Characterization of a Cdc42 Protein Inhibitor and Its Use as a Molecular Probe

Cdc42 plays important roles in cytoskeleton organization, cell cycle progression, signal transduction, and vesicle trafficking. Overactive Cdc42 has been implicated in the pathology of cancers, immune diseases, and neuronal disorders. Therefore, Cdc42 inhibitors would be useful in probing molecular pathways and could have therapeutic potential. Previous inhibitors have lacked selectivity and trended toward toxicity. We report here the characterization of a Cdc42-selective guanine nucleotide binding lead inhibitor that was identified by high throughput screening. A second active analog was identified via structure-activity relationship studies. The compounds demonstrated excellent selectivity with no inhibition toward Rho and Rac in the same GTPase family. Biochemical characterization showed that the compounds act as noncompetitive allosteric inhibitors. When tested in cellular assays, the lead compound inhibited Cdc42-related filopodia formation and cell migration. The lead compound was also used to clarify the involvement of Cdc42 in the Sin Nombre virus internalization and the signaling pathway of integrin VLA-4. Together, these data present the characterization of a novel Cdc42-selective allosteric inhibitor and a related analog, the use of which will facilitate drug development targeting Cdc42-related diseases and molecular pathway studies that involve GTPases.This work was supported by National Science Foundation (NSF) Grant MCB0956027 and National Institutes of Health Grant R03 MH081231-01 from the Molecular Libraries Program (to A. W. N.); University of New Mexico Center for Molecular Discovery Molecular Libraries Probe Production Centers (UNMCMD MLPCN) National Institutes of Health Grants U54MH084690 and R01HL081062 (to L. A. S.); UNM National Center for Research Resources (NCRR) Grant 5P20RR016480 (to L. G. H.); National Institutes of Health Grant R21 CA170375-01 through the NCI (to A. W. N., L. G. H., and J. E. G.); National Institutes of Health Grants NS066429 and AI092130 (to T. B.); and University of Kansas Specialized Chemistry Center (KUSCC) MLPCN National Institutes of Health Grant U54HG005031 (to J. A.)

A Radio Flare in the Long-Lived Afterglow of the Distant Short GRB 210726A: Energy Injection or a Reverse Shock from Shell Collisions?

We present the discovery of the radio afterglow of the short $\gamma$-ray burst (GRB) 210726A, localized to a galaxy at a photometric redshift of $z\sim 2.4$. While radio observations commenced $\lesssim 1~$day after the burst, no radio emission was detected until $\sim11$~days. The radio afterglow subsequently brightened by a factor of $\sim 3$ in the span of a week, followed by a rapid decay (a ``radio flare''). We find that a forward shock afterglow model cannot self-consistently describe the multi-wavelength X-ray and radio data, and underpredicts the flux of the radio flare by a factor of $\approx 5$. We find that the addition of substantial energy injection, which increases the isotropic kinetic energy of the burst by a factor of $\approx 4$, or a reverse shock from a shell collision are viable solutions to match the broad-band behavior. At $z\sim 2.4$, GRB\,210726A is among the highest redshift short GRBs discovered to date as well as the most luminous in radio and X-rays. Combining and comparing all previous radio afterglow observations of short GRBs, we find that the majority of published radio searches conclude by $\lesssim 10~$days after the burst, potentially missing these late rising, luminous radio afterglows.Comment: 28 pages, 10 figures, submitted to Ap

