Publications

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Cai, X;Hu, CH;Wang, J;Zeng, XH;Luo, JX;Li, M;Liu, ZQ;Zheng, YG.
Bioresource technology,
326
, 124768
(2021)
Corncob is an abundant and renewable resource that could be enzymatically hydrolyzed to fermentable sugar. A major impediment in corncob utilization is the low hydrolysis efficiency at high-solids content. This study attempted different pretreatment methods and fed-batch modes to achieve a 25% solids content hydrolysis with high yields. Natural corncobs were compared with acid-treated and acid-alkali-treated corncobs in terms of kinetics parameters, conversion rate and glucose titer. By feeding in batches, a “low amount and high frequency” mode (10%-3%-3%-3%-3%-3%, every 5 h) was confirmed to be optimal for a 25% high-solids hydrolysis system with a cellulase loading of 12 mg/g (7.3 FPU/g), resulted with an 84.4% glucose yield at 96 h. Our results demonstrated that combination of both optimized pretreatment method and fed-batch mode were a favored process model for high-solids hydrolysis of lignocellulose, boosting cellulose hydrolysis efficiency and sugar yields on an industrial scale.
Ida, H;Takahashi, Y;Kumatani, A;Shiku, H;Murayama, T;Hirose, H;Futaki, S;Matsue, T.
Analytical chemistry,
(2021)
The interactions between the cell membrane and biomolecules remain poorly understood. For example, arginine-rich cell-penetrating peptides (CPPs), including octaarginines (R8), are internalized by interactions with cell membranes. However, during the internalization process, the exact membrane dynamics introduced by these CPPs are still unknown. Here, we visualize arginine-rich CPPs and cell-membrane interaction-induced morphological changes using a system that combines scanning ion-conductance microscopy and spinning-disk confocal microscopy, using fluorescently labeled R8. This system allows time-dependent, nanoscale visualization of structural dynamics in live-cell membranes. Various types of membrane remodeling caused by arginine-rich CPPs are thus observed. The induction of membrane ruffling and the cup closure are observed as a process of endocytic uptake of the peptide. Alternatively suggested is the concave structural formation accompanied by direct peptide translocation through cell membranes. Studies using R8 without fluorescent labeling also demonstrate a non-negligible effect of the fluorescent moiety on membrane structural alteration.
Geiser, P;Di Martino, ML;Samperio Ventayol, P;Eriksson, J;Sima, E;Al-Saffar, AK;Ahl, D;Phillipson, M;Webb, DL;Sundbom, M;Hellström, PM;Sellin, ME.
mBio,
12
(1)
(2021)
Enterobacterial pathogens infect the gut by a multistep process, resulting in colonization of both the lumen and the mucosal epithelium. Due to experimental constraints, it remains challenging to address how luminal and epithelium-lodged pathogen populations cross-feed each other in vivo Enteroids are cultured three-dimensional miniature intestinal organs with a single layer of primary intestinal epithelial cells (IECs) surrounding a central lumen. They offer new opportunities to study enterobacterial infection under near-physiological conditions, at a temporal and spatial resolution not attainable in animal models, but remain poorly explored in this context. We employed microinjection, time-lapse microscopy, bacterial genetics, and barcoded consortium infections to describe the complete infection cycle of Salmonella enterica serovar Typhimurium in both human and murine enteroids. Flagellar motility and type III secretion system 1 (TTSS-1) promoted Salmonella Typhimurium targeting of the intraepithelial compartment and breaching of the epithelial barrier. Strikingly, however, TTSS-1 also potently boosted colonization of the enteroid lumen. By tracing the infection over time, we identified a cycle(s) of TTSS-1-driven IEC invasion, intraepithelial replication, and reemergence through infected IEC expulsion as a key mechanism for Salmonella Typhimurium luminal colonization. These findings suggest a positive feed-forward loop, through which IEC invasion by planktonic bacteria fuels further luminal population expansion, thereby ensuring efficient colonization of both the intraepithelial and luminal niches.IMPORTANCE Pathogenic gut bacteria are common causes of intestinal disease. Enteroids-cultured three-dimensional replicas of the mammalian gut-offer an emerging model system to study disease mechanisms under conditions that recapitulate key features of the intestinal tract. In this study, we describe the full life cycle of the prototype gut pathogen Salmonella enterica serovar Typhimurium within human and mouse enteroids. We map the consecutive steps and define the bacterial virulence factors that drive colonization of luminal and epithelial compartments, as well as breaching of the epithelial barrier. Strikingly, our work reveals how bacterial colonization of the epithelium potently fuels expansion also in the luminal compartment, through a mechanism involving the death and expulsion of bacterium-infected epithelial cells. These findings have repercussions for our understanding of the Salmonella infection cycle. Moreover, our work provides a comprehensive foundation for the use of microinjected enteroids to model gut bacterial diseases.
