Biology subjects

Jacobs, H.

Publications and source records attributed to Jacobs, H..

At least 19 recordsLinked to original sources

bioRxiv2026

In vivo modulation of locus coeruleus activity by light

Dysfunction of the Locus coeruleus (LC), a small brainstem nucleus which consists of the brains primary source of norepinephrine, is linked to various neurological and psychiatric disorders. Light exposure influences many non-image-forming (NIF) biological functions including those modulated by LC activity. Yet direct evidence of light-driven modulation of the LC has remained elusive due to the structures small size and deep location. Using ultra-high-field (7 Tesla) functional MRI during an emotional task under varying illuminances, we demonstrate that light modulates LC activity in an emotion-dependent manner. We show that increased illuminance dampens LC responses to negative emotional stimuli while enhancing responses to neutral stimuli. Furthermore, we provide tentative evidence that within an emotional context, light may affect LC activity through the basomedial nucleus of the amygdala as well as through a region of the hypothalamus encompassing the lateral hypothalamus. These findings open avenues for the development of targeted, non-pharmacological treatments leveraging light to modulate norepinephrine tone and/or LC activity in several neuropsychiatric disorders. Significance StatementDysfunction of the Locus Coeruleus (LC), a small nucleus of brain and the main source of norepinephrine, is linked to various brain disorders. Here we provide in vivo evidence that exposure to light can alter the activity of the LC with higher illuminance leading to dampened LC responses to negative emotional stimuli. These findings identify the LC as a key target for the therapeutic effects of light on emotion, offering a biological framework for using light to treat neuropsychiatric disorders.

neuroscience↗

bioRxiv2026

Age-related reconfiguration of locus coeruleus-cortical functional organization

The locus coeruleus (LC) regulates attention, arousal, and adaptive behavior via widespread noradrenergic projections to cortex, yet its large-scale cortical organization and age-related vulnerability remain poorly understood. Using 7T MRI during naturalistic movie-viewing with neutral and negative emotional valence, study-specific LC delineation, and PET-derived receptor-transporter maps, we characterized LC-linked cortical organization in younger and older adults. Functional gradient analysis revealed two dominant axes: a stable primary gradient anchored by catecholaminergic receptor-transporter distributions, and a context-sensitive secondary gradient aligning with the visual-somatomotor (V-S) axis in neutral movie-viewing and the sensorimotor-association (S-A) axis in negative movie-viewing. During negative movie-viewing, older adults exhibited higher global and within-frontoparietal control network dispersion, indicating reduced functional differentiation, a pattern further associated with poorer emotional wellbeing. By revealing chemoarchitectural and context-sensitive LC-linked cortical organization, current work identifies mechanisms underlying age-related LC-linked cortical reorganization with consequences for mental health.

neuroscience↗

bioRxiv2025

Clastogenesis by nucleotide lesions requires the completion of two cell cycles.

Damaged DNA nucleotides can trigger genome rearrangements through clastogenesis, a process driven by erroneous repair of double-strand breaks (DSBs) and associated with cancer development. While DSBs are known to arise from endonuclease activity at stalled replication forks, the clastogenic potential of such DSBs has remained uncertain. Here, we identify a previously unrecognized mechanism of clastogenesis using wild-type, nucleotide excision repair (NER)-deficient and translesion synthesis (TLS)-deficient cells, combined with advanced cytogenetic analyses. We demonstrate that, single-stranded DNA (ssDNA) tracts harboring unrepaired lesions rather than DSBs at collapsed replication forks can persist through mitosis. Only during the subsequent S phase, these tracts are converted into a new class of, highly clastogenic, DSBs. Consistent with a role of this mechanism in carcinogenesis, prostate cancers exhibiting extensive genomic rearrangements frequently harbor somatic defects in NER or in error-free homologous recombination-mediated DSB repair. These findings provide critical mechanistic insight and highlight potential implications for routine clastogenicity testing. Graphical abstractNucleotide lesions (light blue triangle) can trigger double-strand breaks (DSBs) through endonucleolytic cleavage at stalled or reversed replication forks. Traditionally, these DSBs were assumed to drive genome rearrangements, a process termed clastogenesis. Here we describe a distinct, delayed, mechanism of clastogenesis. Thus, unreplicated nucleotide lesions within single-stranded (ss) DNA regions persist through mitosis into the next cell cycle. During the subsequent S phase, these ssDNA tracts collapse into DSBs, presumably via replication runoff. These delayed DSBs then promote extensive genomic reshuffling. Supporting this model, prostate cancers with high levels of genomic rearrangements are frequently associated with somatic defects in nucleotide excision repair (NER)--a pathway that normally prevents lesion-induced clastogenesis. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=138 SRC="FIGDIR/small/694654v1_ufig1.gif" ALT="Figure 1"> View larger version (45K): org.highwire.dtl.DTLVardef@7c37dborg.highwire.dtl.DTLVardef@13721aeorg.highwire.dtl.DTLVardef@842e4forg.highwire.dtl.DTLVardef@1fc7c31_HPS_FORMAT_FIGEXP M_FIG C_FIG

