Kentucky Outreach Service Kiosk (KyOSK) Study protocol: a community-level, controlled quasi-experimental, type 1 hybrid effectiveness study to assess implementation, effectiveness and cost-effectiveness of a community-tailored harm reduction kiosk on HIV, HCV and overdose risk in rural Appalachia.

INTRODUCTION: Many rural communities bear a disproportionate share of drug-related harms. Innovative harm reduction service models, such as vending machines or kiosks, can expand access to services that reduce drug-related harms. However, few kiosks operate in the USA, and their implementation, impact and cost-effectiveness have not been adequately evaluated in rural settings. This paper describes the Kentucky Outreach Service Kiosk (KyOSK) Study protocol to test the effectiveness, implementation outcomes and cost-effectiveness of a community-tailored, harm reduction kiosk in reducing HIV, hepatitis C and overdose risk in rural Appalachia. METHODS AND ANALYSIS: KyOSK is a community-level, controlled quasi-experimental, non-randomised trial. KyOSK involves two cohorts of people who use drugs, one in an intervention county (n=425) and one in a control county (n=325). People who are 18 years or older, are community-dwelling residents in the target counties and have used drugs to get high in the past 6 months are eligible. The trial compares the effectiveness of a fixed-site, staffed syringe service programme (standard of care) with the standard of care supplemented with a kiosk. The kiosk will contain various harm reduction supplies accessible to participants upon valid code entry, allowing dispensing data to be linked to participant survey data. The kiosk will include a call-back feature that allows participants to select needed services and receive linkage-to-care services from a peer recovery coach. The cohorts complete follow-up surveys every 6 months for 36 months (three preceding kiosk implementation and four post-implementation). The study will test the effectiveness of the kiosk on reducing risk behaviours associated with overdose, HIV and hepatitis C, as well as implementation outcomes and cost-effectiveness. ETHICS AND DISSEMINATION: The University of Kentucky Institutional Review Board approved the protocol. Results will be disseminated in academic conferences and peer-reviewed journals, online and print media, and community meetings. TRIAL REGISTRATION NUMBER: NCT05657106.

Fbw7 dimerization determines the specificity and robustness of substrate degradation.

The Fbw7 tumor suppressor targets a broad network of proteins for ubiquitylation. Here we show critical functions for Fbw7 dimerization in regulating the specificity and robustness of degradation. Dimerization enables Fbw7 to target substrates through concerted binding to two suboptimal and independent recognition sites. Accordingly, an endogenous dimerization-deficient Fbw7 mutation stabilizes suboptimal substrates. Dimerization increases Fbw7's robustness by preserving its function in the setting of mutations that disable Fbw7 monomers, thereby buffering against pathogenic mutations. Finally, dimerization regulates Fbw7 stability, and this likely involves Fbw7 trans-autoubiquitylation. Our study reveals novel functions of Fbw7 dimerization and an unanticipated complexity in substrate degradation.

Cand1 promotes assembly of new SCF complexes through dynamic exchange of F box proteins.

The modular SCF (Skp1, cullin, and F box) ubiquitin ligases feature a large family of F box protein substrate receptors that enable recognition of diverse targets. However, how the repertoire of SCF complexes is sustained remains unclear. Real-time measurements of formation and disassembly indicate that SCF(Fbxw7) is extraordinarily stable, but, in the Nedd8-deconjugated state, the cullin-binding protein Cand1 augments its dissociation by one-million-fold. Binding and ubiquitylation assays show that Cand1 is a protein exchange factor that accelerates the rate at which Cul1-Rbx1 equilibrates with multiple F box protein-Skp1 modules. Depletion of Cand1 from cells impedes recruitment of new F box proteins to pre-existing Cul1 and profoundly alters the cellular landscape of SCF complexes. We suggest that catalyzed protein exchange may be a general feature of dynamic macromolecular machines and propose a hypothesis for how substrates, Nedd8, and Cand1 collaborate to regulate the cellular repertoire of SCF complexes.

Using high throughput screening to define virus clearance by chromatography resins.

High throughput screening (HTS) of chromatography resins can accelerate downstream process development by rapidly providing information on product and impurity partitioning over a wide range of experimental conditions. In addition to the removal of typical product and process-related impurities, chromatography steps are also used to remove potential adventitious viral contaminants and non-infectious retrovirus-like particles expressed by rodent cell lines used for production. This article evaluates the feasibility of using HTS in a 96-well batch-binding format to study removal of the model retrovirus xenotropic murine leukemia virus (xMuLV) from product streams. Two resins were examined: the anion exchange resin Q Sepharose Fast Flow™ (QSFF) and Capto adhere™, a mixed mode resin. QSFF batch-binding HTS data was generated using two mAbs at various pHs, NaCl concentrations, and levels of impurities. Comparison of HTS data to that generated using the column format showed good agreement with respect to virus retentation at different pHs, NaCl concentrations and impurity levels. Results indicate that NaCl concentration and impurity level, but not pH, are key parameters that can impact xMuLV binding to both resins. Binding of xMuLV to Capto adhere appeared to tolerate higher levels of NaCl and impurity than QSFF, and showed some product-specific impact on binding that was not observed with QSFF. Overall, the results demonstrate that the 96-well batch-binding HTS technique can be an effective tool for rapidly defining conditions for robust virus clearance on chromatographic resins.

The SCF-Fbw7 ubiquitin ligase degrades MED13 and MED13L and regulates CDK8 module association with Mediator.

The Mediator complex is an essential transcription regulator that bridges transcription factors with RNA polymerase II. This interaction is controlled by dynamic interactions between Mediator and the CDK8 module, but the mechanisms governing CDK8 module-Mediator association remain poorly understood. We show that Fbw7, a tumor suppressor and ubiquitin ligase, binds to CDK8-Mediator and targets MED13/13L for degradation. MED13/13L physically link the CDK8 module to Mediator, and Fbw7 loss increases CDK8 module-Mediator association. Our work reveals a novel mechanism regulating CDK8 module-Mediator association and suggests an expanded role for Fbw7 in transcriptional control and an unanticipated relationship with the CDK8 oncogene.

Nucleolar targeting of the fbw7 ubiquitin ligase by a pseudosubstrate and glycogen synthase kinase 3.

E3 ubiquitin ligases catalyze protein degradation by the ubiquitin-proteasome system, and their activity is tightly controlled. One level of regulation involves subcellular localization, and the Fbw7 tumor suppressor exemplifies this type of control. Fbw7 is the substrate-binding component of an SCF ubiquitin ligase that degrades critical oncoproteins. Alternative splicing produces three Fbw7 protein isoforms that occupy distinct compartments: Fbw7α is nucleoplasmic, Fbw7ß is cytoplasmic, and Fbw7γ is nucleolar. We found that cancer-associated Fbw7 mutations that disrupt substrate binding prevent Fbw7γ nucleolar localization, implicating a substrate-like interaction in nucleolar targeting. We identified EBNA1-binding protein 2 (Ebp2) as the critical nucleolar factor that directly mediates Fbw7 nucleolar targeting. Ebp2 binds to Fbw7 like a substrate, and this is mediated by an Ebp2 degron that is phosphorylated by glycogen synthase kinase 3. However, despite these canonical substrate-like interactions, Fbw7 binding is largely uncoupled from Ebp2 turnover in vivo. Ebp2 thus acts like a pseudosubstrate that directly recruits Fbw7 to nucleoli.