The radial migration of cortical pyramidal neurons (PNs) during corticogenesis is necessary for establishing a multilayered cerebral cortex. Neuronal migration defects are considered a critical etiology of neurodevelopmental disorders, including autism spectrum disorders (ASDs), schizophrenia, epilepsy, and intellectual disability (ID). TRIO is a high-risk candidate gene for ASDs and ID. However, its role in embryonic radial migration and the etiology of ASDs and ID are not fully understood. In this study, we found that the in vivo conditional knockout or in utero knockout of Trio in excitatory precursors in the neocortex caused aberrant polarity and halted the migration of late-born PNs. Further investigation of the underlying mechanism revealed that the interaction of the Trio N-terminal SH3 domain with Myosin X mediated the adherence of migrating neurons to radial glial fibers through regulating the membrane location of neuronal cadherin (N-cadherin). Also, independent or synergistic overexpression of RAC1 and RHOA showed different phenotypic recoveries of the abnormal neuronal migration by affecting the morphological transition and/or the glial fiber-dependent locomotion. Taken together, our findings clarify a novel mechanism of Trio in regulating N-cadherin cell surface expression via the interaction of Myosin X with its N-terminal SH3 domain. These results suggest the vital roles of the guanine nucleotide exchange factor 1 (GEF1) and GEF2 domains in regulating radial migration by activating their Rho GTPase effectors in both distinct and cooperative manners, which might be associated with the abnormal phenotypes in neurodevelopmental disorders.
Autism Spectrum Disorder/metabolism* ; Cell Movement/genetics* ; Humans ; Interneurons/metabolism* ; Neurodevelopmental Disorders/genetics* ; Neurons/metabolism* ; Rho Guanine Nucleotide Exchange Factors/genetics*

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.
Animals ; B-Lymphocytes/*cytology/*metabolism ; Cell Differentiation/genetics/*physiology ; Cell Line ; Cells, Cultured ; Female ; Guanine Nucleotide Exchange Factors/genetics/*metabolism ; Humans ; Lymphocyte Activation/genetics/*physiology ; Mice ; Mice, Inbred BALB C ; Plasma Cells/*cytology/*metabolism ; rhoA GTP-Binding Protein/genetics/metabolism

Adult ; Aged ; Aged, 80 and over ; Female ; Guanine Nucleotide Exchange Factors ; genetics ; metabolism ; Humans ; Keratin-18 ; genetics ; metabolism ; Lymph Nodes ; metabolism ; pathology ; Lymphatic Metastasis ; Male ; Middle Aged ; RNA, Messenger ; metabolism ; Stomach Neoplasms ; metabolism ; pathology ; T-Lymphoma Invasion and Metastasis-inducing Protein 1

BACKGROUNDT-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.

METHODSWe 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.

RESULTSTiam1 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.

CONCLUSIONSIn 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.

Cell Line, Tumor ; Cell Movement ; genetics ; physiology ; Cell Proliferation ; Guanine Nucleotide Exchange Factors ; genetics ; metabolism ; Humans ; Neoplasm Metastasis ; genetics ; Stomach Neoplasms ; genetics ; metabolism ; pathology ; T-Lymphoma Invasion and Metastasis-inducing Protein 1

OBJECTIVETo investigate the expression of T lymphoma invasion and metastasis inducing factor 1 (Tiam1) in breast carcinomas, and explore its association with the clinicopathological features of breast carcinoma.

METHODSImmunohistochemistry was used to detect Tiam1 expression in normal breast tissue and 126 breast carcinoma tissues, and the expression levels of Tiam1 mRNA and protein were detected by reverse transcriptase polymerase chain reaction (RT-PCR) and Western blotting, respectively.

RESULTSThe expression of Tiam1 was significantly higher in breast carcinomas than in normal breast tissue (P<0.05). Tiam1 expression was not correlated to the age of the patients or the histological type (P>0.05), but to lymph node metastasis and clinical stages of the tumor (P<0.01). Tiam1 mRNA and protein expressions were stronger in breast carcinoma cell line MDA-MB-435 with high metastatic potential than in breast carcinoma cell line MCF-7.

