Kymera Therapeutics

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Adaptation to fluctuating nutrient supply is essential for organismal survival, but how human cells monitor the abundance of many critical nutrients remains undefined. Characterizing the conditional degradation of CDO1, the critical enzyme responsible for cysteine catabolism, here we identify a Cullin-RING E3 ligase complex defined by the substrate adaptor LRRC58 that is sensitive to cysteine abundance. When cysteine is replete, LRRC58 activity is restrained through ubiquitination and proteasomal degradation. Upon cysteine deprivation, LRRC58 is stabilized to permit CDO1 degradation. Through saturation mutagenesis stability profiling, we systematically validate a structural model of the CDO1-LRRC58 interaction and identify residues at the LRRC58 C terminus required for cysteine-dependent instability. CDO1 degradation prevents ferroptotic cell death upon cysteine scarcity, and CDO1 mutations causing neurodevelopmental defects in humans encode dominant-active proteins refractory to LRRC58 recognition. Altogether, these data reveal the CDO1-LRRC58 axis as a critical regulator of cysteine homeostasis that safeguards neural development.

Castration-resistant prostate cancer (CRPC) lethality arises from epigenetic-driven resistance to androgen deprivation therapy (ADT). Here, we uncover a compensatory epigenetic switch between DNA methylation and H3K27me3-mediated repression as a critical barrier to epigenetic therapy in CRPC. Integrative multiomics analyses reveal that DNMT inhibitors (DNMTis) trigger EZH2-dependent H3K27me3 accumulation at the ADAMTS1 locus-a master collagenase essential for extracellular matrix (ECM) remodeling-perpetuating fibrotic niche formation and therapy resistance. Dual targeting of DNMTs and EZH2 disrupts this epigenetic plasticity, synergistically reactivating ADAMTS1 to degrade collagen-rich stroma, suppress FAK/MAPK mechanotransduction signaling, and reverse epithelial-mesenchymal transition (EMT). Crucially, in immunocompetent models, this strategy achieves >90% tumor suppression and reverses immunosuppression by enhancing cytotoxic CD8+ T cell infiltration 11.4-fold while depleting immunosuppressive macrophages and Tregs. Mechanistically, dual therapy inactivates the FAK/MAPK/EMT axis via ADAMTS1-mediated ECM degradation, overcoming stromal-mediated resistance. Our work establishes epigenetic-ECM coevolution as a hallmark of CRPC and provides a rationally designed combination therapy to dismantle the therapy-resistant niche.

Gap junctional intercellular communication (GJIC) enables the direct transfer of signaling molecules between neighboring cells and plays an important role in innate antiviral immunity by facilitating bystander defense responses. We previously showed that the alphaherpesvirus pseudorabies virus (PRV) suppresses GJIC through ERK1/2-mediated phosphorylation and degradation of the main gap junction (GJ) protein connexin 43 (Cx43), triggered by the viral tegument protein pUL46. Here, we identify the prenylated viral protein pUS2 as a second important regulator of this process during PRV infection. Using the attenuated PRV vaccine strain Bartha K61 and a panel of isogenic deletion mutants, we show that pUS2 is required for efficient Cx43 phosphorylation and GJIC suppression but is dispensable for ERK1/2 activation itself. We further demonstrate that this function of pUS2 depends on its C-terminal CAAX prenylation motif. A prenylation-deficient pUS2 mutant fails to localize ERK1/2 to the plasma membrane and, likely as a consequence, does not induce efficient Cx43 phosphorylation or GJIC downregulation. Our data support a model in which PRV employs a two-step strategy to suppress GJIC in infected cells: pUL46 triggers ERK1/2 activation, while newly expressed, prenylated pUS2 redirects the activated kinase to the plasma membrane to facilitate phosphorylation of Cx43. This work reveals how PRV exploits the spatial control of host kinase signaling to suppress gap junction intercellular communication.IMPORTANCEGap junctions (GJs) constitute key communication channels between cells in multicellular organisms. GJs allow the intercellular transfer of different small biomolecules, including messengers involved in the innate and adaptive antiviral response. We showed earlier that, during infection of epithelial cells with the porcine alphaherpesvirus pseudorabies virus (PRV), the viral tegument protein pUL46 triggers activation of ERK1/2, which in turn leads to phosphorylation of the major gap junction protein connexin 43 (Cx43) and closure of GJs. In the current report, we show that a second PRV protein, pUS2, contributes to Cx43 phosphorylation and GJ closure, likely by recruiting ERK1/2 to the plasma membrane. This function of pUS2 depends on its CAAX prenylation motif. The current data suggest that PRV-mediated Cx43 phosphorylation and GJ closure occur via a two-step process, involving the viral pUL46 and pUS2 proteins, and point to GJ modulation as a possible target for antiviral strategies.

