Analysis of IQSEC2 gene variant in a child with X-linked mental retardation / 中华医学遗传学杂志

OBJECTIVE@#To analyze the clinical phenotype and genetic variants of a child with X-linked mental retardation caused by IQSEC2 gene mutation, and provide reference for the diagnosis of the disease.@*METHODS@#The child was subjected to next generation sequencing (NGS), and the diagnosis was made by taking consideration of her clinical characteristics.@*RESULTS@#The child has presented with global developmental delay, particularly in fine motor skill and language development, in addition with intellectual disability. Genetic testing revealed that she has harbored a heterozygous c.1861dup variant of the IQSEC2 gene, which was not detected in either parent.@*CONCLUSION@#The de novo c.186ldup variant of the IQSEC2 gene probably underlay the X-linked mental retardation in this child. Above finding has, expanded the spectrum of IQSEC2 gene mutations and provide a basis for the diagnosis of similar cases.

PREX2 gene's expression in gastric antral epithelial cells of patients with H. pylori infection / Expressão do gene PREX2 em células epiteliais antrais gástricas em pacientes com infecção por H. pylori

ABSTRACT BACKGROUND: The Prex2 protein is a member of the Rac family proteins that belongs to small G proteins with a critical role in cell migration, cell proliferation, and apoptosis through its effects on PI3K cell signaling pathway and phosphatase activity of PTEN protein. The effect of PREX2 gene expression has been shown in some cancer cells. A survey of PREX2 gene expression in gastric antral epithelial cells of gastric cancer patients with Helicobacter pylori various genotypes infection can conduct to better understanding H. pylori infection's carcinogenesis. METHODS: In a case-control study, PREX2 gene expression was evaluated in gastric antral biopsy samples on four groups of patients referred to Sanandaj hospitals, including gastritis with (n=23) and without (n=27) H. pylori infection and gastric cancer with (n=21) and without (n=32) H. pylori infection. Each gastric biopsy sample's total RNA was extracted and cDNA synthesized by using Kits (Takara Company). The PREX2 gene expression was measured using the relative quantitative real-time RT-PCR method and ΔΔCt formula. RESULTS: The PREX2 gene expression increased in gastric antral biopsy samples of gastritis and gastric cancer patients with H. pylori infection (case groups) than patients without H. pylori infection (control groups) 2.38 and 2.27 times, respectively. The patients with H. pylori vacA s1m1 and sabB genotypes infection showed a significant increase of PREX2 gene expression in gastric cancer antral epithelial cells. CONCLUSION: H. pylori vacA s1m1 and sabB genotypes have the positive correlations with PREX2 gene expression in gastric antral epithelial cells of gastritis and gastric cancer patients.

RESUMO CONTEXTO: A proteína Prex2 é membro das proteínas da família Rac que pertencem a pequenas proteínas G com um papel crítico na migração celular, na proliferação celular e na apoptose através de seus efeitos na via de sinalização celular PI3K e atividade fosfatase da proteína PTEN. O efeito da expressão genética PREX2 tem sido mostrada em algumas células cancerosas. Um levantamento da expressão genética PREX2 em células epiteliais antrais gástricas de pacientes infectados com vários genótipos de Helicobacter pylori pode conduzir a um melhor entendimento da carcinogênese da infecção por H. pylori. MÉTODOS: Em estudo de caso-controle, a expressão genética PREX2 foi avaliada em amostras de biópsia antral gástrica em quatro grupos de pacientes encaminhados aos hospitais de Sanandaj, incluindo gastrite com (n=23) e sem (n=27) infecção por H. pylori e de câncer gástrico com (n=21) e sem (n=32) infecção por H. pylori. O RNA total de cada amostra de biópsia gástrica foi extraído e cDNA sintetizado por meio de kits (Takara Company). A expressão genética PREX2 foi medida utilizando-se o método RT-PCR em tempo real quantitativo relativo e a fórmula ΔΔCt. RESULTADOS: A expressão genética PREX2 aumentou em amostras de biópsia antral gástrica de pacientes com gastrite e câncer gástrico com infecção por H. pylori (grupos de casos) em relação aos sem infecção por H. pylori (grupos de controle) 2,38 e 2,27 vezes, respectivamente. Os pacientes com infecção por genótipos H. pylori vacA s1m1 e sabB apresentaram um aumento significativo da expressão genética PREX2 em células epiteliais antrais de câncer gástrico. CONCLUSÃO: Os genótipos H. pylori vacA s1m1 e sabB têm correlações positivas com a expressão genética PREX2 em células epiteliais antrais gástricas de pacientes com câncer gástrico e gastrites.

