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Biology subjects

Lu, K.

Publications and source records attributed to Lu, K..

At least 19 recordsLinked to original sources

RPDynaFlow: Generating RNA-Protein Conformational Ensembles by Atomic Conditional Flow Matching

Conformation ensembles of biomolecules provide the basis for understanding structural transformations and drug design. Deep-learning generative models have advanced protein and small molecule ensemble generation, while RNA-Protein complexes remain unaddressed due to the chemical heterogeneity, limited dataset size and the different flexibility scales of RNA and protein components. We present RPDynaFlow, a flow-matching model to generate conformation ensembles of RNA-protein complexes, trained on 600 ns trajectories of molecular dynamics(MD) simulation. The results show our model extends the sampling range of the phase space compared to MD simulation, which couldbe treated as a rapid and efficient complement to MD trajectoriesfor studying RNA-protein interactions.

biophysics↗

Structure-Property-Performance Engineering of Hydrogel Depots for Long-Acting Peptide Delivery

Controlled release systems for subcutaneous peptide delivery often exhibit a pronounced initial burst release followed by inadequate maintenance of therapeutic exposure, limiting depot lifetime and increasing pharmacokinetic variability. Here, we engineer a dynamic, injectable hydrogel depot technology for months-long delivery of lipidated peptides. Using semaglutide as a model, we establish a modular formulation framework integrating: (i) formulation-driven tuning of depot mechanics to control release kinetics, (ii) cargo complexation strategies leveraging hydrophobic and multivalent ion-mediated interactions, and (iii) oxidative stabilization through sacrificial antioxidant excipients. We evaluated depot performance by rheology, in vitro cargo release, and in vivo pharmacokinetic and pharmacodynamic studies in rodents. Optimized formulations sustained semaglutide exposure for over six weeks from a single administration with two-fold reduction in peak-to-trough exposure and comparable total bioavailability relative to daily dosing, resulting in improved glucose control, weight regulation, and preservation of pancreatic islet content. These results suggest potential for quarterly dosing in humans. Together, this work establishes integrated and generalizable structure-property-performance relationships that account for cargo-matrix and cargo-excipient interactions across burst, diffusion, and erosion regimes to inform a practical formulation framework for engineering long-acting depots for sustained peptide delivery.

bioengineering↗

Molecular Dosimetry of DNA Adducts in Mice Exposed to Ethylene Oxide

Ethylene oxide (EtO) is a highly reactive industrial chemical and classified as a known human carcinogen with a putative mutagenic mode of action (MOA). Its genotoxic potential is primarily mediated through alkylation of DNA, resulting in the formation of the mutagenic adduct O6-(2-hydroxyethyl)-2-deoxyguanosine (O6-HE-dG). The N7-(2-hydroxyethyl)guanine (N7-HE-G) adduct is formed in greater abundance and is generally considered to be non-mutagenic. However, dose-response relationships of these DNA adducts, particularly at low inhalation exposure levels (i. e., below 3 ppm), remain unknown. These data are necessary to inform the biological plausibility of different statistical dose-response models that have been applied to human or animal data used for cancer risk assessment. In the present study, male and female B6C3F1 mice were exposed to EtO (0, 0.05, 0.1, 0.5, 1, 50, 100, and 200 ppm) 6 hours/day for 28 consecutive days. Immediately following the last exposure, DNA was extracted from lung, liver, bone marrow, and mammary gland, and further utilized to measure DNA adduct levels using highly sensitive mass spectrometry platforms. N7-HE-G was detected in all tissues and exposure groups, showing linear dose-response relationships in the low-dose range ([&le;]1 ppm) and increased sharply and exposure-disproportionately in the high-dose range ([&ge;]50 ppm). Despite a very low limit of detection, O6-HE-dG, in contrast, was not detected at exposures <50 ppm in any tissue consistent with at most a shallow linear exposure response. At higher exposures ([&ge;]50 ppm), O6-HE-dG exhibited a dose-response pattern of N7-HE-G. Notably the mammary gland, despite being anatomically distant from the site of inhalation, exhibited the second-highest levels of both adducts at higher doses. This study provides the first reliable quantitative dose-response evidence of DNA adducts in tumor target and non-target (liver) tissues across a wide range of EtO exposures. The two DNA adducts differ markedly in their abundance, repairability and mutagenic potential and together provide a molecular MOA dose-response framework to inform both quantitative cancer risk assessment and genotoxic hazard characterization.

