Biology subjects

Chang, C.-Y.

Publications and source records attributed to Chang, C.-Y..

At least 19 recordsLinked to original sources

bioRxiv2026

Single Cell-Type Spatial Proteomics Uncovers Regional Heterogeneity of Astrocytes

Astrocytes are a subset of glial cells in the central nervous system (CNS) that support numerous processes essential for brain function. Their functional diversity is thought to arise from specialized subpopulations with distinct molecular profiles. Although single-cell and single-nucleus RNA sequencing (scRNA-seq and snRNA-seq) have greatly advanced our understanding of astrocyte transcriptomic heterogeneity, mRNA abundance does not always correlate with protein levels because of post-transcriptional and translational regulation. Therefore, studying protein profiles remains essential to accurately capture astrocyte functional states and heterogeneity. Here, we used Microscoop Mint, a microscopy-guided spatial proteomics platform that integrates subcellular, region-specific sample preparation with LC-MS/MS-based mass spectrometry, enabling direct protein profiling of astrocytes in paraformaldehyde-fixed, optimal cutting temperature (OCT)-embedded mouse brain tissue. By applying this approach, we uncovered distinct regional-associated astrocyte proteomic signatures in the cerebral cortex and hippocampus and selected novel candidate protein markers for subsequent validation by immunofluorescence. Notably, MINK1 and PLEKHB1 showed preferential expression in hippocampal and cortical astrocytes, respectively, highlighting their potential as region-specific astrocyte markers. Overall, this strategy enables high-precision, unbiased spatial proteomic discovery at subcellular resolution, providing a powerful framework for linking molecular diversity to functional specialization in astrocyte biology.

neuroscience↗

bioRxiv2026

Microhomology-mediated end joining acts directly on replication forks to repair single-ended double strand breaks

Replication stress, intrinsic to oncogenesis, often leads to fork breakage and double-strand break (DSB) formation. Conventionally, break-induced replication (BIR) is considered the primary mechanism for repairing replication-associated single-ended DSBs (seDSBs). Here, we demonstrate that microhomology-mediated end joining (MMEJ) acts directly to repair seDSBs at broken replication forks (fork-MMEJ), preferentially on the leading strands, and functions cooperatively with BIR. We also showed that while fork-MMEJ is promoted by Pol{theta}, it operates independently of MRE11/CtIP-mediated end resection, relies on RPA, and produces asymmetric deletion patterns, which is distinct from canonical MMEJ (cMMEJ) defined at replication-independent double-ended DSBs (deDSBs). ATR, activated as end resection proceeds, serves as a pivotal switch to suppress fork-MMEJ while promoting BIR. Combined inactivation of ATR and Pol{theta} synergistically kills cancer cells under high replication stress with minimal toxicity to normal cells. Together, our study provides fundamental insights into the MMEJ mechanism and offers new strategies for cancer treatment.

molecular biology↗

bioRxiv2025

Tissue-guided multi-omics profiling identifies extracellular vesicle biomarkers indicative of lung pathology in acute respiratory distress syndrome

BackgroundAcute respiratory distress syndrome (ARDS) remains a lethal inflammatory lung condition lacking reliable biomarkers that reflect lung-specific pathology. Extracellular vesicles (EVs) circulate systemically and may carry molecular signals from injured organs, but the correspondence between EV cargo and lung tissue alterations remains unclear. MethodsWe established aspiration-, lipopolysaccharide (LPS)-, and COVID-19-induced murine ARDS models and applied a tissue-guided multiomics framework integrating proteomic and metabolomic analyses of lung tissue and plasma-derived EVs to identify lung-originating circulating biomarkers. ResultsFour proteins--haptoglobin (HP), inter-alpha-trypsin inhibitor heavy chains 3 and 4 (ITIH3, ITIH4), and clusterin (CLU)--were consistently upregulated in both lung tissue and plasma EVs across all ARDS etiologies. Metabolomic integration revealed dysregulation of arachidonic acid metabolism as a unifying inflammatory axis. Multiomics network analysis further distinguished etiology-specific molecular programs, including glycolytic activation in aspiration-induced, platelet aggregation in LPS-induced, and vascular smooth muscle dysregulation in COVID-19-induced ARDS. ConclusionsThis study establishes a tissue-informed EV profiling framework that links local lung pathology to systemic molecular signatures, revealing HP, ITIH3, ITIH4, CLU, and arachidonic-acid-related metabolites as potential diagnostic markers for ARDS. These findings provide a foundation for developing clinically translatable, EV-based biomarker assays for early detection and molecular subtyping of lung injury.

