Biology subjects

Tan, L.

Publications and source records attributed to Tan, L..

At least 73 records · Page 4Linked to original sources

bioRxiv2023

Artificially cultivated duckweed: a high-efficiency starch producer

The increasing demand for starch has been a social struggle. We report a new technology that efficiently produces starch from duckweed. Although Landoltia punctata has a dramatic contraction of gene families, its starch content and productivity reached 72.2% (dry basis) and 10.4 g m-2 d-1 in 10 days, equivalent to a yield of 38.0 t ha-1 y-1 under nutrient limitation and CO2 elevation treatment. Meanwhile, we also examined the mechanism of duckweeds high starch accumulation. This is exhibited in the regulation of DNA methylation and transcription factors as well as the significantly up-regulated transcription levels and the increased enzyme activities of key genes in starch biosynthesis. Meantime, while nitrogen redistribution was enhanced, sucrose biosynthesis and transportation, and lignocellulose biosynthesis were all reduced. These alterations led to a reduction in lignocellulose and protein content and ultimately an increase in an accumulation of starch in the chloroplast. This work demonstrates duckweeds potential of being a highly efficient starch producer.

plant biology↗

bioRxiv2023

Coronavirus endoribonuclease nsp15 induces host cellular protein synthesis shutoff

The endoribonuclease (EndoU) nsp15 of coronaviruses plays an important role in evasion of host innate immune responses by reducing the abundance of viral double-stranded RNA, whereas less is known about potential host cellular targets of nsp15. In this study, we show that cellular protein synthesis is inhibited upon over-expression of nsp15 from four genera of coronaviruses and this is accompanied by nuclear retention of the poly(A) binding protein cytoplasmic 1 (PABPC1). We also show that the EndoU activity of nsp15 is indispensable for both, inhibition of protein synthesis and PABPC1 nuclear relocation. FISH analysis using oligo-dT probes, revealed an overlap between the localization of cellular mRNA and that of overexpressed nsp15 in some cells, suggesting that, when expressed alone, nsp15 may target host mRNA. When investigating the association of nsp15 on protein shut off in the context of a viral infection, we observed that the{gamma} -coronavirus infectious bronchitis virus (IBV), induced host translation shutoff in an p-eIF2-independent manner and mainly retained PABPC1 in the cytoplasm, whereas the nsp15 EndoU-deficient IBV accumulated viral dsRNA and caused p-PKR-p-eIF2-dependent host protein translation shutoff, accompanied with PABPC1 nuclear relocation or stress granule (SG) localization. This phenomenon suggests that during infection with wild type IBV, although the cellular translation is inhibited, initiation of viral mRNA translation leads to PABPC1 binding to viral mRNA, thereby preventing its nuclear entry; during infection with nsp15 EndoU-deficient IBV however, the eIF2-dependent host protein translation shutoff prevents both host and viral mRNA translation initiation, releasing PABPC1 from binding to cytosolic and viral mRNA, thereby relocating it to the nucleus or to SG. Altogether, this study reveals unique yet conserved mechanisms of host protein shutoff that add to our understanding of how coronaviruses regulate host protein expression through a mechanism that involves catalytically active nsp15 EndoU, and describes how nsp15 may target both, viral and host mRNA. Author summaryIt has been reported that coronavirus infection suppresses host protein translation, - and {beta}- coronavirus nsp1 is responsible for inhibition of host gene expression. However, for{gamma} - and{delta} -coronavirus, there is no nsp1 and the underlying mechanisms by which virus regulates host translation are not well characterized. Here, we show that coronavirus endoribonuclease nsp15 is responsible for the inhibition of host translation by targeting to host factors, meanwhile it helps virus bypass the PKR-eIF2 mediated host translation shutoff, which is harmful for virus gene expression, by reducing the accumulation of viral dsRNA. This novel finding gives insight how does nsp15 targets to both host factors and viral RNA, to facilitate virus replication. Moreover, the novel function of nsp15 is found to be conserved among coronaviruses, revealing the essential role of this endoribonuclease in hijacking host translation machinery for virus replication.

microbiology↗

bioRxiv2023

Opposing, spatially-determined epigenetic forces impose restrictions on stochastic olfactory receptor choice

