Search results for RND1

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Identifier: R-HSA-9696273
Species: Homo sapiens
RND1 is an atypical RHO GTPase from the RND subfamily. RND1 is constitutively bound to GTP and lacks GTPase activity. No guanine nucleotide exchange factors (GEFs), GTPase activator proteins (GAPs) or guanine nucleotide dissociation inhibitors (GDIs) act on RND1. RND1 localizes to the plasma membrane, but can be extracted from the plasma membrane and sequestered to the cytosol upon phosphorylation-induced binding to 14-3-3 protein. RND1 antagonizes RHOA, leading to reduced actomyosin contractility and loss of stress fibers and focal adhesions, which results in a rounded cell phenotype. RND1 plays a role in embryogenesis, neuronal development, myometrium changes during pregnancy, and angiogenesis. RND1 is frequently downregulated in cancer and is implicated as a tumor suppressor, but may play an oncogenic role in some cancer types. RND1 expression increases in response to anti-cancer agents and in may be involved in resistance to treatment. For review, please refer to Mouly et al. 2019.
Identifier: R-HSA-9696270
Species: Homo sapiens
RND2 (RHON) is an atypical RHO GTPase and the least studied member of the RND subfamily. RND2 is constitutively bound to GTP and lacks GTPase activity. No guanine nucleotide exchange factors (GEFs), GTPase activator proteins (GAPs) or guanine nucleotide dissociation inhibitors (GDIs) act on RND2. RND2 is predominantly expressed in brain, testis and liver (Nobes et al. 1998; Nishi et al. 1999). RND2 regulates neurite outgrowth and branching (Fujita et al. 2002; Kakimoto et al. 2004; Tanaka et al. 2006; Wakita et al. 2011) and migration of newborn neurons within the embryonic cerebral cortex (Nakamura et al. 2006; Heng et al. 2008; Alfano et al. 2011; Pacary et al. 2011; Gladwyn-Ng et al. 2015; Heng et al. 2015).
Identifier: R-HSA-9012999
Species: Homo sapiens
RHO family of GTPases is large and diverse, with many of its members considered to be master regulators of actin cytoskeleton. RHO GTPases are involved in the regulation of many cellular processes that depend on dynamic reorganization of the cytoskeleton, including cell migration, cell adhesion, cell division, establishment of cellular polarity and intracellular transport. As a consequence, RHO GTPases play important roles in neuronal development, immunity and cardio-vascular homeostasis. RHO GTPases are involved in the etiology of infectious diseases, congenital immunodeficiencies, neurodegenerative diseases and cancer. For review, please refer to Jaffe and Hall 2005, Lemichez and Aktories 2013, Ridley 2015, Hodge and Ridley 2016, Haga and Ridley 2016, Olson 2018, and Kalpachidou et al. 2019.

