bluuebunny/crossref_metadata_2025 huggingface dataset:
Omega-3 fatty acids and intracranial aneurysms: a Mendelian randomization study
Authors: Wei Dachao , Chen Xiheng , Gui Siming , Jiang Jia , Gao Yuan , Lin Jun , Deng Dingwei , You Wei , Lv Jian , Tang Yudi , Chen Ting , Yang Shu , Jin Hengwei , Jiang Yuhua , Liu Peng , Tai Hongfei , Liu Xinke , Ge Huijian , Lv Ming , Meng Fangang , Li Youxiang
Published: October 2024

Introduction

Recent studies suggest that omega-3 polyunsaturated fatty acids (PUFAs) supplementation benefits for cardiovascular disease and abdominal aortic aneurysms, but its role in intracranial aneurysms (IAs) remains unclear. This study evaluates the effect of omega-3 PUFAs on IAs.

Patients and methods

A two-sample Mendelian Randomization study (MR) was conducted to examine the associations between omega-3 PUFAs and IAs, as well as aneurysmal subarachnoid hemorrhage (aSAH). The largest genome-wide association study dataset was used for primary analysis, with replication using independent sources. Two-step MR was used to evaluate the mediating effects of nine aneurysm risk factors and 91 inflammatory cytokines.

Results

Higher genetically predicted levels of total omega-3, omega-3 percentage, and docosahexaenoic acid (DHA) were associated with reduced risks of IAs (combined OR 0.88, 95% CI 0.83-0.94, P<0.001; 0.86, 0.81-0.92, P<0.001; 0.84, 0.78-0.90, P<0.001, respectively) and aSAH (0.85, 0.79-0.91, P=0.009; 0.84, 0.75-0.93, P<0.001; 0.80, 0.71-0.90, P<0.001, respectively). Genetically predicted eicosapentaenoic acid level showed a tendency to increase risk (1.05, 1.01-1.10, P=0.022 for IAs; 1.11, 0.96-1.28, P=0.160 for aSAH). Mediation analysis revealed diastolic blood pressure (DBP) and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) mediated DHA’s effects on IAs (proportion mediated 8.5%, P=0.019; 25.2%, P=0.049) and aSAH (5.7%, P=0.024; 27.5%, P=0.041).

Conclusions

Our study suggests that omega-3 PUFAs, particularly DHA, are associated with a reduced risk of IAs and aSAH. This association may be partially mediated by DBP and TRAIL.
Sex Differences in Management, Time to Intervention, and In-Hospital Mortality of Acute Myocardial Infarction and Non-Myocardial Infarction Related Cardiogenic Shock
Authors: Desai Anushka , Rani Rohan , Minhas Anum , Rahman Faisal
Published: October 2024

Background

Limited data are available on sex differences in the time to treatment of cardiogenic shock (CS) with and without acute myocardial infarction (AMI).

Methods

For this retrospective cohort study, we used nationally representative hospital survey data from the National Inpatient Sample (years 2016-2021) to assess sex differences in interventions, time to treatment (within versus after 24 hours of admission), and in-hospital mortality for AMI-CS and non-AMI-CS, adjusting for age, race, income, insurance, comorbidities, and prior cardiac interventions.

Results

We identified 1,052,360 weighted CS hospitalizations (60% non-AMI-CS; 40% AMI-CS). Women with CS had significantly lower rates of all interventions. For AMI-CS, women had a higher likelihood of in-hospital mortality after: revascularization (adjusted odds ratio (aOR) 1.15 [95% CI 1.09-1.22]), mechanical circulatory support (MCS) (1.15 [1.08-1.22]), right heart catheterization (RHC) (1.10 [1.02-1.19]) (all p<0.001). Similar trends were found for the non-AMI-CS group. Women with AMI-CS were less likely to receive early (within 24 hours of admission) revascularization (0.93 [0.89-0.96]), MCS (0.76 [0.73-0.80]), or RHC (0.89 [0.84-0.95]) than men; women with non-AMI-CS were less likely to receive early revascularization (0.78 [0.73-0.84]), IABP (0.85 [0.78-0.94]), pLVAD (0.88 [0.77-0.99]) or RHC (0.83 [0.79-0.88]) than men (all p<0.001). For both types of CS, in-hospital mortality was not significantly different between men and women receiving early ECMO, pLVAD, or PCI.

Conclusions

Sex disparities in the frequency of treatment of CS persist on a national scale, with women being more likely to die following treatment and less likely to receive early treatment. However, when comparing patients who received early treatment, in-hospital mortality does not differ significantly when men and women are treated equally within 24 hours of admission. Early intervention if clinically indicated could mitigate sex-based differences in CS outcomes and should be made a priority in the management of CS.

Clinical Perspective

What is new?

Women have increased in-hospital mortality with cardiogenic shock and have lower odds of early intervention (within 24 hours of admission) compared to men.

When men and women with cardiogenic shock are treated equally in terms of early intervention within 24 hours of admission, sex differences in in-hospital mortality disappear.

What are the clinical implications?

Sex-based disparities are present in the utilization of treatment and time to intervention for patients with cardiogenic shock.

