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Cope, J.

Publications and source records attributed to Cope, J..

3 recordsLinked to original sources
bioRxiv2026

Structural basis of receptor retro-translocation in peroxisomal protein import

Peroxisomes import all matrix proteins post-translationally from the cytosol, a process that requires recycling of cargo receptors across the peroxisomal membrane. The membrane-embedded ubiquitin ligase, composed of Pex2, Pex10, and Pex12, is central to this process, but its mechanism remains unclear. Here we determined cryo-electron microscopy structures of the Saccharomyces cerevisiae Pex2-10-12 complex in closed and open states bound to Pex8, an essential factor of previously undefined function. The structures reveal how Pex2-10-12 gates its retro-translocation pore to control receptor entry and how the closed-to-open transition repositions the Pex10 RING domain to enable receptor mono-ubiquitination. Pex8 docks onto Pex2-10-12 from the matrix and guides receptors into the pore. Functional analyses show that the receptors N-terminal segment downstream of its mono-ubiquitination site initiates a loop insertion into the pore. These findings establish how Pex2-10-12 coordinates receptor recognition, retro-translocation, and ubiquitination, providing the molecular basis for receptor recycling in peroxisomal protein import.

biochemistry↗
bioRxiv2024

Advancing Clinical Response Against Glioblastoma: Evaluating SHP1705 CRY2 Activator Efficacy in Preclinical Models and Safety in Phase I Trials

BackgroundIt has been reported that circadian clock components, Brain and Muscle ARNT-Like 1 (BMAL1) and Circadian Locomotor Output Cycles Kaput (CLOCK), are uniquely essential for glioblastoma (GBM) stem cell (GSC) biology and survival. Consequently, we developed a novel Cryptochrome (CRY) activator SHP1705, which inhibits BMAL1-CLOCK transcriptional activity. MethodsWe analyzed buffy coats isolated from Phase 1 clinical trial subjects blood to assess any changes to circadian, housekeeping, and blood transcriptome-based biomarkers following SHP1705 treatment. We utilized GlioVis to determine which circadian genes are differentially expressed in non-tumor versus GBM tissues. We employed in vitro and in vivo methods to test the efficacy of SHP1705 against patient-derived GSCs and xenografts in comparison to earlier CRY activator scaffolds. Additionally, we applied a novel-REV-ERB agonist SR29065, which inhibits BMAL1 transcription, to determine whether targeting both negative limbs of the circadian transcription-translation feedback loop (TTFL) would yield synergistic effects against various GBM cells. ResultsSHP1705 is safe and well-tolerated in Phase I clinical trials. SHP1705 has increased selectivity for the CRY2 isoform and potency against GSC viability compared to previously published CRY activators. SHP1705 prolonged survival in mice bearing GBM tumors established with GSCs. When combined with the novel REV-ERB agonist SR29065, SHP1705 displayed synergy against multiple GSC lines and differentiated GSCs (DGCs). ConclusionsThese demonstrate the efficacy of SHP1705 against GSCs, which pose for GBM patient outcomes. They highlight the potential of novel circadian clock compounds in targeting GBM as single agents or in combination with each other or current standard-of-care. KEY POINTSO_LISHP1705 is a novel CRY2 activator that has shown success in Phase 1 safety trials C_LIO_LISHP1705 has a significantly improved efficacy against GSCs and GBM PDX tumors C_LIO_LINovel REV-ERB agonist SR29065 and SHP1705 display synergistic effects against GSCs C_LI IMPORTANCE OF THE STUDYCRY2 is decreased in GBM tissues compared to CRY1 suggesting that promoting CRY2 activity will be an efficacious GBM treatment paradigm. SHP1705, a CRY2 activator that has shown success in Phase 1 safety trials, has significantly improved preclinical efficacy. Novel REV-ERB agonist SR29065 displays synergistic effects against diverse GBM cells.

cancer biology↗
bioRxiv2024

VASP phase separation with priming proteins of fast endophilin mediated endocytosis modulates actin polymerization

Actin polymerization is essential in several clathrin-independent endocytic pathways including fast endophilin mediated endocytosis (FEME), however the actin machinery involved in FEME has been elusive. Here, we show that the actin polymerase VASP colocalizes and interacts directly with the FEME priming complex. We identify Endophilin as a VASP binding partner and establish novel non-canonical interactions between Endophilin and VASP. The major FEME regulators Endophilin and Lamellipodin interact multivalently with VASP to form liquid-like condensates both in solution and on lipid membranes that localize actin polymerization with the extent of actin polymerized regulated by multivalent Endophilin-Lamellipodin interactions. We identify a novel function for Endophilin condensates in bundling actin filaments and show that Endophilin directly binds filamentous actin. Our findings support a model that explains the connection between local actin polymerization and dynamic formation and dissolution of endocytic priming patches in FEME.

biochemistry↗