GRB-associated Binding Protein 2 Research Articles

MicroRNA‑373‑3p inhibits the proliferation and invasion of non‑small‑cell lung cancer cells by targeting the GAB2/PI3K/AKT pathway.

MicroRNAs (miRNAs) were previously demonstrated to be involved in the pathogenesis of non-small-cell lung cancer (NSCLC); however, the roles of certain miRNAs in NSCLC remain to be elucidated. The present study aimed to investigate the functions of screened miRNAs in NSCLC and the potential mechanisms. First, expression profiles of miRNAs were downloaded from the Gene Expression Omnibus (dataset no. GSE29248) and the differentially expressed miRNAs were analyzed by bioinformatics methods. Reverse transcription-quantitative PCR was used to validate the differential expression of miR-373 in clinical samples. The association between miR-373 expression levels and clinicopathological characteristics was also investigated. To further examine how miR-373 mediates the emergence of NSCLC, western blot, Cell Counting Kit-8, cell invasion and wound-healing assays, as well as apoptosis detection and a luciferase assay were used. The results indicated significant downregulation of miR-373 in NSCLC tissues and its low expression was closely associated with the degree of differentiation, clinical stage and tumor size, and was indicative of an unfavorable prognosis for patients with NSCLC. A functional study indicated that overexpression of miR-373 inhibited the proliferation, promoted apoptosis, and suppressed invasion and migration of NSCLC cells. Bioinformatics prediction and functional assays suggested that Grb-associated binding protein 2 (GAB2) was a direct target of miR-373. In addition, GAB2 was found to be significantly upregulated in NSCLC tissues, and clinically, miR-373 was negatively associated with GAB2. Furthermore, overexpression of GAB2 blocked the tumor suppressive effects of miR-373 on NSCLC cells. Mechanistically, miR-373 mimics were able to reduce the expression of GAB2 and subsequently decrease the phosphorylation level of AKT and mTOR protein. The present results indicate that miR-373 exerts its anti-tumor effects in NSCLC cells by targeting the GAB2/PI3K/AKT pathway, suggesting that miR-373 may be a potential therapeutic target in NSCLC.

Predictive value of protease-activated receptor-2 (PAR2 ) in cervical cancer metastasis.

Metastasis is the primary cause of an unfavourable prognosis in patients with malignant cancer. Over the last decade, the role of proteinases in the tumour microenvironment has attracted increasing attention. As a sensor of proteinases, proteinase‐activated receptor 2 (PAR2) plays crucial roles in the metastatic progression of cervical cancer. In the present study, the expression of PAR2 in multiple types of cancer was analysed by Gene Expression Profiling Interactive Analysis (GEPIA). Kaplan‐Meier plotter was used to calculate the correlation between survival and the levels of PAR2, Grb‐associated binding protein 2(Gab2) and miR‐125b. Immunohistochemistry (IHC) was performed to examine PAR2 expression in a tissue microarray (TMA) of CESCs. Empower Stats was used to assess the predictive value of PAR2 in the metastatic potential of CESC. We found that PAR2 up‐regulation was observed in multiple types of cancer. Moreover, PAR2 expression was positively correlated with the clinicopathologic characteristics of CESC. miR‐125b and its target Gab2, which are strongly associated with PAR2‐induced cell migration, are well‐characterized as predictors of the prognostic value of CESC. Most importantly, the Cancer Genome Atlas (TCGA) data set analysis showed that the area under the curve (AUC) of the PAR2 model was significantly greater than that of the traditional model (0.833 vs 0.790, P < .05), demonstrating the predictive value of PAR2 in CESC metastasis. Our results suggest that PAR2 may serve as a prognostic factor for metastasis in CESC patients.

GRB2-associated binding protein 2 regulates multiple pathways associated with the development of prostate cancer.

The development of prostate cancer is complicated and involves a number of tumor-associated gene expression level abnormalities. Gene chip technology is a high-throughput method that can detect gene expression levels in different tissues and cells on a large scale. In the present study, gene chip technology was used to screen differentially expressed genes in PC-3 human prostate cancer cells following GRB-associated binding protein 2 (GAB2) gene knockdown, and the corresponding biological information was analyzed to investigate the role of GAB2 in prostate cancer. The PC-3 human prostate cancer cell GAB2 gene was knocked out and gene chip hybridization and bioinformatics methods were used to analyze the classical pathway and predict upstream regulatory molecules, disease and function associations and genetic interaction networks. According to the screening conditions |fold change|>1 and P<0.05, 1,242 differential genes were screened; 665 genes were upregulated, and 577 genes were downregulated. Ingenuity Pathway Analysis software demonstrated that GAB2 regulates pathways, such as the superpathway of cholesterol biosynthesis and p53 signaling in cells, and serves a role in diseases and functions such as ‘non-melanoma solid tumors’, ‘viral infections’ and ‘morbidity or mortality’. In the occurrence and development of prostate cancer, factors such as the activation of genes involved in the proliferative cycle, abnormalities in metabolism-associated enzyme gene activities and viral infection play key roles. The present study provides novel research directions and therapeutic targets for prostate cancer.