Early recognition and intervention for cardiogenic shock among women should be considered to improve clinical outcomes.
Phylogenetically and ecologically delimited species pool affect the inference of age-dependent extinction
Authors: Gonçalves-Neto Salatiel , Quental Tiago B.
Published: October 2024

According to Van Valen’s seminal work (1973), extinction occurs at a constantly stochastic rate within ecologically homogeneous groups or adaptive zones, giving long and short-lived species equal chances of extinction. Van Valen highlighted the difficulty in defining and identifying the species pool within an adaptive zone, but fundamentally viewed it through ecological factors. Most studies have used taxonomically or phylogenetically defined species pools to test the “Law of Constant Extinction.” Here, we investigate how different species pools defined by phylogeny or ecology influence the inference of age-independent extinction. Using the Canidae fossil record and a Bayesian framework, we show that species pools defined by phylogeny or ecology exhibit different age-dependent extinction dynamics. The age-dependent extinction (ADE) signal varies depending on the species pool choice, time window, and taxonomic level. Within phylogenetic species pools, we observe mixed evidence for ADE, with both positive—older species more likely to go extinct (Hesperocyoninae and Borophaginae)—and negative—younger species more likely to go extinct (Caninae)—trends. Combining subfamilies into a family-level analysis yields weak evidence for ADE or strong support for age-independent extinction, depending on the period analyzed. Within ecologically defined species pools, hypercarnivores show strong evidence for positive ADE, whereas non-hypercarnivores show signals akin to age-independent extinction. Phylogenetic pools with more hypercarnivores tended to show evidence of positive ADE, while those with fewer tended toward negative ADE. These findings emphasize that the choice of species pool significantly influences observed age-dependent extinction dynamics and that ecology impacts the regime of age-dependent extinction.
A striosomal accumbens pathway drives compulsive seeking behaviors through an aversive Esr1+ hypothalamic-habenula circuit
Authors: Contesse Thomas , Bektash Buse Yel , Graziano Marta , Forastieri Chiara , Contestabile Alessandro , Hahne Salome , Jung Felix , Nikolakopoulou Ifigeneia , Cao Xiao , Skara Vasiliki , Mantas Ioannis , Giatrellis Sarantis , Carlén Marie , Sandberg Rickard , Calvigioni Daniela , Meletis Konstantinos
Published: October 2024

The lateral hypothalamic area (LHA) integrates external stimuli with internal states to drive the choice between competing innate or value-driven motivated behaviors. Projections from the LHA to the lateral habenula (LHb) shape internal states, with excitatory estrogen receptor 1-expressing (Esr1+) LHA-LHb neurons driving aversive responses and sustained negative states. Here, we identify and functionally characterize a specific projection from the nucleus accumbens (ACB) that targets Esr1+ LHA-LHb neurons. Using cell-type-specific tracing of monosynaptic inputs, single-nucleus RNA sequencing, and neuroanatomical mapping, we demonstrate that the Esr1+ LHA-LHb pathway receives a major input from a striosomal Tac1+/Tshz1+/Oprm1+ ACB neuron subtype. Intersectional cell-type-specific and input-output defined optogenetic manipulation of this ACB-LHA-LHb pathway revealed its role in signaling aversion after repeated activation, with the negative behavioral state being dependent on recruitment of Esr1+ LHA-LHb neurons. Importantly, we found that activation of the D1+ ACB-LHA pathway drives reward-independent compulsive-like seeking behaviors, expressed as compulsive digging or poking behaviors. We found that these complex yet stereotyped behaviors compete with highly motivated states and can override the need for natural rewards or social stimuli. Our findings reveal a discrete striosomal Tac1+ ACB projection targeting the aversive Esr1+ LHA-LHb pathway as a key circuit that promotes compulsive seeking behaviors over goal-directed actions.
Peripherally administered TNF inhibitor is not protective against α-synuclein-induced dopaminergic neuronal death in rats
Authors: Christiansen Josefine R. , Ferreira Sara A. , Szymkowski David E. , Jakobsson Johan , Tansey Malú Gámez , Romero-Ramos Marina
Published: October 2024

The underlying cause of neuronal loss in Parkinson’s disease (PD) remains unknown, but evidence implicates neuroinflammation in PD pathobiology. The pro-inflammatory cytokine soluble tumor necrosis factor (TNF) seems to play an important role and thus has been proposed as a therapeutic target for modulation of the neuroinflammatory processes in PD. In this regard, dominant-negative TNF (DN-TNF) agents are promising antagonists that selectively inhibit soluble TNF signaling, while preserving the beneficial effects of transmembrane TNF. Previous studies have tested the protective potential of DN-TNF-based therapy in toxin-based PD models. Here we test for the first time the protective potential of a DN-TNF therapeutic against α-synuclein-driven neurodegeneration in the viral vector-based PD rat model. To do so, we administered the DN-TNF agent XPro1595 subcutaneously for a period of 12 weeks. In contrast to previous studies using different PD models, neuroprotection was not achieved by systemic XPro1595 treatment. α-synuclein-induced loss of nigrostriatal neurons, accumulation of pathological inclusions and microgliosis was detected in both XPro1595- and saline-treated animals. XPro1595 treatment increased the percentage of the hypertrophic/ameboid Iba1+ cells in SN and reduced the striatal MHCII+ microglia in the striatum of α-synuclein-overexpressing animals. However, the treatment did not prevent the MHCII upregulation seen in the SN of the model, nor the increase of CD68+ phagocytic cells. Therefore, despite an apparently positive immune effect, this did not suffice to protect against viral vector-derived α-synuclein-induced neurotoxicity. Further studies are warranted to better elucidate the therapeutic potential of soluble TNF inhibitors in PD.
Improved protein binder design using beta-pairing targeted RFdiffusion
Authors: Sappington Isaac , Toul Martin , Lee David S. , Robinson Stephanie A. , Goreshnik Inna , McCurdy Clara , Chan Tung Ching , Buchholz Nic , Huang Buwei , Vafeados Dionne , Garcia-Sanchez Mariana , Roullier Nicole , Glögl Matthias , Kim Christopher J. , Watson Joseph L. , Torres Susana Vázquez , Verschueren Koen H. G. , Verstraete Kenneth , Hinck Cynthia S. , Benard-Valle Melisa , Coventry Brian , Sims Jeremiah Nelson , Ahn Green , Wang Xinru , Hinck Andrew P. , Jenkins Timothy P. , Ruohola-Baker Hannele , Banik Steven M. , Savvides Savvas N. , Baker David
Published: October 2024