biochemistry↗

bioRxiv2025

A Chemoproteomic Atlas of the Human Purine Interactome for Regioselective Ligand Discovery

Purines are essential bioactive molecules that interact with a large fraction of the human proteome. Despite their importance, the scope of actionable purine-binding pockets for ligand discovery remains limited. Here, we developed a quantitative chemoproteomics platform using sulfonyl-purine (SuPUR) chemistry to produce a massive and functional map of the human purine interactome. The SuPUR platform captured 31,000+ targetable tyrosine and lysine sites, representing the most comprehensive beyond cysteine chemoproteomics database for enabling protein ligand discovery. SuPUR ligands that bind through a regioselective fashion serve as enabling starting points for developing potent (nanomolar) and proteome-wide-selective modulators of enzymatic and protein-protein interaction function. Phenotypic screening identified a site-specific (Y237) and regioselective SuPUR ligand of ACAT2 to reveal an unexpected metabolic dependency in cancer cells. A crystal structure of SuPUR ligand-bound ACAT2 revealed the purine group binds deep in the CoA pocket forming key interactions with catalytic residues via a water bridge to guide future structure-based ligand design.

biochemistry↗

bioRxiv2025

Dietary methionine restriction primes T cell metabolism for activation and tumor inhibition and enhances the efficacy of immune checkpoint blockade

The proliferation of many cancer cells is methionine dependent and dietary methionine restriction (MR) has shown anti-tumor effects in a wide variety of immunodeficiency preclinical models. Yet, whether MR exerts an anti-tumor effect in the presence of an immune-competent background remains inconclusive. Accumulating evidence has shown an essential role of methionine in immune cell differentiation and function. Thus, competition for methionine between tumor cells and immune cells in the tumor microenvironment may drive tumor growth and tumor response to therapy. Here, we aim to define the impact of MR on tumor growth and associated immunity. We first assessed the effect of MR in a series of immunocompetent mouse models of melanoma, colorectal cancer, breast cancer, and lung. MR led to a broad tumor inhibition effect across these models and such tumor inhibition was not sex-or genetic background-dependent but appears to be fully or partially immune-dependent. Through flow cytometry analysis, we found a consistent increase in intratumoral activated CD8+ T cells across different tumor models and depletion of CD8+ T cells partially or completely reversed MR-induced tumor inhibition in a model dependent manner. Interestingly in young healthy non-tumor-bearing mice, MR increased spleen CD3+ and CD8+ T cell populations. Metabolomics and RNAseq analysis of spleen-derived CD8+ T cells revealed significant increase in purine metabolism and amino acid metabolism and that are in line with the metabolic feature of activated T cells. Furthermore, MR improved the efficacy of anti-PD1 immune checkpoint blockade. Together, MR primes T cell metabolism for its anti-tumor effect and improves the efficacy of anti-PD1 checkpoint blockade.

cell biology↗

bioRxiv2025

CDDO-Imidazole regulates RBC alloimmunization to the KEL antigen by activating Nrf2