Olfactory receptor (OR) choice represents an example of genetically hardwired stochasticity, where every olfactory neuron expresses one out of [~]2000 OR alleles in a probabilistic, yet stereotypic fashion. Here, we propose that topographic restrictions in OR expression are established in neuronal progenitors by two opposing forces: polygenic transcription and genomic silencing, both of which are influenced by dorsoventral gradients of transcription factors NFIA, B, and X. Polygenic transcription of OR genes may define spatially constrained OR repertoires, among which one OR allele is selected for singular expression later in development. Heterochromatin assembly and genomic compartmentalization of OR alleles also vary across the axes of the olfactory epithelium and may preferentially eliminate ectopically expressed ORs with more dorsal expression destinations from this "privileged" repertoire. Our experiments identify early transcription as a potential "epigenetic" contributor to future developmental patterning and reveal how two spatially responsive probabilistic processes may act in concert to establish deterministic, precise, and reproducible territories of stochastic gene expression.

genomics↗

bioRxiv2023

Cerebellar Granule Cells Develop Non-neuronal 3D Genome Architecture over the Lifespan

The cerebellum contains most of the neurons in the human brain, and exhibits unique modes of development, malformation, and aging. For example, granule cells--the most abundant neuron type--develop unusually late and exhibit unique nuclear morphology. Here, by developing our high-resolution single-cell 3D genome assay Dip-C into population-scale (Pop-C) and virus-enriched (vDip-C) modes, we were able to resolve the first 3D genome structures of single cerebellar cells, create life-spanning 3D genome atlases for both human and mouse, and jointly measure transcriptome and chromatin accessibility during development. We found that while the transcriptome and chromatin accessibility of human granule cells exhibit a characteristic maturation pattern within the first year of postnatal life, 3D genome architecture gradually remodels throughout life into a non-neuronal state with ultra-long-range intra-chromosomal contacts and specific inter-chromosomal contacts. This 3D genome remodeling is conserved in mice, and robust to heterozygous deletion of chromatin remodeling disease-associated genes (Chd8 or Arid1b). Together these results reveal unexpected and evolutionarily-conserved molecular processes underlying the unique development and aging of the mammalian cerebellum.

neuroscience↗

bioRxiv2023

Targeting DNA2 Overcomes Metabolic Reprogramming in Multiple Myeloma

DNA damage resistance is a major barrier to effective DNA-damaging therapy in multiple myeloma (MM). To discover novel mechanisms through which MM cells overcome DNA damage, we investigated how MM cells become resistant to antisense oligonucleotide (ASO) therapy targeting ILF2, a DNA damage regulator that is overexpressed in 70% of MM patients whose disease has progressed after standard therapies have failed. Here, we show that MM cells undergo an adaptive metabolic rewiring and rely on oxidative phosphorylation to restore energy balance and promote survival in response to DNA damage activation. Using a CRISPR/Cas9 screening strategy, we identified the mitochondrial DNA repair protein DNA2, whose loss of function suppresses MM cells ability to overcome ILF2 ASO-induced DNA damage, as being essential to counteracting oxidative DNA damage and maintaining mitochondrial respiration. Our study revealed a novel vulnerability of MM cells that have an increased demand for mitochondrial metabolism upon DNA damage activation. STATEMENT OF SIGNIFICANCEMetabolic reprogramming is a mechanism through which cancer cells maintain survival and become resistant to DNA-damaging therapy. Here, we show that targeting DNA2 is synthetically lethal in myeloma cells that undergo metabolic adaptation and rely on oxidative phosphorylation to maintain survival after DNA damage activation.

cancer biology↗

bioRxiv2023

Extruding transcription elongation loops observed in high-resolution single-cell 3D genomes

Inside human nuclei, genes are transcribed within a highly packed genome, whose organization is facilitated by cohesin-mediated loop extrusion. However, whether cohesin-mediated loop extrusion participates in transcription is unknown. Here we report that the cohesin-mediated loop extrusion participates in transcription by forming a topoisomerases-regulated transcription elongation loop (TEL), in which cohesin is stalled at the transcription start site (TSS) and gradually extrudes loops asymmetrically until reaching the transcription termination site (TTS). By improving the spatial resolution of single-cell 3D genome mapping to 5 kb with micrococcal nuclease (MNase) in our new single-cell Micro-C (scMicro-C) method, we directly observed the loop expansion of TELs. Furthermore, TELs biological function is to ensure high transcriptional burst frequencies by fast re-initiation of RNA Pol II. One-Sentence SummarySingle-cell high-resolution 3D genome structures reveal that cohesin-mediated loop extrusion participates in transcription.