pharmacology and toxicology↗

INVESTIGATION OF ETHYLENE OXIDE GENOTOXICITY DOSE-RESPONSE TO INFORM CANCER RISK ASSESSMENT

Ethylene oxide (EtO) is primarily used as an intermediate in the manufacture of chemicals, with a minor use as a sterilant for medical equipment and food products. It is a direct-acting alkylating agent that reacts with cellular macromolecules, including proteins and DNA. EtO has been shown to induce tumors in rodents and humans. DNA reactivity has been the postulated mode of action (MOA) for its carcinogenicity. The current study has investigated the dose response for EtO-induced genetic damage to inform the biological plausibility of a dose-response model for cancer risk assessment. Male and female B6C3F1 mice were exposed to 0, 0.05, 0.1, 0.5, 1, 50, 100, or 200 ppm EtO by whole-body inhalation (6 hours/day for 28 days, 7 days/week). Mutagenicity was assessed by determining the frequency of mutant Pig-a phenotype in reticulocytes (RET) and mature red blood cells (RBC) on Day 28. Cytogenetic damage was evaluated by the erythrocyte micronucleus (MN) test in blood samples collected on Days 5 and 28. EtO is a relatively weak genotoxicant with treatment-related increases in Pig-a and MN frequencies being seen primarily at 200 ppm. The hockey-stick shaped dose response for genetic damage may be conservatively interpreted as being no more than a linear response with a single slope. Thus, a cancer risk assessment dose-response model consisting of a single linear slope throughout the exposure range is biologically plausible and consistent if EtO were acting through a mutagenic MoA for its carcinogenicity.

pharmacology and toxicology↗

OSTM1 is a ubiquitin E3 ligase that suppresses B-cell malignancy by activating the cAMP/PKA/CREB pathway

Osteoclastogenesis-associated transmembrane protein 1 (OSTM1) is a glycosylated, membrane-integral protein that regulates lysosomal homeostasis, with loss-of-function mutations causing autosomal recessive osteopetrosis. Through a whole-genome CRISPR/Cas9 screen, we identified OSTM1 as a previously unrecognized tumor suppressor in B-cell malignancies. Consistent with this role, OSTM1 is frequently deleted or downregulated across a broad spectrum of human B-cell cancers. In mice, B-cell-specific monoallelic or biallelic ablation of Ostm1 cooperates with Cdkn2a loss to drive lymphomagenesis with near-complete penetrance. Mechanistically, we uncover a cytosolic, non-glycosylated fraction of OSTM1 that functions as a ubiquitin E3 ligase to promote proteasomal degradation of phosphodiesterase 3B (PDE3B). As PDE3B hydrolyzes cAMP and suppresses the tumor-protective PKA/CREB/CREBBP signaling axis, loss of OSTM1 leads to PDE3B stabilization, attenuation of cAMP signaling, and enhanced oncogenic transformation. Together, our findings establish OSTM1 as a critical suppressor of B-cell lymphomagenesis through regulation of the cAMP/PKA/CREB pathway.

cancer biology↗

Ptf1a robustly drives the gliogenic switch in the rodent embryonic cortex in a dosage-dependent manner by activating pro-glial gene expression programs

It is widely believed that the gliogenic switch during rodent embryonic development is governed by the orchestrated crosstalk between a cohort of genes and extracellular cues. Here we report that ectopic expression of the single bHLH factor, pancreas transcription factor 1 (PTF1A), is sufficient to drive radial glial progenitors (RGPs)-regardless of progenitor heterogeneity and developmental stage-to differentiate into glial cells. Ptf1a- expressing RGPs exhibit progenitor behaviors indicative of a neurogenic-to-gliogenic fate transition, resembling endogenous progenitors at the late stages of embryonic development, and preferentially produce OLIG2+ oligodendrocytes in vivo, some of which are positive for PDGFR or CC1. This robust gliogenic competency depends on the dosage of stable Ptf1a expression in RGPs. RNAseq reveals the glial transcriptome, including upregulated expression of several notch signaling components and the endothelin receptors in Ptf1a RGPs. We further identify Ednrb as one of the downstream targets of Ptf1a that directs RGPs toward gliogenesis via the ERK1/2 signaling pathway. In summary, our study uncovers a novel and robust role for Ptf1a in glial fate specification, offering a potential strategy for generating human oligodendrocytes in vitro.