Fattinger, SA;Geiser, P;Samperio Ventayol, P;Di Martino, ML;Furter, M;Felmy, B;Bakkeren, E;Hausmann, A;Barthel-Scherrer, M;Gül, E;Hardt, WD;Sellin, ME.
Mucosal immunology,
(2021)
The gut epithelium is a critical protective barrier. Its NAIP/NLRC4 inflammasome senses infection by Gram-negative bacteria, including Salmonella Typhimurium (S.Tm) and promotes expulsion of infected enterocytes. During the first ~12-24 h, this reduces mucosal S.Tm loads at the price of moderate enteropathy. It remained unknown how this NAIP/NLRC4-dependent tradeoff would develop during subsequent infection stages. In NAIP/NLRC4-deficient mice, S.Tm elicited severe enteropathy within 72 h, characterized by elevated mucosal TNF (>20 pg/mg) production from bone marrow-derived cells, reduced regeneration, excessive enterocyte loss, and a collapse of the epithelial barrier. TNF-depleting antibodies prevented this destructive pathology. In hosts proficient for epithelial NAIP/NLRC4, a heterogeneous enterocyte death response with both apoptotic and pyroptotic features kept S.Tm loads persistently in check, thereby preventing this dire outcome altogether. Our results demonstrate that immediate and selective removal of infected enterocytes, by locally acting epithelium-autonomous NAIP/NLRC4, is required to avoid a TNF-driven inflammatory hyper-reaction that otherwise destroys the epithelial barrier.
Spena, S;Cordiglieri, C;Garagiola, I;Peyvandi, F.
International journal of molecular sciences,
22
(4)
(2021)
Hemophilia is an X-linked recessive bleeding disorder. In pregnant women carrier of hemophilia, the fetal sex can be determined by non-invasive analysis of fetal DNA circulating in the maternal blood. However, in case of a male fetus, conventional invasive procedures are required for the diagnosis of hemophilia. Fetal cells, circulating in the maternal bloodstream, are an ideal target for a safe non-invasive prenatal diagnosis. Nevertheless, the small number of cells and the lack of specific fetal markers have been the most limiting factors for their isolation. We aimed to develop monoclonal antibodies (mAbs) against the ribosomal protein RPS4Y1 expressed in male cells. By Western blotting, immunoprecipitation and immunofluorescence analyses performed on cell lysates from male human hepatoma (HepG2) and female human embryonic kidney (HEK293) we developed and characterized a specific monoclonal antibody against the native form of the male RPS4Y1 protein that can distinguish male from female cells. The availability of the RPS4Y1-targeting monoclonal antibody should facilitate the development of novel methods for the reliable isolation of male fetal cells from the maternal blood and their future use for non-invasive prenatal diagnosis of X-linked inherited disease such as hemophilia.
Ibayashi, M;Aizawa, R;Tsukamoto, S.
