Biology subjects

Dai, G.

Publications and source records attributed to Dai, G..

At least 19 recordsLinked to original sources

bioRxiv2026

Automated culture and monitoring of a high-throughput human heart-on-a-chip

Organ chips offer a disruptive innovation to study human diseases with tissue-specific resolution within a predictable and tunable in vitro environment. However, these platform technologies have for the most part failed to translate to broad use in the private sector due to a lack of high-throughput, user-friendly platforms. Here we present an automated high-throughput organ chip seeded with iPSC-derived cardiomyocytes transduced with GCaMP6f and interface with translational technologies to bridge the current academia-industry gap. Cardiomyocytes were seeded on-chip fully hands-free using an entry-level fluid handling robot to significantly reduce user handling requirements. Pipette interfaces were paramount to facilitating seeding and feeding through improved tolerances for establishing a functional connection to dispense and collect small fluidic volumes. Following successful seeding, GCaMP6f activity on-chip was monitored with our automated, non-invasive fiber-optic sensing platform. We show a significant decrease in cardiomyocyte beat rate in response to decreased ambient culture temperature using data collected with our optical sensing platform. This study provides a potential translational blueprint for academia-industry partnership toward broad adoption of organ chip technology in drug development and disease modeling.

bioengineering↗

bioRxiv2025

Design and fabrication of demountable 3D microphysiological systems for modeling barrier function and underlying tissue interactions

Several recent advances in microphysiological systems (MPSs) or organ-on-chip technology have demonstrated its potential for replacing traditional in vitro and animal models in the coming years. Despite the physiological relevance and cost-effectiveness of organ chips, there are several hurdles that must be overcome for widespread adoption for biological studies. Many shortcomings of manufacturing and scalability have been overcome by a transition from PDMS to thermoplastics. However, challenges have arisen in these sealed, brittle systems related to end-point tissue analyses, harvest, and high-resolution imaging, which is particularly difficult for multi-layer organ chips. Here, we present low-cost organ chips that are fluidically sealed but demountable, fabricated using a cut-and-assemble method without the need for cleanroom technologies. We have validated the capabilities of this method by demonstrating the culture of human aortic smooth muscle cells and induced pluripotent stem cell-derived neural cells, encapsulated in gelatin methacryloyl (GelMA) hydrogel on chip, for up to 27 days. The 3D culture layer of the organ chip was removed, and high-resolution images were obtained via immunostaining. Furthermore, these organ chips facilitate rapid redesign and manufacture for alternative tissue and/or interface systems. To our knowledge, this is the first innervated organ chip with multiple removable cell culture layers, as well as the first humanized nerve-artery model that includes a three-dimensional hydrogel culture. In future work, these unique features of our platform can be utilized for investigating the crosstalk mechanisms between different cell types in co-culture. Impact StatementWe present here a new method for fabricating low-cost demountable organ-on-a-chip platforms. This method leverages our recent cut & assemble method for layered 3D organ chips comprised of gas impermeable thermoplastics.

bioengineering↗

bioRxiv2025

An Allosteric Model for Electromechanical Coupling in Cardiac CNBD Channels

Ion channels in the cyclic nucleotide-binding domain (CNBD) family, including hyperpolarization-activated cyclic nucleotide-gated (HCN) channels and human ether-a-go-go-related gene (hERG) channels, play pivotal roles in regulating cardiac action potentials. HCN channels are uniquely activated by hyperpolarization, rather than depolarization, a critical mechanism for controlling the involuntary pacemaker activity of the heart. In contrast, hERG channels are depolarization-activated and mediate K+ currents essential for action potential repolarization. Notably, certain hERG mutations, including those associated with long-QT syndrome, can induce biphasic activation by both hyperpolarization and depolarization. Despite the diverse voltage-dependent gating behaviors observed in CNBD channels, a unified mechanistic framework remains lacking. Here, we propose an allosteric model for their electromechanical coupling, featuring a single voltage-sensor transition coupled to two distinct conformational coupling modes between voltage-sensing and pore domains. With only three or four free parameters, this model recapitulates the biphasic U-shaped and bell-shaped conductance-voltage relationships commonly seen in CNBD channels. Fluorescence anisotropy-based homo-FRET experiments employing site-specifically incorporated noncanonical amino acids provide further support for the hypothesis, suggesting that the S5 helix movement plays a key role in hyperpolarization-dependent activation, while S4-S6 helix interactions are required for depolarization-dependent gating.