Despite recent advances in the computational design of protein binders, designing proteins that bind with high affinity to polar protein targets remains an outstanding problem. Here we show that RFdiffusion can be conditioned to efficiently generate protein scaffolds that form geometrically matched extended beta-sheets with target protein edge beta-strands in which polar groups on the target are nearly perfectly complemented with hydrogen bonding groups on the design. We use this approach to design binders against a set of therapeutically relevant polar targets (KIT, PDGFRɑ, ALK-2, ALK-3, FCRL5, and NRP1) and find that beta-strand-targeted design yields higher affinities and success rates than unconditioned RFdiffusion. All by all binding experiments show that the designs have affinities ranging from 137 pM to mid nM for their targets and essentially no off target binding despite the sharing of beta-strand interactions, likely reflecting the precise customization of interacting beta-strand geometry and additional designed binder-target interactions. A co-crystal structure of one such design in complex with the KIT receptor is nearly identical to the computational design model confirming the accuracy of the design approach. The ability to robustly generate binders displaying high affinity and specificity to polar interaction surfaces with exposed beta-strands considerably increases the range and capabilities of computational binder design.
Thrombolysis exacerbates cerebrovascular injury after ischemic stroke via a VEGF-B dependent effect on adipose lipolysis
Authors: Nilsson Ingrid , Su Enming J. , Fredriksson Linda , Sahlgren Benjamin Heller , Bagoly Zsuzsa , Moessinger Christine , Stefanitsch Christina , Ning Frank Chenfei , Zeitelhofer Manuel , Muhl Lars , Lawrence Anna-Lisa E. , Scotney Pierre D. , Lu Li , Samén Erik , Ho Heidi , Keep Richard F. , Medcalf Robert L. , Lawrence Daniel A. , Eriksson Ulf
Published: October 2024

Cerebrovascular injuries leading to edema and hemorrhage after ischemic stroke are common. The mechanisms underlying these events and how they are connected to known risk factors for poor outcome, like obesity and diabetes, is relatively unknown. Herein we demonstrate that increased adipose tissue lipolysis is a dominating risk factor for the development of a compromised cerebrovasculature in ischemic stroke. Reducing adipose lipolysis by VEGF-B antagonism improved vascular integrity by reducing ectopic cerebrovascular lipid deposition. Thrombolytic therapy in ischemic stroke using tissue plasminogen activator (tPA) leads to increased risk of hemorrhagic complications, substantially limiting the use of thrombolytic therapy. We provide evidence that thrombolysis with tPA promotes adipose tissue lipolysis, leading to a rise in plasma fatty acids and lipid accumulation in the ischemic cerebrovasculature after stroke. VEGF-B blockade improved the efficacy and safety of thrombolysis suggesting the potential use of anti-VEGF-B therapy to extend the therapeutic window for stroke management.
HDAC Inhibitors recapitulate Human Disease-Associated Microglia Signaturesin vitro
Authors: Haage Verena , Tuddenham John F. , Bautista Alex , White Charles C. , Garcia Frankie , Patel Ronak , Comandante-Lou Natacha , Marshe Victoria , Soni Rajesh Kumar , Sims Peter A. , Menon Vilas , Sproul Andrew A. , De Jager Philip L.
Published: October 2024

Disease-associated microglia (DAM), initially described in mouse models of neurodegenerative diseases, have been classified into two related states; starting from a TREM2-independent DAM1 state to a TREM2 dependent state termed DAM2, with each state being characterized by the expression of specific marker genes1. Recently, single-cell (sc)RNA-Seq studies have reported the existence of DAMs in humans2–6; however, whether DAMs play beneficial or detrimental roles in the context of neurodegeneration is still under debate7,8. Here, we present a pharmacological approach to mimic human DAMin vitroby exposing different human microglia models to selected histone deacetylase (HDAC) inhibitors. We also provide an initial functional characterization of our model system, showing a specific increase of amyloid beta phagocytosis along with a reduction of MCP-1 secretion. Additionally, we report an increase inMITFexpression, a transcription factor previously described to drive expression towards the DAM phenotype. We further identifyCADM1,LIPAandSCINas DAM- marker genes shared across various proposed DAM signatures and in our model systems. Overall, our strategy for targeted microglial polarization bears great potential to further explore human DAM function and biology.
Neuronal correlates of sleep in honey bees
Authors: Moguilner Sebastian , Tiraboschi Ettore , Fantoni Giacomo , Strelevitz Heather , Soleimani Hamid , Del Torre Luca , Hasson Uri , Haase Albrecht
Published: October 2024

