Over-expression of LRIG1 suppresses biological function of pituitary adenoma via attenuation of PI3K/AKT and Ras/Raf/ERK pathways in vivo and in vitro / 华中科技大学学报（医学）（英德文版）

Pituitary adenomas (PAs) are well known as a common intracranial benign tumor, and a portion of PAs are refractory to current therapeutic methods. ErbB receptors family signaling pathway regulates the expression of PAs activation associated gene. Inhibition of epidermal growth factor receptor (EGFR) can inhibit proliferation of PAs. Leucine-rich repeats and immunoglobulin-like domains protein 1 ( LRIG1), a negative mediated gene of ErbB receptors family, plays a role in many tumors. However, there are seldom researches about the functional role of LRIG1 in PAs. The aim of this study is to explore the potential effect of LRIG1 and its regulating mechanism in PAs. First, we investigated the role of LRIG1 in cell migration, invasion of PAs with transfected LRIG1 or control. Then, we explored its impact on cell proliferation and apoptosis of PAs in vivo. To study the regulating mechanism of LRIG1, we examined the expression of molecular factor of PI3K/AKT and Ras/Raf/ERK pathway using Western blotting in vitro and RT-PCR in vitro and in vivo. It was found that LRIG1 over-expression inhibited cell migration, invasion and proliferation, and promoted apoptosis of PAs in vivo and in vitro. Furthermore, LRIG1 suppressed the expression of signaling of PI3K/AKT and Ras/Raf/ERK pathways in PAs. LRIG1, as a negative mediated gene of tumor, can inhibit biological function of PAs via inhibiting PI3K/AKT and Ras/Raf/ERK pathways, and it might be a new target for gene therapy of PAs.

In vitro studies of Raf-CREB, Akt-CREB, and CaMK II -CREB signal transduction pathway regulated by ginsenosides Rb1, Rg1 and Re / 中国中药杂志

<p><b>OBJECTIVE</b>Effects of ginsenoside Rb1, Rg1 and Re on neurotrophic factor signal transduction pathway using liposome-mediated transfection of eukaryotic cells approach.</p><p><b>METHOD</b>The injury model was established by treating SH-SY5Y cells with 0.6 mmol x L(-1) of corticosterone (CORT) by 24 h. SH-SY5Y cell were pretreated with CORT for 30 min followed by co-treated with 120,60 and 20 micromol x L(-1) of Rb1, 120, 80 and 40 micromol x L(-1) of Rg1 and 120, 80 and 40 micromol x L(-1) of Re for 24 h. Cells viability was determined by Cell Counting Kit (CCK) assay. CREB expressing Luciferase reporter gene was constructed and transfected with plasmid containing hRaf, hcAMP, hAkt, hCaMK gene into human embryonic kidney (HEK293) cells using liposornal transfection reagent lipofection 2000. The expression of CREB before and after it addion of Rb1, Rg1 and Re was examined by Luc assay system and Western blotting.</p><p><b>RESULT</b>Compared with normal control group, CORT significantly decreased the viability of SH-SY5Y cells to 67.21% (P < 0.01). CCK results show that Rb1 (60 micromol x L(-1)), Rg1 (80 micromol x L(-1)) and Re (80 micromol x L(-1)) on SH-SY5Y cells have significant protective effect (P < 0.01). Lucassay and Western blotting results show that the gene and protein levels of CREB increased significantly through the pathway of Raf and Akt with Rb1 and Rg1 (P < 0.01), Re can increase significantly the gene and protein levels of CREB through the pathway of Raf and CaMK II.</p><p><b>CONCLUSION</b>Rb1, Rg1 and Re protects SH-SY5Y cells from CORT-induced damage and the neuroprotective mechanism may be associated with the Raf-CREB, Akt-CREB and CaMK II -CREB pathways.</p>

