Cell Reports

Novel (nua) Kinase 1 (NUAK1) encodes a serine-threonine protein kinase, mutations in which are associated with autism spectrum disorder. Direct phosphorylation targets of NUAK1 have been elusive hindering mechanistic understanding of its role in brain development. Here, we characterize autism-associated NUAK1 variants and show their differential impact on catalytic activity and subcellular distribution. We engineered ATP-analog sensitive NUAK1 and utilized its specificity towards bulky analogs to identify over 30 hitherto unknown direct phosphorylation targets of NUAK1. We demonstrate that Pleckstrin Homology and Sec7-domain containing protein 3 (PSD3) is a bona fide phosphorylation target of NUAK1. A guanine exchange factor (GEF) for ARF6 GTPase, PSD3 is phosphorylated by NUAK1 at S476. Expression of phosphodeficient PSD3 leads to aberrant activation of ARF6 and generation of PI(4,5)P2 that accumulates in intracellular vesicles. In neurons, phosphomutant PSD3 leads to enhanced spine maturation in an ARF6 dependent fashion. This study reveals direct neuronal substrates of an autism risk gene NUAK1, and delineates a mechanism by which PSD3 phosphorylation regulates ARF6 activation and spine maturation.

Survival during infection depends on both pathogen clearance and the ability to tolerate infection-induced physiological changes. Metabolic adaptations are a central component of this tolerance, but the mechanisms underlying these responses remain incompletely defined. Here, we identify white adipose tissue (WAT) lipolysis as a central regulator of metabolic tolerance to infection. In patients with sepsis, higher circulating non-esterified fatty acid (NEFA) levels were associated with reduced mortality. In mouse models of polymicrobial sepsis, infection induced robust adipose lipolysis and increased circulating NEFAs. Genetic ablation of adipose triglyceride lipase (ATGL) in adipose tissue impaired lipolysis, leading to hypothermia, bradycardia, and increased mortality without altering immune cell populations or pathogen burden, consistent with a defect in tolerance rather than resistance. Mechanistically, lipolysis-derived NEFAs, but not glycerol, were required for protection, as restoring circulating NEFAs rescued autonomic stability and survival in adipose tissue ATGL-deficient mice. Infection-induced lipolysis was redundantly regulated and did not depend on any single upstream signaling pathway. Both pharmacologic activation of lipolysis using a {beta}3-adrenergic agonist and exogenous fatty acid supplementation increased circulating NEFAs, improved survival, and promoted tolerance in mice. Consistent with these findings, analysis of real-world electronic health record data demonstrated that septic patients receiving FDA-approved {beta}3-adrenergic agonists had reduced mortality or hospice discharge in a propensity-matched cohort. Together, these results identify WAT lipolysis and circulating fatty acids as key mediators of tolerance to infection and support a therapeutic strategy based on repurposing clinically available {beta}3-adrenergic agonists to improve outcomes in sepsis. One Sentence SummaryWhite adipose tissue lipolysis promotes metabolic tolerance to infection through circulating fatty acids and is associated with improved survival in sepsis

Aging is a major risk factor for joint disease, yet the impact of physiological aging on the synovium remains poorly defined. Here we generate a single-cell atlas of murine ankle synovium across age and identify the sublining stromal-myeloid niche as a major site of age-associated remodeling. Aging shifted fibroblast states toward oxidative stress and matrix-remodeling programs, accompanied by sublining collagen accumulation, reduced cellularity, and loss of THY1+ sublining fibroblasts. In parallel, resident synovial macrophages exhibited altered inflammatory and phagocytic responses together with a preferential decline in TIM4+VSIG4- sublining macrophages, without overt local myeloid expansion despite systemic inflammaging. Macrophage depletion experiments further supported a link between sublining macrophages and extracellular matrix homeostasis. Together, these findings provide a reference framework for synovial aging and uncover niche-specific stromal and macrophage alterations associated with aging.