Phylogenetically, RHO GTPases can be grouped into four clusters. The first cluster consists of three subfamilies: Rho, RhoD/RhoF and Rnd. The second cluster consists of three subfamilies: Rac, Cdc42 and RhoU/RhoV. The third cluster consists of the RhoH subfamily. The fourth cluster consists of the RhoBTB subfamily. Miro GTPases and RHOBTB3 ATPase are sometimes described as Rho family members, but they are phylogenetically distant from the Rho family and constitute two separate families of Ras-like GTPases, which, besides Rho, Miro and RHOBTB3 also includes Ran, Arf, Rab and Ras families (Boureux et al. 2007). Based on their activation type, RHO GTPases can be divided into classical (typical) and atypical (reviewed by Haga and Ridley 2016, and Kalpachidou et al. 2019). Classical RHO GTPases cycle between active GTP-bound states and inactive GDP-bound states through steps that are tightly controlled by members of three classes of proteins: (1) guanine nucleotide dissociation inhibitors or GDIs, which maintain Rho proteins in an inactive state in the cytoplasm, (2) guanine nucleotide exchange factors or GEFs, which destabilize the interaction between Rho proteins and their bound nucleotide, the net result of which is the exchange of bound GDP for the more abundant GTP, and (3) GTPase activating proteins or GAPs, which stimulate the low intrinsic GTP hydrolysis activity of Rho family members, thus promoting their inactivation. GDIs, GEFs, and GAPs are themselves subject to tight regulation, and the overall level of Rho activity reflects the balance of their activities. Many of the Rho-specific GEFs, GAPs, and GDIs act on multiple Rho GTPases, so that regulation of these control proteins can have complex effects on the functions of multiple Rho GTPases (reviewed by Van Aelst and D'Souza-Schorey 1997, and Hodge and Ridley 2016). The classical Rho GTPase cycle is diagrammed in the figure below. External or internal cues promote the release of Rho GTPases from the GDI inhibitory complexes (1) which allows them to associate with the plasma membrane (2), where they are activated by GEFs (3), and can signal to effector proteins (3.5). Then, GAPs inactivate the GTPases by accelerating the intrinsic GTPase activity, leading to the GDP bound form (4). Once again, the GDI molecules stabilize the inactive GDP bound form in the cytoplasm, waiting for further instructions (5) (Tcherkezian and Lamarche-Vane, 2007). Classical RHO GTPases include four subfamilies: Rho (includes RHOA, RHOB and RHOC), Rac (includes RAC1, RAC2, RAC3 and RHOG), Cdc42 (includes CDC42, RHOJ and RHOQ) and RhoD/RhoF (includes RHOD and RHOF). RHOA, the founding member of the RHO GTPase family, regulates the actin cytoskeleton, formation of stress fibers and cell contractility, which is implicated in cell adhesion and migration (Lessey et al. 2012). RHOB and RHOC functions resemble RHOA (Vega and Ridley 2018; Guan et al. 2018). RHOB is also involved in membrane trafficking and DNA repair (Vega and Ridley 2018). RAC1 regulates the cytoskeleton and the production of reactive oxygen species (ROS) (Acevedo and Gonzalez-Billault 2018), and is involved in cell adhesion and cell migration (Marei and Malliri 2017). RAC2 expression is restricted to hematopoietic cells and RAC2 is a component of the phagocytic oxidase complex in neutrophils (Troeger and Williams 2013). RAC3 shares 92% sequence identity with RAC1 and is highly expressed in neurons (de Curtis 2019). CDC42 regulate the cytoskeleton and cell polarity, and is involved in cell adhesion and migration as well as in intracellular membrane trafficking (Egorov and Polishchuk 2017; Xiao et al. 2018; Pichaud et al. 2019; Woods and Lew 2019). RHOJ is highly expressed in endothelial cells, regulating their motility and vascular morphogenesis (Leszczynska et al. 2011; Shi et al. 2016). RHOQ is highly activated on exocytosing vesicles and recycling endosomes (Donnelly et al. 2014) and is involved in trafficking of CFTR (cystic fibrosis transmembrane conductance regulator) (Cheng et al. 2005). RHOD regulates cytoskeletal dynamics and intracellular transport of vesicles (Randazzo 2003; Gad and Aspenstrom 2010; Aspenstrom et al. 2014). RHOF regulates cytoskeletal dynamics (Gad and Aspenstrom 2010; Aspenstrom et al. 2014) and promotes the formation of filopodia and stress fibers (Fan and Mellor 2012). RHOD and RHOF do possess GTPase activity and are therefore grouped with classical RHO GTPases, but they are atypical in the sense that they possess high intrinsic guanine nucleotide exchange activity and do not require GEFs for activation.

Atypical RHO GTPases do not possess GTPase activity. They therefore constitutively exist in the active GTP-bound state. Atypical RHO GTPases include three subfamilies: Rnd (includes RND1, RND2 and RND3), RhoBTB (includes RHOBTB1 and RHOBTB2), RhoH (RHOH is the only member) and RhoU/RhoV (includes RHOU and RHOV). RND1 and RND3 can antagonize RHOA activity, leading to loss of stress fibers and cell rounding (Haga and Ridley 2016). RND1, RND2 and RND3 regulate cell migration (Ridley 2015; Mouly et al. 2019). RHOBTB1 is a component of a signaling cascade that regulates vascular function and blood pressure (Ji and Rivero 2016). RHOBTB2 is involved in COP9 signalosome-regulated and CUL3-dependent protein ubiquitination (Berthold et al. 2008; Ji and Rivero 2016). RHOH expression is restricted to hematopoietic cells, and it is known to be involved in T cell receptor (TCR) signaling and T cell development (Suzuki and Oda 2008; Troeger and Williams 2013). RHOU and RHOV expression is induced by WNT signaling and they are involved in regulation of cell shape and cell adhesion (Faure and Fort 2015; and Hodge and Ridley 2016).

