Src kinase is a crucial mediator of adhesion-related signaling and motility. Src binds to focal adhesion kinase (FAK) through its SH2 domain and subsequently activates it for phosphorylation of downstream substrates. In addition to this binding function, data suggested that the SH2 domain might also perform an important role in targeting Src to focal adhesions (FAs) to enable further substrate phosphorylations. To examine this, we engineered an R175L mutation in cSrc to prevent the interaction with FAK pY397. This constitutively open Src kinase mediated up-regulated substrate phosphorylation in SYF cells but was unable to promote malignant transformation. Significantly, SrcR175L cells also had a profound motility defect and an impaired FA generation capacity. Importantly, we were able to recapitulate wild-type motile behavior and FA formation by directing the kinase to FAs, clearly implicating the SH2 domain in recruitment to FAK and indicating that this targeting capacity, and not simply Src-FAK scaffolding, was critical for normal Src function.

The appropriate regulation of the actin cytoskeleton is essential for cell movement, changes in cell shape, and formation of membrane protrusions like lamellipodia and filopodia. Moreover, several regulatory proteins affecting actin dynamics have been identified in the motile regions of cells. Here, we provide evidence for the involvement of SPIN90 in the regulation of actin cytoskeleton and actin comet tail formation. SPIN90 was distributed throughout the cytoplasm in COS-7 cells, but exposing the cells to platelet-derived growth factor (PDGF) caused a redistribution of SPIN90 to the cell cortex and the formation of lamellipodia (or membrane ruffles), both of which were dramatically inhibited in SPIN90-knockdown cells. In addition, the binding of the C terminus of SPIN90 with both the Arp2/3 complex (actin-related proteins Arp 2 and Arp 3) and G-actin activates the former, leading to actin polymerization in vitro. And when coexpressed with phosphatidylinositol 4-phosphate 5 kinase, SPIN90 was observed within actin comet tails. Taken these findings suggest that SPIN90 participates in reorganization of the actin cytoskeleton and in actin-based cell motility.

Rhus toxicodendron (Rhus tox) is a homeopathic remedy with anti-inflammatory activities used for arthritis pain. We studied the effects of 4×, 30×, 30c and 200c homeopathic dilutions of Rhus tox in primary cultured mouse chondrocytes. We examined the expression of collagen type II, a marker protein of chondrocytes, and cyclooxygenase-2 (COX-2), which is responsible for the biosynthesis of prostaglandin E2 (PGE2) and the regulation of the inflammatory response. We assessed the expression of collagen type II and COX-2 using biochemical and immunological methods, such as reverse transcription polymerase chain reaction (RT-PCR), quantitative (or real-time) RT-PCR (qRT-PCR) and immunoblot assays. Stimulation with different concentrations of Rhus tox increased the mRNA expression of COX-2, and stimulation with 30× Rhus tox showed the most prominent mRNA expression in both RT-PCR and qRT-PCR analyses. We also observed that homeopathic dilutions of 4×, 30× and 30c Rhus tox inhibited collagen type II expression, suggesting that Rhus tox induced the dedifferentiation of chondrocytes. In addition, treatment with 30× Rhus tox significantly increased PGE2 release compared with other homeopathic dilutions of Rhus tox. Taken together, these results suggest that homeopathic treatment with Rhus tox induced chondrocyte dedifferentiation and inflammatory responses, such as COX-2 expression and PGE2 production, in primary cultured chondrocytes.

Homeopathic remedy Rhus toxicodendron (Rhus tox) is used for several symptoms including skin irritations, rheumatic pains, mucous membrane afflictions, and typhoid type fever. Previously, we reported that Rhus tox treatment increased the cyclooxygenase-2 (COX-2) mRNA expression in primary cultured mouse chondrocytes. A preosteoblastic mouse cell line, MC3T3-e1, was treated with different homeopathic dilutions of Rhus tox and the COX-2 mRNA and protein expression was examined using reverse transcriptase-polymerase chain reaction (RT-PCR) and immunoblotting. Additionally, nitric oxide (NO) generation was examined in LPS-induced MC3T3-e1 cells using a Griess reaction assay. Stimulation with different concentrations of Rhus tox increased the expression of Cox2 mRNA, with 30X Rhus tox showing the most prominent increase in mRNA expression. In addition, treatment with 30X Rhus tox significantly increased prostaglandin E2 (PGE2) release compared with other homeopathic dilutions. However, the COX-2 protein expression level differed slightly from its mRNA expression, because the 30C Rhus tox treatment increased COX-2 protein to a greater extent compared with other dilutions. NO generation was dramatically decreased in MC3T3-e1 cells after Rhus tox treatment co-stimulated with lipopolysaccharide. Homeopathic dilution of Rhus tox has a dual activity that increases COX-2 expression and decreases NO generation, thus modulating inflammation. Further study is needed to examine the cellular signaling mechanisms that are associated with inflammatory regulation by Rhus tox treatment in greater detail.

Tussilagone, extracted from Tussilago farfara is an oriental medicine used for asthma and bronchitis. We investigated its mechanism of action, its inhibitory effects on lipopolysaccharide-induced inflammation in macrophages, and its impact on viability in a cecal ligation and puncture (CLP)-induced mouse model of sepsis. Tussilagone suppressed the expression of the inflammatory mediators, nitric oxide and prostaglandin E2, and the inflammatory cytokines, tumor necrosis factor-alpha (TNF-α) and high-mobility group box 1 (HMGB1), in lipopolysaccharide-stimulated RAW 264.7 cells and peritoneal macrophages. Tussilagone also reduced the activation of the mitogen-activated protein kinases and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) involved in the activation of various inflammatory mediators in activated macrophages. Moreover, tussilagone administration (1 mg/kg and 10 mg/kg) produced decreased mortality and lung injury in CLP-activated septic mice. Augmented expression of cyclooxygenase (COX)-2 and TNF-α in pulmonary alveolar macrophages of septic mice were attenuated by tussilagone administration. Tussilagone also suppressed the induction of nitric oxide, prostaglandin E2, TNF-α and HMGB1 in the serum of the septic mice. Overall, tussilagone exhibited protective effects against inflammation and polymicrobial sepsis by suppressing inflammatory mediators possibly via the inhibition of NF-κB activation and the MAP kinase pathway. These results suggest the possible use of tussilagone for developing novel therapeutic modalities for sepsis and other inflammatory diseases.