L-type amino acid transporter (LAT1) drives the uptake of essential amino acids (EAA) and activation of mTORC1 signaling in cancer cells. Current models propose that glutamine exchange is required for LAT1-dependent EAA transport; however, in many tumours, including MYC-driven cancers, glutamine is simultaneously consumed for bioenergetic and biosynthetic processes. How LAT1 activity is maintained under these conditions remains unclear. Here, we identify histidine as an efficient bidirectional LAT1 substrate that is preferentially utilised under glutamine-limitation in Gln-dependent tumour cells. Histidine uptake is modulated by glutamine availability, revealing an unexpected role for histidine in maintaining amino acid homeostasis. We demonstrate that histidine availability supports LAT1-mediated transport, promotes mTORC1/4E-BP1 signaling, and enhances protein synthesis and supports tumour cell proliferation. Under histidine limitation, MYC and ATF4 induce amino acid transporter expression, including LAT1, to preserve intracellular EAA levels. Importantly, histidine restriction sensitizes tumour cells to LAT1 inhibition, enhancing sensitivity to LAT1 inhibition and reducing tumour burden. Together, our findings establish histidine as a key regulator of LAT1 function and mTORC1 activity, suggesting a potential metabolic vulnerability in glutamine-dependent tumours.

Diet is a major determinant of gut microbiome structure and function, yet the role of dietary electrolytes--particularly sodium--remains poorly defined. Here, we identify dietary sodium availability as a key regulator of gut microbial fermentation and host energy harvest. Using a controlled sodium-sufficient versus sodium-deprived dietary intervention in rats, we integrated shotgun metagenomic sequencing, functional pathway analysis, targeted short-chain fatty acid (SCFA) quantification, and host physiological phenotyping. Sodium deprivation induced a coordinated restructuring of the gut microbiome, characterized by depletion of classical saccharolytic Firmicutes, including multiple Lactobacillus species, and enrichment of stress-tolerant, metabolically flexible taxa. Functional profiling revealed a shift away from growth-associated metabolic programs toward stress-adaptive and nutrient-scavenging pathways. Consistent with these changes, fecal concentrations of key SCFAs--including acetate, butyrate, hexanoate, and valerate--were significantly reduced, indicating impaired microbial fermentative capacity. These microbiome-level alterations translated into measurable host phenotypes, including reduced cecal mass and attenuated weight gain, consistent with decreased microbial energy harvest. Together, these findings establish a functional link between luminal sodium availability, microbial metabolic efficiency, and host energy balance, extending the framework of diet-microbiome interactions beyond macronutrients to include dietary electrolytes. This work identifies sodium as a previously underappreciated ecological constraint shaping gut microbial metabolism and suggests that modulation of dietary sodium intake may influence host metabolic outcomes through microbiome-mediated mechanisms.

Obesity affects one in three adults and is complicated by adipose inflammation, lipotoxicity and cell death. We previously identified RIPK1 as a genetic determinant of human obesity risk and adipose inflammation. Because RIPK1 is the apical kinase in the necroptosis pathway upstream of RIPK3 and the executioner protein MLKL, and emerging evidence links MLKL to lipid metabolism, MLKL has surfaced as a potential metabolic regulator. However, conflicting findings in Mlkl knockout mice fed a high fat diet have left its therapeutic relevance unresolved. MLKL has not been previously targeted through therapeutic knockdown in vivo in the context of diet-induced obesity. Here, we evaluated two independent MLKL antisense oligonucleotides (ASOs) in high fat diet (HFD)-fed C57BL/6J mice. In a 24-week progression model, MLKL ASO markedly reduced body weight, fat mass and hepatic steatosis compared with controls, while preserving lean mass. MLKL knockdown also lowered the respiratory exchange ratio, indicating a shift toward increased fat oxidation. In the intervention model, once obesity was established after 12 weeks of HFD feeding, both MLKL ASOs, and similarly, two independent RIPK1 ASOs, reversed weight gain and improved systemic glucose control. In vitro, MLKL-CRISPR/Cas9 knockout blocked 3T3-L1 adipogenesis, indicating a requirement for MLKL during adipocyte differentiation. However, in mature adipocytes, MLKL siRNA reduced palmitic acid-induced lipid accumulation, increased isoprenaline-stimulated lipolysis, and prevented TNF-mediated suppression of insulin-mediated AKT signalling and glucose uptake. Collectively, these findings demonstrate that partial MLKL suppression reprograms whole-body energy metabolism, enhances insulin sensitivity and limits diet-induced adiposity. MLKL, therefore, represents a promising and mechanistically novel therapeutic target for obesity and insulin resistance.