During red blood cell (RBC) transfusion, production of alloantibodies can promote significant hemolytic events. However, most transfusion recipients do not form anti-RBC alloantibodies. Identifying mechanisms that inhibit alloimmunization may lead to prophylactic interventions. One potential regulatory mechanism is activation of the transcription factor, nuclear factor erythroid-derived 2-like 2 (Nrf2), a master regulatory of antioxidant pathways. Pharmacologic Nrf2 activators improve sequelae of sickle cell disease in pre-clinical models. The Nrf2 activator, 1-[2-cyano-3-,12-dioxooleana-1,9(11)-dien-28-oyl]imidazole (CDDO-Im), suppresses production of inflammatory cytokines including type 1 interferons (IFN/{beta}), which have been implicated in promoting RBC alloimmunization in transfusion models. Thus, we tested the hypothesis that the Nrf2 activator, CDDO-Im, regulates RBC alloimmunization. Here, we report that CDDO-Im induced Nrf2 activated gene expression and suppressed poly(I:C)-induced IFN/{beta}-stimulated gene (ISG) expression in human macrophages and murine blood leukocytes. In addition, following transfusion of wildtype mice with RBCs expressing the KEL antigen, CDDO-Im treatment inhibited poly(I:C)-induced anti-KEL IgG production and promoted post-transfusion recovery of KEL+ RBCs, but failed to do so in Nrf2-/- mice. Results indicate that activation of the Nrf2 antioxidant pathway regulates RBC alloimmunization to the KEL antigen in a pre-clinical model. If findings translate to other models and human studies, Nrf2 activators may represent a potential prophylactic intervention to inhibit alloimmunization. Key PointsO_LIThe antioxidant pathway, Nrf2, inhibits anti-RBC alloantibody responses in a pre-clinical transfusion model. C_LIO_LINrf2 activation may represent a prophylactic strategy to inhibit RBC alloimmunization in transfusion recipients. C_LI

immunology↗

bioRxiv2025

Testing for divergence in a plant symbiont across two natural environmental gradients

Many plant endosymbionts are facultative, switching between host-associated and free-living stages. Extensive genomic and experimental studies suggest that adaptation during the saprophytic, off-host phase, rather than adaptation to hosts, primarily constrains the biogeographic distribution of these microbes. To test this hypothesis, we analyzed the growth capacities and genomic features of 38 Sinorhizobium strains nodulating Medicago lupulina (black medic), collected from two regions with distinct thermal environments. The warmer region is predominantly inhabited by S. meliloti, while S. medicae and non-symbiotic strains (lacking symbiosis genes, such as S. canadensis and S. adherens) are more common in the cooler region. Laboratory assays demonstrated that at 40{degrees}C, the upper temperature limit of their region of origin, S. meliloti remained viable, albeit with reduced growth, whereas S. medicae and non-symbiotic strains failed to grow under heat stress. Comparative genomics revealed isolation-by-distance in both the core and accessory genomes, particularly in S. meliloti in the warmer region, which exhibits less within-region thermal variation. This is consistent with an isolation-by-distance model where population divergence is governed by restricted gene flow. These findings suggest that metabolic constraints shape the regional distribution of this facultative microbial symbiont, while limited gene flow influences local population structure.

evolutionary biology↗

bioRxiv2024

Estrogens increase cancer cell efferocytosis to establish an immunosuppressive tumor microenvironment

Phagocytic clearance of apoptotic cancer cells (efferocytosis) by tumor-associated macrophages (TAMs) contributes in a substantial manner to the establishment of an immunosuppressive tumor microenvironment. This puts in context our observation that the female steroid hormone 17{beta}- estradiol (E2) facilitates tumor immune resistance through cancer cell extrinsic Estrogen Receptor (ER) signaling in TAMs. Notable was the finding that E2 induces the expression of CX3CR1 in TAMs to enable efferocytosis of apoptotic cancer cells which results in the suppression of type I interferon (IFN) signaling. Mechanistically, E2 facilitates calcium-dependent activation of the transcription factor NFATC1, which in turn induces CX3CR1 expression. This drives macrophage polarization towards an immune-suppressive state, increasing the ability of TAMs to engulf pro- inflammatory apoptotic cancer cells. Genetic or pharmacological inhibition of the E2/ER/CX3CR1 axis reversed the efferocytic activity of TAMs, rescued E2-dependent suppression of type I IFN signaling, and potentiated intratumoral adaptive immune cell function. Efferocytosis following radiation-induced cancer cell apoptosis limits the efficacy of radiation therapy. Importantly, we determined that preconditioning with either ER-directed endocrine therapies or CX3CR1 inhibition enhanced the antitumor efficacy of radiation therapy by reversing macrophage suppression and reviving intratumoral T cell activation. Our work defines the mechanisms by which E2 increases the efferocytotic activity of TAMs to establish an immunosuppressive tumor microenvironment and demonstrates how this process can be reversed with endocrine therapies which target ER.