Biochemical and Biophysical Research Communications,
555
, 128-133
(2021)
mRNA decapping is a critical step in posttranscriptional regulation of gene expression in eukaryotes. Although Dcp1a is a well characterized and widely conserved mRNA decapping factor, little is known about its physiological function. To extend our understanding of Dcp1a function in vivo, we employed a transgenic rescue strategy to produce Dcp1a-deficient mice using the CRISPR/Cas9 system. This approach arrowed us to generate heterozygous Dcp1a mice and define the phenotype of Dcp1a-deficient embryos. We found that expression of Dcp1a protein, which is detectable in most mouse tissues, was developmentally regulated through embryonic growth, and that depletion of the Dcp1a gene resulted in embryonic lethality around embryonic day 10.5 (E10.5) concomitant with massive growth retardation and cardiac developmental defects. Moreover, the embryonic lethality was fully rescued by transgenic expression of exogenous human Dcp1a. Together, our results suggest that Dcp1a is required for embryonic growth.
Vignoli, B;Sansevero, G;Sasi, M;Rimondini-Giorgini, R;Blum, R;Santi, S;Berardi, N;Lu, B;Canossa, M.
Research Square,
(2021)
Memory consolidation requires astrocytic microdomains for protein recycling; but whether this lays a mechanistic foundation for long-term information storage remains enigmatic. Here we demonstrate that persistent synaptic strengthening invited astrocytic microdomains to convert initially internalized (pro)-brain-derived neurotrophic factor (proBDNF) into active prodomain (BDNFpro) and mature BDNF (mBDNF) for synaptic re-use. While mBDNF activates TrkB, we uncovered a previously unsuspected function for the cleaved BDNFpro, which increases TrkB/SorCS2 receptor complex at post-synaptic sites. Astrocytic BDNFpro release reinforced TrkB phosphorylation to sustain long-term synaptic potentiation and to retain memory in the novel object recognition behavioral test. Thus, the switch from one inactive state to a multi-functional one of the proBDNF provides post-synaptic changes that survive the initial activation (molecular memory). This molecular asset confines local information storage in astrocytic microdomains to selectively support memory circuits.
Birke, R;Ast, J;Roosen, D;Mathes, B;Roßmann, K;Huhn, C;Jones, B;Lehmann, M;Haucke, V;Hodson, D;Broichhagen, J.
bioRxiv,
(2021)
Sulfonated rhodamines that endow xanthene dyes with cellular impermeability are presented. We fuse charged sulfonates to red and far-red dyes to obtain Sulfo549 and Sulfo646, respectively, and further link these to SNAP- and Halo-tag substrates for protein self-labelling. Cellular impermeability is validated in live cell imaging experiments in transfected HEK cells and neurons derived from induced pluripotent stem cells (iPSCs). Lastly, we show that Sulfo646 is amenable to STED nanoscopy by recording membranes of SNAP/Halo-surface-labelled human iPSC-derived neuronal axons. We therefore provide an avenue for rendering dyes impermeable for exclusive extracellular visualization via self-labelling protein tags.
Graham, K;Spruston, N;Bloss, E.
bioRxiv,
(2021)
Neural circuits within the frontal cortex support the flexible selection of goal-directed behaviors by integrating input from brain regions associated with sensory, emotional, episodic, and semantic memory functions. From a connectomics perspective, determining how these disparate afferent inputs target their synapses to specific cell types in the frontal cortex may prove crucial in understanding circuit-level information processing. Here, we used monosynaptic retrograde rabies mapping to examine the distribution of afferent neurons targeting four distinct classes of local inhibitory interneurons and four distinct classes of excitatory projection neurons in mouse infralimbic cortex. Interneurons expressing parvalbumin, somatostatin, or vasoactive intestinal peptide received a large proportion of inputs from hippocampal regions, while interneurons expressing neuron-derived neurotrophic factor received a large proportion of inputs from thalamic regions. A more moderate hippocampal-thalamic dichotomy was found among the inputs targeting excitatory neurons that project to the basolateral amygdala, lateral entorhinal cortex, nucleus reuniens of the thalamus, and the periaqueductal gray. Together, these results show a prominent bias among hippocampal and thalamic afferent systems in their targeting to genetically or anatomically defined sets of frontal cortical neurons. Moreover, they suggest the presence of two distinct local microcircuits that control how different inputs govern frontal cortical information processing.