Aging reshapes the cellular and molecular landscape of mammalian tissues. These changes can be progressive, preceding linearly with age, or occur as abrupt transitions of the course of lifespan. To investigate the age-dependent cellular and molecular shifts we profiled matched proteomes and transcriptomes from male and female murine spleens across eight time points, from stable adults through late life. The spleen was chosen to integrate understanding of age-dependent changes associated with immune surveillance, inflammaging, and immune-related proteostasis. Male and female mice follow distinct aging trajectories particularly in protein-RNA correlation in late life, reflecting both compositional shifts and failure of post-transcriptional buffering. To investigate whether these changes could be attributed to specific cell-types within the spleen, we developed Celestial, a machine-learning framework to identify cell-type-specific changes in bulk tissue samples. We found that age-related bulk molecular changes could be attributed in part to compositional remodeling of cell-types--expansion of GZMK+ CD8+ T cells and C1Q+ macrophages alongside naive T cell and global B cell loss. These results demonstrate that cell-type-aware interpretation can inform bulk multi-omic data for accurate mechanistic inference in heterogeneous tissues undergoing complex molecular remodeling.

The central role of microglia in CNS function in health and disease has resulted in large interest in targeting microglial as treatments for neurodegenerative disease; understanding the factors that regulate microglial gene expression will be crucial to this goal. microRNAs (miRNAs) are among the most abundant post transcriptional regulators of gene expression. miRNAs suggests miRNA were likely key to significant evolutionary events as regulators of gene expression. The miRNAome of microglia is critical to their correct functioning but the miRNA that define microglia identity and regulate key functions have not been fully defined. In this study we performed a detailed analysis of the microglial miRNAome to identify miRNA enriched in microglia that are conserved across species (human, mouse, and xenopus). We further characterised the expression of these conserved miRNAs during demyelination and remyelination and identified conserved function of a microglial-enriched miRNA across species. These findings reveal evolutionary conservation of specific miRNAs, suggesting an important role in establishing and maintaining microglial identity. They also highlight miRNAs that may be critical for microglial function in the central nervous system in both health and disease. Overall, this work advances our understanding of the factors that regulate microglial gene expression.

Metabolic dysfunction-associated steatotic liver disease (MASLD) is the most prevalent chronic liver disease and strongly linked to obesity and insulin resistance. We previously reported that the common nuclear envelope variant rs6461378 (g.842031C>T; SUN1 H118Y) associated with MASLD and related traits including insulin resistance. To gain insight into how wild-type (WT) and H118Y SUN1 might differentially impact insulin signaling, we performed affinity purification-mass spectrometry (AP-MS) in human liver-derived cells stably expressing WT or H118Y SUN1. Unbiased AP-MS revealed a novel SUN1-CUL3 interaction, with comparative analysis showing that WT SUN1 interacted robustly with CUL3, while CUL3 interaction was markedly diminished with H118Y SUN1. Cells in which SUN1 was silenced via siRNA, or in which H118Y SUN1 was ectopically expressed, showed increased CUL3 neddylation, which is required for cullin RING ligase (CRL)-mediated ubiquitination of insulin receptor substrate (IRS) proteins. Inhibition of neddylation restored IRS-1 levels and insulin signaling in H118Y SUN1-expressing cells. Together, our findings provide a potential mechanism of H118Y SUN1-driven insulin resistance and a viable therapeutic approach for its reversal.

A long-standing hypothesis in sensory neuroscience suggests that the evolutionary expansion of cortex in mammals may contribute to sensory-dependent adaptation by acting on subcortical pathways that drive innate behavior. However, direct experimental evidence is lacking. Taking the visual system as a model, it is known that there is significant interaction between the evolutionarily conserved Superior Colliculus (SC) and the comparatively modern Visual Cortex (VC), key structures in the mammalian visual system. In the SC, local alignment is established between a retinotopic map of the visual field and a map of orienting movement vectors during development and drives accurate visually guided orienting behavior throughout an organisms lifespan. Interestingly mammals, like humans and non-human primates, readily adapt to altered visual experiences, while evolutionarily older vertebrates, like amphibians, lack this behavioral plasticity. To address this outstanding question, we have developed a novel behavioral paradigm for inducing visuomotor adaptation in freely moving mice that is analogous to paradigms utilized in primates. Our paradigm combines a visually guided orienting task and a novel mouse prism goggle system to shift the visual field. Using this paradigm, we demonstrate for the first time that mice gradually adapt to a chronic shift of their full visual field, suggesting this type of behavioral plasticity is conserved across mammalian species. Furthermore, we show that lesioning primary visual cortex (V1) prior to shifting the visual field disrupts normal visuomotor adaptation, suggesting that VC may play a generative role in the plasticity of fundamental visually guided behaviors. These findings lend support to the hypothesis that a particular evolutionary benefit of sensory cortex is the allowance for experience-dependent behavioral plasticity.