Honey beesApis melliferafollow the day-night cycle for their foraging activity, entering rest periods during dark. To date, studies of bee sleep have focused mostly on behavioural markers; it is not known if these resting states manifest reduced information processing at the level of brain networks, a defining signature of sleep. We used two-photon calcium imaging of the antennal lobes (AL) in head-fixed bees to analyse brain activity in motion/rest epochs during the nocturnal period. The neuronal activity data during these epochs were then computationally described, and machine learning was applied to determine whether a classifier could distinguish the two states after motion correction. Out-of-sample classification accuracy reached up to 93%. The feature importance analysis suggested network features to be decisive. Accordingly, the glomerular connectivity was found to be significantly increased in the rest-state patterns. A full simulation of the AL using a leaky spiking neural network revealed that such a transition in network connectivity could be achieved by weakly correlated input noise and a reduction of synaptic conductance of the inhibitive local neurons (LNs) which couple the AL network nodes. The difference in the AL response maps between awake- and sleep-like states generated by the simulation showed a decreased specificity of the odour code in the sleep state, suggesting reduced information processing during sleep. Since LNs in the bee brain are GABAergic, this suggests that the GABAergic system plays a central role in sleep regulation in bees as in many higher species including humans. Such conservation of sleep mechanisms throughout evolution indicates that bees can serve as a model for studying these mechanisms on the level of individual neurons.
Evolution of taste processing shifts dietary preference
Authors: Bertolini Enrico , Münch Daniel , Pascual Justine , Sgammeglia Noemi , Ribeiro Carlos , Auer Thomas O.
Published: October 2024

Food choice is an important driver of speciation and invasion of novel ecological niches. However, we know little about the mechanisms leading to changes in dietary preference. Here, we use the three closely-related speciesDrosophila sechellia,D. simulansandD. melanogasterto study taste circuit and food choice evolution.D. sechellia,a host specialist, feeds exclusively on a single fruit (Morinda citrifolia, noni) - the latter two are generalists living on various substrates. Using quantitative feeding assays, we recapitulate the preference for noni inD. sechelliaand detect conserved sweet but altered bitter sensitivity via calcium imaging in peripheral taste neurons. Noni surprisingly activates bitter sensing neurons more strongly inD. sechelliadue to a small deletion in one single gustatory receptor. Using volumetric calcium imaging in the ventral brain, we show that instead of peripheral physiology, species-specific processing of noni and sugar signals in sensorimotor circuits recapitulates differences in dietary preference. Our data support that peripheral receptor changes alone cannot explain altered food choice but rather modifications in how sensory information is transformed into feeding motor commands.
The consonance of chords: The effect of subsemitone changes to each of the notes in a trichord on its perceived consonance
Authors: Varkevisser J.M. , Kruitwagen J.M. , Spierings M. J.
Published: October 2024

Consonance plays a key role in how listeners experience music, but the factors influencing consonance perception remain a topic of discussion, for instance regarding the role of the familiarity of note combinations. Previous empirical studies of consonance have used common, familiar chords, making it harder to separate the effect of acoustic features from familiarity. Here we explored consonance perception in an unfamiliar, non-standardly tuned 0-5-10 trichord. A test was conducted in which 100 musicians and 100 nonmusicians compared the consonance of an original, non-standard, 0-5-10 chord and an adapted version, in which the lowest, middle or upper note was raised or lowered with 25 or 50 cents. According to a model based on continuous acoustic features, any adaptation to a 0-5-10 chord should yield a comparable decrease in consonance. We indeed found a general consonance decrease, but this was stronger for adaptations enlarging the distance between the lowest and the upper note, i.e. lowering the lowest or raising the highest note, than for other adaptations. These results deviate from the model’s predictions and from patterns observed in standard, more familiar chords. Future research should examine the generalizability of these findings to other chords than the 0-5-10 trichord.
STAT3 signalling enhances tissue expansion during postimplantation mouse development
Authors: Azami Takuya , Theeuwes Bart , Ton Mai-Linh N , Mansfield William , Harland Luke , Kinoshita Masaki , Gottgens Berthold , Nichols Jennifer
Published: October 2024

STAT3 signalling has been studied extensively in the context of self-renewal and differentiation of mouse embryonic stem cells. Zygotic STAT3 is required for normal postimplantation development. On an outbred genetic background,Stat3null embryos consistently lagged behind their littermates, beginning with significant reduction of epiblast cells at implantation. Remarkably, mutants closely resemble non-affected embryos from the previous day at all postimplantation stages examined. We pinpoint this phenotype to loss of the serine-phosphorylated form of STAT3 which predominates in postimplantation embryonic tissues. Bulk RNA-sequencing analysis of isolated mouse epiblasts confirmedStat3null embryos exhibited developmental delay transcriptionally. Single cell RNA sequencing of mid gestation chimaeras containing STAT3 null embryonic stem cells revealed exclusion of mutant cells exclusively from the erythroid lineage. Although Stat3 null embryonic stem cells can differentiate into erythroid and hematopoietic lineages in vitro, they are out-competed when mixed with wild type cells. Combined with the reduced size of STAT3 null epiblasts after implantation, our results implicate a role for STAT3 in cell proliferation affecting temporal control of embryonic progression and rapid differentiation.