Pickford, P;Lucey, M;Rujan, R;McGlone, E;Bitsi, S;Ashford, F;Corrêa, I;Hodson, D;Tomas, A;Deganutti, G;Reynolds, C;Owen, B;Tan, T;Minnion, J;Jones, B;Bloom, S.
bioRxiv,
(2021)
Objective: Glucagon-like peptide-1 and glucagon receptor (GLP-1R/GCGR) co-agonism can maximise weight loss and improve glycaemic control in type 2 diabetes and obesity. In this study we investigated the cellular and metabolic effects of modulating the balance between G protein activation and β-arrestin-2 recruitment at GLP-1R and GCGR using oxyntomodulin (OXM)-derived co-agonists. This strategy has been previously shown to improve the duration of action of GLP-1R mono-agonists by reducing target desensitisation and downregulation. Methods: Dipeptidyl dipeptidase-4 (DPP-4)-resistant OXM analogues were generated and assessed for a variety of cellular readouts. Molecular dynamic simulations were used to gain insights into the molecular interactions involved. In vivo studies were performed in mice to identify effects on glucose homeostasis and weight loss. Results: Ligand-specific reductions in β-arrestin-2 recruitment led to reduced GLP-1R internalisation and prolonged glucose-lowering action in vivo. The putative benefits of GCGR agonism were retained, with equivalent weight loss compared to the GLP-1R mono-agonist liraglutide in spite of a lesser degree of food intake suppression. The compounds tested showed only a minor degree of biased agonism between G protein and β-arrestin-2 recruitment at both receptors and were best classified as partial agonists for the two pathways measured. Conclusions: Diminishing β-arrestin-2 recruitment may be an effective way to increase the therapeutic efficacy of GLP-1R/GCGR co-agonists. These benefits can be achieved by partial rather than biased agonism.
Basilico, B;Ferrucci, L;Ratano, P;Golia, M;Grimaldi, A;Rosito, M;Ferretti, V;Reverte, I;Marrone, M;Giubettini, M;De Turris, V;Salerno, D;Garofalo, S;St-Pierre, M;Carrier, M;Renzi, M;Pagani, F;Raspa, M;Scavizzi, F;Gross, C;Marinelli, S;Tremblay, M;Caprioli, D;Maggi, L;Limatola, C;Di Angelantonio, S;Ragozzino, D.
bioRxiv,
(2021)
Microglial cells are active players in regulating synaptic development and plasticity in the brain. However, how these cells influence the normal functioning of synapses is largely unknown. In this study, we characterized the effects of pharmacological depletion of microglia, achieved by administration of PLX5622, on hippocampal CA3-CA1 synapses of adult wild type mice. Following microglial depletion, we observed a reduction of spontaneous and evoked glutamatergic activity associated with a decrease of dendritic spine density. We also observed the appearance of immature synaptic features accompanied by higher levels of plasticity. In addition, microglia depleted mice showed a deficit in the acquisition of the Novel Object Recognition task. Remarkably, microglial repopulation after PLX5622 withdrawal was associated with the recovery of hippocampal synapses and learning functions. Altogether, these data demonstrate that microglia contribute to normal synaptic functioning in the adult brain and that their removal induces reversible changes in synaptic organization and activity of glutamatergic synapses.