Analysis of FGD1 gene variant in a child with Aarskog-Scott syndrome / 中华医学遗传学杂志

OBJECTIVE@#To detect pathogenic variant of the FGD1 gene in a boy with Aarskog-Scott syndrome.@*METHODS@#Genetic variant was detected by high-throughput sequencing. Suspected variant was verified by Sanger sequencing. The nature and impact of the candidate variant were predicted by bioinformatic analysis.@*RESULTS@#The child was found to harbor a novel c.1906C>T hemizygous variant of the FGD1 gene, which has led to conversion of Arginine to Tryptophane at codon 636(p.Arg636Trp). The same variant was found in his mother but not father. Based on the American College of Medical Genetics and Genomics guidelines, the c.1906C>T variant of FGD1 gene was predicted to be likely pathogenic(PM1+PM2+PM5+PP2+PP3+PP4).@*CONCLUSION@#The novel c.1906C>T variant of the FGD1 gene may underlay the Aarskog-Scott syndrome in this child. Above finding has enabled diagnosis for the boy.

Analysis of DOCK6 gene mutation in a child affected with Adams-Oliver syndrome type 2 / 中华医学遗传学杂志

OBJECTIVE@#To detect pathogenic mutation of DOCK6 gene in a patient with convulsive seizure and refractory epilepsy.@*METHODS@#CytoScan HD-Array and next generation sequencing were used to detect the potential mutation in the patient.@*RESULTS@#The proband has carried compound heterozygous mutations of c.188C>T (p.Arg63Gln) and c.5374C>T (p.Glu1792Lys) of the DOCK6 gene, which were respectively inherited from his mother and father. Neither mutation was reported previously. Bioinformatic analysis indicated that the two amino acids are highly conserved. Based on the ACMG guidelines, the c.188C>T mutation was predicted to be likely pathogenic, while the c.5374C>T mutation was of uncertain significance.@*CONCLUSION@#The compound heterozygous mutations of c.188C>T (p.Arg63Gln) and c.5374C>T (p.Glu1792Lys) of the DOCK6 gene probably underlie the disease in this patient.

The role of the exocyst in renal ciliogenesis, cystogenesis, tubulogenesis, and development

The exocyst is a highly conserved eight-subunit protein complex (EXOC1–8) involved in the targeting and docking of exocytic vesicles translocating from the trans-Golgi network to various sites in renal cells. EXOC5 is a central exocyst component because it connects EXOC6, bound to the vesicles exiting the trans-Golgi network via the small GTPase RAB8, to the rest of the exocyst complex at the plasma membrane. In the kidney, the exocyst complex is involved in primary ciliognesis, cystogenesis, and tubulogenesis. The exocyst, and its regulators, have also been found in urinary extracellular vesicles, and may be centrally involved in urocrine signaling and repair following acute kidney injury. The exocyst is centrally involved in the development of other organs, including the eye, ear, and heart. The exocyst is regulated by many different small GTPases of the RHO, RAL, RAB, and ARF families. The small GTPases, and their guanine nucleotide exchange factors and GTPase-activating proteins, likely give the exocyst specificity of function. The recent development of a floxed Exoc5 mouse line will aid researchers in studying the role of the exocyst in multiple cells and organ types by allowing for tissue-specific knockout, in conjunction with Cre-driver mouse lines.

Mon1 Is Essential for Fungal Virulence and Stress Survival in Cryptococcus neoformans

Mon1 is a guanine nucleotide exchange factor subunit that activates the Ypt7 Rab GTPase and is essential for vacuole trafficking and autophagy in eukaryotic organisms. Here, we identified and characterized the function of Mon1, an ortholog of Saccharomyces cerevisiae Mon1, in a human fungal pathogen, Cryptococcus neoformans. Mutation in mon1 resulted in hypersensitivity to thermal stress. The mon1 deletion mutant exhibited increased sensitivity to cell wall and endoplasmic reticulum stress. However, the mon1 deletion mutant showed more resistance to the antifungal agent fluconazole. In vivo studies demonstrated that compared to the wild-type strain, the mon1 deletion mutant attenuated virulence in the Galleria mellonella insect model. Moreover, the mon1 deletion mutant was avirulent in the murine inhalation model. These results demonstrate that Mon1 plays a crucial role in stress survival and pathogenicity in C. neoformans.

