Project description:Delineating the mechanisms controlling the invasive spread of non-diseased and transformed cells is central to understanding diverse processes including cancer progression. Here, we found that Yes-associated protein (YAP), a central transcriptional regulator implicated in controlling organ and body size, modulated a Rho-GTPase switch that drives cellular migration by transactivating the Rac1-GEF protein TRIO through direct modulation of its intronic enhancer. Additionally, YAP and TRIO may promote invasive behavior through putative crosstalk with STAT3 signaling, a potential downstream target. Although we found this YAP-dependent infiltrative program in many cell types, it was particularly enhanced in a patient-specific manner in the most common malignant brain tumor, glioblastoma (GBM), where hyperactivation of the YAP, TRIO, and STAT3 signatures also conferred poor clinical outcome. Our analysis suggests that the YAP-TRIO-Rho-GTPase signaling network identified in this study is a ubiquitous regulator of invasive cell spread in both physiological and pathological contexts. In this dataset, we knocked down YAP in two patient-derived GBM primary cell lines (JHGB612 and JHGB651) and performed microarray analysis.
Project description:RhoBTB2 is a novel Rho GTPase that undergoes loss, underexpression and mutation in breast and lung cancer. We have shown that we can mimic loss of RhoBTB2 through siRNA treatment of primary cells. We propose to perform comparative microarray analysis of primary lung cells to establish the identification of the gene targets of RhoBTb2 regulation. Keywords: Effects of siRNA expression
Project description:The aim of this study is to characterize the mechanistic role of TRIM67 in glioma biogenesis. Towards this goal, here we utilized engineered human neural stem cells and patient-derived tumor sphere lines with or without IDH mutations and 1p/19q co-deletions to study the function of TRIM67 in gliomas. We found that upregulated TRIM67 induces membrane blebbing through Rho GTPase-mediated signaling, resulting in more advanced cell motility and tumor expansion.
Project description:Although Rho GTPases are essential molecular switches involved in many cellular processes, an unbiased experimental comparison of their interaction partners was not yet performed. Here, we develop quantitative GTPase affinity purification (qGAP) to systematically identify interaction partners of six Rho GTPases (Cdc42, Rac1, RhoA, RhoB, RhoC, RhoD) depending on their nucleotide loading state. We use Stable isotope labeling by Amino acids in cell culture (SILAC) and label free quantification (LFQ). Our interaction network contains many new proteins, reveals highly promiscuous binding of several effectors and mirrors evolutionary relationships of Rho GTPases.
Project description:Cell migration is dependent on the dynamic formation and disassembly of actin filament-based structures, including lamellipodia, filopodia, invadopodia, and membrane blebs, as well as on cell-cell and cell-extracellular matrix adhesions. These processes all involve Rho family small guanosine triphosphatases (GTPases), which are regulated by the opposing actions of guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs). Rho GTPase activity needs to be precisely tuned at distinct cellular locations to enable cells to move in response to different environments and stimuli. In this review, we focus on the ability of RhoGEFs and RhoGAPs to form complexes with diverse binding partners, and describe how this influences their ability to control localized GTPase activity in the context of migration and invasion.
Project description:Splicing dysregulations extensively occur in cancers, yet the biological consequences of such alterations are mostly undefined. Here we report that the Hippo-YAP signaling, a key pathway that regulates cell proliferation and organ size, is under control of a new splicing switch. We show that TEAD4, the transcription factor that mediates Hippo-YAP signaling, undergoes alternative splicing facilitated by the tumor suppressor RBM4, producing a truncated isoform, TEAD4-S, which lacks N-terminal DNA-binding domain but maintains YAP-interaction domain. TEAD4-S is located in both nucleus and cytoplasm, acting as a dominant negative isoform to YAP activity. Consistently, TEAD4-S is reduced in cancer cells, and its re-expression suppresses cancer cell proliferation and migration, inhibiting tumor growth in xenograft mouse model. Furthermore, TEAD4-S is reduced in human cancers, and patients with elevated TEAD4-S levels have improved survival. Altogether these data reveal a novel RBM4-mediated splicing switch that serves to fine-tune Hippo-YAP pathway. Cell lines stably expressing YAP, YAP/TEAD4-S, YAP/TEAD4-FL, YAP/RBM4 and control vector were created, and the total RNA was purified from the cells using TRIzol reagents. The polyadenylated RNAs were purified for construction of sequencing library using kapa TruSeq Total RNA Sample Prep kits (UNC High Throughput Sequencing Facility).
Project description:Small GTPase proteins usually serve as molecular switches in various biological process, such as the proliferation, survival, and migration of cells. Mutations or aberrant activations of small GTPase proteins, such as Ras, are frequently observed in various kinds of cancers. Drug discovery efforts that target the Ras family proteins are making breakthroughs, while the discovery of efficient inhibitors that target the Rho family proteins is still stagnant. Protein members from the Rho family, such as RhoA and Cdc42, are key regulators of the migration and invasion of cancer cells. Thus inhibitors of the Rho family proteins are promising to become drug candidates that target cancer metastasis, which is a principal cause of cancer recurrence and chemotherapy failure. Here we show the discovery and characterization of a novel covalent inhibitor named DC-RC-063 that targets the Rho family proteins, using a combined approach of computations and experiments. Revealed by solved crystal structures, compound DC-RC-063 inhibited the activation of RhoA, by disrupting protein-protein interactions, in an allosteric manner. As compound DC-RC-063 inhibited the migration and invasion of breast cancer MDA-MB-231 cells, our findings proved that the Rho family proteins are targetable for covalent inhibitors via an allosteric mechanism. The novel binding site revealed by this inhibitor can be exploited for further development of anti-cancer drugs that target cancer metastasis.
Project description:Lymphatic drainage generates force that induces prostate cancer cell motility via activation of Yes-associated protein (YAP), but whether this response to fluid force is conserved across cancer types is unclear. Here, we show that shear stress corresponding to fluid flow in the initial lymphatics modifies taxis in breast cancer. Whereas some cell lines employ rapid amoeboid migration behavior in response to fluid flow, a separate subset decrease movement. Positive responders displayed transcriptional profiles typical of an amoeboid cell state. Regulation of the HIPPO tumor suppressor pathway and YAP activity also differed between breast subsets and prostate cancer. Although subcellular localization of YAP to the nucleus positively correlated with overall velocity of locomotion, YAP gain- and loss-of-function demonstrates that YAP inhibits breast cancer motility but is outcompeted by other pro-taxis mediators in the context of flow. Specifically, we show that RhoA dictates response to flow. GTPase activity of RhoA, but not Rac1 or Cdc42 Rho family GTPases, is elevated in cells that positively respond to flow and is unchanged in cells that decelerate under flow. Disruption of RhoA or the RhoA effector, Rho-associated kinase (ROCK), blocked shear stress-induced motility. Collectively, these findings demonstrate stratification of breast cancer subsets by flow-sensing mechanotransduction pathways and point to a role for biophysical force in regulation of an amoeboid cell state.
Project description:This is a ordinary differential equation mathematical model describing the Rho GTPase cycle in which Rho GDP-dissociation inhibitors (RhoGDIs) inhibit the regulatory activities of guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs) by interacting with them directly as well as by sequestering the Rho GTPases. The model was constructed with the intent of analyzing the role of RhoGDIs in Rho GTPase signaling.