Janská, L;Anandi, L;Kirchberger, N;Marinkovic, Z;Schachtner, L;Guzelsoy, G;Carmona-Fontaine, C.
bioRxiv,
(2021)
There is an urgent need for accurate, scalable, and cost-efficient models of the complexity and heterogeneity of the tumor microenvironment. Here, we detail how to fabricate and use the Metabolic Microenvironment Chamber (MEMIC) – a 3D-printed ex vivo model of intratumoral heterogeneity. A major driver of the cellular and molecular diversity in tumors is the accessibility to the blood stream that provides key resources such as oxygen and nutrients. While some tumor cells have direct access to these resources, many others must survive under progressively more ischemic environments as they reside further from the vasculature. The MEMIC is designed to simulate the differential access to nutrients and allows co-culturing different cell types, such as tumor and immune cells. This system is optimized for live imaging and other microscopy-based approaches and it is a powerful tool to study tumor features such as the effect of nutrient scarcity on tumor-stroma interactions. Due to its adaptable design and full experimental control, the MEMIC can provide novel insights into the tumor microenvironment that would be difficult to obtain via other methods. As a proof of principle, we show that cells can sense gradual changes in metabolite concentration, and tune intracellular cell signaling to form multicellular spatial patterns of cell proliferation. We also show that ischemic macrophages reduce epithelial features in neighboring tumor cells highlighting the power of this system to study cell-cell interactions and non-cell autonomous effects of the metabolic microenvironment. We propose that the MEMIC can be easily adapted to study early development, ischemic stroke, and other systems where multiple cell types interact within heterogeneous environments.
Satoh, A;Fujioka, Y;Kashiwagi, S;Yoshida, A;Fujioka, M;Sasajima, H;Nanbo, A;Amano, M;Ohba, Y.
Cell Press,
(2021)
Intracellular organelles of mammalian cells communicate with each other during various cellular processes. The functions and molecular mechanisms of such interorganelle association remain largely unclear, however. We here identified voltage-dependent anion channel 2 (VDAC2), a mitochondrial outer membrane protein, as a binding partner of phosphoinositide 3-kinase (PI3K), a regulator of clathrin-independent endocytosis downstream of the small GTPase Ras. VDAC2 was found to tether endosomes positive for the Ras-PI3K complex to mitochondria in response to cell stimulation with epidermal growth factor and to promote clathrin-independent endocytosis as well as endosome maturation at membrane contact sites. With a newly developed optogenetics system to induce mitochondrion-endosome association, we found that, in addition to its structural role in such association, the pore function of VDAC2 is also required for the promotion of endosome maturation. Our findings thus uncover a previously unappreciated role of mitochondrion-endosome association in the regulation of endocytosis and endosome maturation.HighlightsThe mitochondrial protein VDAC2 binds PI3K and tethers endosomes to mitochondriaVDAC2 promotes clathrin-independent endocytosisVDAC2-PI3K interaction induces acidification of endosomes associated with mitochondriaThe pore function of VDAC2 also contributes to endosome maturation at contact sites
Baruffaldi, D;Pirri, C;Frascella, F.
Bioprinting,
22
, e00135
(2021)
Traditional in vitro culture models are unable to fully reflect the organ microenvironment, due to differences in terms of cell morphology, protein expression, cell-cell and cell-matrix interactions, and drug response. In contrast, the flexibility of bioprinting modes allows for the deposition of cell-containing biomaterials in any free-form-inspired 3D structures on chip. The main purpose of this study was to design and optimize commercially available Carbopol-based 3D printing formulations, because of their many advantages, such as low-cost, the ability to produce clear and stable gels, and the water thickening. For this purpose, three different Carbopol gels (EDT 2020 NF, Ultrez 10 NF and NF-980) were tested in terms of printability and biocompatibility, with lung cancer epithelial (A549) and normal lung fibroblast (MRC-5) cells. This study demonstrates that Carbopol is a promising candidate for the 3D printing of cell-laden constructs, both in terms of rheology and printing performance.
Brighi, C;Salaris, F;Soloperto, A;Cordella, F;Ghirga, S;de Turris, V;Rosito, M;Porceddu, PF;D'Antoni, C;Reggiani, A;Rosa, A;Di Angelantonio, S.
