiescent fibroblasts are more active in expressing cyclooxygenase-2 and other proinflammatory genes than proliferative fibroblasts. The underlying transcriptional mechanism is unclear.

Thrombospondin-1 modulates VEGF signaling via CD36 by recruiting SHP-1 to VEGFR2 complex in microvascular endothelial cells.

Thrombospondin-1 (TSP-1) inhibits growth factor signaling at the receptor level in microvascular endothelial cells (MVEC), and CD36 has been suggested to be involved in this inhibition, but the mechanisms are not known. We hypothesized that CD36-TSP-1 interaction recruits Src homology 2 domain-containing protein tyrosine phosphatase (SHP)-1 to the vascular endothelial growth factor receptor 2 (VEGFR2) signaling complex and attenuates vascular endothelial growth factor (VEGF) signaling. Western blots of anti-CD36 and anti-VEGFR2 immunoprecipitates from VEGF-treated MVEC showed that exposure of the cells to a recombinant protein containing the CD36 binding domain of thrombospondin-1 (known as the TSR domain) induced association of SHP-1 with the VEGFR2/CD36 signaling complex and thereby suppressed VEGFR2 phosphorylation.

Prostacyclin and PPARα agonists control vascular smooth muscle cell apoptosis and phenotypic switch through distinct 14-3-3 isoforms.

We hypothesized that prostacyclin (PGI2) protects vascular smooth muscle cell (VSMC) against apoptosis and phenotypic switch through peroxisome proliferator-activated receptor-α (PPARα) activation and 14-3-3 upregulation. Here we showed that transfection of rat aortic VSMC, A-10, with PGI2-producing vectors, Ad-COPI, resulted in attenuated H2O2-induced apoptosis accompanied by a selective increase in 14-3-3β and 14-3-3θ expression. Carbaprostacyclin (cPGI2) and Wy14,643 exerted a similar effect.

CD36 ectodomain phosphorylation blocks thrombospondin-1 binding: structure-function relationships and regulation by protein kinase C.

Objective: CD36 phosphorylation on its extracellular domain inhibits binding of thrombospondin-1. The mechanisms of cellular CD36 ectodomain phosphorylation and whether it can be regulated in cells are not known. We determined structure-function relationships of CD36 phosphorylation related to thrombospondin-1 peptide binding in vitro and explored mechanisms regulating phosphorylation by protein kinase C (PKC) in melanoma cells.

Dimerize RACK1 upon transformation with oncogenic ras.

From our previous studies, we learned that syndecan-2/p120-GAP complex provided docking site for Src to prosecute tyrosine kinase activity upon transformation with oncogenic ras. And, RACK1 protein was reactive with syndecan-2 to keep Src inactivated, but not when Ras was overexpressed. In the present study, we characterized the reaction between RACK1 protein and Ras.