Protein-specific Guanine Nucleotide-releasing Factor Research Articles

Genetic variants of SOS2, MAP2K1 and RASGRF2 in the RAS pathway genes predict survival of HBV-related hepatocellular carcinoma patients.

The RAS pathway participates in the cascade of proliferation and cell division process, and the activated RAS pathway can lead to tumorigenesis including hepatocellular carcinoma (HCC). However, few studies have explored the effects of genetic variants in the RAS pathway-related genes on the survival of patients with HBV-related HCC. In the present study, we assessed the associations between 11,658 single-nucleotide polymorphisms (SNPs) in 62 RAS pathway genes and the overall survival (OS) of 866 HBV-related HCC individuals, which were randomly split (1:1) into discovery and validation datasets. As a result, three potentially functional SNPs were identified, based on multivariable cox proportional hazards regression analyses, in SOS Ras/Rho guanine nucleotide exchange factor 2 (SOS2, rs4632055 A > G), Ras protein-specific guanine nucleotide releasing factor 2 (RASGRF2, rs26418A > G) and mitogen-activated protein kinase 1 (MAP2K1,rs57120695 C > T), which were significantly and independently associated with OS of HBV-related HCC patients [adjusted hazards ratios (HRs) of 1.42, 1.32 and 1.50, respectively; 95% confidence intervals (CI), 1.14 to 1.76, 1.15 to 1.53 and 1.15 to 1.97, respectively; P = 0.001, < 0.001 and 0.003, respectively]. Additionally, the joint effects as the unfavorable genotypes of these three SNPs showed a significant association with the poor survival of HCC (trend test P < 0.001). The expression quantitative trait loci (eQTL) analysis further revealed that the rs4632055 G allele and the rs26418 A allele were associated with lower mRNA expression levels of SOS2 and RASGRF2, respectively. Collectively, these potentially functional SNPs of RASGRF2, SOS2 and M2PAK1 may become potential prognostic biomarkers for HBV-related HCC after hepatectomy.

Deciphering the Heterogeneity of the Internal Environment of Hippocampal Neurons during Maturation by Raman Spectroscopy.

Hippocampal neurons are sensitive to changes in the internal environment and play a significant role in controlling learning, memory, and emotions. A remarkable characteristic of the aging brain is its ability to shift from a state of normal inflammation to excessive inflammation. Various cognitive abilities of the elderly may suffer from serious harm due to the change in the neural environment. Hippocampal neurons may have various subsets involved in controlling their internal environment at different stages of development. Developmental differences may eventually result from complex changes in the dynamic neuronal system brought on by metabolic changes. In this study, we used an in vitro hippocampal neuron model cultured in C57BL/6J mice in conjugation with Raman spectroscopy to examine the relative alterations in potential biomarkers, such as levels of metabolites in the internal environment of hippocampal neurons at various developmental stages. The various differentially expressed genes (DEGs) of hippocampal neurons at various developmental stages were simultaneously screened using bioinformatics, and the biological functions as well as the various regulatory pathways of DEGs were preliminarily analyzed, providing an essential reference for investigating novel therapeutic approaches for diseases that cause cognitive impairment, such as Alzheimer’s disease. A stable hippocampal neuron model was established using the GIBCO C57BL/6J hippocampal neuron cell line as a donor and in vitro hippocampal neuron culture technology. The Raman peak intensities of culture supernatants from the experimental groups incubated for 0, 7, and 14 days in vitro(DIV) were examined. The GEO database was used to screen for different DEGs associated with various developmental stages. The data was then analyzed using a statistical method called orthogonal partial least squares discriminant analysis (OPLS-DA). The levels of ketogenic and glycogenic amino acids (such as tryptophan, phenylalanine, and tyrosine), lipid intake rate, glucose utilization rate, and nucleic acid expression in the internal environment of hippocampal neurons were significantly different in the 14 DIV group compared to the 0 DIV and 7 DIV groups (P < 0.01). The top 10 DEGs with neuronal maturation were screened, and the results were compared to the OPLS-DA model’s analysis of the differential peaks. It was found that different genes involved in maturation can directly relate to changes in the body’s levels of ketogenic and glycogenic amino acids (P < 0.01). The altered expression of the maturation-related genes epidermal growth factor receptor, protein tyrosine kinase 2-beta, discs large MAGUK scaffold protein 2, and Ras protein-specific guanine nucleotide releasing factor 1 may be connected to the altered uptake of ketogenic and glycogenic amino acids and nucleic acids in the internal environment of neurons at different developmental stages. The levels of ketogenic, glycogenic amino acids, and lipid intake increased while glucose utilization decreased, which may be related to mature neurons’ metabolism and energy use. The decline in nucleic acid consumption could be connected to synaptic failure. The Raman spectroscopy fingerprint results of relevant biomarkers in conjugation with multivariable analysis and biological action targets suggested by differential genes interpret the heterogeneity of the internal environment of mature hippocampal neurons in the process of maturation, open a new idea for exploring the dynamic mechanism of the exchange energy metabolism of information molecules in the internal environment of hippocampal neurons, and provide a new method for studying this process.