molecular biology↗

bioRxiv2025

Androgen receptor imprints satellite cells stemness and preserves their reservoir for lifelong regeneration and optimal repair

Skeletal muscle stem cells (MuSC) are the guardians of muscle regeneration, sustaining tissue integrity through a delicate balance of quiescence, activation, and lineage commitment. While numerous molecular cues have been implicated in regulating these processes, the influence of androgen receptor (AR) signaling, an essential hormonal pathway for male muscle physiology, has remained largely unexplored. Here, we show that AR expression defines quiescent MuSC and acts as a safeguard of their dormancy. Integrated multi-omic analyses reveal a redistribution of AR binding from quiescence-maintenance loci to regulatory elements driving activation and metabolic reprogramming during repair. Loss of AR in young adult mice disrupts this balance, precipitating premature cell-cycle entry, skewed division modalities, depletion of the stem cell reservoir, and destabilization of the niche. These defects converge with hallmarks of aging-associated androgen decline, while androgen supplementation restores regenerative competence. Together, our findings establish AR signaling as a pivotal determinant of MuSC fate and a cornerstone of skeletal muscle homeostasis.

developmental biology↗

bioRxiv2025

Arousal increases locus coeruleus blood flow, salience-related brain responses, and modulates negative-valence attentional biases

The amygdala helps prioritize emotional over neutral information. However, it responds similarly to positive and negative stimuli, and so is unlikely to be the source of valence-specific effects within affective networks. We hypothesized that the locus coeruleus (LC) is a key contributor to negative biases in attention. Using ultra-high field 7T magnetic resonance imaging, we tested how arousal modulates processing of emotional faces during an oddball task in twenty-two young adults during two separate sessions. Arousal induced by isometric handgrip increased LC cerebral blood flow and amplified brain responses to target and angry faces, but not to happy faces. The amygdala exhibited valence-general responses that were not modulated by arousal. LC connectivity with the default mode network decreased during processing target and angry faces, and arousal further modulated responses in the salience network and visual cortex. Behaviorally, arousal enhanced recognition of angry faces only when allocating attentional resources and memory performance was linked to left LC brain activity. These findings highlight the LC as a key structure through which arousal shapes valence processing, biases attention, and informs mechanisms related to affective disorders.

neuroscience↗

bioRxiv2025

Disrupted transcriptional networks regulated by CHD1L during neurodevelopment underlie the mirrored neuroanatomical and growth phenotypes of the 1q21.1 copy number variant