Breast cancer is globally the most common cancer among women. Although the five-year survival rate exceeds 80% for patients with localized disease, it drops to approximately 30% once metastasis occurs, underscoring the urgent need to define mechanisms that drive metastatic progression. Breast is a highly innervated organ and most of its innervation is sensory. However, whether sensory neurons can directly impact breast cancer cells remains an understudied topic. Here, we show that mammary tumors have increased CGRP sensory innervation. Using our novel microfluidic Device for Cancer cell-Axon Interaction Testing (DACIT), we demonstrate that the presence of axons strongly inhibits ECM-degrading ability of cancer cells. The sensory neuron secretome suppresses assembly and function of invadopodia, which are cancer cell protrusions controlling ECM degradation, and essential for intravasation and metastasis. We identify calcitonin gene-related peptide (CGRP) as the key component of the sensory neuron secretome responsible for the inhibitory effect. CGRP signaling occurs through the CRLR/RAMP1 receptor complex expressed by breast cancer cells, inducing a rapid increase in intracellular cAMP levels in breast cancer cells, followed by an increase in RhoC activity and suppression of invadopodia and ECM degradation. Loss of RAMP1 function enhances 3D spheroid invasion, cancer cell motility in vivo and significantly increases the number and the size of lung metastatic foci. Consistently, in silico analyses of both mouse and human RNASeq data point to a link between increasingly invasive subtypes with a gradual decrease in expression of RAMP1 and CRLR. To validate in silico findings, we compare RAMP1 expression in the patient breast tumors with adjacent normal tissues, confirming the invasive breast tumors have reduced levels of RAMP1. Together, our findings identify a protective role for the paracrine CGRP signaling in limiting breast cancer invasion and metastasis. We also demonstrate how cancer cells circumvent CGRP inhibition by suppressing RAMP1 expression, highlighting CGRP-RAMP1-cAMP axis as a potential therapeutic target in breast cancer.

Kaposis Sarcoma Herpesvirus (KSHV), an enveloped double-stranded DNA virus, is the etiological agent of Kaposis sarcoma (KS), an endothelial cell-based tumor. KSHV is a leading cause of infection-related cancers in sub-Saharan Africa and immunocompromised individuals worldwide. Therefore, it is vital to identify the underlying mechanisms of viral infection and transmission to effectively identify specific therapeutic strategies and combat the disease. Here, we demonstrate that KSHV rewires the host cell lipidome during lytic infection. Bulk lipidomic analysis shows significant changes in the abundance of neutral lipids and phospholipids during lytic infection. We further investigated fatty acid-binding proteins (FABPs) to understand the underlying mechanisms that support KSHV pathogenesis. Using the doxycyclin-inducible iSLK.BAC16 cell line, we find that FABP genes are differentially regulated by lytic KSHV infection compared to latent infection. We report that FABP4 is significantly upregulated during lytic infection. Loss of FABP4 during lytic infection does not impact viral gene transcription however, lytic protein translation is reduced. Moreover, our intracellular and extracellular viral titers indicate that FABP4 affects maximal infectious virion production. This study highlights the role of FABP4 and its therapeutic potential as a target that facilitates KSHV infection and pathogenesis.