cancer biology↗

bioRxiv2024

Innovative platelet-derived extracellular vesicle drug delivery system for the treatment of corneal neovascularization

Platelet-derived extracellular vesicles (PEVs) have drawn attention due to their multifunctionality, ease of procurement, and abundant supply from clinical-grade platelet concentrates. PEVs can be easily endocytosed owing to their lipid bilayer membrane and nanosized structure, thereby increasing the bioavailability and functionality of their therapeutic effects. PEVs also possess multiple trophic factors that make them effective therapeutic agents. Since nanomedicine offers advantages over traditional therapies for eye diseases by overcoming physical ocular barriers, PEVs combined with an anti-angiogenic agent, kaempferol (KM), were evaluated for their ability to inhibit abnormal vessel formation in the cornea. Characterization of the nanoparticles indicated successful preparation of KM- loaded PEVs (PEV-KM) with a mean diameter of [~]160 nm and an encapsulation efficiency of [~]61%. PEV-KM was efficiently internalized into human vascular endothelial cells, resulting in inhibited function, evidenced by lower wound closure rates, reduced tube formation capacity, and downregulation of angiogenesis-related gene expression. Moreover, prolonged ocular retention was observed followed by topical application of PEV and PEV-KM in mouse eyes. In an alkali-burned corneal neovascularization (CoNV) mouse model, PEV (1%) was found to reduce vessel formation in the injured cornea. PEV with KM (1% PEV with KM 6 {micro}g/mL) showed an even stronger effect in suppressing CoNV and reducing the expression of proangiogenic and inflammatory cytokines. Together, our data suggests that topical administration of PEVs or in combination with KM (PEV-KM) is a promising therapeutic for managing CoNV.

bioengineering↗

bioRxiv2024

Global remodeling of ADP-ribosylation by PARP1 suppresses influenza A virus infection

ADP-ribosylation is a highly dynamic and fully reversible post-translational modification performed by poly(ADP-ribose) polymerases (PARPs) that modulates protein function, abundance, localization and turnover. Here we show that influenza A virus infection causes a rapid and dramatic upregulation of global ADP-ribosylation that inhibits viral replication. Mass spectrometry defined for the first time the global ADP-ribosylome during infection, creating an infection-specific profile with almost 4,300 modification sites on [~]1,080 host proteins, as well as over 100 modification sites on viral proteins. Our data indicate that the global increase likely reflects a change in the form of ADP-ribosylation rather than modification of new targets. Functional assays demonstrated that modification of the viral replication machinery antagonizes its activity and further revealed that the anti-viral activity of PARPs and ADP-ribosylation is counteracted by the influenza A virus protein NS1, assigning a new activity to the primary viral antagonist of innate immunity. We identified PARP1 as the enzyme producing the majority of poly(ADP-ribose) present during infection. Influenza A virus replicated faster in cells lacking PARP1, linking PARP1 and ADP-ribosylation to the anti-viral phenotype. Together, these data establish ADP-ribosylation as an anti-viral innate immune-like response to viral infection antagonized by a previously unknown activity of NS1.

