Focal adhesions are foci for tyrosine-based signal transduction via GIV/Girdin and G proteins.

GIV/Girdin is a multimodular signal transducer and a bona fide metastasis-related protein. As a guanidine exchange factor (GEF), GIV modulates signals initiated by growth factors (chemical signals) by activating the G protein Gαi. Here we report that mechanical signals triggered by the extracellular matrix (ECM) also converge on GIV-GEF via β1 integrins and that focal adhesions (FAs) serve as the major hubs for mechanochemical signaling via GIV. GIV interacts with focal adhesion kinase (FAK) and ligand-activated β1 integrins. Phosphorylation of GIV by FAK enhances PI3K-Akt signaling, the integrity of FAs, increases cell-ECM adhesion, and triggers ECM-induced cell motility. Activation of Gαi by GIV-GEF further potentiates FAK-GIV-PI3K-Akt signaling at the FAs. Spatially restricted signaling via tyrosine phosphorylated GIV at the FAs is enhanced during cancer metastasis. Thus GIV-GEF serves as a unifying platform for integration and amplification of adhesion (mechanical) and growth factor (chemical) signals during cancer progression

Activation of G proteins by GIV-GEF is a pivot point for insulin resistance and sensitivity.

Insulin resistance (IR) is a metabolic disorder characterized by impaired insulin signaling and cellular glucose uptake. The current paradigm for insulin signaling centers upon the insulin receptor (InsR) and its substrate IRS1; the latter is believed to be the sole conduit for postreceptor signaling. Here we challenge that paradigm and show that GIV/Girdin, a guanidine exchange factor (GEF) for the trimeric G protein Gαi, is another major hierarchical conduit for the metabolic insulin response. By virtue of its ability to directly bind InsR, IRS1, and phosphoinositide 3-kinase, GIV serves as a key hub in the immediate postreceptor level, which coordinately enhances the metabolic insulin response and glucose uptake in myotubes via its GEF function. Site-directed mutagenesis or phosphoinhibition of GIV-GEF by the fatty acid/protein kinase C-theta pathway triggers IR. Insulin sensitizers reverse phosphoinhibition of GIV and reinstate insulin sensitivity. We also provide evidence for such reversible regulation of GIV-GEF in skeletal muscles from patients with IR. Thus GIV is an essential upstream component that couples InsR to G-protein signaling to enhance the metabolic insulin response, and impairment of such coupling triggers IR. We also provide evidence that GIV-GEF serves as therapeutic target for exogenous manipulation of physiological insulin response and reversal of IR in skeletal muscles

The Veterans Health Administration: Quality, Value, Accountability, and Information as Transforming Strategies for Patient-Centered Care

Abstract Countries around the world are in need of electronic medical record (EMR) systems that meet their specific needs. This paper describes briefly the benefits of EMRs in developing countries. It focuses on the basic EMR information, including types of EMRs, components of EMRs, and already existing EMRs, in order to establish which EMR systems would be feasible and effective for specific situations. Electronic Medical Record Systems for Developing Countries: Review Structure of Systems A. Data Model • Flat file structures (spread-sheet like) as compared with relational databases B. Networks • Stand-alone • Systems which are deployed on a single machine • Local area networks • Wide area network solutions • Deployed across a much larger area Discussion When choosing which electronic medical record system to implement, one should consider the following factors: population, location, and availability of resources. OpenMRS may be the best choice for today's EMR

Allosteric mechanisms and consequences of Gi activation via the Guanine-nucleotide Exchange Modulator, GIV