TAp63, a member of the p53 family, serves as a central quality control factor in oocytes, safeguarding genomic integrity during the prolonged dictyate arrest of meiosis. In healthy oocytes, TAp63 is maintained in an inactive dimeric state; upon DNA damage, it undergoes phosphorylation-dependent tetramerization, enabling transcriptional activation of pathways that determine oocyte fate. While the upstream activation cascade of TAp63 has been well characterized, the mechanisms that regulate its stability during the DNA damage response remain incompletely understood. Here, we identify the kinases HIPK2 and IKK{beta} as key regulators of TAp63 stability. We show that TAp63 interacts with both kinases and is phosphorylated at distinct residues, T452 by HIPK2 and S4/S12 by IKK{beta} in vitro and in vivo, in addition to previously described CHK2 and CK1-mediated phosphorylation. Functionally, these phosphorylation events do not primarily contribute to activation, but instead stabilize TAp63 by limiting MDM4-dependent ubiquitination and subsequent proteasomal degradation. Mechanistically, our data support a model in which CHK2 and CK1 initiate TAp63 phosphorylation, while HIPK2 and IKK{beta} act in a complementary manner to maintain protein stability during genotoxic stress. Disruption of HIPK2 or IKK{beta} activity reduces TAp63 stability, whereas their inhibition in vivo attenuates oocyte loss following DNA damage, resulting in increased preservation of the follicle pool. Importantly, these effects are observed across multiple systems, including mouse models and ex vivo goat ovary cultures, supporting an evolutionarily conserved role for this regulatory axis. Together, our findings uncover a previously unidentified layer of TAp63 regulation, in which phosphorylation not only contributes to its activation but also enhances protein stability, thereby fine-tuning oocyte responses to DNA damage. Our results further indicate that HIPK2 and IKK{beta}-mediated phosphorylation modulates oocyte survival under genotoxic stress, highlighting this pathway as a potential target for strategies aimed at limiting oocyte loss.

The heat shock transcription factor HSF1 is best known as a master regulator of the proteotoxic stress response, yet its functions in animal development remain incompletely defined. In Drosophila melanogaster, heat shock factor (HSF) is essential for viability, but the mechanisms by which it promotes development are unclear. Here, we show that Hsf null larvae arrest at the early 2nd instar stage and exhibit a significant reduction in basal levels of the chaperone HSP83. Tissue-specific knockdown of Hsf revealed widespread and organ-specific requirements, including defects in endoreplication and cell growth in larval prothoracic and salivary glands, adult wing defects following larval imaginal disc perturbation, follicle degeneration in the ovary, and melanotic tumor upon hemocyte depletion. In these tissues, loss of HSF typically leads to reduced HSP83 levels, and restoration of HSP83 expression partially or fully rescues these defects. These findings identify HSP83 as a critical downstream effector of HSF and demonstrate that HSF promotes development largely by maintaining basal chaperone expression. Together, our results establish HSF as a key regulator of developmental progression and highlight a central role for proteostasis in supporting tissue growth under non-stress conditions.

Gut microbiota are critical determinants of effective immune checkpoint therapy (ICT), yet the microbial mediators and host mechanisms that enhance antitumor immunity remain poorly understood. Here, we identify the microbiota-derived bile acid taurodeoxycholic acid (TDCA) as a metabolite associated with immune checkpoint therapy (ICT) response. TDCA administration alone is sufficient to overcome antibiotic-induced ICT hyporesponsiveness across multiple murine tumor models. Mechanistically, TDCA directly enhances CD8 T cell-mediated antitumor immunity, increasing cytotoxicity. These effects required signaling through the bile acid receptor TGR5. Together, these findings reveal TDCA as a gut microbial metabolite that restores ICT efficacy after antibiotic disruption by directly augmenting CD8 T cell anti-tumor activity. This work supports metabolite replacement as a therapeutic strategy to mitigate antibiotic-associated loss of cancer immunotherapy response. SignificanceTDCA is a microbiota-derived metabolite that restores immune checkpoint therapy efficacy after antibiotic disruption by directly enhancing CD8 T-cell-mediated anti-tumor immunity through bile acid receptor TGR5 signaling. Our findings suggest that supplementation with defined microbial metabolites can mitigate antibiotic-associated loss of immunotherapy response without requiring broader microbiome reconstitution.