biophysics↗

bioRxiv2025

RhoA activation promotes ordered membrane domain coalescence and suppresses neuronal excitability

The formation of ordered proteolipid membrane domains (OMDs) within the plasma membrane has emerged as a fundamental process that modifies membrane function, particularly in response to cell stresses that promote pathological states. Here, we identify a previously unrecognized role for the small GTPase RhoA to promote the coalescence of OMDs, thereby linking cytoskeletal remodeling and membrane mechanics to OMD formation. Pharmacological and optogenetic manipulation of RhoA rapidly altered OMD dimensions in both human cell lines and dorsal root ganglion (DRG) nociceptors. The RhoA-dependent OMD expansion required actin remodeling, changes in membrane mechanical state, and protein palmitoylation. Functionally, RhoA inhibition increased action potential firing and potentiated HCN channel activity in DRG neurons. Conversely, in a spared nerve injury model characterized by altered membrane mechanics, reduced OMD size, and hyperexcitability, RhoA activation enlarged OMDs, suppressed HCN channel activity, and reduced firing. These findings highlight alterations in plasma membrane physical properties, including changes in OMD organization and membrane tension, as key features of neuropathic stress. RhoA/ROCK-driven OMD remodeling may serve as a compensatory membrane adaptation that counteracts neuropathic hyperexcitability.

biophysics↗

bioRxiv2025

Cholesterol Inhibits HCN Channels through Dual Mechanisms in Neuropathic Pain

Cholesterol, abundantly present in distinct plasma membrane pools, is a critical modulator of ion channel function, including hyperpolarization-activated cyclic nucleotide-gated (HCN) channels that regulate the excitability of dorsal root ganglion (DRG) nociceptor neurons. Depletion of membrane cholesterol potentiated HCN channel opening and accelerated activation kinetics, whereas cholesterol supplementation reduced channel opening and slowed activation kinetics. However, the relative contributions of cholesterol that organizes ordered membrane domains (OMDs) versus freely accessible cholesterol pools to HCN channel modulation remain unknown. Using fluorescence lifetime imaging microscopy and Forster resonance energy transfer (FRET), and fluorescence anisotropy techniques, we examined how supplementing cholesterol alters plasma membrane properties and HCN gating in nociceptor DRG neurons. We uncovered a process of sequential, stepwise membrane remodeling: an initial phase with OMD expansion and a rapid rise in free cholesterol, followed by continued accumulation of free cholesterol without further OMD expansion. Notably, the slope factor of the HCN conductance- voltage relationship is sensitive to OMD expansion but remains unaffected by changes in free cholesterol. Other gating parameters, including open probability and activation kinetics, were affected by elevating free cholesterol. In a rat model of nerve injury, where DRG neurons exhibit reduced free cholesterol levels and smaller OMDs, HCN channel modulation by cholesterol involves contributions from both OMD expansion and free cholesterol accumulation. In contrast, in naive DRG neurons--characterized by high cholesterol and large OMDs--modulation occurs mostly via increased free cholesterol. These findings deepen our understanding of cholesterols role in modulating ion channels and contributing to neuropathic pain.

neuroscience↗

bioRxiv2025

Using green space virtual reality to prevent stress-induced working memory impairment