Análise da relação da ocorrência de polimorfismo de nucleotídeo único do gene DOCK9 em ceratocone / Relation analysis of the occurrence of single nucleotide polymorphism of the DOCK9 gene in keratoconus

RESUMO Objetivo: Avaliar a ocorrência de mutação em locus gênico candidato e sua relação com ceratocone em pacientes atendidos no Brasil comparados a voluntários saudáveis, através da análise de polimorfismo de nucleotídeo único no gene DOCK9. Métodos: Neste estudo clínico foram avaliados 108 indivíduos, sendo 46 pacientes com ceratocone e 62 voluntários saudáveis (controles). Amostras de DNA foram obtidas do sangue coletado de pacientes com ceratocone e controles para a realização de análise de genotipagem. O genótipo do polimorfismo de nucleotídeo único rs7995432 no gene DOCK9 foi determinado através de reação em cadeia da polimerase em tempo real (qPCR). Resultados: A frequência do alelo mutante (C) foi de 4,8% para os pacientes e 7,6% para os controles. Para o alelo selvagem (T), as frequências foram de 95,2% para os pacientes e 92,4% para os controles. O genótipo heterozigótico esteve presente em 9,5% dos pacientes e 11% dos controles, enquanto o genótipo homozigótico para o alelo selvagem (TT) foi encontrado em 90,5% e 87% para os pacientes e controles, respectivamente. Conclusão: Não foram observadas diferenças significativas na frequência e discriminação dos alelos mutante e selvagem entre os pacientes com ceratocone e os controles. Portanto, não foi possível fazer uma associação destas mutações no gene DOCK9 com a ocorrência do ceratocone para esta população.

ABSTRACT Objective: To evaluate the occurrence of a mutation in candidate genetic loci and its relation with keratoconus in patients treated in Brazil compared to healthy volunteers, through analysis of single nucleotide polymorphism in the DOCK9 gene. Methods: In this clinical study, 108 participants were evaluated, including 46 keratoconus patients and 62 healthy volunteers (controls). DNA samples were extracted from collected blood from keratoconus patients and controls. The genotyping of the single nucleotide polymorphism rs7995432 in the DOCK9 gene was determined through a real-time polymerase chain reaction (qPCR). Results: The frequency of the mutant allele (C) was 4.8% in patients and 7.6% in controls. For the wild allele (T), the frequencies were 95.2% in patients and 92.4% in controls. The heterozygous genotype was present in 9.5% of patients and 11% of controls, while the homozygous genotype for the wild allele (TT) was found in 90.5% and 87% for patients and controls, respectively. Conclusion: There were no significant differences un the frequency and discrimination of the mutant and wild alleles between patients and controls. Therefore, these results confirm no association of these mutations in the DOCK9 gene and the occurrence of keratoconus for this population.

Association of TIAM1 gene polymorphisms with Kawasaki disease and its clinical characteristics / 中国当代儿科杂志

<p><b>OBJECTIVE</b>To investigate the association of single nucleotide polymorphisms (SNP) rs22833188 and rs2833195 in TIAM1 gene with the susceptibility to Kawasaki disease (KD) and its clinical characteristic in children.</p><p><b>METHODS</b>A case-control study was performed in this study. One hundred and eighty-eight children with KD and 197 normal children served as controls were enrolled. The genotypes of two SNPs rs22833188 and rs2833195 in TIAM1 gene were detected using PCR-RFLP.</p><p><b>RESULTS</b>There were no significant differences in the genotype (AA, AG and GG) and allele frequencies of SNP rs2833188 between the KD and control groups. Significant differences in the genotype (CC, GC and GG) frequency of SNP rs2833195 were noted between the KD and control groups (P=0.017). The frequency of C allele in the KD group was higher than in the control group (P=0.015). The polymorphism of SNP rs2833188 was associated with the occurrence of rash (P=0.011), and the polymorphism of SNP rs2833195 was associated with the occurrence of conjunctival hyperemia (P=0.021).</p><p><b>CONCLUSIONS</b>The polymorphism of rs2833195 in TIAM1 gene is associated with the susceptibility to KD. The polymorphisms rs2833188 and rs2833195 in TIAM1 gene may be associated with some clinical characteristics in children with KD.</p>

The prognostic value of Tiam1 protein expression in head and neck squamous cell carcinoma: a retrospective study / 癌症