Deletion of RasGRF1 Attenuated Interstitial Fibrosis in Streptozotocin-Induced Diabetic Cardiomyopathy in Mice through Affecting Inflammation and Oxidative Stress.

Background: Diabetic cardiomyopathy (DCM) is characterized by cardiac fibrosis and stiffness, which often develops into heart failure. This study investigated the role of Ras protein-specific guanine nucleotide releasing factor 1 (RasGRF1) in the development of DCM. Methods: Forty-eight mice were divided into four groups (n = 12 per group): Group 1: Wild-type (WT) mice, Group 2: RasGRF1 deficiency (RasGRF1−/−) mice. Group 3: Streptozotocin (STZ)-induced diabetic WT mice, Group 4: STZ-induced diabetic RasGRF1−/− mice. Myocardial functions were assessed by cardiac echography. Heart tissues from all of the mice were investigated for cardiac fibrosis, inflammation, and oxidative stress markers. Results: Worse impaired diastolic function with elevation serum interleukin (IL)-6 was found in the diabetic group compared with the non-diabetic groups. Serum IL-6 levels were found to be elevated in the diabetic compared with the non-diabetic groups. However, the diabetic RasGRF1−/− mice exhibited lower serum IL-6 levels and better diastolic function than the diabetic WT mice. The diabetic RasGRF1−/− mice were associated with reduced cardiac inflammation, which was shown by lower invading inflammation cells, lower expression of matrix metalloproteinase 9, and less chemokines compared to the diabetic WT mice. Furthermore, less oxidative stress as well as extracellular matrix deposition leading to a reduction in cardiac fibrosis was also found in the diabetic RasGRF1−/− mice compared with the diabetic WT mice. Conclusion: The deletion of RasGRF1 attenuated myocardial fibrosis and improved cardiac function in diabetic mice through inhibiting inflammation and oxidative stress.

Admixture Mapping of Subclinical Atherosclerosis and Subsequent Clinical Events Among African Americans in 2 Large Cohort Studies.

Local ancestry may contribute to the disproportionate burden of subclinical and clinical cardiovascular disease among admixed African Americans compared with other populations, suggesting a rationale for admixture mapping. We estimated local European ancestry (LEA) using Local Ancestry inference in adMixed Populations using Linkage Disequilibrium method (LAMP-LD) and evaluated the association with common carotid artery intima-media thickness (cCIMT) using multivariable linear regression analysis among 1554 African Americans from MESA (Multi-Ethnic Study of Atherosclerosis). We conducted secondary analysis to examine the significant cCIMT-LEA associations with clinical cardiovascular disease events. We observed genome-wide significance in relation to cCIMT association with the SERGEF gene (secretion-regulating guanine nucleotide exchange factor; β=0.0137; P=2.98×10-4), also associated with higher odds of stroke (odds ratio=1.71; P=0.02). Several regions, in particular CADPS gene (Ca2+-dependent secretion activator 1) region identified in MESA, were also replicated in the ARIC cohort (Atherosclerosis Risk in Communities). We observed other cCIMT-LEA regions associated with other clinical events, most notably the regions harboring CKMT2 gene (creatine kinase, mitochondrial 2) and RASGRF2 gene (Ras protein-specific guanine nucleotide-releasing factor 2) with all clinical events except stroke, the LRRC3B gene (leucine-rich repeat containing 3B) with myocardial infarction, the PRMT3 gene (protein arginine methyltransferase 3) with stroke, and the LHFPL2 gene (lipoma high mobility group protein I-C fusion partner-like 2) with hard and all coronary heart disease. We identified several novel LEA regions, in addition to previously identified genetic variations, associated with cCIMT and cardiovascular disease events among African Americans.