Dissecting the sequence determinants for dephosphorylation by the catalytic subunits of phosphatases PP1 and PP2A

The phosphatases PP1 and PP2A are responsible for the majority of dephosphorylation reactions on phosphoserine (pSer) and phosphothreonine (pThr), and are involved in virtually all cellular processes and numerous diseases. The catalytic subunits exist in cells in form of holoenzymes, which impart substrate specificity. The contribution of the catalytic subunits to the recognition of substrates is unclear. By developing a phosphopeptide library approach and a phosphoproteomic assay, we demonstrate that the specificity of PP1 and PP2A holoenzymes towards pThr and of PP1 for basic motifs adjacent to the phosphorylation site are due to intrinsic properties of the catalytic subunits. Thus, we dissect this amino acid specificity of the catalytic subunits from the contribution of regulatory proteins. Furthermore, our approach enables discovering a role for PP1 as regulator of the GRB-associated-binding protein 2 (GAB2)/14-3-3 complex. Beyond this, we expect that this approach is broadly applicable to detect enzyme-substrate recognition preferences.

Proteinase-activated Receptor 2 Promotes Cancer Cell Migration through RNA Methylation-mediated Repression of miR-125b

Proteinase activated-receptor 2 (PAR2) participates in cancer metastasis promoted by serine proteinases. The current study aimed to test the molecular mechanism by which PAR2 promotes cancer cell migration. In different cancer cells, activation of PAR2 by activating peptide (PAR2-AP) dramatically increased cell migration, whereas knock down of PAR2 inhibited cellular motility. The PAR2 activation also repressed miR-125b expression while miR-125b mimic successfully blocked PAR2-induced cell migration. Moreover, Grb associated-binding protein 2 (Gab2) was identified as a novel target gene of miR-125b and it mediated PAR2-induced cell migration. The correlation of PAR2 with miR-125b and Gab2 was further supported by the findings obtained from human colorectal carcinoma specimens. Remarkably, knock down of NOP2/Sun domain family, member 2 (NSun2), a RNA methyltransferase, blocked the reduction in miR-125b induced by PAR2. Furthermore, PAR2 activation increased the level of N(6)-methyladenosine (m(6)A)-containing pre-miR-125b in NSun2-dependent manner. Taken together, our results demonstrated that miR-125b mediates PAR2-induced cancer cell migration by targeting Gab2 and that NSun2-dependent RNA methylation contributes to the down-regulation of miR-125b by PAR2 signaling. These findings suggest a novel epigenetic mechanism by which microenvironment regulates cancer cell migration by altering miRNA expression.

GAB2 polymorphism rs2373115 confers susceptibility to sporadic Alzheimer's disease

It has been reported that a single nucleotide polymorphism (SNP), rs2373115, in the GRB-associated binding protein 2 (GAB2) gene was associated with late-onset AD in Caucasians. Subsequently, other researchers have attempted to validate this finding in different ethnic populations. However, these findings have produced both negative and positive results. To derive a more precise estimation for whether GAB2 polymorphism rs2373115 is associated with sporadic Alzheimer's disease (SAD), we performed the present meta-analysis. Databases including PubMed, AlzGene, China National Knowledge Infrastructure (CNKI) and Wan Fang were searched to find relevant studies. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of association. All analyses were calculated using STATA Version 11.0 and RevMan (v.5.1) software. Ten total case–control studies were included. The statistical results showed that GAB2 SNP rs2373115 is significantly associated with an increased risk for SAD, and the subgroup analysis showed that SNP rs2373115 may only be associated with an increased risk for SAD risk in Caucasians but not in Asians. Furthermore, in APOE ɛ4 carriers or noncarriers, those with rs2373115 genotype GG did not have a significantly higher risk for SAD compared with those with genotype GT and TT (APOE ɛ4 carriers: OR=1.20, 95% CI=0.92–1.56, P=0.178; APOE ɛ4 noncarriers: OR=1.08, 95% CI=0.97–1.20, P=0.157) in the present study. The current meta-analysis further supports previous findings that the GAB2 gene may be associated with SAD risk.