A kilonova following a long-duration gamma-ray burst at 350 Mpc

Here, we report the discovery of a kilonova associated with the nearby (350 Mpc) minute-duration GRB 211211A. In tandem with deep optical limits that rule out the presence of an accompanying supernova to $M_I > -13$ mag at 17.7 days post-burst, the identification of a kilonova confirms that this burst's progenitor was a compact object merger. While the spectrally softer tail in GRB 211211A's gamma-ray light curve is reminiscent of previous extended emission short GRBs (EE-SGRBs), its prompt, bright spikes last $\gtrsim 12$ s, separating it from past EE-SGRBs. GRB 211211A's kilonova has a similar luminosity, duration and color to AT2017gfo, the kilonova found in association with the gravitational wave (GW)-detected binary neutron star (BNS) merger GW170817. We find that the merger ejected $\approx 0.04 M_{\odot}$ of r-process-rich material, and is consistent with the merger of two neutron stars (NSs) with masses close to the canonical $1.4 M_{\odot}$. This discovery implies that GRBs with long, complex light curves can be spawned from compact object merger events and that a population of kilonovae following GRBs with durations $\gg 2$ s should be accounted for in calculations of the NS merger r-process contribution and rate. At 350 Mpc, the current network of GW interferometers at design sensitivity would have detected the merger precipitating GRB 211211A, had it been operating at the time of the event. Further searches for GW signals coincident with long GRBs are therefore a promising route for future multi-messenger astronomy.Comment: Submitted. 69 pages, 11 figures, 3 table

Functionally Biased D2R Antagonists: Targeting the β‑Arrestin Pathway to Improve Antipsychotic Treatment

Schizophrenia is a severe neuropsychiatric disease that lacks completely effective and safe therapies. As a polygenic disorder, genetic studies have only started to shed light on its complex etiology. To date, the positive symptoms of schizophrenia are well-managed by antipsychotic drugs, which primarily target the dopamine D2 receptor (D2R). However, these antipsychotics are often accompanied by severe side effects, including motoric symptoms. At D2R, antipsychotic drugs antagonize both G-protein dependent (Gα_i/o) signaling and G-protein independent (β-arrestin) signaling. However, the relevant contributions of the distinct D2R signaling pathways to antipsychotic efficacy and on-target side effects (motoric) are still incompletely understood. Recent evidence from mouse genetic and pharmacological studies point to β-arrestin signaling as the major driver of antipsychotic efficacy and suggest that a β-arrestin biased D2R antagonist could achieve an additional level of selectivity at D2R, increasing the therapeutic index of next generation antipsychotics. Here, we characterize <b>BRD5814</b>, a highly brain penetrant β-arrestin biased D2R antagonist. <b>BRD5814</b> demonstrated good target engagement <i>via</i> PET imaging, achieving efficacy in an amphetamine-induced hyperlocomotion mouse model with strongly reduced motoric side effects in a rotarod performance test. This proof of concept study opens the possibility for the development of a new generation of pathway selective antipsychotics at D2R with reduced side effect profiles for the treatment of schizophrenia

A Systematic Framework to Rapidly Obtain Data on Patients with Cancer and COVID-19: CCC19 Governance, Protocol, and Quality Assurance

When the COVID-19 pandemic began, formal frameworks to collect data about affected patients were lacking. The COVID-19 and Cancer Consortium (CCC19) was formed to collect granular data on patients with cancer and COVID-19 at scale and as rapidly as possible. CCC19 has grown from five initial institutions to 125 institutions with >400 collaborators. More than 5,000 cases with complete baseline data have been accrued. Future directions include increased electronic health record integration for direct data ingestion, expansion to additional domestic and international sites, more intentional patient involvement, and granular analyses of still-unanswered questions related to cancer subtypes and treatments. When the COVID-19 pandemic began, formal frameworks to collect data about affected patients were lacking. The COVID-19 and Cancer Consortium (CCC19) was formed to collect granular data on patients with cancer and COVID-19 at scale and as rapidly as possible. CCC19 has grown from five initial institutions to 125 institutions with >400 collaborators. More than 5,000 cases with complete baseline data have been accrued. Future directions include increased electronic health record integration for direct data ingestion, expansion to additional domestic and international sites, more intentional patient involvement, and granular analyses of still-unanswered questions related to cancer subtypes and treatments

Make EU trade with Brazil sustainable

Brazil, home to one of the planet's last great forests, is currently in trade negotiations with its second largest trading partner, the European Union (EU). We urge the EU to seize this critical opportunity to ensure that Brazil protects human rights and the environment