For the purpose of Open Access, the author has applied a CC BY public copyright licence to any Author Accepted Manuscript version arising from this submission.
Functional contribution of astrocytic Kir4.1 channels to spasticity after spinal cord injury
Authors: Barbay Tony , Pecchi Emilie , Franco Jose Jorge Ramirez , Ivanov Anton , Brocard Frédéric , Rouach Nathalie , Bos Rémi
Published: October 2024

Spasticity, a prevalent motor issue characterized by network hyperexcitability, causes pain and discomfort, with existing treatments offering limited relief. While past research has focused on neuronal factors, the role of astrocytes in spasticity has been overlooked. This study explores the potential of restoring astrocytic potassium (K+) uptake to reduce spasticity following SCI. Astrocytes buffer extracellular K+via Kir4.1 channels, preventing neuronal hyperexcitability. Following spinal cord injury (SCI), Kir4.1 levels decrease at the injury site, though the consequences and mechanisms of this reduction within the motor output area have not been investigated. Utilizing advanced techniques, we demonstrate that lumbar astrocytes in a juvenile thoracic SCI mouse model switch to reactive phenotype, displaying morpho-functional and pro-inflammatory changes. These astrocytes also experience NBCe1-mediated intracellular acidosis, leading to Kir4.1 dysfunction and impaired K+uptake. Enhancing Kir4.1 function reduces spasticity in SCI mice, revealing new therapeutic targets for neurological diseases associated with neuronal hyperexcitability.

Highlights

Lumbar astrocytes adopt a reactive phenotype following a thoracic SCI

NBCe1-mediated acidosis in astrocytes disrupts Kir4.1 function post-SCI.

Impaired K+ uptake leads to motoneuron hyperexcitability post-SCI.

Enhanced astroglial Kir4.1 function reduces spastic-like symptoms in SCI mice.
Fetal Liver-like Organoids Recapitulate Blood-Liver Niche Development and Multipotent Hematopoiesis from Human Pluripotent Stem Cells
Authors: Rezvani Milad , Lewis Kyle , Quach Susanna , Iwasawa Kentaro , Weihs Julian , Reza Hasan Al , Cai Yuqi , Kimura Masaki , Zhang RanRan , Milton Yuka , Chaturvedi Praneet , Thorner Konrad , Nayak Ramesh C. , Munera Jorge , Kramer Phillip , Davis Brian R. , Balamurugan Appakalai N. , Ahmed Yeni Ait , Finke Marcel , Behncke Rose Yinghan , Guillot Adrien , Hägerling René , Polansky Julia K. , Bufler Philip , Cancelas Jose A , Wells James M. , Yoshimoto Momoko , Takebe Takanori
Published: October 2024

The fetal liver is a hematopoietic organ, hosting a diverse and evolving progenitor population. While human liver organoids derived from pluripotent stem cells (PSCs) mimic aspects of embryonic and fetal development, they typically lack the complex hematopoietic niche and the interaction between hepatic and hematopoietic development. We describe the generation of human Fetal Liver-like Organoids (FLOs), that model human hepato-hematopoietic interactions previously characterized in mouse models. Developing FLOs first integrate a yolk sac-like hemogenic endothelium into hepatic endoderm and mesoderm specification. As the hepatic and hematopoietic lineages differentiate, the FLO culture model establishes an autonomous niche capable of driving subsequent progenitor differentiation without exogenous factors. Consistent with yolk sac-derived waves, hematopoietic progenitor cells (HPCs) within FLOs exhibit multipotency with a preference for myeloid lineage commitment, while retaining fetal B and T cell differentiation potential. We reconstruct in FLOs the embryonic monocyte-to-macrophage and granulocyte immune trajectories within the FLO microenvironment and assess their functional responses in the liver niche.In vivo, FLOs demonstrate a liver engraftment bias of hematopoietic cells, recapitulating a key phenomenon of human hematopoietic ontogeny. Our findings highlight the intrinsic capacity of liver organoids to support hematopoietic development, establishing FLOs as a platform for modeling and manipulating human blood-liver niche interactions during critical stages of development and disease.
Astrocyte regional specialization is shaped by postnatal development
Authors: Schroeder Margaret E. , McCormack Dana M. , Metzner Lukas , Kang Jinyoung , Li Katelyn X. , Yu Eunah , Levandowski Kirsten M. , Zaniewski Heather , Zhang Qiangge , Boyden Edward S. , Krienen Fenna M. , Feng Guoping
Published: October 2024

Astrocytes are an abundant class of glial cells with critical roles in neural circuit assembly and function. Though many studies have uncovered significant molecular distinctions between astrocytes from different brain regions, how this regionalization unfolds over development is not fully understood. We used single-nucleus RNA sequencing to characterize the molecular diversity of brain cells across six developmental stages and four brain regions in the mouse and marmoset brain. Our analysis of over 170,000 single astrocyte nuclei revealed striking regional heterogeneity among astrocytes, particularly between telencephalic and diencephalic regions, at all developmental time points surveyed in both species. At the stages sampled, most of the region patterning was private to astrocytes and not shared with neurons or other glial types. Though astrocytes were already regionally patterned in late embryonic stages, this region-specific astrocyte gene expression signature changed dramatically over postnatal development, and its composition suggests that regional astrocytes further specialize postnatally to support their local neuronal circuits. Comparing across species, we found divergence in the expression of astrocytic region- and age-differentially expressed genes and the timing of astrocyte maturation relative to birth between mouse and marmoset, as well as hundreds of species differentially expressed genes. Finally, we used expansion microscopy to show that astrocyte morphology is largely conserved across gray matter regions of prefrontal cortex, striatum, and thalamus in the mouse, despite substantial molecular divergence.
tDCS Cranial Nerve Co-Stimulation: Unveiling Brainstem Pathways Involved in Trigeminal Nerve Direct Current Stimulation in Rats
Authors: Majdi Alireza , Larsen Lars E. , Raedt Robrecht , Laughlin Myles Mc
Published: October 2024