Linking protective GAB2 variants, increased cortical GAB2 expression and decreased Alzheimer's disease pathology.

GRB-associated binding protein 2 (GAB2) represents a compelling genome-wide association signal for late-onset Alzheimer’s disease (LOAD) with reported odds ratios (ORs) ranging from 0.75–0.85. We tested eight GAB2 variants in four North American Caucasian case-control series (2,316 LOAD, 2,538 controls) for association with LOAD. Meta-analyses revealed ORs ranging from (0.61–1.20) with no significant association (all p>0.32). Four variants were hetergeneous across the populations (all p<0.02) due to a potentially inflated effect size (OR = 0.61–0.66) only observed in the smallest series (702 LOAD, 209 controls). Despite the lack of association in our series, the previously reported protective association for GAB2 remained after meta-analyses of our data with all available previously published series (11,952-22,253 samples; OR = 0.82–0.88; all p<0.04). Using a freely available database of lymphoblastoid cell lines we found that protective GAB2 variants were associated with increased GAB2 expression (p = 9.5×10−7−9.3×10−6). We next measured GAB2 mRNA levels in 249 brains and found that decreased neurofibrillary tangle (r = −0.34, p = 0.0006) and senile plaque counts (r = −0.32, p = 0.001) were both good predictors of increased GAB2 mRNA levels albeit that sex (r = −0.28, p = 0.005) may have been a contributing factor. In summary, we hypothesise that GAB2 variants that are protective against LOAD in some populations may act functionally to increase GAB2 mRNA levels (in lymphoblastoid cells) and that increased GAB2 mRNA levels are associated with significantly decreased LOAD pathology. These findings support the hypothesis that Gab2 may protect neurons against LOAD but due to significant population heterogeneity, it is still unclear whether this protection is detectable at the genetic level.

Association analysis between polymorphism rs2373115 of gene GRB-associated binding protein 2 and Mongolian Alzheimer patients

GRB-associated binding protein 2 ( GAB2) may function as a risk factor of Alzheimer disease (AD) by affecting hyperphosphorylation of tau, causing neurofibrillary tangles. There had been genomewide analysis discovering polymorphism rs2373115 correlated with AD and in this study we performed an association analysis on this polymorphism in 107:100 Mongolian Alzheimer patients and controls in order to discover whether this correlation can be replicated in Chinese minority group. The results showed negative results, indicating GAB2 rs2373115 polymorphism was not a remarkable factor in developing Alzheimer disease among Mongolian.

GRB-associated binding protein 2 (GAB2) interacts with APOE to alter risk of late-onset Alzheimer's disease

GRB-associated binding protein 2 (GAB2) interacts with APOE to alter risk of late-onset Alzheimer's disease

Implication of GAB2 Gene Polymorphism in Italian Patients with Alzheimer's Disease

A common polymorphism (rs2373115) in the GRB-associated binding protein 2 (GAB2) gene has been recently associated with the risk of developing Alzheimer's disease (AD) in 644 apolipoprotein E (ApoE) epsilon4 carriers. In order to assess the involvement of the GAB2 polymorphism in the risk of developing AD, we analyzed the genotype and allele distributions of the GAB2 rs2373115 polymorphism in 579 Italian subjects. Our results support a possible implication of GAB2 genetic variant in AD. However, the observed association was confined to ApoE epsilon4 non-carriers, thus suggesting a possible role of GAB2 as an independent risk factor for AD.