genomics↗

bioRxiv2023

TERT accelerates BRAF mutant-induced thyroid cancer dedifferentiation and progression by regulating ribosome biogenesis

TERT reactivation occurs frequently in human malignancies. While BRAF activating mutation widely existed in cancers at various stages, TERT reactivation mainly occurs in advanced tumors. However, in vivo evidence for TERT role in cancer progression and the underlying mechanism is currently lacking. In this study, we induced TERT and/or BRAF V600E expression in mouse thyroid epithelium. TERT overexpression alone had no evident effect on tumor initiation. BRAFVE expression itself induced mediocre papillary thyroid cancer (PTC). Notably, the co-expression of BRAFVE and TERT resulted in aggressive poorly differentiated thyroid carcinoma (PDTC). Spatial transcriptome revealed that tumors from co-mutant mice were highly heterogeneous and dedifferentiation process significantly correlated with ribosomal pathways. Mechanistically, TERT boosted ribosomal RNA expression and protein synthesis. CX-5461, a rRNA transcription inhibitor, effectively blocked proliferation and induced redifferentiation. Thus, TERT promotes thyroid cancer progression by inducing dedifferentiation, and ribosome biogenesis inhibition represents a potential treatment strategy for TERT-reactivated cancers. Highlights[tpltrtarr] TERT accelerated thyroid cancer dedifferentiation and metastasis in vivo [tpltrtarr]TERT regulated rRNA metabolism and MTORC1/ S6K/RPS6 activities [tpltrtarr]CX-5461 inhibited the progression of TERT-reactivated melanoma and thyroid cancer [tpltrtarr]Inhibition of rRNA induced redifferentiation of advanced thyroid cancer with TERT activation

cancer biology↗

bioRxiv2023

Disrupted trans-placental thyroid hormone transport in a human model for MCT8 deficiency

Introduction ABSTRACT Introduction Results Discussion Materials and methods Author contributions Conflict of interest statement The Paper Explained Problem Results Impact Expanded View Figures References Thyroid hormones, the collective name for the prohormone T4 and the active hormone T3, are crucial for neurodevelopment. During prenatal neurodevelopment, maternal-to-fetal T4 transfer is critical, particularly during the first half of pregnancy with the fetal thyroid gland being immature (Patel et al, 2011). Therefore, maternal thyroid dysfunction negatively impacts brain structure and function in the offspring (Jansen et al, 2019; ...

pathology↗

bioRxiv2022

Vitamin B2 enables peroxisome proliferator-activated receptor α regulation of fasting glucose availability

Flavin adenine dinucleotide (FAD) interacts with flavoproteins to mediate oxidation-reduction reactions required for cellular energy demands. Not surprisingly, mutations that alter FAD binding to flavoproteins cause rare inborn errors of metabolism (IEMs) that disrupt liver function and render fasting intolerance, hepatic steatosis, and lipodystrophy. In our study, depleting FAD pools in mice with a vitamin B2 deficient diet (B2D) caused phenotypes associated with organic acidemias and other IEMs, including reduced body weight, hypoglycemia, and fatty liver disease. Integrated discovery approaches revealed B2D tempered fasting activation of target genes for the nuclear receptor PPAR, including those required for gluconeogenesis. Treatment with the PPAR agonist fenofibrate activated the integrated stress response and refilled amino acid substrates to rescue fasting glucose availability and overcome B2D phenotypes. Overall, these findings reveal PPAR governs metabolic responses to FAD availability and nominate its pharmacologic activation as strategies for organic acidemias.