<p><b>INTRODUCTION</b>Head and neck squamous cell carcinoma (HNSCC) is a common cancer worldwide and has a poor prognosis. A biomarker predicting the clinical outcome of HNSCC patients could be useful in guiding treatment planning. Overexpression of the T lymphoma invasion and metastasis 1 (Tiam1) protein has been implicated in the migration and invasion of neoplasms. However, its role in HNSCC progression needs to be further validated. We detected the expression of Tiam1 in normal and tumor tissues and determined its association with clinical outcomes in patients with HNSCC.</p><p><b>METHODS</b>We measured the expression of Tiam1 in normal and cancerous tissue samples from the patients with HNSCC treated at Sun Yat-sen University Cancer Center between 2001 and 2008. The Tiam1 expression was scored from 0 to 12 based on the percentage of positively stained cells and the staining intensity. We then determined the diagnostic performance of this score in predicting overall survival (OS) and disease-free survival (DFS).</p><p><b>RESULTS</b>Of the 194 evaluable patients, those with advanced disease, lymph node metastasis at diagnosis, and recurrence or metastasis during follow-up had a higher tendency of having high Tiam1 expression as compared with their counterparts (P < 0.05). The proportion of samples with high Tiam1 expression was also higher in cancerous tissues than in non-cancerous tissues (57.7% vs. 13.9%, P < 0.001). Cox proportional hazards regression analysis revealed that Tiam1 expression scores of 5 and greater independently predicted short OS and DFS.</p><p><b>CONCLUSION</b>The Tiam1 expression is shown as a promising biomarker of clinical outcomes in patients with HNSCC and should be evaluated in prospective trials.</p>

Effect of Tiam 1 on cell proliferation and migration in head and neck squamous cell carcinoma cells / 临床耳鼻咽喉头颈外科杂志

OBJECTIVE@#To investigate the effect of T lymphoma invasion and metastasis 1 (Tiam 1) overexpression in head and neck squamous cell carcinoma (HNSCC) cells.@*METHOD@#Endogenous expression of Tiam 1 in 8 head and neck squamous cell carcinoma cell (HNSCC) lines was investigated by real-time RT-PCR. A lentivirus vector containing Tiaml was transfected into UM-SCC-47 cells, a head and neck squamous cell carcinoma cell line with little endogenous Tiaml expression. Stable clone, obtained by G418 screening, were assayed by RT-PCR and Western blot to validate the gene expression efficiency. The biological behaviors of the transduced cells were determined by cell counting, MTT and in-vitro migration assay.@*RESULT@#Tiam 1 gene was highly expressed in M2 cell line and it's low level expression was found in UM-SCC-47. Cell counting and MTT assay showed that over-expression of Tiaml significantly promoted cell proliferation (P < 0.05). The cell monolayers overexpressed Tiaml that resulted in a significant increasment of cell migration in infected head and neck squamous cell carcinoma cell lines (P < 0.05).@*CONCLUSION@#Tiam 1 gene plays an important role in the growth and migration in head and neck squamous cell carcinoma cell lines. It may be a useful marker for metastasis of head and neck squamous cell carcinoma.

Inmunodeficiencia combinada con compromiso cutáneo asociada a mutación en DOCK8 / Combined immunodeficiency with cutaneous manifestations associated with DOCK8 mutation

Diferentes inmunodeficiencias primarias se caracterizan por niveles elevados de IgE e infecciones cutáneas de origen viral. Describimos el caso de un niño de 2 años y 8 meses de edad, con inmunodeficiencia combinada, dermatitis y molusco contagioso diseminado. El paciente presentaba niveles aumentados de IgE, eosinofilia y marcada linfopenia a predominio de TCD8. Se encontraron alteraciones en los ensayos funcionales por cultivo y en la respuesta a la vacunación. Resultados normales de la proteína ZAP-70, funcionalidad NK y niveles de HLA I, tendientes a verificar alteraciones cuantitativas y funcionales de las células citotóxicas, llevaron a la sospecha de deficiencia en el gen DOCK8. El resultado positivo del estudio molecular, junto con las características clínicas e inmunológicas del paciente, confirmaron el diagnóstico de esta nueva inmunodeficiencia, que, de acuerdo con nuestro conocimiento, sería el primer caso diagnosticado en un hospital pediátrico en nuestro país.

Different primary immunodeficiencies present increased levels of IgE and cutaneous infections of viral etiology. We report a case of a 2 y, 8 m old boy with combined immunodeficiency, dermatitis and disseminated molluscum contagiosum. The patient presented high titers of IgE, eosinophilia and pronounced TCD8 lymphopenia. Impaired proliferation assays and abnormal antibody response to vaccination were found. Normal results of ZAP-70 protein, NK function, and HLA I levels, to test quantitatives and functional defects of cytotoxic cells, lead us to suspect a mutation in DOCK8 gene. Positive result in molecular study together with clinical and immunology features in the patient confirmed the diagnosis of this new immunodeficiency, being to the authors ́ knowledge the first case recorded in a paediatric hospital in our country.