neuroscience↗

Long-acting hydrogel-based depot formulations of tirzepatide and semaglutide for the management of type 2 diabetes and weight

Several incretin hormone therapies have been clinically approved and have revolutionized the treatment of diabetes and obesity. Promising therapeutics include semaglutide (Ozempic(R) and Wegovy(R)), an agonist for glucagon-like peptide-1 (GLP-1) receptor, and tirzepatide (Mounjaro(R)), a dual agonist for GLP-1 and glucose-dependent insulinotropic polypeptide (GIP) receptors. These molecules help to regulate blood glucose levels, enhance insulin secretion and sensitivity, and reduce appetite. Currently, these treatments require weekly injections, which can be challenging for patients to adhere to. We recently reported the development of an injectable hydrogel depot technology enabling months-long release of semaglutide (Sema). Here, we further develop this technology for improved prolonged release of both Sema and tirzepatide (TZP). In a rat model of diabetes, we show a single administration of hydrogel-based formulations of either Sema or TZP maintained relevant drug levels for over 6 weeks. In these studies, single administrations of long-acting hydrogel-based therapies of Sema or TZP were similarly effective at regulating blood glucose and weight compared to daily injections of either Sema or TZP in standard aqueous vehicles. This hydrogel depot technology is easy to manufacture, injectable, and exhibits excellent biocompatibility, enabling months-long-acting treatments with the potential to improve management of diabetes and weight.

bioengineering↗

Coenzyme Q10 alleviates the mitochondrial damage by high-fat load in hepatocytes of spotted seabass (Lateolabrax maculatus) via promoting mitophagy

Coenzyme Q10, as a natural fat-soluble compound, can play a role in protecting mitochondria, but the mechanism is still unclear. Here, we explored the mechanism of coenzyme Q10 enhancing mitochondrial function using hepatocytes of spotted seabass. Three groups were set: normal medium as control group, fatty acid group containing 100 mol/L FA (FA group), and 100 mol/L FA and 5 mol/L coenzyme Q10 group (FA+COQ10). After the culture, the results showed that FA treatment significantly increased the triglyceride content in the cells. Bodipy staining showed that many lipid droplets appeared in the FA group, while coenzyme Q10 reduced triglycerides content and lipid droplets. Moreover, coenzyme Q10 significantly reduced the content of ROS in cells. After scavenging ROS, the liver cell damage caused by FA was alleviated, the mitochondrial membrane potential and its mitochondrial metabolic enzyme activity were restored, and the ATP content was increased. Further analysis showed that FA significantly down-regulated the expression of mitophagy key genes pink, parkin and lc3b, while up-regulated the expression of p62. Through mitochondrial fluorescence staining and mtDNA content detection, it was found that the number of mitochondria in FA-treated cells decreased significantly, while the number of mitochondria increased significantly after FA+COQ10 treatment. This indicates that coenzyme Q10 can significantly promote the mitophagy process. In order to further study whether the enhancement of mitochondrial function by coenzyme Q10 is related to the activation of autophagy, we set up FA group, FA+COQ10 group and FA+COQ10+Mdivi-1 group (pretreatment with mitophagy inhibitor Mdivi-1). After Mtphagy Dye staining, it was found that the number of autophagosomes in the FA+COQ10+Mdivi-1 group was lower than that in the FA+COQ10 group, indicating that the activation of mitophagy by coenzyme Q10 was inhibited. The results of this study indicate that coenzyme Q10 enhances mitochondrial function and alleviates excessive fat deposition dependent on PINK1-mediated mitophagy.

cell biology↗

Formaldehyde induces and promotes Alzheimer's disease pathologies in a 3D human neural cell culture system

Alzheimers disease (AD) arises from complex multilevel interactions between genetic, epigenetic, and environmental factors. Recent studies suggest that exposure to the environmental and occupational toxicant formaldehyde (FA) may play a significant role in AD development. However, the effects of FA exposure on A{beta} and tau pathologies in human neural cell 3D culture systems remain unexplored. To investigate FAs role in AD initiation, we differentiated 3D-cultured immortalized human neural progenitor ReN cells (ReNcell VM) into neurons and glial cells, followed by FA treatment. FA exposure for 12 weeks resulted in a dose-dependent increase in A{beta}40, A{beta}42, and phosphorylated tau levels. To further examine FAs role in AD progression, we established a 3D human neural cell culture AD model by transfecting ReN cells with AD-related mutant genes, including mutant APP and PSEN1, which recapitulate key AD pathological events. Our findings demonstrate that FA exposure significantly elevated A{beta}40, A{beta}42, and phosphorylated tau levels in this 3D-cultured AD model. These results suggest that FA exposure contributes to the initiation and progression of AD pathology in 3D-cultured human neural cells.