Mutations in the neutrophil elastase gene (ELANE) have classically been established as the primary genetic etiology of severe congenital neutropenia (SCN) and cyclic neutropenia (CyN), characterized by early-stage granulocytic maturation arrest and a predisposition to life-threatening infections. However, recent high-throughput transcriptomic, multi-omics, and functional studies have unveiled a paradigm-shifting, multidimensional role for neutrophil elastase (NE) that extends far beyond the confines of bone marrow failure. As a highly active serine protease, NE has emerged as a central hub in regulating recently discovered forms of regulated cell death (RCD), including pyroptosis, ferroptosis, and NETosis, and orchestrating the tumor immune microenvironment (TIME). Within the bone marrow, mutant NE triggers intense proteotoxic stress, reactive oxygen species (ROS) accumulation, and a unique proapoptotic "aggrephagy" (the selective autophagic degradation of misfolded protein aggregates), driving granulocyte colony-stimulating factor (G-CSF) resistance and clonal evolution toward acute myeloid leukemia (AML). Extracellularly, NE released via neutrophil extracellular traps (NETs) acts as a fascinating double-edged sword: it possesses the intrinsic capability to selectively eradicate genetically diverse cancer cells by cleaving the CD95 death domain and interacting with histone H1 isoforms, yet it concomitantly mediates immunosuppression, chemoresistance, and systemic inflammatory response syndrome (SIRS) in sepsis by reprogramming macrophage polarization. This review systematically synthesizes the intricate molecular mechanisms of NE, emphasizing the profound crosstalk between hematopoietic failure, inflammatory cell death pathways, and tumor immunology. Furthermore, this review highlights the translational potential of these discoveries, exploring cutting-edge therapeutic strategies, including CRISPR/Cas9-based precise base editing, dual-nickase promoter targeting, and selective allosteric small-molecule inhibitors, ultimately aiming to bridge the critical gaps from bench to bedside.

Tumor-associated macrophages (TAMs) are key regulators of immunological responses in tumor microenvironment (TME), exerting a profound impact on cancer progression. The current study aimed to explore TAMs-targeted strategies designed to overcome the immunosuppressive effects and restore antitumor immunity. Our findings demonstrated that selective CDK4/6 inhibitors promote the polarization of M2 macrophages toward the M1 phenotype, which was validated in both in vitro experiments and preclinical tumor models. Concurrently, CDK4/6 inhibitors significantly enhanced the phagocytic capacity of macrophages and activated effector T cell-mediated immune responses. Mechanistically, CDK4/6 inhibitors reduced p53 levels by altering p53 mRNA expression and facilitating its protein degradation. Furthermore, CDK4/6 inhibitor combined with CD47 blockade represents a promising strategy suppressing breast cancer growth. Taken together, our findings unveil a previously unappreciated antitumor mechanism mediated by CDK4/6 inhibition and propose a novel macrophage-based breast cancer immunotherapeutic approach.

Semaphorins (SEMAs) comprise a diverse family of membrane-associated proteins whose dysregulation is implicated in various cancers, influencing tumor progression and immune responses. However, the role of SEMAs in colorectal cancer (CRC) remains underexplored. This study demonstrates that Semaphorin 6A (SEMA6A) is downregulated in CRC tissues, with low SEMA6A expression correlating with increased tumor aggressiveness and poor prognosis in CRC patients. Functional assays illustrate that SEMA6A overexpression exerts anti-tumor effects both in vitro and in vivo, while integrated RNA-seq and proteomic analyses identify ISG15 as a key downstream effector negatively regulated by SEMA6A. Mechanistically, SEMA6A inhibits the JAK-STAT3 pathway, leading to decreased ISG15 expression, which in turn abrogates the ISGylation-dependent stabilization of TGF-β1 and promotes its degradation, as confirmed by molecular docking, co-immunoprecipitation, and cycloheximide chase assays. Consequently, in vitro co-culture assays and in vivo experiments reveal that SEMA6A overexpression in tumor cells enhances CD8+ T cell cytotoxicity via blocking the ISG15/TGFβ axis. Bioinformatics analyses indicate that patients with CRC exhibiting high SEMA6A and low ISG15 expression show improved responses to immunotherapy. Importantly, SEMA6A overexpression reshapes the tumor microenvironment, boosts anti-tumor immunity of CD8+ T cells and inhibits immune evasion, thereby potentiating anti-PD-1 immunotherapy in vivo. Collectively, these findings highlight the potential of SEMA6A as a dual therapeutic strategy in CRC: inhibiting cancer progression while enhancing anti-tumor immunity by targeting the ISG15/TGF-β1 axis. Thus, SEMA6A represents both a prognostic indicator and a promising target to improve immunotherapy efficacy and enable personalized treatment strategies in CRC.