Biology subjects

Kessler, P.

Publications and source records attributed to Kessler, P..

6 recordsLinked to original sources

bioRxiv2024

CREB3 gain of function variants protect against ALS

Amyotrophic lateral sclerosis (ALS) is a fatal and rapidly evolving neurodegenerative disease that arises from the loss of glutamatergic corticospinal neurons (CSN) and cholinergic motoneurons (MN). The disease is mostly sporadic, but genetics is expected to highly contribute to disease onset and progression. Genome wide association studies identified a few genetic disease modifiers, mostly associated with a negative outcome, and demonstrated that ALS is primarily a disease of excitatory glutamatergic neurons. Here, we reasoned that at least a subpart of genetic disease modifiers may directly modulate the molecular pathways selectively activated in vulnerable neurons as the disease progresses, and concentrated on CSN for their selective vulnerability and glutamatergic identity. We implemented comparative cross-species transcriptomics using snRNAseq data from postmortem motor cortex of ALS patients and controls, and longitudinal RNAseq data from anatomically defined CSN purified from the Sod1G86R mouse model of ALS. We report that disease vulnerable neuronal populations undergo ER stress and altered mRNA translation, and identify the transcription factor CREB3 and its regulatory network as a resilience marker of neuronal dysfunction in ALS. Using genetic and epidemiologic analyses we further identify the rare variant CREB3R119G (rs11538707) as a new disease modifier in ALS. Through gain of function, CREB3R119G decreases both the risk of developing ALS and the progression rate of ALS patients. This study reveals novel genetic variants that protect against ALS and highlights the benefice of combining transcriptomics and genetics to identify new disease modifiers and therapeutic targets.

genomics↗

bioRxiv2024

Inflammatory Cytokines Can Induce Synthesis Of Type-I Interferon

Type I interferon (IFN) is induced in virus infected cells, secreted and it inhibits viral replication in neighboring cells. IFN is also an important player in many non-viral diseases and in the development of normal immune cells. Although the signaling pathways for IFN induction by viral RNA or DNA have been extensively studied, its mode of induction in uninfected cells remains obscure. Here, we report that inflammatory cytokines, such as TNF- and IL-1{beta}, can induce IFN-{beta} through activation of the cytoplasmic RIG-I signaling pathway. However, RIG-I is activated not by RNA, but by PACT, the protein activator of PKR. In cell lines or primary cells expressing RIG-I and PACT, activation of the MAPK, p38, by cytokine signaling, leads to phosphorylation of PACT, which binds to primed RIG-I and activates its signaling pathway. Thus, a new mode of type I IFN induction by ubiquitous inflammatory cytokines has been revealed. Key pointsO_LICytochalasin D followed by TNF- / IL-1{beta} treatment activates IFN-{beta} expression. C_LIO_LIIFN-{beta} expression happens due to activation of RIG-I signaling. C_LIO_LIInteraction between RIG-I and PACT activates IFN-{beta} expression. C_LI

cell biology↗

bioRxiv2023

A synthetic delivery vector for mucosal vaccination

The success of mRNA-based vaccines during the Covid-19 pandemic has highlighted the value of this new platform for vaccine development against infectious disease. However, the CD8+ T cell response remains modest with mRNA vaccines, and these do not induce mucosal immunity, which would be needed to prevent viral spread in the healthy population. To address this drawback, we developed a dendritic cell targeting mucosal vaccination vector, the homopentameric STxB. Here, we describe the highly efficient chemical synthesis of the protein, and its in vitro folding. This straightforward preparation led to a synthetic delivery tool whose biophysical and intracellular trafficking characteristics were largely indistinguishable from recombinant STxB. The chemical approach allowed for the generation of new variants with bioorthogonal handles. Selected variants were chemically coupled to several types of antigens derived from the mucosal viruses SARS-CoV-2 and type 16 human papillomavirus. Upon intranasal administration in mice, mucosal immunity, including resident memory CD8+ T cells and IgA antibodies was induced against these antigens. Our study thereby identifies a novel synthetic antigen delivery tool for mucosal vaccination with an unmatched potential to respond to an urgent medical need.

biochemistry↗

bioRxiv2020

Cytoplasmic accumulation of FUS triggers early behavioral alterations linked to cortical neuronal hyperactivity and defects in inhibitory synapses