200 Years After Darwin

ON FEBRUARY 12, 2009, WE CELEBRATE THE 200TH anniversary of the birth of Charles Darwin. He has earned the scientific reputation as being the most influential naturalist-biologist of his generation and perhaps of all time. Achievement of his esteemed status resulted initially from studying the geographical distribution of wildlife and fossils collected on his 5-year voyage on the Beagle and concluding that the “transmutation of species” was due to natural selection. In 1858, he was in the process of documenting his research when he received an essay from Alfred Russel Wallace putting forth the same concept of natural selection as the mechanism for generation of new species, resulting in a joint publication that same year. On the Origin of Species was published by Darwin in 1859, making it now the 150th anniversary of its publication. This book proposed evolution as the scientific basis of diversity and species generation produced through the effects of natural selection. Evolution has been proven to be the mechanism for species generation and the engine for change is natural selection, providing the evolved species, beginning from a common organism, adaptation and fitness to maximize reproduction and survival. Dobzhansky put it succinctly by saying that “nothing in biology makes sense except in the light of evolution.” Darwin expressed it eloquently in 1859: There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being evolved. Two hundred years after Darwin’s birth, molecular genomic analyses of the human genome have been implemented, seeking the genetic basis for natural selection providing biological fitness and also risk of developing disease. Genome-wide association studies (GWASs) seeking gene variations, or single-nucleotide polymorphisms (SNPs), causal of several human diseases have been conducted in recent years. These diseases include autism, schizophrenia, obesity, diabetes, and heart disease. Several GWASs for risk association with neurological diseases,orneuromicstudies,havebeenreported. Increasedrisks foramyotrophic lateral sclerosis,Alzheimerdisease(AD), restless legssyndrome,andmultiplesclerosishavebeenassociated with polymorphisms in specific genes. It was hoped that these observationswouldadvanceanunderstandingof thecausation of inherited, complexpolygenetic,multifactorialneurological diseases. They have been made possible by the publication of thehumangenomeandhaplotypestudies (HapMapanalyses). Awhole-genomeanalysisofsporadicamyotrophiclateralsclerosis was published by Dunckley et al. They identified 10 genetic loci that were associated with sporadic amyotrophic lateral sclerosis in 3 independent series of patients and control subjects.Themostsignificantassociationwithdiseasewasfound foraSNPnearanuncharacterizedgeneknownasFLJ10986on chromosome1.Thus, theydescribedspecificSNPs that areassociated with onset of sporadic amyotrophic lateral sclerosis. Reiman et al conducted a genome-wide survey of 502 627 SNPs to characterize and confirm late-onset AD susceptibility genes. They found that late-onset AD was associated with 6 SNPs from the GRB-associated binding protein 2 (GAB2) gene and a common haplotype encompassing the entire GAB2 gene. The GAB2 gene was overexpressed in pathologically vulnerable neurons, and interference with GAB2 gene expression increased tau phosphorylation. They concluded that GAB2 modifies late-onset AD risk in apolipoprotein E (APOE) e4 allele carriers. Coon et al found a single SNP in linkage disequilibrium to the APOE e4 allele in a neurome-wide association study. Grupe et al described 3 additional SNPs on chromosome 19 in linkage disequilibrium to the APOE e4 locus also in a neurome-wide association study. Liu et al described significant linkage to 3q23 markers associated with AD in a genetically isolated Dutch population. In 2008, Li et al described SNPs associated with risk and ageatonsetofADinaGWASof469 438SNPs.They identified theAPOE linkagedisequilibriumregionasthestrongestgenetic risk factor for AD. They concluded that this event could be a consequence of the coevolution of more than 1 susceptibility allele, includingAPOC1, inthesameregion.Additionalpotential at-riskgenes forADwereof interestandrequire furtherstudies.

Common variation inGRB-associated Binding Protein 2 (GAB2)and increased risk for Alzheimer dementia

GRB-associated binding protein 2 (GAB2) was recently reported to be a modifier of late-onset Alzheimer dementia (AD) risk in carriers of the APOE epsilon4 allele in a genome-wide association analysis. We aimed to investigate this association in a well-characterized Belgian late-onset AD patient/control group: 528 Belgian AD patients (mean onset age 79.0+/-5.2 years, 70.2% females) and 601 ethnically matched control individuals (mean age 61.9+/-15.3 years, 57.1% females) were genotyped for 10 SNPs across the GAB2 locus. For 2 SNPs the most common genotype was associated with risk for AD, with the most significant result for rs4945261 [OR 1.49 (95%CI 1.04-2.15)]. After stratification by presence or absence of APOE epsilon4 these associations were present in APOE epsilon4 carriers only. When assessing the effect of APOE and rs4945261 in one model, rs4945261 did not show a main effect, but the joint risk effect of rs4945261-GG and APOE epsilon4 on AD was significant (OR 3.87, 95%CI 2.66-5.63; p=1.0E-12), with a deviation of 1.87 from the multiplicative model of interaction. Haplotype analyses showed evidence of association in the total (global p(sim) 0.04) and APOE epsilon4+ (global p(sim) 0.02) but not in the APOE epsilon4 - group (global p(sim) 0.6). The association was driven by a higher frequency of the major haplotype in patients. Our data independently replicate an association between GAB2 and late-onset AD, which appears to be limited to APOE epsilon4 carriers.