physiology↗

bioRxiv2022

Diving Behavior Reveals Humidity Sensing Ability of Water Deprived Planarians

Humidity sensing ability is crucial to terrestrial animals for fitting the environment. Researchers made great progress in recent study about humidity sensing mechanisms of terrestrial animals. However, it is poorly understood whether humidity sensing exists in aquatic animals. Here, we demonstrate that the aquatic planarians, one of the primitive forerunners of later animals, has the ability of humidity sensing and is capable of using the ability to perceive the water beneath itself from a drought place to seek survival. The behavior we discovered is described as diving because the worms twist its body to break away from the mucus that make them adhere to the drought place and drop into the water. The behavior is triggered by rapidly increasing humidity. This finding suggests that humidity sensing ability exists in the lower aquatic animals, and the ability might be used to seek for water when aquatic animals are facing desiccation. The finding also suggests that survival-seeking and decision-making behavior have appeared in the primitive planarian worms.

animal behavior and cognition↗

bioRxiv2022

lincRNA RP24-315D19.10 promotes endometrialdecidualization via upregulation of hnRNPA2B1

Sufficient decidualization is necessary to maintain successful pregnancy. The physiological function and underlying molecular mechanisms of intergenic long non-coding RNA (lincRNAs) in this process remain largely unknown. Herein, we identified a lincRNA, RP24-315D19.10, which is highly expressed during mouse decidualization during early pregnancy, by performing RNA-sequencing (RNA-seq) analysis and weighted gene co-expression network analysis (WGCNA). Detailed cell and molecular assays revealed that lincRNA RP24-315D19.10 knockdown blocked decidualization in primary mouse endometrial stromal cells (mESCs), suggesting that RP24-315D19.10 is a promoting factor for decidualization. Mechanistically, cytoplasmic RP24-315D19.10 directly interacted with heterogeneous nuclear ribonucleoprotein A2B1 (hnRNPA2B1) and upregulated its protein level. Moreover, we found that hnRNPA2B1 is involved in the regulation of decidualization through loss- and gain-of-function studies in vitro. Clinically, patients diagnosed with spontaneous miscarriage were found to have lower hnRNPA2B1 levels than healthy individuals, suggesting that RP24-315D19.10-regulated hnRNPA2B1 may participate in the development and progression of early spontaneous abortion. Our study indicates that RP24-315D19.10 enhances endometrial decidualization in a hnRNPA2B1-dependent manner, providing further insights into this physiological process.

molecular biology↗

bioRxiv2022

Nitroimidazopyrazinones with oral activity against tuberculosis and Chagas disease in mouse models of infection

Tuberculosis remains one of the leading causes of death from a single infectious agent, surpassing both AIDS and malaria. In recent years, two bicyclic nitroimidazole drugs, delamanid and pretomanid have been approved to treat this airborne infection. This has spurred a renewed interest in developing new and improved nitroimidazole analogs. We have previously identified a new bicyclic heteroaromatic subclass, the nitroimidazopyrazinones, with substituted analogs showing promising activity against Mycobacterium tuberculosis under both aerobic and hypoxic environments. A second generation of nitroimidazopyrazinones with extended biaryl side chain also possessed good antiparasitic activity against Trypanosoma brucei brucei and Trypanosoma cruzi, suggesting the utility of this new scaffold for development into potential candidates against both tuberculosis and the kinetoplastid parasites which cause neglected tropical diseases. In this study, we further evaluated the properties of nitroimidazopyrazinone derivatives by assessing their selectivity against different mycobacterial species, measuring their reduction potential, and determining the kinetic parameters as substrates of the deazaflavin-dependent nitroreductase (Ddn), which is the activating enzyme of delamanid and pretomanid in M. tuberculosis. We also conducted an in vivo evaluation of a lead compound, MCC8967 that demonstrated a favorable pharmacokinetic profile, with good oral bioavailability and efficacy in an acute M. tuberculosis infection model. Two other promising compounds MCC9481 and MCC9482, with good in vitro activity (IC50 = 0.016 and 0.10 {micro}M, respectively) against T. cruzi, the causative agent for Chagas diseases, were similarly tested for in vivo activity. These compounds also exhibited good oral bioavailability, and transiently reduced the acute-stage parasite burden by >98-99% at doses of 50 mg/kg once or twice daily, similar to benznidazole at 100 mg/kg once daily. Overall, we have demonstrated that active nitroimidazopyrazinones have potential to be developed as clinical candidates against both tuberculosis and Chagas disease. Author SummaryTuberculosis and parasitic infections continue to impose a significant threat to public health and economic growth worldwide. Most of the efforts to control these diseases still rely on drug treatments with limited effectiveness and significant side effects. There is now an urgent need to develop new treatments to combat these infections. Here, we report the in vitro and in vivo profile of a new bicyclic nitroimidazole subclass, namely nitroimidazopyrazinones, against mycobacteria and Trypanosoma cruzi. We found that derivatives with monocyclic side chains are selective against Mycobacterium tuberculosis, the causative agent of tuberculosis, but not active against other nontuberculosis mycobacteria. In an acute mouse model, they were able to reduce the bacterial load in lungs via oral administration. From a biochemistry perspective, we demonstrated that deazaflavin-dependent nitroreductase (Ddn) could act effectively on nitroimidazopyrazinones, indicating the potential of Ddn as an activating enzyme for these new compounds in M. tuberculosis. We also showed that derivatives with extended biaryl side chain were effective in suppressing infection in an acute T. cruzi infected murine model, with satisfactory oral bioavailability. These findings improve the understanding of the biological profile of nitroimidazopyrazinones for further development as potential antitubercular and antiparasitic agents.