Almost every classical RHO GTPase interacts with multiple GEFs, GAPs and GDIs, and every RHO GTPase activates multiple downstream effectors. There are 82 Rho GEFs (71 Dbl, reviewed in Fort and Blangy 2017, and 11 DOCK, reviewed in Meller et al. 2005), 66 Rho GAPs (Amin et al. 2016) and 3 Rho GDIs (Dransart et al. 2005) encoded by the human genome. To keep our reaction annotations compact, we have grouped the GEF, GAP, GDI and effector proteins associated with each RHO GTPase into sets. Within a set, we have distinguished full set members from candidate members on the basis of the amount of experimental evidence supporting the member’s molecular function. Note that members of a set can otherwise be functionally quite diverse. Annotation of upstream activators of GEFs, GAPs and GDIs was outside the scope of this catalogue pathway and is or will be shown elsewhere in Reactome. Signaling through downstream effectors is shown in more detail in the Reactome pathway “RHO GTPase Effectors”.
Identifier: R-HSA-416550
Species: Homo sapiens
Compartment: plasma membrane
Repulsive Sema4D-Plexin-B1 signaling involves four GTPases, Rnd1, R-Ras, Rho and Rac1. Sema4D-Plexin-B1 binding promotes Rnd1-dependent activation of the plexin-B1 GAP domain and transient suppression of R-Ras activity. R-Ras inactivation promotes PI3K and Akt inactivation followed by GSK-3beta activation and CRMP2 inactivation. Plexin-B1 also transiently associates with and activates p190Rho-GAP, triggering a transient decrease in activated Rho.
Identifier: R-HSA-9696264
Species: Homo sapiens
RND3 (RHOE) is an atypical RHO GTPase from the RND subfamily. RND3 is constitutively bound to GTP and lacks GTPase activity. No guanine nucleotide exchange factors (GEFs), GTPase activator proteins (GAPs) or guanine nucleotide dissociation inhibitors (GDIs) act on RND3. RND3 is a direct antagonist of ROCK1 kinase activity. RND3 prevents phosphorylation of ROCK1 targets and, similar to RND1, induces stress fiber disassembly. RND3 regulates cell migration, establishment of neuronal polarity, heart development, and myometrium changes during pregnancy. Defective RND3 function is related to cardiomyopathy, hydrocephalus and cancer. Like RND1, RND3 is implicated both as a tumor suppressor and an oncogene in cancer, and can both increase and decrease sensitivity to chemotherapeutic agents, which depends on cancer type and stage. For review, please refer to Jie et al. 2015 and Paysan et al. 2016.
Identifier: R-HSA-194315
Species: Homo sapiens
The Rho family of small guanine nucleotide binding proteins is one of five generally recognized branches of the Ras superfamily. Like most Ras superfamily members, typical Rho proteins function as binary switches controlling a variety of biological processes. They perform this function by cycling between active GTP-bound and inactive GDP-bound conformations. Mammalian Rho GTPases include RhoA, RhoB and RhoC (Rho proteins), Rac1 3 (Rac proteins), Cdc42, TC10, TCL, Wrch1, Chp/Wrch2, RhoD and RhoG, to name some. The family also includes RhoH and Rnd1-3, which lack GTPase activity and are predicted to exist in a constitutively active state.

Members of the Rho family have been identified in all eukaryotes. Including the atypical RHOBTB1-3 and RHOT1-2 proteins, 24 Rho family members have been identified in mammals (Jaffe and Hall, 2005; Bernards, 2005; Ridley, 2006). Among Rho GTPases, RhoA, Rac1 and Cdc42 have been most extensively studied. These proteins are best known for their ability to induce dynamic rearrangements of the plasma membrane-associated actin cytoskeleton (Aspenstrom et al, 2004; Murphy et al, 1999; Govek et al, 2005). Beyond this function, Rho GTPases also regulate actomyosin contractility and microtubule dynamics. Rho mediated effects on transcription and membrane trafficking are believed to be secondary to these functions. At the more macroscopic level, Rho GTPases have been implicated in many important cell biological processes, including cell growth control, cytokinesis, cell motility, cell cell and cell extracellular matrix adhesion, cell transformation and invasion, and development (Govek et al., 2005). The illustration below lists Rho GTPase effectors implicated in actin and microtubule dynamics (courtesy: Govek et al., 2005, Genes and Development, CSHL Press).

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