Exposure to green space is associated with both physical and mental health benefits, including the potential to buffer acute stress responses, positioning it as a promising non-pharmacological approach to protect cognitive functions against stress. However, urban residents often face significant barriers in accessing green spaces, which are not equitably distributed. Virtual Reality (VR) technology offers a potential solution by simulating green space that could be made accessible to a broader demographic. Here, we explored whether VR-stimulated green space could dampen biological stress responses (i.e., heart rate and cortical response) and prevent stress-induced working memory (WM) impairment. Healthy young participants underwent acute stress induction followed by 15 minutes of VR-based green space (N=36) or control empty space (N=30) intervention. Although we observed the expected stress-induced increase in heart rates and elevated cortisol levels under stress, VR green space exposure failed to temper cortisol responses compared to the control VR space. Further, VR green space exposure did not bring benefits to protect working memory performance under stress across three WM tasks. Applying a Bayesian analysis approach throughout enabled us to find substantial evidence for the absence of an effect of VR-based green space exposure on biological markers of acute stress responses and working memory performance. Our findings suggest that VR-generated green space may not effectively replicate the stress-buffering effects of actual green space exposure. We discussed the implications of our findings regarding the potential and limitations of using VR or green space exposure to buffer stress responses.

neuroscience↗

bioRxiv2024

Sociability genetically separable from social hierarchy in amniotes

The emergence of social structure and organization is essential for the evolution of amniotes, including human beings. Sociability and social hierarchy are two key features to form a social group. However, it remains unknown whether sociability and social hierarchy are genetically separable. In this study, we examined the social hierarchy, social and social novelty preference of PAS1 (placental-accelerated sequence 1) knock-out and knock-in mice. PAS1 is a social enhancer that modulates social hierarchy. We found that PAS1 knock-out mice lack social hierarchy while wallaby/chicken PAS1 knock-in mice establish stable social ranks. Moreover, social and social novelty preference was observed in all PAS1-mutated mice. PAS1 knock-in mice have stronger preference to interact with other mice than wild-type mice (C57BL/6). No aggressive alteration was found in PAS1-mutated mice. Overall, our results showed that PAS1 is an indispensable regulatory element in the formation of social hierarchy while PAS1 regulates one of pathways modulating sociability. Therefore, sociability is genetically separable from social hierarchy in amniotes, providing insights into how social structure and organization evolved. HighlightsPAS1, a social enhancer, is indispensable for amniotes to establish social hierarchy. PAS1 modulates sociability in amniotes. Sociability and social hierarchy are regulated differently in amniotes. The frequency of PAS1 allele was not rare when social hierarchy first appeared.

animal behavior and cognition↗

bioRxiv2024

3D Brain Vascular Niche Model Captures Invasive Behavior and Gene Signatures of Glioblastoma

Glioblastoma (GBM) is a lethal brain cancer with no effective treatment; understanding how GBM cells respond to tumor microenvironment remains challenging as conventional cell cultures lack proper cytoarchitecture while in vivo animal models present complexity all at once. Developing a culture system to bridge the gap is thus crucial. Here, we employed a multicellular approach using human glia and vascular cells to optimize a 3-dimensional (3D) brain vascular niche model that enabled not only long-term culture of patient derived GBM cells but also recapitulation of key features of GBM heterogeneity, in particular invasion behavior and vascular association. Comparative transcriptomics of identical patient derived GBM cells in 3D and in vivo xenotransplants models revealed that glia-vascular contact induced genes concerning neural/glia development, synaptic regulation, as well as immune suppression. This gene signature displayed region specific enrichment in the leading edge and microvascular proliferation zones in human GBM and predicted poor prognosis. Gene variance analysis also uncovered histone demethylation and xylosyltransferase activity as main themes for gene adaption of GBM cells in vivo. Furthermore, our 3D model also demonstrated the capacity to provide a quiescence and a protective niche against chemotherapy. In summary, an advanced 3D brain vascular model can bridge the gap between 2D cultures and in vivo models in capturing key features of GBM heterogeneity and unveil previously unrecognized influence of glia-vascular contact for transcriptional adaption in GBM cells featuring neural/synaptic interaction and immunosuppression.

bioengineering↗

bioRxiv2024

Phasor FLIM-FRET Analysis of Voltage Sensor Conformational Heterogeneity in hERG Potassium Channels