Vav3, a GEF for RhoA, Plays a Critical Role under High Glucose Conditions

BACKGROUND: The role of small GTPase molecules is poorly understood under high glucose conditions. METHODS: We analyzed the expression pattern of Vav3 in skeletal muscle C2C12 cells under high glucose culture condition with reverse transcription-polymerase chain reaction and Western blot analysis. We also measured glucose uptake using isotope-labelled glucose. RESULTS: We showed that expression of Vav3 (a guanine nucleotide exchange factor for RhoA) increased. mRNA and protein levels in skeletal muscle C2C12 cells under high glucose conditions. The AMP-activated protein kinase (AMPK) activator AMPK agonist 5-aminoimidazole-4-carboxy-amide-1-d-ribofuranoside (AICAR) suppressed high glucose-induced Vav3 induction. In addition, exposure of cells to high glucose concentration increased the phosphorylation of PAK-1, a molecule downstream of RhoA. The phosphorylation of paxillin, a downstream molecule of PAK-1, was also increased by exposure to high glucose. Phosphorylation of these molecules was not observed in the presence of AICAR, indicating that AMPK is involved in the RhoA signal pathway under high glucose conditions. Knock down of Vav3 enhances metformin-mediated glucose uptake. Inhibition of AMPK blocked the increases of Vav3 knock down-induced glucose uptake. Metformin-mediated Glut4 translocation was also increased by Vav3 knock-down, suggesting that Vav3 is involved in metformin-mediated glucose uptake. CONCLUSION: These results demonstrate that Vav3 is involved in the process of metformin-mediated glucose regulation.

Inhibition effect of N-acetyl-seryl-aspartyl-lysyl-proline on myofibroblast differentiation of MRC-5 human fetal lung fibroblasts inuced by Ang II / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To explore the inhibition effect of N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP) on myofibroblast differentiation of MRC-5 human fetal lung fibroblasts induced by angiotensin (Ang) II.</p><p><b>METHODS</b>The study was divided into 2 step: (1) MRC-5 human fetal lung fibroblasts was induced for 48 h at different dose of Ang II and at different time point by 100 nmol/L Ang II. Then the expression of collagen type I and α-smooth muscle actin (α-SMA) were mesaured by western blot. (2) MRC-5 human fetal lung fibroblasts were divided into 4 group: (1) control, (2) Ang II, (3) Ang II+Ac-SDKP, (4) Ang II+8-Me-cAMP (a specific activator of Epac). The α-SMA expression was observed by immnocytochemical stain. The protein expression of collagen type I, α-SMA, serum response factor (SRF), myocardin-related transcription factor (MRTF)-A, exchange protein directly activated by cAMP (Epac) 1, 2 were measured by Westen blot.</p><p><b>RESULTS</b>Myofibroblast differentiation could be induced by Ang II from MRC-5 cells with a dose- and time-dependent manner. The up-regulation of SRF and MRTF-A were observed in MRC-5 cells induced by Ang II and accompanied with collagen I and α-SMA increased. Pre-treatment with 8-Me-cAMP or Ac-SDKP could attenuated all this changes induced by Ang II, and promoted the expression of Epac1.</p><p><b>CONCLUSION</b>Ac-SDKP can inhibit the myofibroblast differentiation of MRC-5 cells induced by Ang II via Epac1 activating.</p>