Heterotrimeric G proteins act as molecular switches that gate the flow of information from extracellular cues to intracellular effectors that control cell behavior. Canonically, G Protein-Coupled Receptors (GPCRs) activate G proteins by stimulating GDP to GTP exchange on the G subunit. It has also been extensively documented that G proteins can be non-canonically activated downstream of non-GPCRs, including Receptor Tyrosine Kinases (RTKs). RTKs are traditionally thought to transduce completely distinct signals via phosphorylation of downstream signaling adaptors, but increasing evidence suggests that these two signaling hubs cross-talk to form an integrated signaling network. One recently discovered cross-talk mechanism is mediated via the novel guanine-nucleotide exchange modulator (GEM), GIV. GIV’s C-terminus possesses a unique molecular make-up, containing an SH2-like domain and a GEM motif. The combination of these protein-binding modules allows the formation of RTK-GIV-Gi complexes where GIV can activate Gi in response to growth factor stimulation. Unlike canonical GPCR-mediated G protein signaling however, the structural basis for non-canonical GIV-mediated G protein activation, particularly downstream of growth factor stimulation, remained largely unknown. My dissertation work sought to fill this gap in knowledge by unravelling what binding of GIV may structurally do to Gi to stimulate GDP release, as well as investigating alternative RTK-dependent and GIV-dependent mechanisms of G protein activation. Using structural, computational, and biochemical approaches, I revealed the structural and dynamical basis for GPCR-independent Gi activation by GEMs and found key similarities and differences between GPCR-dependent and -independent G protein activation, specifically identifying the hydrophobic core of Gi as a common allosteric route toward GDP release utilized by both GPCRs and GEMs. Furthermore, I investigated an alternative but parallel GIV-dependent mechanism of RTK-mediated G protein activation via direct RTK phosphorylation of tyrosine residues within the interdomain cleft of Gi. These RTK phosphorylated tyrosines are essential for Gi activation and signaling in cells, and cancer mutation of these tyrosines results in hyperactive G protein. Taken together, my dissertation has formed a holistic understanding, at the atomic level, of the diverse allosteric mechanisms and consequences of non-canonical GIV-mediated G protein activation

Allosteric mechanisms and consequences of Gi activation via the Guanine-nucleotide Exchange Modulator, GIV

Heterotrimeric G proteins act as molecular switches that gate the flow of information from extracellular cues to intracellular effectors that control cell behavior. Canonically, G Protein-Coupled Receptors (GPCRs) activate G proteins by stimulating GDP to GTP exchange on the G subunit. It has also been extensively documented that G proteins can be non-canonically activated downstream of non-GPCRs, including Receptor Tyrosine Kinases (RTKs). RTKs are traditionally thought to transduce completely distinct signals via phosphorylation of downstream signaling adaptors, but increasing evidence suggests that these two signaling hubs cross-talk to form an integrated signaling network. One recently discovered cross-talk mechanism is mediated via the novel guanine-nucleotide exchange modulator (GEM), GIV. GIV’s C-terminus possesses a unique molecular make-up, containing an SH2-like domain and a GEM motif. The combination of these protein-binding modules allows the formation of RTK-GIV-Gi complexes where GIV can activate Gi in response to growth factor stimulation. Unlike canonical GPCR-mediated G protein signaling however, the structural basis for non-canonical GIV-mediated G protein activation, particularly downstream of growth factor stimulation, remained largely unknown. My dissertation work sought to fill this gap in knowledge by unravelling what binding of GIV may structurally do to Gi to stimulate GDP release, as well as investigating alternative RTK-dependent and GIV-dependent mechanisms of G protein activation. Using structural, computational, and biochemical approaches, I revealed the structural and dynamical basis for GPCR-independent Gi activation by GEMs and found key similarities and differences between GPCR-dependent and -independent G protein activation, specifically identifying the hydrophobic core of Gi as a common allosteric route toward GDP release utilized by both GPCRs and GEMs. Furthermore, I investigated an alternative but parallel GIV-dependent mechanism of RTK-mediated G protein activation via direct RTK phosphorylation of tyrosine residues within the interdomain cleft of Gi. These RTK phosphorylated tyrosines are essential for Gi activation and signaling in cells, and cancer mutation of these tyrosines results in hyperactive G protein. Taken together, my dissertation has formed a holistic understanding, at the atomic level, of the diverse allosteric mechanisms and consequences of non-canonical GIV-mediated G protein activation