neuroscience↗

Formaldehyde Exposure Induces Systemic Epigenetic Alterations in Histone Methylation and Acetylation

Formaldehyde (FA) is a pervasive environmental organic pollutant and a Group 1 human carcinogen. While FA has been implicated in various cancers, its genotoxic effects, including DNA damage and DNA-protein crosslinking, have proven insufficient to fully explain its role in carcinogenesis, suggesting the involvement of epigenetic mechanisms. Histone post-translational modifications (PTMs) on H3 and H4, critical for regulating gene expression, may contribute to FA-induced pathogenesis as lysine and arginine residues serve as targets for FA-protein adduct formation. This study aimed to elucidate the effects of FA on histone methylation and acetylation patterns. Human bronchial epithelial cells (BEAS-2B) were exposed to low-dose (100 M) and high-dose (500 M) FA for 1 hour, and their histone extracts were analyzed using high-resolution liquid chromatography-tandem mass spectrometry-based proteomics, followed by PTM-combined peptide analysis and single PTM site/type comparisons. We identified 40 peptides on histone H3 and 16 on histone H4 bearing epigenetic marks. Our findings revealed that FA exposure induced systemic alterations in H3 and H4 methylation and acetylation, including hypomethylation of H3K4 and H3K79 and changes in H3K9, H3K14, H3K18, H3K23, H3K27, H3K36, H3K37, and H3R40, as well as modifications in H4K5, H4K8, H4K12, and H4K16. These FA-induced histone modifications exhibited strong parallels with epigenetic alterations observed in cancers, leukemia, and Alzheimers disease. This study provides novel evidence of FA epigenetic toxicity, offering new insights into the potential mechanisms underlying FA-driven pathogenesis.

pharmacology and toxicology↗

YY1 Enhances the Stability of HIF-1α Protein by Interacting with NUSAP1 in Macrophages within the Prostate Cancer Microenvironment

Immune checkpoint therapy for prostate cancer (PCa) has failed in clinical trials; however, the precise underlying mechanisms involved remain elusive. PCa, a classic "immune-cold" tumor, is characterized by an immunosuppressive tumor microenvironment. Within this milieu, macrophages, the predominant immune cell population, have a propensity to infiltrate the hypoxic zones of tumors. In a previous study, we showed that Yin Yang 1 (YY1) is highly expressed in macrophages in PCa tissues. Here, through multiplexed imaging mass cytometry (IMC) of a PCa tissue microarray, we further demonstrate that YY1+ macrophages aggregate in hypoxic areas of tumors and that hypoxia promotes the phase separation of YY1 in the nucleus by increasing YY1 tyrosine phosphorylation in macrophages. Furthermore, YY1 binds to NUSAP1 and promotes the SUMOylation of HIF-1, which promotes phase separation and stabilization of the HIF-1 protein. We also demonstrated that either treatment with a small molecule inhibitor (tenapanor) to decrease the YY1-NUSAP1-HIF-1 interaction or myeloid-specific YY1 gene knockout impairs subcutaneous PCa tumor formation. Furthermore, we present a first-generation tetrahedral DNA nanostructure (TDN) based on the proteolysis targeting chimera (PROTAC) technique, named YY1-DcTAC, which targets and degrades YY1 in tumor-associated macrophages. In a PCa mouse model, YY1-DcTAC exhibited prolonged drug efficacy, robust macrophage-specific responsiveness, potent antitumor effects, and increased CD8+ T cell tumor infiltration. In summary, our findings underscore the pivotal role of YY1 within the hypoxia/HIF-1 pathway in tumor-associated macrophages and affirm the therapeutic potential of targeting YY1 for treating PCa.

cancer biology↗

Multi-omics analysis reveals the mechanism of BnC07MYB3a is involved in seed coat color in Brassica napus L.