Extracellular vesicles (EVs) mediate intercellular transfer of lipids, proteins, and nucleic acids between nearly all cell types. We previously showed that astrocyte-derived EVs modulate neuronal mitochondria in vitro, but whether endogenous astrocytic EVs are trafficked to neuronal mitochondria in vivo remained unknown. To address this, we generated an EV reporter mouse, Aldh1l1-Cre; CD9-tGFPfl/fl, in which astrocyte-secreted EVs are labeled with a CD9-turboGFP fusion protein (CD9-tGFP). Astrocyte-specific expression of CD9-tGFP was verified in brain tissue and isolated EVs, comprising 13.2 {+/-} 1.6% of total brain EVs. In primary glial cultures, CD9-tGFP was restricted to astrocytes, localizing to vesicular compartments and cell protrusions (filopodia and cilia), with 89.3 {+/-} 2.2% of astrocyte-derived EVs carrying the label. These EVs were enriched with the sphingolipid ceramide, consistent with its co-distribution with CD9-tGFP in astrocytic cell protrusions. In the cortex, hippocampus, and cerebellum, CD9-tGFP was predominantly detected in astrocytic processes co-labeled with GLAST1 and GFAP, forming contacts with laminin-positive capillaries and parvalbumin-positive neurons. CD9-tGFP-labeled EVs were detected inside capillaries and neurons, and super-resolution STED microscopy revealed partial overlap with neuronal mitochondria. Live-cell spinning disk confocal imaging and AI-assisted proximity analysis confirmed uptake of CD9-tGFP EVs by neuronal cells and trafficking of their cargo to mitochondria in vitro. Biochemical isolation of synaptic and non-synaptic mitochondria confirmed EV-derived cargo on mitochondria in vivo, with 3-fold higher association of CD9-tGFP with synaptic than non-synaptic mitochondria. Together, these findings validate the Aldh1l1-Cre; CD9-tGFPfl/fl reporter mouse as a powerful tool for tracking astrocyte-derived EVs in vivo and provide direct evidence that their cargo is preferentially trafficked to synaptic mitochondria. Graphical AbstractAstrocyte-derived extracellular vesicles target neuronal mitochondria in vivo O_FIG O_LINKSMALLFIG WIDTH=156 HEIGHT=200 SRC="FIGDIR/small/718987v1_ufig1.gif" ALT="Figure 1"> View larger version (33K): org.highwire.dtl.DTLVardef@174d92aorg.highwire.dtl.DTLVardef@5d8248org.highwire.dtl.DTLVardef@114483borg.highwire.dtl.DTLVardef@924d55_HPS_FORMAT_FIGEXP M_FIG C_FIG

Diabetes mellitus is characterized by chronic hyperglycemia and loss of pancreatic {beta}-cell function and mass. Current therapies focus on {beta}-cell protection and regeneration, led by GLP-1 receptor agonists. The G protein -subunit (Gs) acts as a key signaling node downstream of numerous GPCRs, integrating diverse signals that impact {beta}-cell mass and function. Elucidating the integrative role of pancreatic Gs signaling is thus crucial for understanding {beta}-cell biology. Our map of the pancreatic Gs-coupled GPCR landscape reveals sophisticated, cell-type-specific networks, positioning Gs as a central hub for intra-pancreatic communication. Previous studies in mice with {beta}-cell-specific or whole-pancreatic Gs deletion demonstrated reduced {beta}-cell mass, impaired insulin secretion, and glucose intolerance. The stronger phenotype in the whole-pancreas model--marked by -cell expansion and abnormal distribution--points to a crucial role for Gs in differential control of postnatal - and {beta}-cell proliferation. Here, we analyze the organ-wide consequences of Gs deletion using pancreas-specific Gs knockout mice (PGsKO). Consistent with prior findings, PGsKO mice exhibit reduced weight gain from four weeks and severe diabetes due to decreased {beta}-cell mass and concomitant -cell expansion. Furthermore, Gs loss induces profound architectural and functional defects in the exocrine pancreas, linked to YAP reactivation in acinar cells. Importantly, we observed attempted {beta}-cell regeneration in PGsKO mice. Although insufficient to reverse diabetes, our results delineate the full pancreatic phenotype that may facilitate these regenerative efforts and suggest that strategically biasing GPCR signaling network away from Gs could be a viable strategy to promote {beta}-cell regeneration from other pancreatic cell types. ARTICLE HIGHLIGHTSO_LIGs is a central signaling hub that integrates diverse GPCR inputs across pancreatic cell types, yet its organ-wide role remained poorly defined. C_LIO_LIWe addressed how pancreas-wide Gs deletion disrupts both endocrine and exocrine compartments, and whether regenerative programs are engaged. C_LIO_LIGs loss caused severe diabetes through {beta}-cell loss and -cell expansion, induced profound exocrine defects with YAP reactivation, and triggered attempted {beta}-cell regeneration from ducts and potentially other cell types. C_LIO_LIOur findings suggest that strategically biasing GPCR signaling away from Gs could promote regeneration from non-{beta}-cell sources, offering new therapeutic avenues for diabetes. C_LI