GIV/girdin binds exocyst subunit-Exo70 and regulates exocytosis of GLUT4 storage vesicles

Insulin resistance (IR) is a metabolic disorder characterized by impaired glucose uptake in response to insulin. The current paradigm for insulin signaling centers upon the insulin receptor (InsR) and its substrate IRS1; the latter is believed to be the chief conduit for post-receptor signaling. We recently demonstrated that GIV, a Guanidine Exchange Factor (GEF) for the trimeric G protein, Gαi, is a major hierarchical conduit for the metabolic insulin response. By virtue of its ability to directly bind the InsR, IRS1 and PI3K, GIV enhances the InsR-IRS1-Akt-AS160 (RabGAP) signaling cascade and cellular glucose uptake via its GEF function. Phosphoinhibition of GIV-GEF by the fatty-acid/PKCθ pathway inhibits the cascade and impairs glucose uptake. Here we show that GIV directly and constitutively binds the exocyst complex subunit Exo-70 and also associates with GLUT4-storage vesicles (GSVs) exclusively upon insulin stimulation. Without GIV or its GEF function, membrane association of Exo-70 as well as exocytosis of GSVs in response to insulin are impaired. Thus, GIV is an essential component within the insulin signaling cascade that couples upstream signal transducers within the InsR and G-Protein signaling cascade to downstream vesicular trafficking events within the exocytic pathway. These findings suggest a role of GIV in coordinating key signaling and trafficking events of metabolic insulin response

GIV•Kindlin Interaction Is Required for Kindlin-Mediated Integrin Recognition and Activation.

Cells perceive and respond to the extracellular matrix via integrin receptors; their dysregulation has been implicated in inflammation and cancer metastasis. Here we show that a guanine nucleotide-exchange modulator of trimeric-GTPase Gαi, GIV (a.k.a Girdin), directly binds the integrin adaptor Kindlin-2. A non-canonical short linear motif within the C terminus of GIV binds Kindlin-2-FERM3 domain at a site that is distinct from the binding site for the canonical NPxY motif on the -integrin tail. Binding of GIV to Kindlin-2 allosterically enhances Kindlin-2's affinity for β1-integrin. Consequently, integrin activation and clustering are maximized, which augments cell adhesion, spreading, and invasion. Findings elucidate how the GIV•Kindlin-2 complex has a 2-fold impact: it allosterically synergizes integrin activation and enables β1-integrins to indirectly access and modulate trimeric GTPases via the complex. Furthermore, Cox proportional-hazard models on tumor transcriptomics provide trans-scale evidence of synergistic interactions between GIV•Kindlin-2•β1-integrin on time to progression to metastasis

Focal adhesions are foci for tyrosine-based signal transduction via GIV/Girdin and G proteins.

GIV/Girdin is a multimodular signal transducer and a bona fide metastasis-related protein. As a guanidine exchange factor (GEF), GIV modulates signals initiated by growth factors (chemical signals) by activating the G protein Gαi. Here we report that mechanical signals triggered by the extracellular matrix (ECM) also converge on GIV-GEF via β1 integrins and that focal adhesions (FAs) serve as the major hubs for mechanochemical signaling via GIV. GIV interacts with focal adhesion kinase (FAK) and ligand-activated β1 integrins. Phosphorylation of GIV by FAK enhances PI3K-Akt signaling, the integrity of FAs, increases cell-ECM adhesion, and triggers ECM-induced cell motility. Activation of Gαi by GIV-GEF further potentiates FAK-GIV-PI3K-Akt signaling at the FAs. Spatially restricted signaling via tyrosine phosphorylated GIV at the FAs is enhanced during cancer metastasis. Thus GIV-GEF serves as a unifying platform for integration and amplification of adhesion (mechanical) and growth factor (chemical) signals during cancer progression