Voltage sensors are essential for electromechanical coupling in hERG K+ channels, critical to cardiac rhythm. These sensors respond to membrane potential changes by moving within the transmembrane electric field. Mutations in hERG voltage-sensing arginines, associated with Long-QT syndrome, alter channel gating, though underlying mechanisms remain unclear. Using live-cell fluorescence lifetime imaging microscopy (FLIM), transition metal FRET (tmFRET), an improved dual stop-codon-mediated strategy for noncanonical amino-acid incorporation, and molecular dynamics (MD) simulations, we identified intermediate voltage-sensor conformations induced by neutralizing key arginines in the charge transfer center. Phasor plot analysis of FLIM data revealed multiple voltage-dependent FRET states in these mutants, in contrast to the single high-FRET state observed in controls. These intermediate FRET states reflect distinct conformations of the voltage sensor, corresponding to predicted structures of voltage sensors in MD simulations. This study provides novel insights into cardiac channelopathies, highlighting a structural mechanism that impairs voltage sensing in cardiac arrhythmias.

biophysics↗

bioRxiv2023

Disruption of Ordered Membrane Domains as a Mechanism Underlying Neuropathic Pain

Cell membranes consist of heterogeneous lipid nanodomains that influence key cellular processes. Using FRET-based fluorescent assays and fluorescence lifetime imaging microscopy (FLIM), we found that the dimension of cholesterol-enriched ordered membrane domains (OMD) varies considerably, depending on specific cell types. Particularly, nociceptor dorsal root ganglion (DRG) neurons exhibit large OMDs. Disruption of OMDs potentiated action potential firing in nociceptor DRG neurons and facilitated the opening of native hyperpolarization-activated cyclic nucleotide-gated (HCN) pacemaker channels. This increased neuronal firing is partially due to an increased open probability and altered gating kinetics of HCN channels. The gating effect on HCN channels was likely due to a direct modulation of their voltage sensors by OMDs. In animal models of neuropathic pain, we observed reduced OMD size and a loss of HCN channel localization within OMDs. Additionally, cholesterol supplementation inhibited HCN channels and reduced neuronal hyperexcitability in pain models. These findings suggest that disturbances in lipid nanodomains play a critical role in regulating HCN channels within nociceptor DRG neurons, influencing pain modulation.

biophysics↗

bioRxiv2023

Extraordinary preservation of gene collinearity over three hundred million years revealed in homosporous lycophytes

Homosporous lycophytes (Lycopodiaceae) are a deeply diverged lineage in the plant tree of life, having split from heterosporous lycophytes (Selaginella and Isoetes) [~]400 million years ago (MYA). Compared to the heterosporous lineage, Lycopodiaceae has markedly larger genome sizes and remains the last major plant clade for which no genomic data has been available. Here, we present chromosomal genome assemblies for two homosporous lycophyte species, the allotetraploid Huperzia asiatica and the diploid Diphasiastrum complanatum. Remarkably, despite that the two species diverged [~]350 MYA, around 30% of the genes are still in syntenic blocks. Furthermore, both genomes had undergone independent whole genome duplications and the resulting intra-genomic syntenies have likewise been preserved relatively well. Such slow genome evolution over deep time is in stark contrast to heterosporous lycophytes and is correlated with a decelerated rate of nucleotide substitution. Together, the genomes of H. asiatica and D. complanatum not only fill a crucial gap in the plant genomic landscape, but also uncover a possibly unique genomic contrast between homosporous and heterosporous species.