The effects of transcranial direct current stimulation (tDCS) are typically attributed to the polarization of cortical neurons by the weak electric fields it generates in the cortex. However, emerging evidence indicates that certain tDCS effects may be mediated through the co-stimulation of peripheral or cranial nerves, particularly the trigeminal nerve (TN), which projects to critical brainstem nuclei that regulate the release of various neurotransmitters throughout the central nervous system. Despite this, the specific pathways involved remain inadequately characterized.

In this study, we examined the effects of acute transcutaneous TN direct current stimulation (TN-DCS) on tonic (i.e. mean spike rate and spike rate over time) and phasic (number of bursts, spike rate per burst, burst duration, and inter-burst interval) activities while simultaneously recording single-neuron activity across three brainstem nuclei in rats: the locus coeruleus (LC), dorsal raphe nucleus (DRN), and median raphe nucleus (MnRN).

We found that TN-DCS significantly modulated tonic activity in the LC, with notable interactions between stimulation amplitude, polarity, and time epoch affecting mean spike rates. Similar effects were observed in the DRN regarding tonic activity. Further, phasic activity in the LC was influenced by TN-DCS, with changes in burst number, duration, and inter-burst intervals linked to stimulation parameters. Conversely, MnRN tonic activity following TN-DCS remained unchanged. Importantly, xylocaine administration to block TN abolished the effects on tonic activities in both the LC and DRN.

These results suggest that tDCS effects may partially arise from indirect modulation of the TN, leading to altered neuronal activity in DRN and LC. Besides, the differential changes in tonic and phasic LC activities underscore their complementary roles in mediating TN-DCS effects on higher cortical regions. This research bears significant translational implications, providing mechanistic insights that could enhance the efficacy of tDCS applications and deepen our understanding of its neurophysiological effects.
Load activated FGFR and beta1 integrins target distinct chondrocyte mechano-response genes
Authors: Dietmar Helen F. , Weidmann Pia A. , Alberton Paolo , Teichwart Terrilyn , Renkawitz Tobias , Vortkamp Andrea , Aszodi Attila , Richter Wiltrud , Diederichs Solvig
Published: October 2024

In response to mechanical stimuli, chondrocytes adapt their transcriptional activity, thereby shaping the cellular mechano-response; however, it remains unclear whether the activation of cell surface receptors during mechanical loading converge in the activation of the same mechano-response genes, or whether pathway-specific genes can be defined. We aimed to determine whether load-activated FGF/FGFR signalling and β1 integrin jointly activate ERK and control the same or distinct subsets of mechano-regulated genes. To this end, tissue-engineered neocartilage was generated from murine costal chondrocytes or human articular chondrocytes and subjected to dynamic unconfined compression with or without FGFR inhibition. To assess the role of β1 integrins, neocartilage was generated from embryonic β1 integrin-deficient or wild type costal chondrocytes.

Load-activated FGFR signalling drove ERK activation in murine chondrocytes, and partially also in human chondrocytes, and mechano-response genes could be classified according to their regulation:Fosl1,Itga5, NgfandTimp1were regulated by load-activated FGFR depending on the developmental stage, whereas β1 integrins controlledInhbaexpression. In human chondrocytes, load-activated FGFR controlled expression ofBMP2,PTGS2andDUSP5,but notFOSB.

We show here that the chondrocyte loading response is coordinated by concurrent activation of multiple receptors, and identified for the first time distinct target genes of activated receptors. These insights open up the opportunity to pharmacologically shape the mechano-response of chondrocytes in future studies with promising implications for the management of osteoarthritis and the development of novel therapeutic strategies.
Neutral lipids restrict the mobility of broken DNA molecules during comet assays
Authors: Soulet Caroline , Josa-Castro Jordi , Moriel-Carretero María
Published: October 2024

One widespread technique to assess in relative terms the amount of broken DNA present in the genome of individual cells consists in immobilizing the cell’s nucleus under an agarose pad (called the nucleoid) and subject the whole genome to electrophoresis to force broken DNA molecules out of it. Since the migrating DNA molecules create a tail behind the nucleoid, this technique is named the comet assay. While performing comet assays regularly, we systematically observed circular regions devoid of DNA within the nucleoid region. We characterize here that these correspond to clusters of neutral (apolar) lipids, since they could be labelled with neutral lipid-dying molecules, increased when cells were fed with oleic acid, and were irresponsive to the electrophoretic field. Of relevance, de-lipidation assays eitherin vivo, orin vitro, show that these neutral lipids within the nucleoid limit the ability of broken DNA molecules to migrate into the comet tail. From a technical point of view, we show that de-lipidation permits a wider range for the detection of broken DNA molecules. Biologically, we put forward the notion that neutral lipids in contact with DNA may locally exert regulatory functions within the cell’s nucleus.
Light modulates glucose and lipid homeostasis via the sympathetic nervous system
Authors: Chen Xiangning , Lin Eugene , Haghighatian Mozhan M. , Shepard Logan Wallace , Hattar Samer , Kuruvilla Rejji , Zhao Haiqing
Published: October 2024