Effect of downregulation of Tiam1 by siRNA on esophageal squamous cell carcinoma EC9706 cells / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To explore the effect of downregulation of Tiam1 by siRNA on the esophageal squamous cell carcinoma (ESCC) EC9706 cells, and provide theoretical basis for gene therapy of ESCC using Tiam1 as a molecular target.</p><p><b>METHODS</b>Tiam1 siRNA was transfected into EC9706 cells, and expression changes of Tiam1 mRNA and protein after transfection were detected by quantitative real-time PCR and Western blotting. Cell proliferation was analyzed using CCK-8 kit. Cell cycle and apoptosis of the EC9706 cells were assessed by flow cytometry. Cell cycle-related proteins and cell apoptosis-associated proteins were analyzed by Western blotting.</p><p><b>RESULTS</b>Compared with the untreated group and control siRNA group, the relative expression levels of Tiam1 mRNA (1.00 and 0.11 ± 0.02) were not significantly different (P > 0.05). The relative expression levels of Tiam1 mRNA in the Tiam1 siRNA group at 24, 48 and 72 h after transfection were 0.30 ± 0.04, 0.09 ± 0.01 and 0.09 ± 0.006, respectively, significantly lower than that of the untreated group (P < 0.05 for all). The expression level of Tiam1 protein at 24 h after Tiam1 siRNA transfection in the EC9706 cells was 0.11 ± 0.02, significantly lower than that in the un-treated group (0.44 ± 0.05) and control siRNA group (0.44 ± 0.04, P < 0.05 for all). The percentages of G0/G1 cells in the Tiam1 siRNA group, untreated group and control siRNA group were (54.48 ± 2.14)%, (40.69 ± 1.85)% and (41.78 ± 1.31)%, respectively (P < 0.01). The percentages of S phase cells in the Tiam1 siRNA group, untreated group and control siRNA group were (27.18 ± 1.65)%, (32.32 ± 1.15)% and (30.35 ± 1.09)%, respectively (P < 0.01). The expression levels of cyclin D1 protein in the untreated group, control siRNA group and Tiam1 siRNA group were 0.43 ± 0.02, 0.41 ± 0.01 and 0.11 ± 0.02, respectively (P < 0.05). The expression levels of p27 protein in the untreated group, control siRNA group and Tiam1 siRNA group were 0.10 ± 0.01, 0.09 ± 0.02 and 0.20 ± 0.02, respectively (P < 0.05). The ratios of early apoptotic cells in the untreated group, control siRNA group and Tiam1 siRNA group were (10 ± 0.9)%, (10 ± 0.5)% and (27 ± 0.7)%, respectively (P < 0.01). The expression levels of Mcl-1 protein in EC9706 cells of untreated group, control siRNA group and Tiam1 siRNA group were 0.47 ± 0.12, 0.48 ± 0.13 and 0.16 ± 0.02, respectively (P < 0.05). The expression levels of Bcl-2 protein in EC9706 cells of the untreated group, control siRNA group and Tiam1 siRNA group were 0.49 ± 0.08, 0.50 ± 0.05 and 0.04 ± 0.03, respectively (P < 0.05). The caspase-3 activities in the untreated group, control siRNA group and Tiam1 siRNA group were 2.3 ± 0.09, 2.3 ± 0.10 and 16.0 ± 1.50, respectively; and that of caspase-9 were 2.3 ± 0.08, 2.3 ± 0.11 and 14.5 ± 0.9, respectively (P < 0.05 for all).</p><p><b>CONCLUSIONS</b>Tiam1 siRNA can significantly inhibit the proliferation of esophageal cancer EC9706 cells, induce cell cycle arrest and cell apoptosis. These effects are related to the regulation of the expressions of cell cycle-related genes (cyclin D1 and p27) and cell apoptosis-related genes (Mcl-1, Bcl-1, caspase-3 and caspase-9) by Tiam1 siRNA.</p>

RIC-8B, uma GEF de sistema olfatório, é essencial para o desenvolvimento do sistema nervoso / RIC-8B, an olfactory GEF, is essential for the development of the nervous system

RIC-8B é um fator trocador de nucleotídeo de guanina (GEF) predominantemente expresso em neurônios olfatórios maduros de camundongos adultos. Trabalhos desenvolvidos em nosso laboratório mostraram que RIC-8B interage com Gαolf e Gγ13, duas subunidades de proteína G que estão enriquecidas nos cílios dos neurônios olfatórios, onde participam da transdução do sinal de odorantes. In vitro, RIC-8B é capaz de amplificar a sinalização de receptores olfatórios através de Gαolf, no entanto, seu papel fisiológico ainda é desconhecido. Para determinar a função desempenhada por essa proteína in vivo, nós utilizamos a tecnologia de Gene Trap com o objetivo de produzir um camundongo knockout para Ric-8B. Apesar de a expressão de Ric-8B ser restrita a poucos tecidos no camundongo adulto, descobrimos que homozigotos para a mutação em Ric-8B são inviáveis e morrem por volta do dia embrionário E10,5. Além disso, são menores e apresentam evidente falha no fechamento do tubo neural na região cranial (exencefalia). Utilizamos o gene repórter ß-galactosidase expresso pelo alelo mutado para determinar o padrão de expressão de Ric-8B em embriões durante o desenvolvimento. Observamos que, no estágio E8,5, Ric-8B é expresso nas pregas neurais da região cefálica e na notocorda. De E9,5 a E12,5, a expressão de Ric-8B é detectada predominante no assoalho da placa. Esse padrão de expressão se assemelha ao de outro gene importante para a embriogênese, Sonic hedgehog (Shh). SHH é um morfógeno diretamente responsável pela padronização dorsoventral do sistema nervoso central e sua sinalização depende de cílio primário. Cílio primário é uma organela baseada em microtúbulos que se projeta da superfície da maioria das células de mamíferos e funciona como um centro de sinalização intracelular. Nossos dados mostram que fibroblastos embrionários Ric-8B-/- formam cílios primários, assim como alguns tecidos do embrião. Além disso, não encontramos alterações na sinalização de Shh em embriões homozigotos mutantes. No entanto, observamos que esses embriões apresentam apoptose aumentada em células migratórias da crista neural cranial. Shh é importante para a sobrevivência de células da crista neural migratória, sugerindo um possível papel para Ric-8B a downstream da sinalização de SHH