genomics↗

bioRxiv2023

DIRECT REGULATION OF THE VOLTAGE-SENSING DOMAIN OF HCN CHANNELS BY MEMBRANE LIPID COMPARTMENTALIZATION

Ion channels function within a membrane environment characterized by dynamic lipid compartmentalization. Limited knowledge exists regarding the response of voltage-gated ion channels to transmembrane potential within distinct membrane compartments. By leveraging fluorescence lifetime imaging microscopy (FLIM) and Forster resonance energy transfer (FRET), we visualized the localization of hyperpolarization-activated cyclic nucleotide-gated (HCN) channels in membrane domains. HCN4 exhibits a greater propensity for incorporation into ordered lipid domains compared to HCN1. To investigate the conformational changes of the S4 helix voltage sensor of HCN channels, we used dual stop-codon suppression to incorporate different noncanonical amino acids, orthogonal click chemistry for site-specific fluorescence labeling, and transition metal FLIM-FRET. Remarkably, altered FRET levels were observed between VSD sites within HCN channels upon disruption of membrane domains. We propose that the voltage-sensor rearrangements, directly influenced by membrane lipid domains, can explain the heightened activity of pacemaker HCN channels when localized in cholesterol-poor, disordered lipid domains, leading to membrane hyperexcitability and diseases.

physiology↗

bioRxiv2022

Maternal Hepatocytes Heterogeneously and Dynamically Exhibit Developmental Phenotypes Partially via YAP1 during Pregnancy

Background and AimsPregnancy induces reprogramming of maternal physiology to support fetal development and growth. Maternal hepatocytes undergo hypertrophy and hyperplasia to drive maternal liver growth and alter their gene expression profiles simultaneously. This study aimed to further understand maternal hepatocyte adaptation to pregnancy. MethodsTimed pregnancies were generated in mice. ResultsIn a non-pregnant state, most hepatocytes expressed Cd133, -fetalprotein (Afp,) and epithelial cell adhesion molecule (Epcam) mRNAs, whereas overall, at the protein level, they exhibited a CD133-/AFP- phenotype; however, pericentral hepatocytes were EpCAM+. As pregnancy advanced, while most maternal hepatocytes retained Cd133, Afp, and Epcam mRNA expression, they generally displayed a phenotype of CD133+/AFP+, and EpCAM protein expression was switched from pericentral to periportal maternal hepatocytes. In addition, we found that the Hippo/yes-associated protein (YAP) pathway does not respond to pregnancy. Yap1 gene deletion specifically in maternal hepatocytes did not affect maternal liver growth or metabolic zonation. However, the absence of Yap1 gene eliminated CD133 protein expression without interfering with Cd133 transcript expression in maternal livers. ConclusionsWe demonstrated that maternal hepatocytes acquire heterogeneous and dynamic developmental phenotypes, resembling fetal hepatocytes, partially via YAP1 through a post-transcriptional mechanism. Moreover, maternal liver is a new source of AFP. In addition, maternal liver grows and maintains its metabolic zonation independent of the Hippo/YAP1 pathway. Our findings revealed a novel and gestation-dependent phenotypic plasticity in adult hepatocytes. SynopsisWe found that maternal hepatocytes exhibit developmental phenotypes in a temporal and spatial manner, similarly to fetal hepatocytes. They acquire this new property partially via yes-associated protein 1.

physiology↗

bioRxiv2022

A GSVA based gene set synergizing with CD4+T cell bearing harmful factors yield risk signals in HBV related diseases via amalgamation of artificial intelligence

Genes encoding chemokines and extracellular matrix (ECM) play pivotal roles in chronic HBV infection (CHB), HBV related fibrosis (HBV-LF) and hepatocellular carcinoma (HBV-HCC). The landscape and potential of these genes in prognosis across diseases stages have not been fully and systemically understood. In this study, we defined an HBV-LF associated gene set comprised of chemokines and ECM related genes directly induced by initial HBV infection through GSVA algorithm that named as CLST (C stands for CXCL9, CXCL10, CCL19 and CCL20; L for LUM; S for SOX9 and SPP1; T for THBS1, THBS2) and evaluated its biomarker values in CHB and HBV-LF. Enrichment scores (ES) of CLST was subsequently observed synergized with activated CD4+T cells (aCD4) highly related to T helper cell 17 (TH17) associated genes and immune checkpoints and addressed as risk signals due to bearing harmful prognosis factors in tumor tissues of patients with HBV-HCC. Dual higher enrichment score (ES) of CLST and aCD4 in HBV-HCC patients exhibited worse overall survival (OS). Feature genes specific to these two gene sets showed promising clinical relevance in early-stage of HBV-HCC definition and OS prediction incorporating laboratory parameters via artificial intelligence (AI) systems. Finally, a novel mechanistic insight into the issue was proposed that PEG IFN- as an immunotherapy through modulating CLST signal in treatment responders and these immune signals down-regulation could be beneficial for HBV related diseases control and prevention. Together, our study provides GSVA and AI derived immunogenomic prognosis signatures and clinical utility of these signals will be benefit for HBV related diseases cure.