In rapeseed (Brassica napus), yellow-seeded varieties accumulate less flavonoid pigments (anthocyanins/proanthocyanidins) in their seed coats compared with black-seeded varieties. The yellow-seeded trait is associated with greatly improved seed oil yield, quality, and commercial value. Many R2R3 MYB activators have been characterized in rapeseed, but how MYB-type repressors affect pigment biosynthesis is not yet fully understood. In this study, we performed transcriptome sequencing and metabolomic analysis of B. napus varieties with extreme differences in seed coat color, combined with weighted gene co-expression network analysis. This analysis identified an R2R3-MYB-type transcription factor, BnC07MYB3a (BnaC07G0178800ZS), as a candidate regulator of the yellow-seeded trait in B. napus. Overexpressing BnC07MYB3a in Arabidopsis thaliana and B. napus downregulated the expression of flavonoid biosynthetic genes, resulting in significantly lower anthocyanin and proanthocyanidin accumulation than in the wild-type and a lighter seed coat color in transgenic plants. BnC07MYB3a directly binds to the promoter of the TRANSPARENT TESTA (TT) gene BnTT6 and represses its expression. BnC07MYB3a also physically interacts with BnA06bHLH92a and the WD40 transcription factor TRANSPARENT TESTA GLABRA1 (BnTTG1), suggesting that they might form a previously unidentified MYB-bHLH-WD40 transcription factor complex. Our results reveal the molecular mechanism and regulatory network of BnC07MYB3a in determining seed coat color in B. napus and provide a genetic resource for breeding yellow-seeded cultivars of B. napus.

molecular biology↗

Sex-specific effects of gut microbiome on shaping bile acid metabolism

Gut microbiome is a group of microorganisms that plays important roles in contributing to health and diseases. These bacterial compositions have been demonstrated to impact bile acids (BAs) profiles, either by directly metabolizing primary BAs to secondary BAs or indirect ways through host metabolism by influencing BAs synthesis, transportation and conjugation in liver. It has been observed sexually dimorphic gut microbiome and bile acids composition, with variations in expression levels of bile acid metabolizing genes in the liver. However, associations betweensex-specific differences in gut microbiome and BAs profiles are not well understood. This study aimed to investigate whether gut microbiome could influence BAs profiles in host in a sex-specific manner. We transplanted cecum feces of male and female C57BL/6 mice to male mice and measured BAs concentrations in feces, serum and liver samples 7 days after fecal transplantation. We found different BAs profiles between mice with male and female gut microbiome, including altering levels and proportions of secondary BAs. We also observed varied expression levels of genes related to bile acid metabolism in the liver and distal ileum.Our results highlight sex-specific effects of gut microbiome on shaping bile acid metabolism through gut bacteria and regulation of host genes.

microbiology↗

Temporal-Coherence Induces Binding in Responses to Sound Sequences in Ferret Auditory Cortex

Binding the attributes of a sensory source is necessary to perceive it as a unified entity, one that can be attended to and extracted from its surrounding scene. In auditory perception, this is the essence of the cocktail party problem in which a listener segregates one speaker from a mixture of voices, or a musical stream from simultaneous others. It is postulated that coherence of the temporal modulations of a sources features is necessary to bind them. The focus of this study is on the role of temporal-coherence in binding and segregation, and specifically as evidenced by the neural correlates of rapid plasticity that enhance cortical responses among synchronized neurons, while suppressing them among asynchronized ones. In a first experiment, we find that attention to a sound sequence rapidly binds it to other coherent sequences while suppressing nearby incoherent sequences, thus enhancing the contrast between the two groups. In a second experiment, a sequence of synchronized multi-tone complexes, embedded in a cloud of randomly dispersed background of desynchronized tones, perceptually and neurally pops-out after a fraction of a second highlighting the binding among its coherent tones against the incoherent background. These findings demonstrate the role of temporal-coherence in binding and segregation.

neuroscience↗

Two major-effect loci influence assortative mating in females of the sibling species, Drosophila simulans and D. sechellia

Secondary contact between incompletely isolated species can produce a wide variety of outcomes, including production of new species and adaptive radiations. The vinegar flies Drosophila simulans and D. sechellia diverged on islands in the Indian Ocean and are currently separated by partial pre- and postzygotic barriers. The recent discovery of hybridization between D. simulans and D. sechellia in the wild presents an opportunity to monitor the prevalence of alleles that influence introgression between these species. We therefore sought to identify those loci that affect assortative mating, and we adapted a two-choice assay to test behavioral isolation in females. Using high-resolution seq-based QTL mapping, we found two major effect loci on the third chromosome that have a profound effect upon assortative mating of females. Each major QTL accounts for 32-37% of the difference in phenotype on its own, which is highly significant for a behavioral trait. The two major QTL of both backcrosses co-localize in one-dimensional analyses, suggesting that they may be alternate alleles of the same loci. The major-effect loci also co-localize with genes that encode enzymes required for female- and species-specific production of the pheromone, 7,11-heptacosadiene, emphasizing the importance of female attractiveness to males in separation of these species. Moreover, the genetic architecture of female assortative mating may be a factor in species separation, since alleles that influence assortative mating in females are linked to major-effect loci that influence assortative mating in males, and to loci that contribute to host fruit adaptation in D. sechellia.