Ric-8B is a guanine nucleotide exchange factor (GEF) which is predominantly expressed in mature olfactory sensory neurons in adult mice. We have previously shown that RIC-8B interacts with both Gαolf and Gγ13, two G protein subunits, which are enriched in olfactory cilia and are required for odorant signal transduction. In vitro, RIC-8B is able to amplify odorant receptor signaling through Gαolf, however, its physiological role remains unknown. To determine the role played by RIC-8B in vivo we used the Gene trap technology to generate a Ric-8B knockout mouse. We found that, despite the limited distribution of Ric-8B gene expression in adult mice, Ric-8B homozygous mutants are not viable and die around the E10,5 stage. Mutant embryos are also smaller and fail to close the neural tube at the cranial region (exencephaly). We used the activity of the ß-galactosidase reporter gene to determine the pattern of expression of the Ric-8B gene in heterozygous embryos. At E8,5 the Ric-8B gene is expressed in the notochord and neural folds of the cephalic regions. From E9,5 to E12,5 Ric-8B is predominantly expressed in the floor plate, in a pattern that strongly resembles the one shown by Sonic hedgehog (Shh). SHH is a morphogen directly responsible for the dorsoventral patterning of the central nervous system and its signaling depends on primary cilia. Primary cilia are microtubule-based organelles that protrude from the surface of mammalian cells and act as a signaling center. We show that Ric-8B-/- embryonic fibroblasts and some embryonic tissues grow primary cilia normally. In addition, we did not find alterations in the SHH signaling of homozygous mutants. Instead, we found an increased apopotosis in migratory cells of the cranial neural crest in these embryos. Shh is an important factor to survival of neural crest cells, suggesting a role for RIC-8B downstream of the SHH signaling

Activation of small Rho GTPases by blebbistatin in PC12 cells / 동물의과학연구지

Neuronal differentiation is a complex biological process accompanying cytoskeletal reorganization, including neurite outgrowth and growth cone formation. Therefore, neuronal differentiation is critically regulated by actin-related signaling proteins, such as small Rho GTPases, guanine nucleotide exchange factors (GEFs), and myosins. This study will demonstrate the change in activity of three small Rho GTPases, Rac, Cdc42, and Rho A, by treatment with blebbistatin (BBS), a specific inhibitor for myosin, during bFGF-induced neurite outgrowth in PC12 cells. Treatment with BBS induced morphological changes in growth cones and neurites during differentiation. A marked increase in protrusion and filopodia structures in growth cones, the shaft of neuritis, and cell membranes was observed in the cells treated with BBS. Activity of Rho GTPases showed the alterations in response to BBS. Activities of both Rac and Rho A were inhibited by BBS in a time-dependent manner. By contrast, Cdc42 activity was not changed by BBS. These results suggest that inactivation of myosin II by BBS induced morphological changes in neurites and growth cones and distinct regulation of three Rho GTPases during differentiation of PC12 cells.