CONCLUSIONTiam1 is closely related to the metastasis of breast carcinoma, and may play an important role in promoting metastasis of breast carcinoma.

Adult ; Aged ; Breast Neoplasms ; metabolism ; pathology ; Cell Line, Tumor ; Female ; Guanine Nucleotide Exchange Factors ; genetics ; metabolism ; Humans ; Lymphatic Metastasis ; Middle Aged ; RNA, Messenger ; genetics ; metabolism ; Reverse Transcriptase Polymerase Chain Reaction ; T-Lymphoma Invasion and Metastasis-inducing Protein 1

OBJECTIVETo investigate whether the Tiam1 gene expression enhances the invasive and metastatic capabilities of colorectal carcinoma cells.

METHODSEndogenous expression of Tiam1 in five colorectal carcinoma cell lines was investigated by RT-PCR. Tiam1/C1199HA cDNA was transfected into HT29, a colorectal carcinoma cell line without endogenous Tiam1 expression. RNA and protein expression of Tiam1 gene in the transfectants were detected by RT-PCR, immunohistochemistry and Western blot respectively. The biological behaviors of the transfectants were investigated by MTT and in-vitro invasion assays.

RESULTSTiam1 gene was highly expressed in LoVo and SW620 cells. Low level expression was seen in HCT116 and SW480 and no expression was found in HT29. Transfection of Tiam1 significantly increased the proliferation of HT29 cells along with markedly enhanced in-vitro invasion and metastasis.

CONCLUSIONSTiam1 gene plays an important role in the invasion and metastasis of colorectal carcinoma. It may be a useful marker for metastasis of colorectal carcinoma.

Biomarkers, Tumor ; Cell Line, Tumor ; Cell Proliferation ; Colorectal Neoplasms ; genetics ; metabolism ; pathology ; Gene Expression Regulation, Neoplastic ; Guanine Nucleotide Exchange Factors ; genetics ; metabolism ; physiology ; HT29 Cells ; Humans ; Neoplasm Invasiveness ; Neoplasm Metastasis ; T-Lymphoma Invasion and Metastasis-inducing Protein 1 ; Transfection

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.
Blotting, Western ; Carcinoma, Squamous Cell ; metabolism ; pathology ; Cell Line, Tumor ; Cell Movement ; Cell Proliferation ; Guanine Nucleotide Exchange Factors ; genetics ; metabolism ; Head and Neck Neoplasms ; metabolism ; pathology ; Humans ; Squamous Cell Carcinoma of Head and Neck ; T-Lymphoma Invasion and Metastasis-inducing Protein 1 ; Transfection

OBJECTIVETo explore biological aspects of Tiam1 gene expression in nasopharyngeal carcinoma cells.

METHODSTiam1/C1199HA expression plasmids were transfected into nasopharyngeal carcinoma cells of C666-1 and CNE1 by lipofectamine2000. RT-PCR, real-time PCR and Western blot Analyses were performed to evaluate the expression of Tiam1 mRNA and protein levels, respectively. In vitro cell adhesion, wound healing and matrigel invasion assays were used to study the biological impact of Tiam1 on cell adhesion, mobility and invasion.

RESULTSTiam1 over expression significantly increased the abilities of adhesion, migratory and invasion of C666-1 and CNE1 cells, comparing with that of the control untransfected cells (P < 0.05).

CONCLUSIONTiam1 expression correlates with the invasion and metastasis of nasopharyngeal carcinoma cells.