Gene mutations causing cytoplasmic mislocalization of the RNA-binding protein FUS, lead to severe forms of amyotrophic lateral sclerosis (ALS). Cytoplasmic accumulation of FUS is also observed in other diseases, with unknown consequences. Here, we show that cytoplasmic mislocalization of FUS drives behavioral abnormalities in knock-in mice, including locomotor hyperactivity and alterations in social interactions, in the absence of widespread neuronal loss. Mechanistically, we identified a profound increase in neuronal activity in the frontal cortex of Fus knock-in mice in vivo. Importantly, RNAseq analysis suggested involvement of defects in inhibitory neurons, that was confirmed by ultrastructural and morphological defects of inhibitory synapses and increased synaptosomal levels of mRNAs involved in inhibitory neurotransmission. Thus, cytoplasmic FUS triggers inhibitory synaptic deficits, leading to increased neuronal activity and behavioral phenotypes. FUS mislocalization may trigger deleterious phenotypes beyond motor neuron impairment in ALS, but also in other neurodegenerative diseases with FUS mislocalization.

neuroscience↗

bioRxiv2020

Full cell infiltration and thick tissue formation in vivo in tailored electrospun scaffolds

Electrospun (ESP) scaffolds are a promising type of tissue engineering constructs for large defects with limited depth. To form new functional tissue, the scaffolds need to be infiltrated with cells, which will deposit extracellular matrix. However, due to dense fiber packing and small pores, cell and tissue infiltration of ESP scaffolds is limited. Here, we combine two established methods, increasing fiber diameter and co-spinning sacrificial fibers, to create a porous ESP scaffold that allows robust tissue infiltration. Full cell infiltration across 2 mm thick scaffolds is seen 3 weeks after subcutaneous implantation in rats. After 6 weeks, the ESP scaffolds are almost fully filled with de novo tissue. Cell infiltration and tissue formation in vivo in this thickness has not been previously achieved. In addition, we propose a novel method for in vitro cell seeding to improve cell infiltration and a model to study 3D migration through a fibrous mesh. This easy approach to facilitate cell infiltration further improves previous efforts and could greatly aid tissue engineering approaches utilizing ESP scaffolds. Statement of significanceElectrospinning creates highly porous scaffolds with nano- to micrometer sized fibers and are a promising candidate for a variety of tissue engineering applications. However, smaller fibers also create small pores which are difficult for cells to penetrate, restricting cells to the top layers of the scaffolds. Here, we have improved the cell infiltration by optimizing fiber diameter and by co-spinning a sacrificial polymer. We developed novel culture technique that can be used to improve cell seeding and to study cytokine driven 3D migration through fibrous meshes. After subcutaneous implantation, infiltration of tissue and cells was observed up to throughout up to 2 mm thick scaffolds. This depth of infiltration in vivo had not yet been reported for electrospun scaffolds. The scaffolds we present here can be used for in vitro studies of migration, and for tissue engineering in defects with a large surface area and limited depth.

bioengineering↗

bioRxiv2020

Genetic ablation of SOD1G37R selectively from corticofugal projection neurons protects corticospinal neurons from degeneration without affecting ALS onset and progression

While clinical evidence of combined degeneration of the bulbar and spinal motor neurons (MN) together with the corticospinal neurons (CSN) is required to diagnose Amyotrophic Lateral Sclerosis (ALS), preclinical studies have mostly concentrated on MN, leaving aside the CSN and their contribution to ALS onset and progression. Recent studies carried on ALS patients suggest that the disease may initiate in the motor cortex and spread to its projection targets, along the corticofugal axonal projections (including CSN), either via altered neuronal excitability and subsequent excitotoxicity, or via prion-like propagation of misfolded proteins. We recently provided first experimental arguments in favour of the corticofugal hypothesis of ALS, demonstrating that CSN and other subcerebral projection neurons were toxic in a context of ALS. Here, we aimed to determine how CSN may be detrimental to their downstream targets, and what governs their degeneration. To answer these questions, we took advantage of the FloxedSOD1G37R mouse model of ALS that allows genetic ablation of the mutant transgene in selected cells upon Cre-mediated recombination, and crossed it to the CrymCreERT2 mouse line that we purposely designed to genetically target CSN and other corticofugal projection neurons (CFuPN) populations. We demonstrate that excision of the mutant SOD1G37R transgene from the CSN is sufficient to prevent their death, suggesting that CSN degeneration mostly relies on cell-intrinsic mechanisms. However, genetic ablation of SOD1G37R transgene from the corticofugal neurons had no effect on disease onset and survival. The data thus indicate that the toxicity of CFuPN in the context of ALS, and corticofugal propagation of the disease, are not mediated by the presence of misfolded mutant proteins, but more likely by other aspects of the cortical pathology, possibly hyperexcitability.

neuroscience↗