Cell Death & Disease,
12
(5)
, 1-22
(2021)
Fragile X syndrome (FXS) is a neurodevelopmental disorder, characterized by intellectual disability and sensory deficits, caused by epigenetic silencing of the FMR1 gene and subsequent loss of its protein product, fragile X mental retardation protein (FMRP). Delays in synaptic and neuronal development in the cortex have been reported in FXS mouse models; however, the main goal of translating lab research into pharmacological treatments in clinical trials has been so far largely unsuccessful, leaving FXS a still incurable disease. Here, we generated 2D and 3D in vitro human FXS model systems based on isogenic FMR1 knock-out mutant and wild-type human induced pluripotent stem cell (hiPSC) lines. Phenotypical and functional characterization of cortical neurons derived from FMRP-deficient hiPSCs display altered gene expression and impaired differentiation when compared with the healthy counterpart. FXS cortical cultures show an increased number of GFAP positive cells, likely astrocytes, increased spontaneous network activity, and depolarizing GABAergic transmission. Cortical brain organoid models show an increased number of glial cells, and bigger organoid size. Our findings demonstrate that FMRP is required to correctly support neuronal and glial cell proliferation, and to set the correct excitation/inhibition ratio in human brain development.
Bonnal, RJP;Rossetti, G;Lugli, E;De Simone, M;Gruarin, P;Brummelman, J;Drufuca, L;Passaro, M;Bason, R;Gervasoni, F;Della Chiara, G;D'Oria, C;Martinovic, M;Curti, S;Ranzani, V;Cordiglieri, C;Alvisi, G;Mazza, EMC;Oliveto, S;Silvestri, Y;Carelli, E;Mazzara, S;Bosotti, R;Sarnicola, ML;Godano, C;Bevilacqua, V;Lorenzo, M;Siena, S;Bonoldi, E;Sartore-Bianchi, A;Amatu, A;Veronesi, G;Novellis, P;Alloisio, M;Giani, A;Zucchini, N;Opocher, E;Ceretti, AP;Mariani, N;Biffo, S;Prati, D;Bardelli, A;Geginat, J;Lanzavecchia, A;Abrignani, S;Pagani, M.
Nature immunology,
22
(6)
, 735-745
(2021)
Regulatory T (Treg) cells are a barrier for tumor immunity and a target for immunotherapy. Using single-cell transcriptomics, we found that CD4+ T cells infiltrating primary and metastatic colorectal cancer and non-small-cell lung cancer are highly enriched for two subsets of comparable size and suppressor function comprising forkhead box protein P3+ Treg and eomesodermin homolog (EOMES)+ type 1 regulatory T (Tr1)-like cells also expressing granzyme K and chitinase-3-like protein 2. EOMES+ Tr1-like cells, but not Treg cells, were clonally related to effector T cells and were clonally expanded in primary and metastatic tumors, which is consistent with their proliferation and differentiation in situ. Using chitinase-3-like protein 2 as a subset signature, we found that the EOMES+ Tr1-like subset correlates with disease progression but is also associated with response to programmed cell death protein 1-targeted immunotherapy. Collectively, these findings highlight the heterogeneity of Treg cells that accumulate in primary tumors and metastases and identify a new prospective target for cancer immunotherapy.
Sun, YC;Chen, X;Fischer, S;Lu, S;Zhan, H;Gillis, J;Zador, AM.
Nature neuroscience,
24
(6)
, 873-885
(2021)
Functional circuits consist of neurons with diverse axonal projections and gene expression. Understanding the molecular signature of projections requires high-throughput interrogation of both gene expression and projections to multiple targets in the same cells at cellular resolution, which is difficult to achieve using current technology. Here, we introduce BARseq2, a technique that simultaneously maps projections and detects multiplexed gene expression by in situ sequencing. We determined the expression of cadherins and cell-type markers in 29,933 cells and the projections of 3,164 cells in both the mouse motor cortex and auditory cortex. Associating gene expression and projections in 1,349 neurons revealed shared cadherin signatures of homologous projections across the two cortical areas. These cadherins were enriched across multiple branches of the transcriptomic taxonomy. By correlating multigene expression and projections to many targets in single neurons with high throughput, BARseq2 provides a potential path to uncovering the molecular logic underlying neuronal circuits.