evolutionary biology↗

Distinct functions of EHMT1 and EHMT2 in cancer chemotherapy and immunotherapy

EHTM1 (GLP) and EHMT2 (G9a) are closely related protein lysine methyltransferases often thought to function together as a heterodimer to methylate histone H3 and non-histone substrates in diverse cellular processes including transcriptional regulation, genome methylation, and DNA repair. Here we show that EHMT1/2 inhibitors cause ATM-mediated slowdown of replication fork progression, accumulation of single-stranded replication gaps, emergence of cytosolic DNA, and increased expression of STING. EHMT1/2 inhibition strongly potentiates the efficacy of alkylating chemotherapy and anti-PD-1 immunotherapy in mouse models of tripe negative breast cancer. The effects on DNA replication and alkylating agent sensitivity are largely caused by the loss of EHMT1-mediated methylation of LIG1, whereas the elevated STING expression and remarkable response to immunotherapy appear mainly elicited by the loss of EHMT2 activity. Depletion of UHRF1, a protein known to be associated with EHMT1/2 and LIG1, also induces STING expression, and depletion of either EHMT2 or UHRF1 leads to demethylation of specific CpG sites in the STING1 promoter, suggestive of a distinct EHMT2-UHRF1 axis that regulates DNA methylation and gene transcription. These results highlight distinct functions of the two EHMT paralogs and provide enlightening paradigms and corresponding molecular basis for combination therapies involving alkylating agents and immune checkpoint inhibitors.

cancer biology↗

Activation of a cortical neurogenesis transcriptional program during NEUROD1-induced astrocyte-to-neuron conversion

NEUROD1-induced astrocyte-to-neuron (AtN) conversion has garnered significant attention as a potential therapeutic intervention to neurological disorders. To gain insight into the molecular regulations underlying this neuronal reprogramming process, we applied single-cell multiomics analyses on in vitro ND1-induced AtN conversion to systematically investigate how ND1 changed the fate of astrocytes at transcriptomic and epigenetic levels. Our findings reveal that the initial immature astrocytes go through an intermediate state where both astrocytic and neuronal genes are activated at early stage of AtN conversion. ND1 directly reshapes the chromatin accessibility landscape of astrocytes to that of neurons, promoting expression of endogenous Neurod1 and other neurogenic genes such as Hes6, Insm1 etc. Interestingly, cell proliferation status is highly correlated with conversion rate, and inhibition of cell division significantly reduces the conversion ratio. Moreover, in comparison with another AtN reprogramming transcription factor, ASCL1, external ND1 can activate endogenous Neurod1 and directly promote neuronal gene transcription; whereas external ASCL1 hardly activates endogenous Ascl1, leading to slower and inefficient conversion. Together, our studies demonstrate that in vitro AtN conversion mimics neurogenic transcriptional program in embryonic neurogenesis.

neuroscience↗

Instinct to insight: Neural correlates of ethological strategy learning

In ethological behaviors like parenting, animals innately follow stereotyped patterns of choices to decide between uncertain outcomes but can learn to modify their strategies to incorporate new information. For example, female mice in a T-maze instinctively use spatial-memory to search for pups where they last found them but can learn more efficient strategies employing pup-associated acoustic cues. We uncovered neural correlates for transitioning between these innate and learned strategies. Auditory cortex (ACx) was required during learning. ACx firing at the nest increased with learning and correlated with subsequent search speed but not outcome. Surprisingly, ACx suppression rather than facilitation during search was more prognostic of correct sound-cued outcomes - even before adopting a sound-cued strategy. Meanwhile medial prefrontal cortex encoded the last pup location, but this decayed as the spatial-memory strategy declined. Our results suggest a neural competition between a weakening spatial-memory and strengthening sound-cued neural representation to mediate strategy switches.

neuroscience↗