Biology subjects

Levi, G.

Publications and source records attributed to Levi, G..

10 recordsLinked to original sources

bioRxiv2026

Dlx5/6 regulate perineuronal net-synapse coupling and stabilize adult cortical Parvalbumin neurons networks

The transcriptional mechanisms that maintain adult Parvalbumin (PV) interneuron function and cortical network stability remain poorly understood. We previously showed that the inactivation in GABAergic neurons of Dlx5/6, coding for transcription factors, disrupts social interaction and reduces PV interneuron density in the prefrontal cortex. Here, combining transcriptional and histological analyses with ex vivo electrophysiological and in vivo electroencephalographical (EEG) recordings, we show that Dlx5/6 regulate a molecular program controlling perineuronal net (PNN) homeostasis in the adult cortex. Dlx5/6 inactivation dysregulated the expression of multiple PNN-associated genes and induced region-specific remodelling of PNN mesh architecture in the prefrontal and somatosensory cortices. These structural changes were accompanied by alterations in excitatory and inhibitory synaptic organization and by a disrupted coupling between local PNN structure and synaptic properties. Ex vivo electrophysiological recordings revealed that fast-spiking interneurons displayed altered intrinsic properties and reduced excitatory synaptic drive in a region-specific manner, while EEG recordings during social interaction showed impaired recruitment of prefrontal gamma oscillations. Together, these findings identify Dlx5/6 as regulators of adult PV interneuron stability, linking extracellular matrix homeostasis to synaptic organization and cortical network dynamics. More broadly, it provides a new mechanistic framework connecting Dlx5/6 function to PV-related pathological phenotypes, including neuropsychiatric disorders. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=89 SRC="FIGDIR/small/740286v1_ufig1.gif" ALT="Figure 1"> View larger version (31K): org.highwire.dtl.DTLVardef@147c75dorg.highwire.dtl.DTLVardef@171e7d9org.highwire.dtl.DTLVardef@12c5c67org.highwire.dtl.DTLVardef@166790d_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2026

Increased Osteoclast Activity Contributes to Bone Resorption and Osteopenia in a Rett Syndrome Mouse Model

Rett syndrome is a severe neurodevelopmental disorder caused predominantly by loss-of-function mutations in the X-linked gene MECP2. Besides a vast array of neurological and physiological impairments, patients also frequently develop severe osteopenia with increased fracture risk, however, the mechanisms underlying these skeletal defects are not completely understood. Previous work in Mecp2-null mouse models has suggested that osteopenia is mainly due to impaired osteoblast function and reduced bone formation. Here, we examined bone mass, microarchitecture, and remodeling parameters in a Mecp2-null mouse model during postnatal development, with a particular focus on osteoclast involvement. Micro-computed tomography and histomorphometric analyses showed reduced bone mineral density and trabecular bone volume, associated with increased trabecular separation and cortical thinning. These structural alterations were accompanied by increased osteoclast number per bone surface, elevated urinary deoxypyridinoline, and higher expression of osteoclast-associated genes, including Cathepsin K. Furthermore, gene expression analysis revealed an age-dependent shift in bone remodeling. At postnatal day 35, mutant mice showed reduced expression of Dlx5 and Dlx6, consistent with low bone turnover. By postnatal day 55, Rankl and Cathepsin K were markedly upregulated, suggesting an increase in osteoclast resorptive activity, while key osteoblast markers and the RANKL/OPG ratio did not change significantly. A potential cell-autonomous contribution of Mecp2 to osteoclast maturation is also suggested by the analysis of public transcriptomic datasets on human osteoclast differentiation. Together, our findings identify increased osteoclast activity as a significant contributor to Rett-associated osteopenia and suggest that skeletal pathology in Mecp2 deficiency progresses from an early low-turnover state to a later phase of increased osteoclast resorption. HIGHLIGHTSO_LIWhat are the main findings. O_LIMecp2-null mice display reduced bone mass and altered bone microarchitecture during postnatal development, associated not only with reduced osteoblast activity, but also with increased osteoclast number, elevated urinary deoxypyridinoline, and increased expression of osteoclast-associated genes. C_LIO_LIBone remodelling shows an age-dependent shift in Mecp2 deficiency, from an early low-turnover state at postnatal day 35 to increased osteoclast resorptive activity at postnatal day 55. C_LI C_LIO_LIWhat are the implications of the main findings? O_LIRett-associated osteopenia is not explained solely by impaired osteoblast function, but also involves a significant osteoclast contribution to skeletal deterioration. C_LIO_LIThese findings refine the pathophysiological model of bone involvement in Rett syndrome and support the idea that skeletal alterations evolve dynamically during disease progression. C_LI C_LI

genetics↗

bioRxiv2025

Local B-cell immunity and durable memory following live-attenuated influenza intranasal vaccination of humans