Biferali, B;Bianconi, V;Perez, DF;Kronawitter, SP;Marullo, F;Maggio, R;Santini, T;Polverino, F;Biagioni, S;Summa, V;Toniatti, C;Pasini, D;Stricker, S;Di Fabio, R;Chiacchiera, F;Peruzzi, G;Mozzetta, C.
Science advances,
7
(23)
(2021)
H3K9 methylation maintains cell identity orchestrating stable silencing and anchoring of alternate fate genes within the heterochromatic compartment underneath the nuclear lamina (NL). However, how cell type-specific genomic regions are specifically targeted to the NL is still elusive. Using fibro-adipogenic progenitors (FAPs) as a model, we identified Prdm16 as a nuclear envelope protein that anchors H3K9-methylated chromatin in a cell-specific manner. We show that Prdm16 mediates FAP developmental capacities by orchestrating lamina-associated domain organization and heterochromatin sequestration at the nuclear periphery. We found that Prdm16 localizes at the NL where it cooperates with the H3K9 methyltransferases G9a/GLP to mediate tethering and silencing of myogenic genes, thus repressing an alternative myogenic fate in FAPs. Genetic and pharmacological disruption of this repressive pathway confers to FAP myogenic competence, preventing fibro-adipogenic degeneration of dystrophic muscles. In summary, we reveal a druggable mechanism of heterochromatin perinuclear sequestration exploitable to reprogram FAPs in vivo.
Birolini, G;Verlengia, G;Talpo, F;Maniezzi, C;Zentilin, L;Giacca, M;Conforti, P;Cordiglieri, C;Caccia, C;Leoni, V;Taroni, F;Biella, G;Simonato, M;Cattaneo, E;Valenza, M.
Brain,
(2021)
Brain cholesterol is produced mainly by astrocytes and is important for neuronal function. Its biosynthesis is severely reduced in mouse models of Huntington’s disease. One possible mechanism is a diminished nuclear translocation of the transcription factor sterol regulatory element binding protein 2 (SREBP2) and, consequently, reduced activation of SREBP-controlled genes in the cholesterol biosynthesis pathway. Here we evaluated the efficacy of a gene therapy based on the unilateral intra-striatal injection of a recombinant adeno-associated virus 2/5 (AAV2/5) targeting astrocytes specifically and carrying the transcriptionally active N-terminal fragment of human SREBP2. Robust hSREBP2 expression in striatal glial cells in R6/2 Huntington’s disease mice activated the transcription of cholesterol biosynthesis pathway genes, restored synaptic transmission, reversed Drd2 transcript levels decline, cleared mutant Huntingtin aggregates and attenuated behavioral deficits. We conclude that glial SREBP2 participates in Huntington’s disease brain pathogenesis in vivo and that AAV-based delivery of SREBP2 to astrocytes counteracts key features of the disease.
Gupta, VK;Nam, S;Yim, D;Camuglia, J;Martin, JL;Sanders, EN;O'Brien, LE;Martin, AC;Kim, T;Chaudhuri, O.
The Journal of cell biology,
220
(8)
(2021)
Epithelial cells undergo striking morphological changes during division to ensure proper segregation of genetic and cytoplasmic materials. These morphological changes occur despite dividing cells being mechanically restricted by neighboring cells, indicating the need for extracellular force generation. Beyond driving cell division itself, forces associated with division have been implicated in tissue-scale processes, including development, tissue growth, migration, and epidermal stratification. While forces generated by mitotic rounding are well understood, forces generated after rounding remain unknown. Here, we identify two distinct stages of division force generation that follow rounding: (1) Protrusive forces along the division axis that drive division elongation, and (2) outward forces that facilitate postdivision spreading. Cytokinetic ring contraction of the dividing cell, but not activity of neighboring cells, generates extracellular forces that propel division elongation and contribute to chromosome segregation. Forces from division elongation are observed in epithelia across many model organisms. Thus, division elongation forces represent a universal mechanism that powers cell division in confining epithelia.