microbiology↗

bioRxiv2024

MAGE-A4-Responsive Plasma Cells Promote Non-Small Cell Lung Cancer

Adaptive immunity is critical to eliminate malignant cells, while multiple tumor-intrinsic factors can alter this protective function. Melanoma antigen-A4 (MAGE-A4), a cancer-testis antigen, is expressed in several solid tumors and correlates with poor survival in non-small cell lung cancer (NSCLC), but its role in altering antitumor immunity remains unclear. We found that expression of MAGE-A4 was highly associated with the loss of PTEN, a tumor suppressor, in human NSCLC. Here we show that constitutive expression of human MAGE-A4 combined with the loss of Pten in mouse airway epithelial cells results in metastatic adenocarcinoma enriched in CD138+ CXCR4+ plasma cells, predominantly expressing IgA. Consistently, human NSCLC expressing MAGE-A4 showed increased CD138+ IgA+ plasma cell density surrounding tumors. The abrogation of MAGE-A4-responsive plasma cells (MARPs) decreased tumor burden, increased T cell infiltration and activation, and reduced CD163+CD206+ macrophages in mouse lungs. These findings suggest MAGE-A4 promotes NSCLC tumorigenesis, in part, through the recruitment and retention of IgA+ MARPs in the lungs.

immunology↗

bioRxiv2024

Interferon-Induced PARP14-Mediated ADP-Ribosylation in p62 Bodies Requires an Active Ubiquitin-Proteasome System

Biomolecular condensates are cellular compartments without enveloping membranes, enabling them to dynamically adjust their composition in response to environmental changes through post-translational modifications. A recent study has revealed that interferon-induced ADP-ribosylation (ADPr), which can be reversed by a SARS-CoV-2-encoded hydrolase, is enriched within a condensate. However, the identity of the condensate and responsible host ADP-ribosyltransferase remain elusive. Here, we demonstrate that interferon induces ADPr through transcriptional activation of PARP14, requiring both its physical presence and catalytic activity for condensate formation. Interferon-induced ADPr colocalizes with PARP14, and these PARP14/ADPr condensates contain key components of p62 bodies--including the selective autophagy receptor p62 and its binding partner NBR1, along with K48-linked and K63-linked polyubiquitin chains--but lack the autophagosome marker LC3B. Knockdown of p62 disrupts the formation of these ADPr condensates. Importantly, these structures are unaffected by autophagy inhibition but depend on both ubiquitin activation and proteasome activity. Taken together, these findings demonstrate that interferon triggers PARP14-mediated ADP-ribosylation in p62 bodies, which requires an active ubiquitin-proteasome system.

cell biology↗

bioRxiv2024

Optineurin-facilitated axonal mitochondria delivery promotes neuroprotection and axon regeneration

Optineurin (OPTN) mutations are linked to amyotrophic lateral sclerosis (ALS) and normal tension glaucoma (NTG), but a relevant animal model is lacking, and the molecular mechanisms underlying neurodegeneration are unknown. We found that OPTN C-terminus truncation (OPTN{Delta}C) causes late-onset neurodegeneration of retinal ganglion cells (RGCs), optic nerve (ON), and spinal cord motor neurons, preceded by a striking decrease of axonal mitochondria. Surprisingly, we discover that OPTN directly interacts with both microtubules and the mitochondrial transport complex TRAK1/KIF5B, stabilizing them for proper anterograde axonal mitochondrial transport, in a C- terminus dependent manner. Encouragingly, overexpressing OPTN/TRAK1/KIF5B reverses not only OPTN truncation-induced, but also ocular hypertension-induced neurodegeneration, and promotes striking ON regeneration. Therefore, in addition to generating new animal models for NTG and ALS, our results establish OPTN as a novel facilitator of the microtubule-dependent mitochondrial transport necessary for adequate axonal mitochondria delivery, and its loss as the likely molecular mechanism of neurodegeneration.

neuroscience↗

bioRxiv2023

Evaluating the validity of the eye movement event detection model of Ganzin Sol glasses