Distal 1q21.1 deletions and duplications are associated with variable phenotypes including autism, head circumference and height defects. To elucidate which gene(s) are responsible for the 1q21.1 duplication/deletion-associated phenotypes, we performed gene manipulation in zebrafish and mice. We modeled 1q21.1 duplication by overexpressing the eight human protein-coding genes in zebrafish. We found that overexpression of CHD1L only led to macrocephaly and increased larval body length, whereas chd1l deletion caused opposite phenotypes. These mirrored phenotypes were also observed in mouse embryos. Transcriptomic, cistromic, and chromatin accessibility analyses of CHD1L knock-out hiPSC-derived neuronal progenitor cells revealed that CHD1L regulates the expression levels and chromatin accessibility of genes involved in neuronal differentiation and synaptogenesis, including autism genes. Moreover, we found that CHD1L favors telencephalon development during forebrain regionalization by facilitating chromatin accessibility to pioneer transcription factors including SOX2 and OTX2 while simultaneously compacting chromatin through its interaction with the repressor NuRD complex. Last, atypical 1q21.1 CNV encompassing CHD1L and pathogenic missense and truncating CHD1L variants were found in individuals with autism. Overall, our data reveal a novel role for CHD1L as a master regulator of cell fate and its dosage imbalance contributes to the neuroanatomical and growth phenotypes associated with the 1q21.1 distal CNV. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=71 SRC="FIGDIR/small/638841v1_ufig1.gif" ALT="Figure 1"> View larger version (32K): org.highwire.dtl.DTLVardef@7dd5borg.highwire.dtl.DTLVardef@55a12dorg.highwire.dtl.DTLVardef@1c8ce0corg.highwire.dtl.DTLVardef@4faf29_HPS_FORMAT_FIGEXP M_FIG C_FIG

genomics↗

bioRxiv2025

Histone methyltransferase DOT1L maintains identity and restricts cytotoxic potential of CD8 T cells

The histone methyltransferase DOT1L is emerging as a central epigenetic regulator in immune cells. Loss of DOT1L during development of CD8 T cells in vivo leads to gain of memory-features but has also been reported to compromise CD8 T cell viability and activity. Here, we determined the cell-intrinsic role of DOT1L in mature mouse CD8 T cells. After conditional deletion of Dot1L in vitro, CD8 T cells retained in vivo proliferative capacity and anti-tumor reactivity. Moreover, Dot1L knock-out CD8 T cells showed increased antigen-specific cytotoxicity towards tumor cells in vitro. Mechanistically, loss of DOT1L resulted in an altered cell-identity program with loss of T-cell and gain of NK-cell features. These transcriptional changes were mediated by loss of DOT1L methyltransferase activity in a dose-dependent manner. Our findings show that ablation of DOT1L activity in mature CD8 T cells is well-tolerated and rewires their cell identity towards the NK-cell lineage, concomitantly enhancing intrinsic cytotoxic capacity. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=143 SRC="FIGDIR/small/633937v1_ufig1.gif" ALT="Figure 1"> View larger version (45K): org.highwire.dtl.DTLVardef@1641c55org.highwire.dtl.DTLVardef@1803510org.highwire.dtl.DTLVardef@1bedceorg.highwire.dtl.DTLVardef@199a6d5_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIDifferentiation and identity of cytotoxic T cells depend on the methyltransferase DOT1L C_LIO_LIDOT1L intrinsically limits the cytotoxic activity of mature CD8 T cells C_LIO_LIDOT1L prohibits the acquisition of NK cell features in CD8 T cells C_LIO_LIDOT1L maintains CD8 T cell identity through its catalytic activity in a dose-dependent manner C_LI

immunology↗

bioRxiv2024

Age-related Increase in Locus Coeruleus Activity and Connectivity with Prefrontal Cortex during Ambiguity Processing

Interpreting ambiguous environmental cues, like facial expressions, becomes increasingly challenging with age, especially as cognitive resources decline. Managing these challenges requires adaptive neural mechanisms that are essential for maintaining mental well-being. The locus coeruleus (LC), the brains main norepinephrine source, regulates attention, arousal, and stress response. With extensive cortical connections, the LC supports adapting to cognitive demands and resolving conflicting cues from environment, particularly in later life. Previous research suggests that LC interacts with the prefrontal cortex (PFC) during high-conflict tasks. However, whether LC activity and its connectivity with the PFC support emotional ambiguity processing and contributes to emotional well-being in healthy aging remains unclear. To address this gap, we used 7T-MRI to examine LC function in 75 younger (25.8 {+/-} 4.02years, 35females) and 69 older adults (71.3 {+/-} 4.1 years, 35females) during facial-emotion-recognition task morphed with varying ambiguity: anchor (unambiguous happy or fearful), intermediate-ambiguity (30%happy-70%fearful and 40%happy-60%fearful expressions), and absolute-ambiguity (50%happy-fearful). Behaviorally, participants had longer response times and lower confidence during the absolute-ambiguity condition, while older adults perceived ambiguous faces as happy more frequently than younger adults. Neuroimaging results revealed older adults exhibited greater LC activity and enhanced connectivity with dorsolateral PFC (dlPFC) during absolute-ambiguity compared to younger adults. This heightened connectivity in older adults was linked to better task-independent self-reported mental well-being questionnaires and greater emotional resilience scores derived from principal component analysis. Overall, these findings suggest that greater LC activity supports managing cognitively demanding tasks, while enhanced LC-dlPFC connectivity promotes emotional well-being, highlighting this neural pathways role in healthy aging. Significance StatementUnderstanding how the brain adapts to cognitive and emotional demands with age is key to promoting healthy aging. This study examined whether the locus coeruleus (LC), a brain region critical for regulating attention and arousal, undergoes adaptive changes with age, especially during emotional ambiguity task. Using ultra-high-field imaging, we explored younger and older adults recognize facial expressions with varying ambiguity levels. Our findings indicated that compared to young, older adults showed heightened LC activity and LC-dorsolateral prefrontal cortex (dlPFC) connectivity when processing absolute-ambiguous facial expressions, with enhanced connectivity linked to improved mental well-being. These results suggest higher LC activity supports cognitive demands of ambiguity processing with LC-dlPFC connectivity promoting emotional well-being and resilience, offering insights into mechanisms underlying healthy aging.