Light is an important environmental factor for vision, and for diverse physiological and psychological functions. Light can also modulate glucose metabolism. Here, we show that in mice, light is critical for glucose and lipid homeostasis by regulating the sympathetic nervous system, independent of circadian disruption. Light deprivation from birth elicits insulin hypersecretion, glucagon hyposecretion, lower gluconeogenesis, and reduced lipolysis by 6- 8 weeks, in male, but not, female mice. These metabolic defects are consistent with blunted sympathetic activity, and indeed, sympathetic responses to a cold stimulus are significantly attenuated in dark-reared mice. Further, long-term dark rearing leads to body weight gain, insulin resistance, and glucose intolerance. Notably, metabolic dysfunction can be partially alleviated by 5 weeks exposure to a regular light-dark cycle. These studies provide insight into circadian-independent mechanisms by which light directly influences whole-body physiology and inform new approaches for understanding metabolic disorders linked to aberrant environmental light conditions.

Teaser

Light exerts direct circadian-independent effects on glucose and lipid metabolism.
CellMet: Extracting 3D shape metrics from cells and tissues
Authors: Theis Sophie , Mendieta-Serrano Mario A , Chapa-y-Lazo Bernardo , Chen Juliet , Saunders Timothy E
Published: October 2024

During development and tissue repair, cells reshape and reconfigure to ensure organs take specific shapes. This process is inherently three-dimensional (3D). Yet, in part due to limitations in imaging and data analysis, cell shape analysis within tissues have been studied as a two-dimensional (2D) approximation,e.g., theDrosophilawing disc. With recent advances in imaging and machine learning, there has been significant progress in our understanding of 3D cell and tissue shapein vivo. However, even after gaining 3D segmentation of cells, it remains challenging to extract cell shape metrics beyond volume and surface area for cells within densely packed tissues. In order to extract 3D shape metrics, we have developed CellMet. This user-friendly tool enables extraction of quantitative shape information from 3D cell and tissue segmentation. It is developed for extracting cell scale information from densely packed tissues, such as cell face properties, cell twist, and cell rearrangements. Our method will improve the analysis of 3D cell shape and the understanding of cell organisation within tissues. Our tool is open source, available athttps://github.com/TimSaundersLab/CellMet.
A polymerase ribozyme that can synthesize both itself and its complementary strand
Authors: Gianni Edoardo , Kwok Samantha L. Y. , Wan Christopher J. K. , Goeij Kevin , Clifton Bryce E. , Attwater James , Holliger Philipp
Published: October 2024

The emergence of a chemical system capable of self-replication and evolution is a critical event in the origin of life. RNA polymerase ribozymes could constitute such a system, but their large size and structural complexity hinder their self-replication and make their spontaneous emergence improbable. Here we describe QT45: a 45-nucleotide ribozyme, discovered from a random sequence pool, that catalyzes general RNA-templated RNA synthesis using trinucleotide triphosphate substrates. QT45 can synthesize both its complementary strand from a mix of all 64 trinucleotides and a copy of itself using 13 defined trinucleotides and one hexamer as substrates. The discovery of this complex activity in a small ribozyme suggests that polymerase ribozymes may be more abundant in RNA sequence space than anticipated, thereby facilitating the emergence of self-replication.
Transient proliferation by reversible YAP and mitogen-control of the cyclin D1/p27 ratio
Authors: Ferrick Katherine R. , Fan Yilin , Ratnayeke Nalin , Teruel Mary N. , Meyer Tobias
Published: October 2024

Hippo-YAP signaling orchestrates epithelial tissue repair and is therefore an attractive target in regenerative medicine. Yet it is unresolved how YAP integrates with mitogen signaling and contact inhibition to control the underlying transient proliferative response. Here we show that reduced contact inhibition, increased mitogen signaling, and YAP-TEAD activation converge on increasing the nuclear cyclin D1/p27 protein ratio during G1 phase, towards a threshold ratio that dictates whether individual cells enter or exit the cell cycle. YAP increases this ratio indirectly, in concert with mitogen signaling, by increasing EGFR and other receptors that signal primarily through ERK. After a delay, contact inhibition suppresses YAP activity which gradually downregulates mitogen signaling and the cyclin D1/p27 ratio. Increasing YAP activity by ablating the suppressor Merlin/NF2 reveals a balancing mechanism in which YAP suppression and contact inhibition of proliferation can be recovered but only at higher local cell density. Thus, critical for tissue repair, robust proliferation responses result from the YAP-induced and receptor-mediated prolonged increase in the cyclin D1/p27 ratio, which is only reversed by delayed suppression of receptor signaling after contact inhibition of YAP.
Comparable anti-ageing efficacies of a multi-ingredient nutraceutical and a senolytic intervention in old mice
Authors: Brookes Charlotte , Fielder Edward , Low Evon , Barardo Diogo , von Zglinicki Thomas , Miwa Satomi
Published: October 2024

