Functional regulation of adipose-derived stem cells by PDGF-D.

Platelet-derived growth factor-D (PDGF-D) was recently identified, and acts as potent mitogen for mesenchymal cells. PDGF-D also induces cellular transformation and promotes tumor growth. However, the functional role of PDGF-D in adipose-derived stem cells (ASCs) has not been identified. Therefore, we primarily investigated the autocrine and paracrine roles of PDGF-D in this study. Furthermore, we identified the signaling pathways and the molecular mechanisms involved in PDGF-D-induced stimulation of ASCs. It is of interest that PDGF-B is not expressed, but PDGF-D and PDGF receptor-ß are expressed in ASCs. PDGF-D showed the strongest mitogenic effect on ASCs, and PDGF-D regulates the proliferation and migration of ASCs through the PI3K/Akt pathways. PDGF-D also increases the proliferation and migration of ASCs through generation of mitochondrial reactive oxygen species (mtROS) and mitochondrial fission. mtROS generation and fission were mediated by p66Shc phosphorylation, and BCL2-related protein A1 and Serpine peptidase inhibitor, clade E, member 1 mediated the proliferation and migration of ASCs. In addition, PDGF-D upregulated the mRNA expression of diverse growth factors such as vascular endothelial growth factor A, fibroblast growth factor 1 (FGF1), FGF5, leukemia inhibitory factor, inhibin, beta A, interleukin 11, and heparin-binding EGF-like growth factor. Therefore, the preconditioning of PDGF-D enhanced the hair-regenerative potential of ASCs. PDGF-D-induced growth factor expression was attenuated by a pharmacological inhibitor of mitogen-activated protein kinase pathway. In summary, PDGF-D is highly expressed by ASCs, where it acts as a potent mitogenic factor. PDGF-D also upregulates growth factor expression in ASCs. Therefore, PDGF-D can be considered a novel ASC stimulator, and used as a preconditioning agent before ASC transplantation.

An inducible sphingosine kinase 1 in hepatic stellate cells potentiates liver fibrosis.

Hepatic stellate cells (HSCs) play a role in hepatic fibrosis and sphingosine kinase (SphK) is involved in biological processes. As studies on the regulatory mechanisms and functions of SphK in HSCs during liver fibrosis are currently limited, this study aimed to elucidate the regulatory mechanism and connected pathways of SphK upon HSC activation. The expression of SphK1 was higher in HSCs than in hepatocytes, and upregulated in activated primary HSCs. SphK1 was also increased in liver homogenates of carbon tetrachloride-treated or bile duct ligated mice and in transforming growth factor-ß (TGF-ß)-treated LX-2 cells. TGF-ß-mediated SphK1 induction was due to Smad3 signaling in LX-2 cells. SphK1 modulation altered the expression of liver fibrogenesis-related genes. This SphK1-mediated profibrogenic effect was dependent on SphK1/sphingosine-1-phosphate/sphingosine-1-phosphate receptor signaling through ERK. EGCG blocked TGF-ß-induced SphK1 expression and hepatic fibrogenesis by attenuating Smad and MAPK activation. SphK1 induced by TGF-ß facilitates HSC activation and liver fibrogenesis, which is reversed by EGCG. Accordingly, SphK1 and related signal transduction may be utilized to treat liver fibrosis.

Src/NF-κB-targeted inhibition of LPS-induced macrophage activation and dextran sodium sulphate-induced colitis by Archidendron clypearia methanol extract.

ETHNOPHARMACOLOGICAL RELEVANCE: Archidendron clypearia Jack. (Fabaceae) has been traditionally used to treat various inflammatory diseases such as pain in the eyes. However, the antiinflammatory mechanism of A. clypearia has not been fully elucidated. This study examined the anti-inflammatory mechanism of a 95% methanol extract (Ac-ME) of A. clypearia in vitro and in vivo. MATERIALS AND METHODS: The effect of Ac-ME on the production of inflammatory mediators in RAW264.7 cells and peritoneal macrophages and on symptoms of colitis in mouse induced by dextran sodium sulphate (DSS) was investigated. Molecular mechanisms underlying the inhibitory effects were elucidated by analyzing the activation of transcription factors and their upstream signaling as well as by evaluating the kinase activity of target enzymes in vitro and in vivo. RESULTS: Ac-ME dose-dependently suppressed the secretion of nitric oxide (NO) and prostaglandin (PG)E2 from RAW264.7 cells and peritoneal macrophages stimulated by lipopolysaccharide (LPS). Ac-ME clearly reduced mRNA expression of inducible NO synthase (iNOS), cyclooxygenase (COX)-2, and tumor necrosis factor (TNF)-α by the blockade of nuclear factor (NF)-κB activation and its upstream signaling events containing protein tyrosine kinase such as Syk and Src. In agreement with this, Ac-ME directly reduced the kinase activities of Src and Syk as well as the formation of molecular signaling complex including p85. DSS-induced colitis was also remarkably inhibited by this extract through the suppression of Src and IκBα phosphorylation. CONCLUSION: Ac-ME displays strong anti-inflammatory activity in vivo by suppressing Src/Syk-mediated NF-κB activation which is linked to its ethno-pharmacological uses as an anti-gastritis remedy. Through preclinical studies, the potential therapeutic application will be tested further.