Seasonal influenza vaccines are most frequently delivered as intramuscular inactivated vaccines which elicit systemic responses against the immunodominant hemagglutinin (HA) head domain. An intranasally administered, live-attenuated influenza vaccine designed to stimulate mucosal immunity, FluMist, is the sole intranasal vaccine approved in the United States. However, FluMist has lower systemic immunogenicity and efficacy in adults compared to intramuscular formulations. In this study, human mucosal and systemic immunity were examined following seasonal intramuscular or intranasal vaccination. Nasopharyngeal swabs of adenoid tissue were used to longitudinally sample the upper airway. Notably, FluMist induced substantial increases in upper respiratory tract IgG+ and IgA+ HA-specific memory B cells, which displayed an activated CD27+CD21- phenotype. H1, H3, and influenza B virus HA-specific memory B cells were all detected in the upper airway after intranasal immunization and remained elevated at 6-months post-vaccination. Recently activated upper airway memory B cells were not readily detected in intramuscular vaccinees, despite marked elevation of systemic antibody and memory B cells. Thus, despite minimal immune response detected in circulation, live-attenuated influenza vaccine can generate substantial local antigen-specific memory B cell responses in adults. These findings have implications for improving influenza vaccines and for mucosal vaccination against other respiratory pathogens. One Sentence SummaryLongitudinal nasopharyngeal sampling reveals local influenza-specific B cell responses following intranasal but not intramuscular vaccination.

immunology↗

bioRxiv2022

Distal-less homeobox genes Dlx5/6 regulate Mulllerian duct regression

Dlx5 and Dlx6 encode distal-less homeodomain transcription factors that are present in the genome as a linked pair at a single locus. Dlx5 and Dlx6 have redundant roles in craniofacial, skeletal, and uterine development. Previously, we performed a transcriptome comparison for anti-Mullerian hormone (AMH)-induced genes expressed in the Mullerian duct mesenchyme of male and female mouse embryos. In that study, we found that Dlx5 transcripts were nearly seven-fold higher in males compared to females and Dlx6 transcripts were found only in males, suggesting they may be AMH-induced genes. Therefore, we investigated the role of Dlx5 and Dlx6 during AMH-induced Mullerian duct regression. We found that Dlx5 was detected in the male Mullerian duct mesenchyme from E14.5 to E16.5. In contrast, in female embryos Dlx5 was detected in the Mullerian duct epithelium. Dlx6 expression in Mullerian duct mesenchyme was restricted to males. Dlx6 expression was not detected in female Mullerian duct mesenchyme or epithelium. Genetic experiments showed that AMH signaling is necessary for Dlx5 and Dlx6 expression. Mullerian duct regression was variable in Dlx5 homozygous mutant males at E16.5, ranging from regression like controls to a block in Mullerian duct regression. In E16.5 Dlx6 homozygous mutants, Mullerian duct tissue persisted primarily in the region adjacent to the testes. In Dlx5-6 double homozygous mutant males Mullerian duct regression was also found to be incomplete but more severe than either single mutant. These studies suggest that Dlx5 and Dlx6 act redundantly to mediate AMH-induced Mullerian duct regression during male differentiation.

developmental biology↗

bioRxiv2020

DLX5/6 GABAergic expression affects social vocalization: implications for human evolution

DLX5 and DLX6 are two closely related transcription factors involved in brain development and in GABAergic differentiation. The DLX5/6 locus is regulated by FoxP2, a gene involved in language evolution and has been associated to neurodevelopmental disorders and mental retardation. Targeted inactivation of Dlx5/6 in mouse GABAergic neurons (Dlx5/6VgatCre mice) results in behavioural and metabolic phenotypes notably increasing lifespan by 33%. Here, we show that Dlx5/6VgatCre mice present a hyper-vocalization and hyper-socialization phenotype. While only 7% of control mice emitted more than 700 vocalizations/10min, 30% and 56% of heterozygous or homozygous Dlx5/6VgatCre mice emitted more than 700 and up to 1400 calls/10min with a higher proportion of complex and modulated calls. Hyper-vocalizing animals were more sociable: the time spent in dynamic interactions with an unknown visitor was more than doubled compared to low-vocalizing individuals. The characters affected by Dlx5/6 in the mouse (sociability, vocalization, skull and brain shape...) overlap those affected in the "domestication syndrome". We therefore explored the possibility that DLX5/6 played a role in human evolution and "self-domestication" comparing DLX5/6 genomic regions from Neanderthal and modern humans. We identify an introgressed Neanderthal haplotype (DLX5/6-N-Haplotype) present in 12.6% of European individuals that covers DLX5/6 coding and regulatory sequences. The DLX5/6-N-Haplotype includes the binding site for GTF2I, a gene associated to Williams-Beuren syndrome, a hyper-sociability and hyper-vocalization neurodevelopmental disorder. The DLX5/6-N-Haplotype is significantly underrepresented in semi-supercentenarians (>105y of age), a well-established human model of healthy ageing and longevity, suggesting their involvement in the co-evolution of longevity, sociability and speech.