neuroscience↗

bioRxiv2024

Widespread naturally variable human exons aid genetic interpretation

Most mammalian genes undergo alternative splicing. The splicing of some exons has been acquired or lost in specific mammalian lineages, but differences in splicing within the human population are poorly characterized. Using GTEx tissue transcriptomes from 838 individuals, we identified 56,415 exons which are included in mRNAs in some individuals but entirely excluded from others, which we term "naturally variable exons" (NVEs). NVEs impact three quarters of protein-coding genes, occur at all population frequencies, and are often absent from reference annotations. NVEs are more abundant in genes depleted of genetic loss-of-function mutations and aid in the interpretation of causal genetic variants. Genetic variants modulate the splicing of many NVEs, and 5UTR and coding-region NVEs are often associated with increased and decreased gene expression, respectively. Together, our findings characterize abundant splicing variation in the human population, with implications for a range of human genetic analyses.

genetics↗

bioRxiv2024

Targeting DOT1L and EZH2 synergizes in breaking the germinal center identity of Diffuse Large B Cell Lymphoma

Differentiation of antigen-activated B cells into pro-proliferative germinal center (GC) B cells depends on the activity of the transcription factor MYC and the epigenetic writers DOT1L and EZH2. GCB-like Diffuse Large B Cell Lymphomas (GCB-DLBCLs) arise from GC B cells and closely resemble their cell of origin. Given the dependency of GC B cells on DOT1L and EZH2, we investigated the role of these epigenetic regulators in GCB-DLBCL cell lines and observed that GCB-DLBCLs synergistically depend on the combined activity of DOT1L and EZH2. Mechanistically, inhibiting both enzymes led to enhanced derepression of PRC2 target genes compared to EZH2 single treatment, along with the suppression of MYC target genes. The sum of all these alterations results in a cell-identity crisis, wherein GCB-DLBCLs lose their pro-proliferative GC identity and partially undergo plasma cell differentiation, a state associated with poor survival. In support of this model, combined epi-drugging of DOT1L and EZH2 prohibited the outgrowth of human GCB-DLBCL xenografts in vivo. We conclude that the malignant behavior of GCB-DLBCLs strictly depends on DOT1L and EZH2 and that combined targeting of both epigenetic writers may provide an alternative differentiation-based treatment modality for GCB-DLBCL. Key pointsO_LIMYC-driven GCB-DLBCL depends on DOT1L and EZH2 and combined targeting provides an alternative differentiation-based therapy. C_LIO_LIDOT1L and EZH2 cooperatively repress PRC2 target genes which is essential for acquiring a plasma cell-like state in GC B cell-like DLBCL. C_LI

cancer biology↗

bioRxiv2023

Molecular dependencies and genomic consequences of a global DNA damage tolerance defect

