Biology subjects

Sorg, T.

Publications and source records attributed to Sorg, T..

6 recordsLinked to original sources

bioRxiv2025

Astroglial deficiency for oligophrenin-1 contributes to intellectual disability

Neurodevelopmental disorders, including X-linked intellectual disability, autism spectrum disorder or schizophrenia, can result from the mutation of oligophrenin-1 (Ophn1), encoding a Rho-GTPase-activating protein. Ophn1 regulates synaptic development and function, in part via cytoskeleton reorganization, and is expressed in both neurons and astrocytes. Despite the crucial role of astrocytes in synapse function, altered in neurodevelopmental disorders, and their Ophn1 expression, the specific impact of astroglial Ophn1 deficiency on synaptic transmission and behavior remains unknown. Here, we show that Ophn1 deficiency postnatally in hippocampal astrocytes impairs synaptic transmission, short-term plasticity and spatial working memory in adults. This involves an adenosine A1 receptor-dependent presynaptic mechanism associated with astroglial morphological rearrangements resulting in increased astroglial synapse coverage. The structural, functional and behavioral alterations induced by astroglial Ophn1 deficiency are rescued in adults by pharmacological inhibition of the RhoA/ROCK pathway. Our findings uncover an important role for astroglial Ophn1 deficiency in synaptic and behavioral dysfunctions, pointing to a novel cellular therapeutic target for neurodevelopmental disorders.

neuroscience↗

bioRxiv2022

E4F1 COORDINATES PYRUVATE METABOLISM AND THE ACTIVITY OF THE ELONGATOR COMPLEX TO ENSURE PROTEIN TRANSLATION FIDELITY DURING NEURONAL DEVELOPMENT

Pyruvate metabolism defects lead to severe neuropathies such as the Leigh syndrome (LS) but the molecular mechanisms underlying neuronal cell death remain poorly understood. Here, we unravel a connection between pyruvate metabolism and the regulation of the epitranscriptome that is relevant to LS pathogenesis. We identified the transcription factor E4F1 as a key coordinator of AcetylCoenzyme A (AcCoA) production by the pyruvate dehydrogenase complex (PDC) and its utilization as an essential co-factor by the Elongator complex to acetylate tRNAs at the wobble position uridine 34 (U34). E4F1-mediated direct transcriptional regulation of Dlat and Elp3, two genes encoding key subunits of the PDC and of the Elongator complex, respectively, ensured proper translation fidelity and cell survival in the central nervous system (CNS) during mouse embryonic development. Furthermore, analysis of PDH-deficient cells highlighted a crosstalk linking the PDC to ELP3 expression that is perturbed in LS patients.

developmental biology↗

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

Isolation, omics characterization and organotypic culture of alveolar type II pulmonary epithelial cells

The alveolar type II (AT2) epithelial cell fraction includes the stem cells of the pulmonary alveoli, functioning in lung homeostasis and post-injury repair. AT2 cells have been characterized primarily in situ, in transgenic mouse models. We report a new methodology for their isolation, their "omics" characterization and stroma-cell-free organotypic culture. Our multi-omics analysis identified high expression of genes involved in oxidative phosphorylation and of AP-1 components, as well as new phosphorylation sites in AT2 biomarkers. Furthermore, we show that supplementation with KGF, FGF10 & HGF suffices for the in vitro proliferation of AT2 cells and formation of alveolar organoids, suggesting that AT2-based organotypic development depends on ligands of the c-Met and FGFR2 receptors. The reported methodology and in-depth molecular characterization provide new tools for the in vitro and in vivo functional analysis of pulmonary cells and of mouse models of lung disease.

cell biology↗

bioRxiv2021

Dyrk1a gene dosage in glutamatergic neurons has key effects in cognitive deficits observed in mouse models of MRD7 and Down syndrome

Perturbation of the excitation/inhibition (E/I) balance leads to neurodevelopmental diseases including to autism spectrum disorders, intellectual disability, and epilepsy. Mutation in the DYRK1A gene located on human chromosome 21 (Hsa21) leads to an intellectual disability syndrome associated with microcephaly, epilepsy, and autistic troubles (MRD7). Overexpression of DYRK1A, on the other hand, has been linked with learning and memory defects observed in people with Down syndrome (DS). Dyrk1a is expressed in both glutamatergic and GABAergic neurons, but its impact on each neuronal population has not yet been elucidated. Here we investigated the impact of Dyrk1a gene copy number variation in glutamatergic neurons using a conditional knockout allele of Dyrk1a crossed with the Tg(Camk2-Cre)4Gsc transgenic mouse. We explored this genetic modification in homozygotes, heterozygotes and combined with the Dp(16Lipi-Zbtb21)1Yey trisomic mouse model to unravel the consequence of Dyrk1a dosage from 0 to 3, to understand its role in normal physiology, and in MRD7 and DS. Overall, Dyrk1a dosage in glutamatergic neurons did not impact locomotor activity, working memory or epileptic susceptibility, but revealed that Dyrk1a is involved in long-term explicit memory. Molecular analyses pointed at a deregulation of transcriptional activity through immediate early genes and a role of DYRK1A at the glutamatergic post-synapse by deregulating and interacting with key post-synaptic proteins implicated in mechanism leading to long-term enhanced synaptic plasticity. Altogether, our work gives important information to understand the action of DYRK1A inhibitors and have a better therapeutic approach. Author summaryThe Dual Specificity Tyrosine Phosphorylation Regulated Kinase 1A, DYRK1A, drives cognitive alterations with increased dose in Down syndrome (DS) or with reduced dose in mental retardation disease 7 (MRD7). Here we report that specific and complete loss of Dyrk1a in glutamatergic neurons induced a range of specific cognitive phenotypes and alter the expression of genes involved in neurotransmission in the hippocampus. We further explored the consequences of Dyrk1a dosage in glutamatergic neurons on the cognitive phenotypes observed respectively in MRD7 and DS mouse models and we found specific roles in long-term explicit memory with no impact on motor activity, short-term working memory, and susceptibility to epilepsy. Then we demonstrated that DYRK1A is a component of the glutamatergic post-synapse and interacts with several component such as NR2B and PSD95. Altogether our work describes a new role of DYRK1A at the glutamatergic synapse that must be considered to understand the consequence of treatment targeting DYRK1A in disease.

neuroscience↗

bioRxiv2019

Human and mouse essentiality screens as a resource for disease gene discovery

Although genomic sequencing has been transformative in the study of rare genetic diseases, identifying causal variants remains a considerable challenge that can be addressed in part by new gene-specific knowledge. Here, we integrate measures of how essential a gene is to supporting life, as inferred from the comprehensive viability and phenotyping screens performed on knockout mice by the International Mouse Phenotyping Consortium and from human cell line essentiality screens. We propose a novel, cross-species gene classification across the Full Spectrum of Intolerance to Loss-of-function (FUSIL) and demonstrate that genes in five mutually exclusive FUSIL categories have differing characteristics in the biological processes they regulate, tissue expression levels and human mutation rates. Most notably, Mendelian disease genes, particularly those associated with developmental disorders, are highly overrepresented in the developmental lethal category, representing genes not essential for cell survival but required for organism development. Exploiting this finding, we have screened developmental disorder cases from three independent disease sequencing consortia and identified potentially pathogenic, de novo variants shared in different patients for several developmental lethal genes that have not previously been associated with rare disease. We therefore propose FUSIL as an efficient resource for disease gene discovery.

genomics↗