evolutionary biology↗

bioRxiv2019

DNetPRO: A network approach for low-dimensional signatures from high-throughput data

The objective of many high-throughput \"omics\" studies is to obtain a relatively low-dimensional set of observables - signature - for sample classification purposes (diagnosis, prognosis, stratification). We propose DNetPRO, Discriminant Analysis with Network PROcessing, a supervised signature identification method based on a bottom-up combinatorial approach that exploits the discriminant power of all variable pairs. The algorithm is easily scalable allowing efficient computing even for high number of observables (104 - 105). We show applications on real high-throughput genomic datasets in which our method outperforms existing results, or compares to them but with a smaller number of selected variables. Moreover the linearity of DNetPRO allows a clearer interpretation of the obtained signatures in comparison to non linear classification models

bioinformatics↗

bioRxiv2019

Dlx5 and Dlx6 expression in GABAergic neurons controls behavior, metabolism, healthy aging and lifespan.

Dlx5 and Dlx6 encode two homeobox transcription factors expressed by developing and mature GABAergic interneurons. During development Dlx5/6 are important for the differentiation of Parvalbumin (Pvalb)-expressing neurons. Perinatal lethality of homozygous mice in which Dlx5/6 have been constitutively deleted has, so far, hindered the study of the function of these genes in adult neurons. We first show that Dlx5 and Dlx6 are expressed by all subclasses of adult cortical GABAergic neurons. Then we analyse Vgat{Delta}Dlx5-6 mice in which Dlx5 and Dlx6 are simultaneously inactivated in all GABAergic interneurons. Vgat{Delta}Dlx5-6 mice present a behavioral pattern suggesting reduction of anxiety and obsessive-compulsive activities. They rapidly access and spend more time in the central region of an open field, bury few marbles in the marble burying test and show little interest in nest building. Male and female 20-month-old Vgat{Delta}Dlx5-6 animals have the same size as their normal littermates, but present a 25% body weight reduction associated with a marked decline in white and brown adipose tissue. Remarkably, both Vgat{Delta}Dlx5-6/+ and Vgat{Delta}Dlx5-6 mice present a 33% longer median survival than their control littermates. Hallmarks of biological aging such as motility, adipose deposition and coat conditions are improved in mutant animals. Our data imply that GABAergic interneurons can regulate mammalian healthspan and lifespan through Dlx5/6-dependent mechanisms. Understanding these regulations can be an entry point to unravel the processes through which the brain affects body homeostasis and, ultimately, longevity and healthy aging.\n\nSIGNIFICANCE STATEMENTDlx5 and Dlx6 are transcription factors controlling several developmental processes, including GABAergic neuronal migration and differentiation. To study their function in adult brain, we selectively inactivated both genes in GABAergic interneurons (Vgat{Delta}Dlx5-6 mice). Mutant mice have reduced anxiety-like and obsessive-compulsive behaviors. Interestingly, Vgat{Delta}Dlx5-6 mice have a 25% body weight reduction and about 70% less white and brown adipose tissue; their general health status is excellent. Vgat{Delta}Dlx5-6 mice have a median survival about 33% longer than their control littermates and hallmarks of biological aging are improved. Dlx5/6-dependent regulations in GABAergic neurons could be an entry point to understand how the brain determines the psychophysiological status of the body and, ultimately, longevity and healthy aging.

physiology↗

bioRxiv2018

Posterior neural tube closure depends on Dlx5/Dlx6 expression at the neural plate border