pharmacology and toxicology↗

bioRxiv2022

Mitochondrial structure and function adaptation in residual triple negative breast cancer cells surviving chemotherapy treatment

Neoadjuvant chemotherapy (NACT) used for triple negative breast cancer (TNBC) eradicates tumors in approximately 45% of patients. Unfortunately, TNBC patients with substantial residual cancer burden have poor metastasis free and overall survival rates. We previously demonstrated mitochondrial oxidative phosphorylation (OXPHOS) was elevated and was a unique therapeutic dependency of residual TNBC cells surviving NACT. We sought to investigate the mechanism underlying this enhanced reliance on mitochondrial metabolism. Mitochondria are morphologically plastic organelles that cycle between fission and fusion to maintain mitochondrial integrity and metabolic homeostasis. The functional impact of mitochondrial structure on metabolic output is highly context dependent and not understood in TNBC. Several chemotherapy agents are conventionally used for neoadjuvant treatment of TNBC patients. Upon comparing mitochondrial effects of commonly used chemotherapies, we found that DNA-damaging agents increased mitochondrial elongation, mitochondrial content, flux of glucose through the TCA cycle, and OXPHOS, whereas taxanes instead decreased mitochondrial elongation and OXPHOS. Additionally, short protein isoform levels of the mitochondrial inner membrane fusion protein optic atrophy 1 (OPA1) were associated with those observations. Further, we observed heightened OXPHOS, OPA1 protein levels, and mitochondrial elongation in a patient-derived xenograft (PDX) model of residual TNBC. Pharmacologic or genetic disruption of mitochondrial fusion and fission resulted in decreased or increased OXPHOS, respectively, revealing that longer mitochondria favor oxphos in TNBC cells. Using TNBC cell lines and an in vivo PDX model of residual TNBC, we found that sequential treatment with DNA-damaging chemotherapy, thus inducing mitochondrial fusion and OXPHOS, followed by MYLS22, a specific inhibitor of OPA1, was able to suppress mitochondrial fusion and OXPHOS and significantly inhibited residual tumor regrowth. Taken together, our findings suggest that TNBC mitochondria can optimize OXPHOS through modulation of mitochondrial structure. This may provide an opportunity to overcome mitochondrial adaptations of chemoresistant TNBC.

cancer biology↗

bioRxiv2022

The development of receptive field tuning properties in mouse binocular primary visual cortex