Cell Adhesion ; Cell Line, Tumor ; Cell Movement ; Gene Expression Regulation, Neoplastic ; Guanine Nucleotide Exchange Factors ; genetics ; metabolism ; physiology ; Humans ; Nasopharyngeal Neoplasms ; metabolism ; pathology ; Neoplasm Invasiveness ; Neoplasm Metastasis ; Plasmids ; RNA, Messenger ; metabolism ; T-Lymphoma Invasion and Metastasis-inducing Protein 1

OBJECTIVETo investigate the relationship between the protein expression of T-lymphoma invasion and metastasis gene 1 (Tiam-1) and the biological behaviors of nasopharyngeal carcinoma (NPC).

METHODSImmunohistochemistry was performed to detect the expressions of Tiam-1 protein in 60 specimens of NPC tissue, 20 specimens of chronic nasopharyngitis (CN) tissue, and 6 tumor tissues from nude mice inoculated with metastatic human NPC cells.

RESULTSThe positivity rate and average score for Tiam-1 expression were significantly higher in NPC tissues than in CN tissue (63.33% vs 36.67%, 2.9167 +/- 1.3057 vs 0.7000 +/- 0.9234; chi(2)=20.429, P=0.001; t=7.0162, P=0.0000, respectively). No difference was found in Tiam-1 expression among NPC patients in different T stages (F=2.36, P=0.0811), while the expression differed significantly between the patients with lymph node metastasis and those without metastasis, and also between patients with organ metastasis and those without (P=0.0001). High Tiam-1 expressions were found in the tumor tissues in nude mice inoculated with metastatic NPC cells.

CONCLUSIONTiam-1 expression is closely associated with the invasiveness and metastasis of NPC, indicating that Tiam-1 is an important factor that promotes the invasion and metastasis of NPC.

Adult ; Aged ; Animals ; Female ; Guanine Nucleotide Exchange Factors ; genetics ; metabolism ; Humans ; Male ; Mice ; Mice, Nude ; Middle Aged ; Nasopharyngeal Neoplasms ; metabolism ; pathology ; Neoplasm Invasiveness ; Neoplasm Metastasis ; Neoplasm Transplantation ; T-Lymphoma Invasion and Metastasis-inducing Protein 1

OBJECTIVETo observe the effect of Tiam-l gene silencing on the metastasis of human colorectal carcinoma cell line SW480 in nude mice by real-time whole-body fluorescence imaging.

METHODSEnhanced green fluorescence protein (EGFP)-labeled human colorectal carcinoma cells, SW480/EGFP(+)/Tiam-1(-) and SW480/EGFP(+), were implanted into nude mice via tail vein injection or orthotopic colonal inoculation, and real-time whole-body fluorescence imaging was performed to compare the difference in tumor progression and metastasis between the two cells.

RESULTSBoth SW480/EGFP(+) and SW480/ EGFP(+)/Tiam-1(-) cells stably expressed EGFP, and Tiam1 gene expression was reduced in SW480/EGFP(+)Tiam-1(-) to 30% of the expression level in SW480/EGFP(+) cells. The growth rate of the two cell lines had no significant difference in vitro (P>0.05), but SW480/EGFP(+)/Tiam1(-) cell proliferation and metastasis were depressed obviously in comparison with SW480/EGFP(+) in vivo (P<0.05).

CONCLUSIONTiam-1 gene may play an important role in invasion and metastasis of human colorectal cancer.

Animals ; Blotting, Western ; Bone Neoplasms ; genetics ; metabolism ; secondary ; Cell Line, Tumor ; Cell Survival ; Colorectal Neoplasms ; genetics ; metabolism ; pathology ; Diagnostic Imaging ; methods ; Female ; Fluorescence ; Gene Silencing ; Green Fluorescent Proteins ; chemistry ; genetics ; metabolism ; Guanine Nucleotide Exchange Factors ; genetics ; metabolism ; Immunohistochemistry ; Liver Neoplasms ; genetics ; metabolism ; secondary ; Lung Neoplasms ; genetics ; metabolism ; secondary ; Mice ; Mice, Nude ; Microscopy, Fluorescence ; Neoplasm Transplantation ; T-Lymphoma Invasion and Metastasis-inducing Protein 1 ; Transplantation, Heterologous