Eye tracking requires precise measurement of gaze data. Identifying fixations and saccades reliably is crucial for eye trackers, given these are fundamental eye movements. The present study evaluated the performance of Ganzin Sol glasses, a wearable eye tracker developed by Ganzin Technology, in detecting eye movement events. Participants performed the fixation and saccade invocation task (Komogortsev et al., 2010) and the gap paradigm (Saslow, 1967) using both Ganzin Sol and Tobii Pro 2 glasses separately at both short (50 cm) and long (300 cm) viewing distance. The fixation and saccade invocation task involved maintaining fixation on a regularly shifting visual target, enabling quantitative and qualitative analysis of participants oculomotor behaviors. In the gap paradigm, participants executed saccades toward a peripheral target when the fixation disappeared (gap condition) or remained visible (overlap condition). Typically, saccade latency in the gap condition is shorter (i.e., the gap effect). Results revealed aligned performances with Ganzin Sol and Tobii Pro 2 glasses in the fixation and saccade invocation task and the observation of the gap effect with both eye trackers. Therefore, the validity of Ganzin Sol glasses was at least comparable to Tobii Pro 2 glasses in the present study.

neuroscience↗

bioRxiv2023

Breast cancer cells can recognize and respond to different levels of progestins to achieve different phenotypic outputs

The steroid hormone progesterone, acting through its nuclear progesterone receptor (PR), has complex physiologic activities with different levels of hormones manifesting distinct and sometimes opposing phenotypic responses in target tissues. However, most of what is currently known about the transcriptional activity of PR comes from studies performed using progestins at levels that are in the high physiologic range ([≥]10nM), relevant only in the luteal phase of the reproductive cycle and pregnancy in humans. These studies do not consider the non-linearity of responses to progestins that exist in physiology and are not informative as to the mechanisms by which low levels of progestins, as occurs during menopause, exert their biological activities. Thus, we undertook to define the mechanisms which enable cells to recognize and respond to different levels of progestins. Using a PR expressing cell model of luminal breast cancer (T47D cells) we demonstrated that low concentration progestins (0.1-0.3nM) drive proliferation while high dose progestins ([≥]10nM) inhibit proliferation. Using both unbiased and targeted approaches, we found that low dose progestins facilitate cell cycle entry by enhanced expression of CCND1 and SGK1, which are both required to initiate a signaling cascade that leads to increased phospho-Rb and E2F1 transcriptional activity. CCND1 cooperates with CDK4/6 to phosphorylate Rb, while SGK1 phosphorylates p21, thereby excluding it from the nucleus and inhibiting its anti-proliferative function. Expression of CCND1 and SGK1 mRNAs are primary responses to low dose progestin treatment. However, these responses occur at very low levels of receptor occupancy and in the absence of receptor phosphorylation events that have been shown to be required for nuclear translocation and transcriptional activity. These findings challenge the assumption of linearity in response to progestin dose. Further, they suggest that concentrations of progestins found in post-menopausal women (0.1-0.3nM) have the potential to exert proliferative responses in PR expressing cancers.

cancer biology↗

bioRxiv2023

Ca2+/Calmodulin Dependent Protein Kinase Kinase-2 (CaMKK2) promotes Protein Kinase G (PKG)-dependent actin cytoskeletal assembly to increase tumor metastasis

