Project description:The T lymphoma invasion and metastasis inducing protein 1 (TIAM1) is a guanine nucleotide exchange factor (GEF) that activates the small GTPase RAC1. We have shown that nuclear TIAM1promotes the migration of NSCLC cells. To investigate the requirement for TIAM1 in regulating gene expression of NSCLC cells, we performed RNA-seq on H441 cells transfected with either siRNA for TIAM1 (siTIAM1) or a control siRNA (siControl) to identify differentially expressed genes.
Project description:The T lymphoma invasion and metastasis inducing protein 1 (TIAM1) is a guanine nucleotide exchange factor (GEF) that activates the small GTPase RAC1. We have shown that nuclear TIAM1 promotes the migration of NSCLC cells and regulates the expression of adhesion genes as part of a repressive complex. To further investigate this, we performed ChIP-Seq analysis to determine the enrichment of TIAM1, TRIM28 and H3K9me3 to chromatin in H441 cells.
Project description:The T lymphoma invasion and metastasis inducing protein 1 (TIAM1) is a guanine nucleotide exchange factor (GEF) that activates the small GTPase RAC1 and regulates a plethora of functions such as cell proliferation, migration, apoptosis and polarity. Recently, we demonstrated that TIAM1 shuttles between the cytoplasm and nucleus. To determine the nuclear role of TIAM1, we performed RNA-seq on SW620 cells transfected either with a specific pre-validated siRNA for TIAM1 (siTIAM1) or a negative control siRNA (siNT) and generated a list of TIAM1 differentially expressed genes. GSEA revealed significant enrichment among TIAM1-regulated genes for YAP-associated molecular signature. To investigate the interplay of TIAM1 with YAP/TAZ we used RNA-seq, generated a list of YAP/TAZ differentially expressed genes from SW620 cells transfected either with specific siRNAs for YAP/TAZ or a negative control siRNA and compared it with the siTIAM1 RNA-seq dataset. Interestingly, we found that 50% of the TAZ/YAP regulated genes were also TIAM1 dependent.
Project description:Lung cancer is the leading cause of cancer deaths. Its high mortality is associated with high metastatic potential. Here, we show that the RAC1-selective guanine nucleotide exchange factor T cell invasion and metastasis-inducing protein 1 (TIAM1) promotes cell migration and invasion in the most common subtype of lung cancer, non-small-cell lung cancer (NSCLC), through an unexpected nuclear function. We show that TIAM1 interacts with TRIM28, a master regulator of gene expression, in the nucleus of NSCLC cells. We reveal that a TIAM1-TRIM28 complex promotes epithelial-to-mesenchymal transition, a phenotypic switch implicated in cell migration and invasion. This occurs through H3K9me3-induced silencing of protocadherins and by decreasing E-cadherin expression, thereby antagonizing cell–cell adhesion. Consistently, TIAM1 or TRIM28 depletion suppresses the migration of NSCLC cells, while migration is restored by the simultaneous depletion of protocadherins. Importantly, high nuclear TIAM1 in clinical specimens is associated with advanced-stage lung adenocarcinoma, decreased patient survival, and inversely correlates with E-cadherin expression.
Project description:The T lymphoma invasion and metastasis inducing protein 1 (TIAM1) is a guanine nucleotide exchange factor (GEF) that activates the small GTPase RAC1 and regulates a plethora of functions such as cell proliferation, migration, apoptosis and polarity. Recently, we demonstrated that TIAM1 shuttles between the cytoplasm and nucleus. Nuclear TIAM1 has an inhibitory role on TAZ transcriptional activity by impairing the interaction of TAZ with TEAD. To further demonstrate the inhibitory role of TIAM1 on TAZ we performed ChIP-Seq analysis to determine the enrichment of TAZ to chromatin of parental or CRISPR-mediated TIAM1 knockout SW480 cells.