Adaptive behavior under threat requires balancing reward pursuit against the risk of harm. During approach-avoidance conflict, animals often pause at decision points, but whether these pauses reflect a unified process or distinct decision states remains unclear. Here, we replicate and extend findings from Calvin et al.1 by analyzing hippocampal activity in rats performing a predator-based foraging task across two cohorts. We compared three behaviors: mid-track aborts (MTAs), mid-track continues (MTCs), and attack-triggered retreats. Behaviorally, MTAs and MTCs emerged from a shared pause state but led to different outcomes, whereas retreats reflected rapid, reactive escape following attack. Despite similar behavioral endpoints (return to safety), retreats and MTAs differed markedly in movement dynamics and neural activity. During retreats, hippocampal representations remained biased toward the attack location, consistent with ongoing encoding of immediate threat. In contrast, MTAs showed a shift in representation toward safe locations following the decision to abort. During pauses, hippocampal activity differentiated future behavioral outcomes before movement diverged: pauses preceding MTAs showed stronger representation of threat-related locations, whereas pauses preceding MTCs emphasized goal-related locations. These representational biases were already present during the outbound approach, indicating that decision-related processes emerged at the beginning of the outbound journey. Across experience, representations of threat and goal locations became increasingly differentiated when encountering an attacking robot, diminished during extinction, and re-emerged when the attack was introduced again. Together, these findings extend prior work by dissociating hippocampal representations associated with reactive escape from those underlying anticipatory, anxiety-like decision-making, suggesting that the hippocampus dynamically tracks behaviorally relevant features to guide decisions under threat.

The neonatal heart undergoes a rapid metabolic transition from fetal glycolysis to oxidative phosphorylation, requiring coordinated metabolic remodeling. Mechanisms driving this transition remain unclear. Here, we demonstrate that sufficient mitochondrial S-adenosylmethionine (mitoSAM), imported via the solute carrier Slc25a26, is essential for this shift by sustaining the lipoylation of 2-oxoacid dehydrogenases, critical for TCA cycle activation. Proteomic and metabolomic profiling revealed that reduced mitoSAM availability impaired lipoylation, blocking TCA cycle function and restricting nucleotide synthesis, while mitochondrial gene expression and respiratory capacity remained largely intact. In vivo EdU labeling showed persistent cardiomyocyte proliferation imposing further strain on nucleotide pools. Supplementation with medium-chain triglycerides during the suckling-to-weaning transition restored metabolic function and normalized cardiac growth and morphology. Our data reveal a critical developmental window in which mitoSAM-dependent lipoylation ensures heart maturation.

Scratching provides transient relief from itch, yet the neural circuit mechanisms that transform scratching into itch relief remain poorly understood. Midbrain dopaminergic neurons and their downstream targets in the lateral shell of the nucleus accumbens (NAc LaSh) are implicated in itch-scratch processing. Previous studies show that pharmacological manipulation of dopamine D1 and D2 receptors in the NAc LaSh alters scratching behavior, but the specific contributions of D1R- and D2R-expressing neurons during acute and chronic itch remain unclear. Here, we show that NAc LaShD1R and D2R neurons bidirectionally regulate scratching behavior across itch states. NAc LaShD1R neurons activity promotes scratching bouts, whereas NAc LaShD2R neurons preferentially facilitate scratch termination. Anterograde viral tracing revealed distinct brain-wide projection patterns of NAc LaShD1R and D2R neurons, which we functionally tested using projection-specific optogenetic manipulations. We found that NAc LaShD2R neurons terminate scratching by inhibiting neurons in the lateral parabrachial nucleus (LPBN), a key hub for itch processing. Furthermore, dopamine levels in the NAc LaSh were elevated during chronic itch compared with acute itch, suggesting enhanced dopaminergic signaling contributes to persistent scratching. Together, these findings identify circuit mechanisms linking reward pathways to itch regulation.