Neural tube defects (NTDs), one of the most common birth defects in human, present a multifactorial etiology with a poorly defined genetic component. The Dlx5 and Dlx6 bigenic cluster encodes two evolutionary conserved homeodomain transcription factors, which are necessary for proper vertebrate development. It has been shown that Dlx5/6 genes are essential for anterior neural tube closure, however their role in the formation of the posterior structures has never been described. Here, we show that Dlx5/6 expression is required during vertebrate posterior axis formation. Dlx5 presents a similar expression pattern in neural plate border cells during posterior neurulation of zebrafish and mouse. Dlx5/6-inactivation in the mouse results in a phenotype reminiscent of NTDs characterized by open thoracic and lumbar vertebral arches and failure of epaxial muscle formation at the dorsal midline. The dlx5a/6a zebrafish morphants present posterior NTDs associated with abnormal delamination of neural crest cells showing altered expression of cell adhesion molecules and defects of motoneuronal development. Our findings provide new molecular leads to decipher the mechanisms of vertebrate posterior neurulation and might help to gather a better understanding of human congenital NTDs etiology.

developmental biology↗

bioRxiv2018

Craniofacial traits determined by neural crest cells-restricted expression of Dlx5/6: probing the origin of matching functional jaws

Gnathostome jaws derive from the first pharyngeal arch (PA1), a complex structure constituted by Neural Crest Cells (NCCs), mesodermal, ectodermal and endodermal cells. Here, to determine the regionalized morphogenetic impact of Dlx5/6 expression, we specifically target their inactivation or overexpression to NCCs. NCC-specific Dlx5/6 inactivation (NCC{Delta}Dlx5/6) generates severely hypomorphic lower jaws that present typical maxillary traits. Therefore, differently from the symmetric jaws obtained after constitutive Dlx5/6 inactivation, NCC{Delta}Dlx5/6 embryos present a strikingly asymmetric mouth. Reciprocally, forced Dlx5 expression in maxillary NCCs provokes the appearance of distinct mandibular characters in the upper jaw. We conclude that: 1) Dlx5/6 activation in NCCs invariably determines lower jaw identity; 2) the morphogenetic processes that generate functional matching jaws depend on the harmonization of Dlx5/6 expression in NCCs and in distinct ectodermal territories. The co-evolution of synergistic opposing jaws requires the coordination of distinct regulatory pathways involving the same transcription factors in distant embryonic territories.

developmental biology↗

bioRxiv2018

Comparative analysis of molecular signatures suggests the use of gabapentin for the management of endometriosis-associated pain

CapsuleComparative analysis of gene expression signatures from endometriosis and mouse models shows that CACNA2{delta}s calcium-channel components involved in nociception are targets for the treatment of endometriosis-associated pain.\n\nContextDifferential gene expression analyses comparing endometriotic lesions to eutopic endometrium have shown that the transcription factors DLX5 and DLX6 are drastically down-regulated in the ectopic implants. These finding suggests that regulatory cascades involving DLX5/6 might be involved in the origin of endometriosis symptoms such as chronic pelvic pain. We have shown that mice in which Dlx5 and Dlx6 are selectively inactivated in the uterus present an endometrial phenotype reminiscent of endometriosis implants.\n\nObjectiveIdentify new targets for the treatment of endometriosis.\n\nDesignTo better focus the search for endometriosis targets we have compared the profile of genes deregulated in normal and ectopic women endometrium to those deregulated in the uterus of normal and Dlx5/Dlx6-null mice.\n\nSettingsAcademic research unit and University Hospital research laboratory\n\nAnimalsMice carrying a uterus-specific deletion of Dlx5/Dlx6.\n\nInterventionsAnalysis of archive sections from normal endometrium and endometriosis implants.\n\nMain OutcomeA novel endometriosis signature suggests that 2{delta}s subunits of voltage-gated calcium channel are targets for the management of endometriosis-associated pain.\n\nResultsWe identify a signature of 30 genes similarly deregulated in human endometriosis implants and in Dlx5/6-null mouse uteri reinforcing the notion that the down-regulation of Dlx5/6 is an early event in the progress of endometriosis. CACNA2D3, a component of the voltage-dependent calcium channel complex is strongly overexpressed both in endometriosis implants and in mutant mouse uteri; other members of the alfa2delta family, CACNA2D1 and CACNA2D2, are also overexpressed in endometriosis.\n\nConclusionCACNA2D1, CACNA2D2 and CACNA2D3 are directly involved in pain perception. In particular, CACNA2D3 has been associated to pain sensitization and heat nociception in animal models while, in patients, variants of this gene are associated to reduced sensitivity to acute noxious stimuli. As CACNA2Ds are targets of gabapentinoids analgesics, our results suggest to consider the use of these drugs for the treatment of endometriosis-associated pain. Indeed, recent small-scale clinical studies have shown that gabapentin can be effective in the treatment of women chronic pelvic pain. Our findings reinforce the need for a large definitive trial.

pharmacology and toxicology↗