DNA damage tolerance (DDT) enables replication to continue in the presence of fork stalling lesions. To determine the molecular and genomic impact of a global DDT defect, we studied PcnaK164R/-;Rev1-/- compound mutants. Double mutant (DM) cells displayed increased replication stress, hypersensitivity to genotoxic agents, replication speed, and repriming. A whole genome CRISPR-Cas9 screen revealed a strict reliance of DM cells on the CST complex, where CST promotes fork stability. Whole genome sequencing indicated that this DM DDT defect favors the generation of large, replication-stress inducible deletions of 0.4-4.0kbp, defined as type 3 deletions. Junction break sites of these deletions revealed preferential microhomology preferences of 1-2 base pairs, differing from the smaller type 1 and type 2 deletions. These differential characteristics suggest the existence of molecularly distinct deletion pathways. Type 3 deletions are abundant in human tumors, can dominate the deletion landscape and are associated with DNA damage response status and treatment modality. Our data highlight the essential contribution of the DDT system to genome maintenance and type 3 deletions as mutational signature of replication stress. The unique characteristics of type 3 deletions implicate the existence of a novel deletion pathway in mice and humans that is counteracted by DDT.

molecular biology↗

bioRxiv2023

Impact of repeated short light exposures on sustained pupil responses in an fMRI environment

Light triggers numerous non-image forming (NIF), or non-visual, biological effects. The brain correlates of these NIF effects have been investigated, notably using Magnetic Resonance Imaging (MRI) and short light exposures varying in irradiance and spectral quality. However, it is not clear whether having light in subsequent blocks may induce carry over effects of one light block onto the next, thus biasing the study. We reasoned that pupil light reflex (PLR) was an easy readout of one of the NIF effects of light that could be used to address this issue. We characterized the sustained PLR in 13 to 16 healthy young individuals under short light exposures during three distinct cognitive processes (executive, emotional and attentional). Light conditions pseudo-randomly alternated between monochromatic orange light [0.16 melanopic Equivalent Daylight Illuminance (mel EDI) lux] and polychromatic blue-enriched white light of three different levels [37, 92, 190 mel EDI lux]. As expected, higher melanopic irradiance was associated with larger sustained PLR in each cognitive domain. This result was stable over the light block sequence under higher melanopic irradiance levels as compared to lower ones. Exploratory frequency-domain analyses further revealed that PLR was more variable within a light block under lower melanopic irradiance levels. Importantly, PLR varied across tasks independently of the light condition pointing to a potential impact of the light history and/or cognitive context on PLR. Together, our results emphasize that the distinct contribution and adaptation of the different retinal photoreceptors influence the NIF effects of light and therefore potentially their brain correlates.

neuroscience↗

bioRxiv2023

In vivo Locus Coeruleus activity while awake is associated with REM sleep quality in healthy older individuals

The locus coeruleus (LC) is the primary source of norepinephrine (NE) in the brain, and the LC-NE system is involved in regulating arousal and sleep. It plays key roles in the transition between sleep and wakefulness, and between slow wave sleep (SWS) and rapid eye movement sleep (REMS). However, it is not clear whether the LC activity during the day predicts sleep quality and sleep properties during the night, and how this varies as a function of age. Here, we used 7 Tesla functional Magnetic Resonance Imaging (7T fMRI), sleep electroencephalography (EEG) and a sleep questionnaire to test whether the LC activity during wakefulness was associated with sleep quality in 52 healthy younger (N=33; ~22y; 28 women) and older (N=19; ~61y; 14 women) individuals. We find that, in older, but not in younger participants, higher LC activity, as probed during an auditory mismatch negativity task, is associated with worse subjective sleep quality and with lower power over the EEG theta band during REMS (4-8Hz), which are two sleep parameters significantly correlated in our sample of older individuals. The results remain robust even when accounting for the age-related changes in the integrity of the LC. These findings suggest that the activity of the LC may contribute to the perception of the sleep quality and to an essential oscillatory mode of REMS, and that the LC may be an important target in the treatment of sleep disorders and age-related diseases.

neuroscience↗

bioRxiv2023

MRI-assessed locus coeruleus contrast and functional response are not associated in young and late middle-aged individuals