Up-regulation of Ras/Raf/ERK1/2 signaling in the spinal cord impairs neural cell migration, neurogenesis, synapse formation, and dendritic spine development / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>The Ras/Raf/ERK1/2 signaling pathway controls many cellular responses such as cell proliferation, migration, differentiation, and death. In the nervous system, emerging evidence also points to a death-promoting role for ERK1/2 in both in vitro and in vivo models of neuronal death. To further investigate how Ras/Raf/ERK1/2 up-regulation may lead to the development of spinal cord injury, we developed a cellular model of Raf/ERK up-regulation by overexpressing c-Raf in cultured spinal cord neurons (SCNs) and dorsal root ganglions (DRGs).</p><p><b>METHODS</b>DRGs and SCNs were prepared from C57BL/6J mouse pups. DRGs or SCNs were infected with Ad-Raf-1 or Ad-Null adenovirus alone. Cell adhesion assay and cell migration assay were investigated, DiI labeling was employed to examine the effect of the up-regulation of Ras/Raf/ERK1/2 signaling on the dendritic formation of spinal neurons. We used the TO-PRO-3 staining to examine the apoptotic effect of c-Raf on DRGs or SCNs. The effect on the synapse formation of neurons was measured by using immunofluorescence.</p><p><b>RESULTS</b>We found that Raf/ERK up-regulation stimulates the migration of both SCNs and DRGs, and impairs the formation of excitatory synapses in SCNs. In addition, we found that Raf/ERK up-regulation inhibits the development of mature dendritic spines in SCNs. Investigating the possible mechanisms through which Raf/ERK up-regulation affects the excitatory synapse formation and dendritic spine development, we discovered that Raf/ERK up-regulation suppresses the development and maturation of SCNs.</p><p><b>CONCLUSION</b>The up-regulation of the Raf/ERK signaling pathway may contribute to the pathogenesis of spinal cord injury through both its impairment of the SCN development and causing neural circuit imbalances.</p>

GRP75 overexpression inhibits apoptosis induced by glucose deprivation via Raf/Mek/Erk1/2 signaling pathway / 生理学报

The purpose of the present study is to investigate whether glucose-regulated protein 75 (GRP75) overexpression inhibits apoptosis induced by glucose deprivation through Raf/Mek/Erk1/2 signaling pathway. After pretreatment with Mek-specific inhibitor U0126, GRP75 overexpressing PC12 cells were incubated in glucose-free DMEM medium for indicated time (6, 12 and 24 h). And DMSO-treated GRP75 overexpressing PC12 cells were applied as control. Western blot was used to determine the expression and phosphorylation level of Erk1/2. MTT assay was used to measure cell viability. Hoechst 33258 staining and flow cytometry using propidium iodide (PI) staining was used to analysis apoptosis. Immunofluorescence with antibody against cytochrome c (Cyt c) was used to detect Cyt c release from mitochondrion. The results showed U0126 prevented the activation of Erk1/2 maintained by GRP75, but the total Erk1/2 expression was not affected. U0126-treated group showed lower cell viability and higher apoptotic rate compared with control group. Immunofluorescence indicated the delay in release of Cyt c was blocked by U0126. These results suggest U0126 prevents protective effect of GRP75 on PC12 cells by inhibiting Erk1/2 phosphorylation, which certifies that GRP75 can inhibit the mitochondria-dependent apoptotic pathway through Raf/Mek/Erk1/2 signaling cascade.

Raf/MEK/ERK1/2 signaling pathway and penile erection / 中华男科学杂志

Penile erection is regulated by the relaxation of corpus cavernosum smooth muscle cells (CCSMCs). It has been recognized that the Ras/MEK/ERK1/2 signaling pathway is closely related to the functions of CCSMCs and endothelial cells, and it is involved in the regulation of penile erection, mainly via phosphorylation of NO synthase. ERK1/2 phosphorylates, inhibits eNOS activity, and thus reduces the relaxation of CCSMCs and penile erection. But the site of phosphorylation is not yet clear. In CCSMCs and endothelial cells, the ERK1/2 pathway interacts with other cascades and regulates the erectile function of the penis. This article presents an overview of the researches on the ERK1/2 signaling cascade, its regulatory role and its interaction with other signaling pathways in penile erection.