The potential of neuroimaging for identifying predictors of adolescent alcohol use initiation and misuse.

Dysfunction in brain regions underlying impulse control, reward processing and executive function have been associated previously with adolescent alcohol misuse. However, identifying pre-existing neurobiological risk factors, as distinct from changes arising from early alcohol-use, is difficult. Here, we outline how neuroimaging data can identify the neural predictors of adolescent alcohol-use initiation and misuse by using prospective longitudinal studies to follow initially alcohol-naive individuals over time and by neuroimaging adolescents with inherited risk factors for alcohol misuse. A comprehensive narrative of the literature regarding neuroimaging studies published between 2010 and 2016 focusing on predictors of adolescent alcohol use initiation and misuse. Prospective, longitudinal neuroimaging studies have identified pre-existing differences between adolescents who remained alcohol-naive and those who transitioned subsequently to alcohol use. Both functional and structural grey matter differences were observed in temporal and frontal regions, including reduced brain activity in the superior frontal gyrus and temporal lobe, and thinner temporal cortices of future alcohol users. Interactions between brain function and genetic predispositions have been identified, including significant association found between the Ras protein-specific guanine nucleotide releasing factor 2 (RASGRF2) gene and reward-related striatal functioning. Neuroimaging predictors of alcohol use have shown modest utility to date. Future research should use out-of-sample performance as a quantitative measure of a predictor's utility. Neuroimaging data should be combined across multiple modalities, including structural information such as volumetrics and cortical thickness, in conjunction with white-matter tractography. A number of relevant neurocognitive systems should be assayed; particularly, inhibitory control, reward processing and executive functioning. Combining a rich magnetic resonance imaging data set could permit the generation of neuroimaging risk scores, which could potentially yield targeted interventions.

Mesenchymal stem cell-derived inflammatory fibroblasts promote monocyte transition into myeloid fibroblasts via an IL-6-dependent mechanism in the aging mouse heart.

Fibrosis in the old mouse heart arises partly as a result of aberrant mesenchymal fibroblast activation. We have previously shown that endogenous mesenchymal stem cells (MSCs) in the aged heart are markedly resistant to TGF-β signaling. Fibroblasts originating from these MSCs retain their TGF-β unresponsiveness and become inflammatory. In current studies, we found that these inflammatory fibroblasts secreted higher levels of IL-6 (3-fold increase, P < 0.05) when compared with fibroblasts derived from the young hearts. Elevated IL-6 levels in fibroblasts derived from old hearts arose from up-regulated expression of Ras protein-specific guanine nucleotide releasing factor 1 (RasGrf1), a Ras activator (5-fold, P < 0.01). Knockdown of RasGrf1 by gene silencing or pharmacologic inhibition of farnesyltransferase (FTase) or ERK caused reduction of IL-6 mRNA (more than 65%, P < 0.01) and decreased levels of secreted IL-6 (by 44%, P < 0.01). In vitro, IL-6 markedly increased monocyte chemoattractant protein-1-driven monocyte-to-myeloid fibroblast formation after transendothelial migration (TEM; 3-fold, P < 0.01). In conclusion, abnormal expression of RasGrf1 promoted production of IL-6 by mesenchymal fibroblasts in the old heart. Secreted IL-6 supported conversion of monocyte into myeloid fibroblasts. This process promotes fibrosis and contributes to the diastolic dysfunction in the aging heart.