The brainstem locus coeruleus (LC) influences a broad range of brain processes, including cognition. The so-called LC contrast is an accepted marker of the integrity of the LC that consists of a local hyperintensity on specific Magnetic Resonance Imaging (MRI) structural images. The small size of the LC has, however, rendered its functional characterization difficult in humans, including in aging. A full characterization of the structural and functional characteristics of the LC in healthy young and late middle-aged individuals is needed to determine to potential roles of the LC in different medical conditions. Here, we wanted to determine whether the activation of the LC in a mismatch negativity task changes in aging and whether the LC functional response was associated to the LC contrast. We used Ultra-High Field (UHF) 7-Tesla functional MRI (fMRI) to record brain response during an auditory oddball task in 53 healthy volunteers, including 34 younger (age: 22.15y {+/-} 3.27; 29 women) and 19 late middle-aged (age: 61.05y {+/-} 5.3; 14 women) individuals. Whole-brain analyses confirmed brain responses in the typical cortical and subcortical regions previously associated with mismatch negativity. When focusing on the brainstem, we found a significant response in the rostral part of the LC probability mask generated based on individual LC images. Although bilateral, the activation was more extensive in the left LC. Individual LC activity was not significantly different between young and late middle-aged individuals. Critically, while the LC contrast was higher in older individuals, the functional response of the LC was not associated with its contrast. These findings show that the age-related alterations of the LC structural integrity may not necessarily be related to changes in its functional response. The results further indicate that LC responses could remain stable in healthy individuals aged 20 to 70.

neuroscience↗

bioRxiv2022

DRAG in situ barcoding reveals an increased number of HSPCs contributing to myelopoiesis with age

Ageing is associated with changes in the cellular composition of the immune system. During ageing, hematopoietic stem and progenitor cells (HSPCs) that produce immune cells are thought to decline in their regenerative capacity. However, HSPC function has been mostly assessed using transplantation assays, and it remains unclear how HSPCs age in the native bone marrow niche. To address this issue, we developed a novel in situ single cell lineage tracing technology to quantify the clonal composition and cell production of single cells in their native niche. Our results demonstrate that a pool of HSPCs with unequal output maintains myelopoiesis through overlapping waves of cell production throughout adult life. During ageing, the increased frequency of myeloid cells is explained by greater numbers of HSPCs contributing to myelopoiesis, rather than increased myeloid output of individual HSPCs. Strikingly, the myeloid output of HSPCs remained constant over time despite accumulating significant transcriptomic changes throughout adulthood. Together, these results show that, unlike emergency myelopoiesis post-transplantation, aged HSPCs in their native microenvironment do not functionally decline in their regenerative capacity.

immunology↗

bioRxiv2021

BACE1, but not BACE2, function is critical for metabolic disorders induced by high-fat diets in C57BL/6N mice

Aims/hypothesisBeta-site amyloid precursor protein-cleaving enzyme 1 (BACE1) is required for the production of toxic amyloid peptides and is highly expressed in the brain, but also to a lesser extent in major peripheral organs such as muscle and liver. In contrast, BACE2 is mainly expressed in peripheral tissues and is enriched in pancreatic beta cells, where it regulates beta- cell function and mass. Previous reports demonstrated that loss of BACE1 function decreases body weight, protects against diet-induced obesity and enhances insulin sensitivity in mice, whereas mice lacking Bace2 exhibit reduced blood glucose levels, improved intraperitoneal glucose tolerance and increased beta-cell mass. Impaired glucose homeostasis and insulin resistance are hallmarks of type 2 diabetes and have been implicated in Alzheimers disease. Therefore, we tested the contribution of the individual BACE isoforms to those metabolic phenotypes by placing Bace1 knockout (KO), Bace2 KO, Bace1/2 double knockout (dKO) and wild-type (WT) mice on a high-fat high-cholesterol diet (HFD) for 16 weeks. MethodsBace1 KO (n = 18), Bace2 KO (n = 18), Bace1/2 dKO (n = 18) and WT C57BL/6N mice (n = 54) were fed a HFD for 16 weeks (age 9-25 weeks). Body composition was measured before initiation of the HFD and after 11 weeks of HFD. Oral glucose tolerance and insulin sensitivity tests were performed after 12 and 13 weeks of HFD, respectively, and full blood chemistry was analyzed after 16 weeks of HFD. The effects of subchronic BACE1/2 inhibition were assessed by administration of 10 mg/kg/day of the dual BACE1/2 inhibitor MBi-3 in a HFD fed to C57BL/6N mice for 3 weeks. ResultsBace1 KO and Bace1/2 dKO mice showed decreased body weight and improved glucose tolerance and insulin resistance vs. WT mice. Conversely, Bace2 KO mice did not show any significant differences in body weight, glucose tolerance or insulin resistance under our experimental conditions. Finally, subchronic MBi-3-mediated BACE1/2 inhibition in mice in conjunction with a HFD resulted in a modest improvement of glucose tolerance. Conclusions/interpretationOur data indicate that lack of BACE1 - but not BACE2 - function contributes mainly to the metabolic phenotypic changes observed in Bace1/2 dKO mice, suggesting that inhibition of BACE1 has the greater role (vs. BACE2) in any potential improvements in metabolic homeostasis. HIGHLIGHTSO_LIInsulin resistance may develop in the brains of patients with Alzheimers disease (83/85 characters) C_LIO_LIBACE1 and BACE2 may play a role in glucose homeostasis and insulin sensitivity (80/85 characters) C_LIO_LIBody weight in mice decreased with Bace1 KO and Bace1/2 KO but not Bace2 KO alone (83/85 characters) C_LIO_LIBace1 and Bace1/2, but not Bace2, KO improved glucose tolerance/insulin resistance (84/85 characters) C_LIO_LIImproved metabolic homeostasis may follow loss of BACE1 rather than BACE 2 activity (85/85 characters) C_LI