Triple-negative breast cancers (TNBCs) tend to become highly invasive early during cancer development. Despite some successes in the initial treatment of patients diagnosed with early-stage localized TNBC, the rate of metastatic recurrence remains high with poor long-term survival outcomes. Here we show that elevated expression of the serine/threonine-kinase, Calcium/Calmodulin (CaM)-dependent protein kinase kinase-2 (CaMKK2), is highly correlated with tumor invasiveness. We determined that genetic disruption of CaMKK2 expression, or inhibition of its activity, disrupted spontaneous metastatic outgrowth from primary tumors in murine xenograft models of TNBC. High-grade serous ovarian cancer (HGSOC), a high-risk, poor-prognosis ovarian cancer subtype, shares many genetic features with TNBC, and importantly, CaMKK2 inhibition effectively blocked metastatic progression in a validated xenograft model of this disease. Probing the mechanistic links between CaMKK2 and metastasis we defined the elements of a new signaling pathway that impacts actin cytoskeletal dynamics in a manner which increases cell migration/invasion and metastasis. Notably, CaMKK2 increases the expression of the phosphodiesterase PDE1A which decreases the cGMP-dependent activity of protein kinase G1 (PKG1). This inhibition of PKG1 results in decreased phosphorylation of Vasodilator-Stimulated Phosphoprotein (VASP), which in its hypophosphorylated state binds to and regulates F-actin assembly to facilitate contraction/cell movement. Together, these data establish a targetable CaMKK2-PDE1A-PKG1-VASP signaling pathway that controls cancer cell motility and metastasis. Further, it credentials CaMKK2 as a therapeutic target that can be exploited in the discovery of agents for use in the neoadjuvant/adjuvant setting to restrict tumor invasiveness in patients diagnosed with early-stage TNBC or localized HGSOC.

cancer biology↗

bioRxiv2022

Emergent coexistence in multispecies microbial communities

Microbial communities are highly diverse, and understanding the factors that promote and modulate this diversity is a major area of research in microbial ecology. Recent work has proposed a reductionist perspective to microbial coexistence, where pairwise coexistence between strains in isolation is required for their coexistence in a more complex community. In this view, species exclusion in pairwise co-culture would preclude their coexistence in a more complex community too. An alternative view is that coexistence is a more complex property of the entire community, requiring the presence of additional community members. If this view were correct, competitive exclusion in pairwise co-culture would not necessarily preclude species coexistence in more complex community contexts. Empirically testing these alternative hypotheses is complicated by the intractably high microbial diversity of most natural communities, and the challenges of reconstituting every pair of coexisting species under the exact same habitat where their community of origin was assembled. To address this challenge, we have experimentally reconstituted all possible pairwise co-cultures between stably coexisting species from 13 different, low-diversity microbial enrichment communities, which had previously been assembled in a well-controlled synthetic habitat. We find that, when isolated from the rest of their community members, most species pairs fail to coexist. This result highlights the importance of community context for microbial coexistence and indicates that pairwise exclusion may not reflect the ability of species to coexist in more complex, multispecies ecosystems.

ecology↗

bioRxiv2022

Increased CaMKK2 expression is an adaptive response that maintains the fitness of tumor-infiltrating natural killer cells

Calcium/calmodulin-dependent protein kinase kinase 2 (CaMKK2) is a key regulator of energy homeostasis in several cell types. Expression of this enzyme in tumor cells promotes proliferation and migration, and expression in tumor-associated immune cells facilitates M2 macrophage polarization and the development of myeloid-derived suppressor cells. Thus, there has been considerable interest in developing CaMKK2 inhibitors as potential cancer therapeutics. However, the roles of CaMKK2 in other cellular compartments within the tumor immune environment remain to be established, an impediment to the clinical development of these agents. We report that CaMKK2 is expressed at low basal levels in natural killer (NK) cells but is significantly upregulated in tumor-infiltrating NK cells where it suppresses apoptosis and promotes proliferation. It was further demonstrated that NK cell-intrinsic deletion of CaMKK2 increased metastatic progression across several murine models, establishing a critical role for this enzyme in NK cell tumor immunity. Interestingly, ablation of the CaMKK2 protein, but not inhibition of its kinase activity, resulted in decreased NK cell survival. These results indicate an important scaffold function for CaMKK2 in NK cells and suggest that competitive CaMKK2 inhibitors and ligand-directed degraders (LDDs) are likely to have distinct therapeutic utilities. Finally, we determined that intracellular lactic acid is a key driver of CaMKK2 expression, suggesting that upregulated expression of this enzyme is an adaptive mechanism by which tumor-infiltrating NK cells mitigate the deleterious effects of a lactate-rich tumor environment. The findings of this study should inform strategies to manipulate the CaMKK2 signaling axis as a therapeutic approach in cancer.

cancer biology↗