Treatment of Chronic Lymphocytic Leukemia Patients with Lenalidomide Induces Down-Regulation of miR342-3p Associated with Over-Expression of Tumor Suppressor RASSF4,

Abstract 3885Lenalidomide has promising clinical activity in patients with chronic lymphocytic leukemia (CLL). Unlike other anti-leukemia drugs, lenalidomide is not cytotoxic for CLL cells in vitro. Similar to CD154, lenalidomide can enhance CLL-cell expression of immune co-stimulatory molecules, formation of immunologic synapse, activation of NK-cells, and generation of anti-tumor immunity. Furthermore, lenalidomide repeatedly can enhance expression of CD154, which we had observed was functionally deficient in patients with CLL. However the exact mechanism of action of lenalidomide is still under investigation.Herein, we studied the gene expression profile and microRNA (miR) of CLL cells collected from 20 patients before and at day 8 and day 15 of treatment with 2.5–5 mg of lenalidomide in the CRC014 trial.We observed significant changes in expression level of 54 genes at day 8 versus pre-treatment samples. We identified significant changes in expression level of 189 genes at day 15 versus pre-treatment samples. This included 44 of the 54 (81%) genes noted at day 8. Forty genes were expressed at significantly higher levels at day 8 and day 15 of lenalidomide treatment. We noted that 7 (17%) of these genes were related to Ras pathway and its downstream signaling pathways (i.e. NF-KappaB pathway): Ras association (RalGDS/AF-6) domain family member 4 (RASSF4), a member of RAS oncogene family (RAB13), Ras protein-specific guanine nucleotide releasing factor 1 (RASGRF1), GTPase IMAP family member 6 (GIMAP6), GTP-binding protein ras homolog gene family member S (RND1), kinase suppressor of Ras 2 (KSR2) and toll-like receptor adaptor molecule 2 (TICAM2). Ras signaling affects many cellular functions, which includes cell proliferation, apoptosis, migration, fate specification, and differentiation. In the resting cells, Ras is tightly bound to GDP (Guanosine Diphosphate), which is exchanged for GTP (Guanosine Triphosphate) upon binding to activated cell membrane receptors. In the GTP-bound form, Ras interacts with a broad range of effector proteins to induce a diverse array of biological consequences. Although typically associated with enhanced growth and transformation, activated Ras also may induce growth antagonistic effects such as senescence or apoptosis. Some of the growth-inhibitory properties of Ras are mediated via the RASSF family of Ras effector/tumor suppressors. RASSF4 is the fifth member of this family and it binds directly to activated K-Ras in a GTP-dependent manner via the effector domain, thus exhibiting the basic properties of a Ras effector. Overexpression of RASSF4 induces Ras-dependent apoptosis in 293-T cells and inhibits the growth of human tumor cell lines. Although broadly expressed in normal tissue, RASSF4 is frequently down-regulated by promoter methylation in human tumor cells and primary tumors.However changes in miR expression also may affect the level of gene expression. Therefore we analyzed miRs expression by microarray in pre treatment, day 8, and day 15 CLL samples. We observed significant changes in expression levels of 33 miRs between day 8 and pre treatment samples. We identified significant changes in expression levels of 11 miRs between day 15 and pre treatment samples. Of the 33 miRs differentially expressed at day 8, only 5 were up-regulated whereas the remaining 28 were down-regulated. Interestingly, among these 28 down-regulated miRs, 5 miRs (miR-103, miR-16, miR-30a, miR-30b and miR-342-3p) target RASSF4. Noteworthy, miR-342-3p was one of the 3 miRs (miR-26a, miR-138 and miR-342-3p) down-regulated both at day 8 and at day 15, suggesting that the down-regulation of such miR has a key role in the overexpression of RASSF4 leading to Ras-dependent apoptosis.Further studies are ongoing to elucidate lenalidomide action on CLL cells via RASSF4 overexpression. This study demonstrates that treatment with lenalidomide can induce down-regulation of miRs associated with changes in gene expression by CLL cells, leading to over-expression of RASSF4 and other Ras or GTPase related proteins that can induce growth antagonistic effects and account in part for the activity of this drug in CLL. Disclosures:James:Celgene: Research Funding. Neuberg:Celgene: Research Funding. Corral:Celgene: Employment. Kipps:Igenica: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Research Funding; Abbott Industries: Research Funding; Genentech: Research Funding; GSK: Research Funding; Gilead Sciences: Consultancy, Research Funding; Amgen: Research Funding.

Ras protein–specific guanine nucleotide–releasing factor 1 (RASGRF1)

Ras protein–specific guanine nucleotide–releasing factor 1 (RASGRF1)