physiology↗

bioRxiv2021

Lymphotoxin-alpha expression in the meninges causes lymphoid tissue formation and neurodegeneration

Lymphotoxin alpha (LT) plays an important role in lymphoid organ development and cellular cytotoxicity in the immune system. LT expression is increased in the cerebrospinal fluid of naive and progressive multiple sclerosis (MS) patients and post-mortem meningeal tissue. Here we show that persistently increased levels of LT in the cerebral meninges can give rise to lymphoid-like structures and underlying MS-like cortical pathology. Stereotaxic injections of recombinant LT into the rat meninges leads to acute meningeal inflammation and subpial demyelination that resolves after 28 days. Injection of an LT lentiviral vector induces lymphoid-like immune cell aggregates, maintained over 3 months, including T-cell rich zones containing podoplanin+ fibroblastic reticular stromal cells and B-cell rich zones with a network of follicular dendritic cells, together with expression of lymphoid chemokines and their receptors. Extensive microglial activation, subpial demyelination and marked neuronal loss occurs in the underlying cortical parenchyma. These results show that chronic LT overexpression is sufficient to induce formation of meningeal lymphoid-like structures and subsequent neurodegeneration. SummaryIncreased release of lymphotoxin-alpha contributes to the pro-inflammatory milieu of the cerebrospinal fluid of MS patients. A persistent elevated expression of this cytokine in the meninges of rats gives rise to chronic inflammation with lymphoid tissue induction and accompanying neurodegenerative and demyelinating pathology in the underlying brain tissue.

neuroscience↗

bioRxiv2021

Multiple 9-1-1 complexes promote homolog synapsis, DSB repair, and ATR signaling during mammalian meiosis

DNA damage response mechanisms have meiotic roles that ensure successful gamete formation. While completion of meiotic double-strand break (DSB) repair requires the canonical RAD9A-RAD1-HUS1 (9A-1-1) complex, mammalian meiocytes also express RAD9A and HUS1 paralogs, RAD9B and HUS1B, predicted to form alternative 9-1-1 complexes. The RAD1 subunit is shared by all predicted 9-1-1 complexes and localizes to meiotic chromosomes even in the absence of HUS1 and RAD9A. Here we report that testis-specific RAD1 disruption resulted in impaired DSB repair, germ cell depletion and infertility. Unlike Hus1 or Rad9a disruption, Rad1 loss also caused defects in homolog synapsis, ATR signaling and meiotic sex chromosome inactivation. Comprehensive testis phosphoproteomics revealed that RAD1 and ATR coordinately regulate numerous proteins involved in DSB repair, meiotic silencing, synaptonemal complex formation, and cohesion. Together, these results establish critical roles for both canonical and alternative 9-1-1 complexes in meiotic ATR activation and successful prophase I completion.

genetics↗