The mouse primary visual cortex is a model system for understanding the relationship between cortical structure, function, and behavior (Seabrook et al., 2017; Chaplin and Margrie, 2020; Hooks and Chen, 2020; Saleem, 2020; Flossmann and Rochefort, 2021). Binocular neurons in V1 are the cellular basis of binocular vision, which is required for predation (Scholl et al., 2013; Hoy et al., 2016; La Chioma et al., 2020; Berson, 2021; Johnson et al., 2021). The normal development of binocular responses, however, has not been systematically measured. Here, we measure tuning properties of neurons to either eye in awake mice of either sex from eye-opening to the closure of the critical period. At eye-opening, we find an adult-like fraction of neurons responding to the contralateral-eye stimulation, which are selective for orientation and spatial frequency; few neurons respond to ipsilateral eye and their tuning is immature. Fraction of ipsilateral-eye responses increases rapidly in the first few days after eye opening and more slowly thereafter, reaching adult levels by critical period closure. Tuning of these responses improves with a similar time course. The development and tuning of binocular responses parallels that of ipsilateral-eye responses. Four days after eye-opening, monocular neurons respond to a full range of orientations but become more biased to cardinal orientations. Binocular responses, by contrast, lose their cardinal bias with age. Together, these data provide an in-depth accounting of the development of monocular and binocular responses in the binocular region of mouse V1 using a consistent set of visual stimuli and measurements. Significance statementIn this manuscript, we present a full accounting of the emergence and refinement of monocular and binocular receptive field tuning properties of thousands of pyramidal neurons in mouse primary visual cortex. Our data reveal new features of monocular and binocular development that revise current models on the emergence of cortical binocularity. Given the recent interest in visually guided behaviors in mice that require binocular vision, e.g. predation, our measures will provide the basis for studies on the emergence of the neural circuitry guiding these behaviors.

neuroscience↗

bioRxiv2021

Diet-derived metabolites and mucus link the gut microbiome to fever after cytotoxic cancer treatment

Not all cancer patients with severe neutropenia develop fever, and the fecal microbiome may play a role. In neutropenic hematopoietic cell transplant patients (n=119), 63 (53%) developed a subsequent fever and had increased fecal Akkermansia muciniphila, a mucus-degrading bacteria (p=0.006, corrected for multiple comparisons). In mouse models, two therapies, irradiation and melphalan, similarly expanded A. muciniphila. Dietary restriction of unirradiated mice also expanded A. muciniphila and thinned the colonic mucus layer. Azithromycin treatment depleted A. muciniphila and preserved colonic mucus. Dietary restriction raised colonic luminal pH and reduced acetate, propionate, and butyrate. Culturing A. muciniphila with lower pH and increased propionate prevented utilization of mucin. Treating irradiated mice with azithromycin or propionate preserved the mucus layer, lessened hypothermia, and reduced inflammatory cytokines in the colon. These results suggest that diet, metabolites and colonic mucus link the microbiome to neutropenic fever, and could guide future microbiome-based preventive strategies.

microbiology↗

bioRxiv2021

Vision is Required for Cell Type Specification in the Visual Cortex

The role of postnatal experience in sculpting cortical circuitry, while long appreciated, is poorly understood at the level of cell types. We explore this in the mouse primary visual cortex (V1) using single-nucleus RNA-sequencing, visual deprivation, genetics, and functional imaging. We find that vision selectively drives the specification of glutamatergic cell types in upper layers (L) (L2/3/4), while deeper-layer glutamatergic, GABAergic, and non-neuronal cell types are established prior to eye opening. L2/3 cell types form an experience-dependent spatial continuum defined by the graded expression of [~]200 genes, including regulators of cell adhesion and synapse formation. Vision-dependent regulation of one of these genes, encoding the inhibitory synaptic cell adhesion molecule IGSF9b, is required for the normal development of binocular responses in L2/3. In summary, vision preferentially regulates the development of upper-layer glutamatergic cell types through the regulation of cell type-specific gene expression programs.

neuroscience↗

bioRxiv2021

Vision is required for the formation of binocular neurons prior to the classical critical period

Depth perception emerges from the development of binocular neurons in primary visual cortex. Vision is required for these neurons to acquire their mature responses to visual stimuli. The prevailing view is that vision does not influence binocular circuitry until the onset of the critical period, about a week after eye opening, and that plasticity of visual responses is triggered by increased inhibition. Here, we show that vision is required to form binocular neurons and to improve binocular tuning and matching from eye opening until critical period closure. Enhancing inhibition does not accelerate this process. Vision soon after eye opening improves the tuning properties of binocular neurons by strengthening and sharpening ipsilateral-eye cortical responses. This progressively changes the population of neurons in the binocular pool and this plasticity is sensitive to interocular differences prior to critical period onset. Thus, vision establishes binocular circuitry and guides binocular plasticity from eye opening.

neuroscience↗

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↗