immunology↗

bioRxiv2021

Insights from the IronTract challenge: optimal methods for mapping brain pathways from multi-shell diffusion MRI

Limitations in the accuracy of brain pathways reconstructed by diffusion MRI (dMRI) tractography have received considerable attention. While the technical advances spearheaded by the Human Connectome Project (HCP) led to significant improvements in dMRI data quality, it remains unclear how these data should be analyzed to maximize tractography accuracy. Over a period of two years, we have engaged the dMRI community in the IronTract Challenge, which aims to answer this question by leveraging a unique dataset. Macaque brains that have received both tracer injections and ex vivo dMRI at high spatial and angular resolution allow a comprehensive, quantitative assessment of tractography accuracy on state-of-the-art dMRI acquisition schemes. We find that, when analysis methods are carefully optimized, the HCP scheme can achieve similar accuracy as a more time-consuming, Cartesian-grid scheme. Importantly, we show that simple pre- and post-processing strategies can improve the accuracy and robustness of many tractography methods. Finally, we find that fiber configurations that go beyond crossing (e.g., fanning, branching) are the most challenging for tractography. The IronTract Challenge remains open and we hope that it can serve as a valuable validation tool for both users and developers of dMRI analysis methods.

neuroscience↗

bioRxiv2021

ITRAQ-based quantitative proteomic analysis of japonica rice seedling during cold stress

Low temperature is one of the important environmental factors that affect rice growth and yield. To better understand the japonica rice responses to cold stress, isobaric tags for relative and absolute quantification (iTRAQ) labeling based quantitative proteomics approach was used to detected changes in protein level. Two-week-old seedlings of the cold tolerance rice variety Kongyu131 were treated at 8{degrees}C for 24, 48 and 72 h, then the total proteins were extracted from tissues and used for quantitative proteomics analysis. A total of 5082 proteins were detected for quantitative analysis, of which 289 proteins were significantly regulated, consisting of 169 uniquely up-regulated proteins and 125 uniquely down-regulated proteins in cold stress groups relative to control group. Functional analysis revealed most of regulation proteins involved in photosynthesis, metabolic pathway, biosynthesis of secondary metabolites and carbon metabolism. Western blot analysis showed that protein regulation was consistent with the iTRAQ data. The corresponding genes of 25 regulation proteins were used for quantitative real time PCR analysis, and the results showed that the mRNA level was not always parallel to the corresponding protein level. The importance of our study is providing new insights into cold stress responses in rice on proteomic aspect.

plant biology↗

bioRxiv2021

Circadian Clock Core Component Bmal1 Dictates Cell Cycle Rhythm of Proliferating Hepatocytes during Liver Regeneration