Single-ingredient dietary supplements have demonstrated some potential to extend lifespan and improve healthspan; however, the efficacy of defined multi-ingredient nutraceuticals remains underexplored. Senolytic interventions have been successful in reducing multi-morbidity, frailty, and cognitive decline in animal models and are seen as promising anti-ageing interventions in mammals. We compared the effects of a 12-ingredient nutraceutical on mice lifespan and healthspan markers with that of a high efficacy senolytic intervention consisting of a low dose of Navitoclax combined with the specific mitochondrial uncoupler BAM15. Both interventions were started at old age (20 months). The supplement was given daily until the end of the experiment (30 months of age), but the senolytic intervention consisted of two short (5 days each) rounds of treatment at 20 and 23 months of age. Despite late onset, both interventions increased median lifespan similarly by around 20% over controls. The senolytic intervention significantly reduced frailty progression and improved cognitive function after the second round of treatment, but without subsequent treatment, these effects appeared to wane at later ages. The multi-ingredient supplement tended to reduce frailty progression steadily with time, albeit not significant, and maintained cognitive function. Mechanistically, in vitro, there was no evidence of senolytic activity of the multi-ingredient nutraceutical as a whole nor of its individual ingredients. Continuous multi-ingredient dietary supplementation shows promise in achieving comparable anti-ageing efficacy as a senolytic intervention.
Activation of Group II Metabotropic Glutamate Receptors in the Basolateral Amygdala Inhibits Reward Seeking Triggered by Discriminative Stimuli
Authors: LeCocq Mandy Rita , Mainville-Berthiaume Amélie , Laplante Isabel , Samaha Anne-Noël
Published: October 2024

Reward-associated cues are essential in guiding reward-seeking behaviours. These cues include conditioned stimuli (CSs) which occur following seeking actions and indicate reward delivery, and discriminative stimuli (DSs) which occur response-independently and signal reward availability. Metabotropic group II glutamate (mGlu2/3) receptors in the basolateral amygdala (BLA) modulate CS-guided reward seeking; however, their role in DS effects is unknown. We first developed a procedure to assess DS and CS effects on reward seeking in the same subjects within the same test session. Female and male rats first self-administered sucrose during sessions where discriminative stimuli signaled periods of sucrose availability (DS+) and unavailability (DS-). During DS+ presentations, active lever presses produced sucrose paired with a CS+. During DS-presentations, active lever presses produced a CS- and no sucrose. Across 14 sessions, rats learned to load up on sucrose during DS+ presentation and inhibit responding during DS-presentation. We then compared the effects of intra-BLA microinfusions of the mGlu2/3receptor agonist LY379268 on cue-evoked sucrose seeking during an extinction test (no sucrose) where the DSs and CSs were presented response-independently. Before test, rats received intra-BLA microinjections of artificial cerebrospinal fluid (aCSF) or LY379268. Under aCSF, only the DS+ and DS+CS+ combined triggered increases in reward-seeking behaviour. The CS+ alone was ineffective. Intra-BLA LY379268 reduced sucrose seeking triggered by the DS+ and DS+CS+ combination. Thus, using a new procedure to test reward seeking induced by DSs and CSs, we show that BLA mGlu2/3receptor activity mediates the conditioned incentive motivational effects of reward predictive DSs.
Efficient delivery of small RNAs to podocytesin vitroby direct exosome transfection
Authors: Lange Tim , Maron Luzia , Weber Claudia , Schlüter Rabea , Endlich Nicole
Published: October 2024

Podocytes are a crucial component of the glomerular filtration barrier and changes in their 3D structure contribute to over 80% of chronic kidney disease (CKD) cases. Exosomal small RNAs play a key role in cell-cell communication in CKD and may serve as nanocarriers for delivering small RNAs into podocytes. However, the uptake of exosomal cargo by podocytes remains poorly understood. This study explores the use of isolated exosomes, directly transfected with fluorescently labeled small RNAs, for tracking and delivering small RNAs to cultured podocytes.

Exosomes were isolated from immortalized murine podocytes and transfected with Cy3-labeled siRNA and miRNA controls using the ExoFect siRNA/miRNA Transfection Kit. We characterized the transfected exosomes via transmission electron microscopy (TEM) and Western blot for exosomal markers CD9 and TSG101. Subsequently, we co-cultured these exosomes with podocytes and used confocal laser-scanning microscopy (cLSM) and structured illumination microscopy (SIM) to visualize cargo uptake. The isolated exosomes were also transfected with pre-miR-21 and filamin A (FlnA)-siRNAs before being co-cultured with podocytes. We confirmed the efficiency of transfection and knockdown using RT-qPCR, Western blotting, and immunofluorescence staining.

TEM revealed that the exosomes maintained a consistent shape and size of approximately 20 nm post-transfection and exhibited a stable expression of CD9 and TSG101. Our imaging showed that podocytes take up Cy3-labeled exosomal miRNAs and siRNAs, utilizing various mechanisms, including encapsulation within vesicular structures, endocytosis and free distribution within the cells. Transfection of exosomes with FlnA-siRNAs resulted in a significant 2.8-fold reduction of FlnA expression in co-cultured podocytes, while pre-miR-21-transfected exosomes led to a remarkable 338-fold increase in mature miR-21 levels.

These findings demonstrate that direct exosome transfection with fluorescently labeled small RNAs is an effective tool for exosomal cargo tracking in podocytes. This study is the first to show that directly transfected exosomes can deliver small RNAs to podocytes in vitro, suggesting their potential as RNA carriers for therapeutic strategies in more complex settings.