Project description:We hypothesized that Tiam1 is involved in invassiveness of retinoblastoma. The fuctional role of Tiam1 in cell progression and metastasis was tested by siRNA mediated knockdown of Tiam1 in retinoblastoma Y79 cells. The genes de-regulated in response to Tiam1 knockdown was analysed by cDNA microarray in which most of the actin cytoskeleton regulation proteins and apoptotic proteins were de-regulated. our results prove that Tiam1 modulates actin cytoskeleton and cell invasion in retinoblastoma. Retinoblastoma Y79 cells were treated with Tiam1 siRNA for 48hrs and cDNA microarray was performed to analyze the genes regulated by Tiam1 silencing compared to untreated Y79 cells. Experiments were performed in triplicates.
Project description:Rac GTPases are required for neutrophil adhesion and migration, and for the neutrophil effector responses that kill pathogens. These Rac-dependent functions are impaired when neutrophils lack the activators of Rac, Rac-GEFs from the Prex, Vav and Dock families. In this study, we demonstrate that Tiam1 is also expressed in neutrophils, governing focal complexes, actin cytoskeletal dynamics, polarisation and migration, in a manner depending on the integrin ligand to which the cells adhere. Tiam1 is dispensable for the generation of reactive oxygen species but mediates degranulation and NETs release in adherent neutrophils, as well as the killing of bacteria. In vivo, Tiam1 is required for neutrophil recruitment during aseptic peritonitis and for the clearance of Streptococcus pneumoniae during pulmonary infection. However, Tiam1 functions differently to other Rac-GEFs. Instead of promoting neutrophil adhesion to ICAM1 and stimulating β2 integrin activity as could be expected, Tiam1 restricts these processes. In accordance with these paradoxical inhibitory roles, Tiam1 limits the fMLP-stimulated activation of Rac1 and Rac2 in adherent neutrophils, rather than activating Rac as expected. Tiam1 promotes the expression of several regulators of small GTPases and cytoskeletal dynamics, including αPix, Psd4, Rasa3 and Tiam2. It also controls the association of Rasa3, and potentially αPix, Git2, Psd4 and 14‐3‐3ζ/δ, with Rac. We propose these latter roles of Tiam1 underlie its effects on Rac and β2 integrin activity and on cell responses. Hence, Tiam1 is a novel regulator of Rac-dependent neutrophil responses that functions differently to other known neutrophil Rac-GEFs.
Project description:We hypothesized that Tiam1 is involved in invassiveness of retinoblastoma. The fuctional role of Tiam1 in cell progression and metastasis was tested by siRNA mediated knockdown of Tiam1 in retinoblastoma Y79 cells. The genes de-regulated in response to Tiam1 knockdown was analysed by cDNA microarray in which most of the actin cytoskeleton regulation proteins and apoptotic proteins were de-regulated. our results prove that Tiam1 modulates actin cytoskeleton and cell invasion in retinoblastoma.
Project description:Metastasis is the key cause of failure of cancer therapy or mortality, but targeting metastatic seeding and colonization remains an unresolved challenge. Here, we report a novel molecular event in cancer metastasis mediated by NSD2/Rac1 signaling and provide a detailed mechanistic investigation of cancer metastasis. We found that NSD2, a histone methyltransferase responsible for di-methylating histone 3 at lysine 36, was overexpressed in metastatic tumors, and overexpressed NSD2 enhanced tumor metastasis both in vitro and in vivo. We further investigated that NSD2 promoted tumor metastasis by activating the Rac1 signaling pathway. Mechanistically, NSD2 methylated Tiam1, a guanine nucleotide exchange factor that facilitates GDP-Rac1 to GTP-Rac1 transition at K724. We demonstrated that Tiam1 K724 methylation plays a crucial role in Tiam1 activation and GDP-Rac1 to GTP-Rac1 transition. Specifically, we identified that Tiam1 K724 methylation could be a predictive factor in cancer prognosis, and we demonstrated that pharmacological blocking of Tiam1 K724 methylation by employing a transmembrane peptide inhibited tumor metastasis both in vitro and in vivo. Thus, NSD2-methylated Tiam1 promoted Rac1 signaling activation and cancer metastasis, which might provide novel insights into tumor metastasis inhibition.