Up-regulation of T-lymphoma and metastasis gene 1 in gastric cancer and its involvement in cell invasion and migration / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>T-lymphoma and metastasis gene 1 (Tiam1) produces a guanine nucleotide exchange factor (GNEF) that regulates guanosine triphosphatase, which transforms guanosine diphosphate to guanosine triphosphate. Recently published data indicate that Tiam1 was associated with gastric cancer. The aim of this study was to investigate biological effects and potential mechanisms of Tiam1 in gastric carcinoma.</p><p><b>METHODS</b>We analyzed the expression of Tiam1 in 114 pair-matched gastric neoplastic and adjacent non-neoplastic tissues by quantitative real-time PCR. We investigated Tiam1 expression and its prognostic value for gastric cancer. Furthermore, the functions of Tiam1 over-expression were analyzed with stable-expression Tiam1 plasmid in human gastric cancer cell lines.</p><p><b>RESULTS</b>Tiam1 expression was significantly associated with cell differentiation and lymphatic metastasis; expression of Tiam1 mRNA was up-regulated in gastric cancer compared to pair-matched adjacent non-tumor tissues. Analyses of surgical tissue samples and 5-year survival of gastric cancer patients showed that those with strong Tiam1 expression had significantly shorter overall survival time than those with negative Tiam1 expression. Ectopic expression of Tiam1 promoted cell growth, migration and invasion of gastric cancer cells in vitro.</p><p><b>CONCLUSIONS</b>In gastric cancer cells, Tiam1 affects multiple properties associated with acquisition of the metastatic phenotype, and may be a marker of gastric cancer progression and metastasis in a subset of cancer.</p>

Mechanisms of Platelet Activation and Integrin alphaIIbeta3

Platelet aggregation is not only an essential part of hemostasis, but also initiates acute coronary syndrome or ischemic stroke. The precise understanding of the activation mechanism of platelet aggregation is fundamental for the development of more effective agents against platelet aggregation. Adenosine diphosphate, thrombin, and thromboxane A2 activate platelet integrin alphaIIbbeta3 through G protein-coupled receptors. G protein-mediated signaling pathways, which are initiated by Gq, G12/G13 or Gi, include phospholipase C with calcium signaling, Rho signaling, protein kinase C and phosphatidylinositol 3-kinase. Rap1b, Ca2+ and diacylglycerol-regulated guanine nucleotide exchange factor I, Rap1-GTP-interacting adaptor molecule, and Akt are important proteins involved in G protein-mediated activation of integrin alphaIIbbeta3. Binding of talin-1 and kindlin-3 to cytoplasmic domains of beta3-integrin triggers a conformational change in the extracellular domains that increases its affinity for ligands, such as fibrinogen or von Willebrand factor. Fibrinogens act as bridges between adjacent platelets to generate a platelet aggregate.

Effects of Tiam1 on invasion and metastasis of breast carcinoma and its mechanisms / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To investigate the significance of Tiam1 in invasion and metastasis of breast carcinoma and its mechanisms.</p><p><b>METHODS</b>Immunohistochemistry was used to detect Tiam1 expression in tumor tissue of 126 breast carcinomas. Tiam1 was silenced by siRNA in breast carcinoma cell line MDA-MB-435, then the expressions of phosphor-ERK 1, ERK 2 and VEGF were detected, and electrophoretic mobility shift assay (EMSA) was used to examine the transcription activiy of AP-1.</p><p><b>RESULTS</b>There was a significant relationship between Tiam1 expression and lymph node metastasis (P < 0.05). Furthermore, after silencing of Tiam1, the expressions of phosphor-ERK 1, ERK 2 and VEGF were decreased, and the transcription activity of AP-1 was down-regulated in the MDA-MB-435 cells.</p><p><b>CONCLUSION</b>Tiam1 is closely related with invasion and metastasis of breast carcinoma, and the cascade Tiam1 through ERK, AP-1 and VEGF pathways may play an important role in enhancing angiogenesis, therefore, to promote invasion and metastasis of breast carcinoma.</p>

Increased p190RhoGEF expression in activated B cells correlates with the induction of the plasma cell differentiation

Previously, we demonstrated that the p190 Rho guanine nucleotide exchange factor (p190RhoGEF) was induced following CD40 stimulation of B cells. In this study, we examined whether p190RhoGEF and a downstream effector molecule RhoA are required for B cell differentiation. Expression of p190RhoGEF positively correlated with the expression of surface markers and transcriptional regulators that are characteristic of mature B cells with plasma cell (PC) phenotypes. Moreover, either the overexpression of p190RhoGEF or the expression of a constitutively active RhoA drove cellular differentiation toward PC phenotypes. B cell maturation was abrogated in cells that overexpressed p190RhoGEF and a dominant-negative form of RhoA simultaneously. CD40-mediated maturation events were also abrogated in cells that overexpressed either dominant-negative p190RhoGEF or RhoA. Together, these data provide evidence that p190RhoGEF signaling through RhoA in CD40-activated B cells drives the induction of the PC differentiation.