Following partial hepatectomy (PH), the majority of remnant hepatocytes synchronously enter and rhythmically progress through the cell cycle for three major rounds to regain lost liver mass. Whether and how the circadian clock core component Bmal1 modulates this process remains elusive. We performed PH on Bmal1+/+ and hepatocyte-specific Bmal1 knockout (Bmal1hep-/-) mice and compared the initiation and progression of the hepatocyte cell cycle. After PH, Bmal1+/+ hepatocytes exhibited three major waves of nuclear DNA synthesis. In contrast, in Bmal1hep-/-hepatocytes, the first wave of nuclear DNA synthesis was delayed by 12 h, and the third such wave was lost. Following PH, Bmal1+/+ hepatocytes underwent three major waves of mitosis, whereas Bmal1hep-/-hepatocytes fully abolished mitotic oscillation. These Bmal1-dependent disruptions in the rhythmicity of hepatocyte cell cycle after PH were accompanied by suppressed expression peaks of a group of cell cycle components and regulators, and dysregulated activation patterns of mitogenic signaling molecules c-Met and EGFR. Moreover, Bmal1+/+ hepatocytes rhythmically accumulated fat as they expanded following PH, whereas this phenomenon was largely inhibited in Bmal1hep-/-hepatocytes. In addition, during late stages of liver regrowth, Bmal1 absence in hepatocytes caused the activation of redox sensor Nrf2, suggesting an oxidative stress state in regenerated liver tissue. Collectively, we demonstrated that during liver regeneration, Bmal1 partially modulates the oscillation of S-phase progression, fully controls the rhythmicity of M-phase advancement, and largely governs fluctuations in fat metabolism in replicating hepatocytes, and eventually determines the redox state of regenerated livers. New and NoteworthyWe demonstrated that Bmal1 centrally controls the synchronicity and rhythmicity of the cell cycle and lipid accumulation in replicating hepatocytes during liver regeneration. Bmal1 plays these roles, at least in part, by ensuring formation of the expression peaks of cell cycle components and regulators, as well as the timing and levels of activation of mitogenic signaling molecules. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=187 SRC="FIGDIR/small/455958v1_ufig1.gif" ALT="Figure 1"> View larger version (17K): org.highwire.dtl.DTLVardef@16dc661org.highwire.dtl.DTLVardef@1fb1a65org.highwire.dtl.DTLVardef@820e1dorg.highwire.dtl.DTLVardef@6cc264_HPS_FORMAT_FIGEXP M_FIG Graphical Abstract C_FIG

pathology↗

bioRxiv2021

Activation of proneuronal transcription factor Ascl1 in maternal liver ensures a healthy pregnancy

Background & AimsMaternal liver exhibits robust adaptations to pregnancy to accommodate the metabolic needs of developing and growing placenta and fetus by largely unknown mechanisms. We found that achaete-scute homolog-like 1 (Ascl1), a basic helix-loop-helix transcription factor essential for neuronal development, is highly activated in maternal hepatocytes during the second half of gestation in mice. MethodsTo investigate whether and how Ascl1 plays a pregnancy-dependent role, we deleted the Ascl1 gene specifically in maternal hepatocytes from mid-gestation until term. ResultsAs a result, we identified multiple Ascl1-dependent phenotypes. Maternal livers lacking Ascl1 exhibited aberrant hepatocyte structure, increased hepatocyte proliferation, enlarged hepatocyte size, reduced albumin production, and elevated release of liver enzymes, indicating maternal liver dysfunction. Simultaneously, maternal pancreas and spleen and the placenta displayed marked overgrowth; and the maternal ceca microbiome showed alterations in relative abundance of several bacterial subpopulations. Moreover, litters born from maternal hepatic Ascl1-deficient dams experienced abnormal postnatal growth after weaning, implying an adverse pregnancy outcome. Mechanistically, we found that maternal hepatocytes deficient for Ascl1 exhibited robust activation of insulin-like growth factor 2 expression, which may contribute to the Ascl1-dependent phenotypes widespread in maternal and uteroplacental compartments. ConclusionIn summary, we demonstrate that maternal liver, via activating Ascl1 expression, modulates the adaptations of maternal organs and the growth of the placenta to maintain a healthy pregnancy. Our studies reveal Ascl1 as a novel and critical regulator of the physiology of pregnancy. SynopsisHow the maternal liver adapts to pregnancy remains elusive. We found that maternal liver activates the expression of Ascl1, a gene encoding a proneuronal transcription factor, to coordinate the adaptations of maternal organs and the growth of the placenta, enabling a healthy pregnancy and normal postnatal growth of the offspring. Graphical Abstract O_FIG_DISPLAY_L [Figure 1] M_FIG_DISPLAY C_FIG_DISPLAY

physiology↗