Biology subjects

Fiore, F.

Publications and source records attributed to Fiore, F..

9 recordsLinked to original sources

bioRxiv2026

Gain- and loss-of-function mutations cause perinatal lethality in mouse models of Birk-Barel syndrome

Birk-Barel syndrome (BBS), also known as KCNK9 imprinting syndrome, is a neurodevelopmental disorder caused by mutations in the maternally expressed paternally imprinted KCNK9 gene that encodes the TASK3 potassium channel. The first mutation identified in patients with BBS was a loss-of-function variant that reduces the potassium current mediated by TASK3. Subsequent studies have uncovered additional pathogenic variants, including gain-of-function mutations, that increase TASK3 activity. Here, we show that both mutations resulted in the expression of the hyperactive Task3M159I variant or the hypoactive Task3G236R variant, which caused early postnatal lethality in mice when maternally inherited, confirming the monogenic nature of BBS. These results indicate that the pathogenesis of BBS involves mechanisms other than alterations in channel activity. Consequently, the proposed therapeutic strategies, such as pharmacological modulation of the TASK3 channel function or epigenetic reactivation of the paternal KCNK9 allele, do not seem to be viable options. These findings also demonstrate that TASK3 knockout mice are not suitable models for studying KCNK9 imprinting syndrome or for developing therapies for affected patients. Therefore, there is an urgent need for animal models that allow conditional expression of BBS-associated mutations.

pharmacology and toxicology↗

bioRxiv2025

The MARK2 kinase acts as a gatekeeper of CD28-dependent co-stimulation in T cells

Naive T cell activation requires not only antigen recognition through the TCR but also a co-stimulatory signal, mainly provided by CD28. Here, using a T cell-specific conditional knockout (cKO) model, we identify the microtubule-affinity kinase 2 (MARK2) as a key intracellular checkpoint that limits CD28-mediated co-stimulation. In vivo, MARK2 deficiency promotes the development of central memory T cells, enhances basal glycolysis activity in naive CD8 T cells, and leads to the development of systemic autoimmunity in aged mice. In MARK2-deficient CD8 T cells, TCR engagement alone drives sustained proliferation, cytokine production, and glycolysis, processes that normally require CD28 co-stimulation. Single-cell transcriptomic analysis reveals that MARK2 regulates the expression of genes involved in CD28 signaling and metabolic switch. We show that MARK2 restrains the PI3K-AKT-mTORC1 pathway by limiting CD28-driven transcriptional and metabolic programs. Mechanistically, we demonstrate that MARK2 phosphorylates CREB regulated transcription coactivator 2 (CRTC2) and suppresses CREB-mediated transcription and mTOR activation, whereas CD28 engagement lifts this inhibition. Together, our results redefine the role of CD28 that not only amplifies TCR signaling but also relieves a MARK2-dependent inhibitory signal. This work provides new insights into T cell activation, metabolism and immune tolerance with potential implications for immunotherapeutic strategies in cancer and autoimmunity.

immunology↗

bioRxiv2025

Two pore domain THIK2 channel is involved in acute and chronic pain signal regulation

Two-pore domain potassium channels (K2P) regulate neuronal excitability by acting as hyperpolarizing leak channels. Among them, THIK2 remain poorly characterized. Although no study has yet clearly linked them to excitability or pain, their selective expression in nociceptive neurons of the Dorsal Root Ganglia (DRG) suggests a role in nociception and pain regulation. This project investigates THIK2 channels in pain pathophysiology through molecular, electrophysiological, and behavioral approaches. We mapped THIK expression patterns and in THIK2 knock-out mice, we examined DRG neuron excitability and pain sensitivity. Results reveal thermal hypersensitivity under both naive and inflammatory conditions, indicating that THIK2 normally limits neuronal hyperexcitability. These findings position THIK2 as a potential therapeutic target in chronic inflammatory pain, with peripheral inhibition potentially offering analgesia without central opioid side effects.

neuroscience↗

bioRxiv2025

Mucosal B cell memory selection integrates tissue-specific microbial cues via the IgA BCR

B cells engender plasma cells (PCs) and memory B cells (MBCs) to combat recurrent pathogens. While B cell receptor (BCR) affinity dictates fate decisions in clonally-restricted set-ups, the driving factors in more complex systems remain unknown. Here, we show that memory selection during mucosal infection is imprinted by inherent cues from barrier tissues: lungs skew selection towards MBCs while the gut favors PC entry, even in response to the same pathogen. This divergence is linked to differential BCR isotype usage across barrier tissues rather than to affinity. In the gut, the commensal-induced TGF-{beta}-rich milieu promotes B cell class-switching to IgA. Consequently, the IgA BCR bias selection towards PCs, a process that is counteracted by its cytosolic tail domain. Overall, mucosal B cell selection integrates tissue-specific cues by strongly relying on BCR isotype usage rather than affinity, with implications for nasal and oral vaccine development. One sentence summaryDivergent B cell memory strategies evolved in lung and gut mucosa to counteract recurrent pathogens.

immunology↗

bioRxiv2024

The chemopreventive effects of Curcumin against oxidative stress induced by Cadmium or H2O2 are mediated by Nrf2/ARE signaling and protective autophagy in myeloid cells

The evidence linking high levels of environmental pollutants to chronic degenerative diseases is alarming, with heavy metals (HM) identified as a key factor. Research suggests that certain phytochemicals in the diet can reduce HM levels and mitigate their adverse health effects.Curcumin (Cur), a natural polyphenol, is particularly effective in protecting against Cadmium (Cd) toxicity. The present study demonstrates that preincubation with low doses of Cur (1 M) in differentiated HL-60 and K-562 human myeloid cells can significantly protect against cytotoxicity induced by Cd and or H2O2. Cur reduced the increased levels of reactive oxygen species (ROS) generated by Cd or H2O2 by inducing a protective form of autophagy. Cur activated mild oxidative stress that triggers the expression of Nrf2-dependent transcripts, such as HO and NQO1. The potential chemopreventive effects of Cur against redox stress have been strengthened by the observation that free and unmetabolized Cur is detectable inside the cells after 5 minutes of treatment, and its presence parallels with increased levels of intracellular GSH. These findings suggest that supplementation with Cur in the form of nutraceuticals may represent a promising way to protect people living in highly polluted areas against the adverse effects of HM contaminants.

cell biology↗

bioRxiv2024

Plasmacytoid dendritic cells are dispensable or detrimental in murine systemic or respiratory viral infections

Plasmacytoid dendritic cells (pDCs) are major producers of type I/III interferons. As interferons are crucial for antiviral defense, pDCs are assumed to play an essential role in this process. However, robust evidence supporting this dogma is scarce. Genetic or pharmacological manipulations that eliminate pDC or disrupt their interferon production often affect other cells, confounding interpretation. To overcome this issue, we engineered pDC-less mice that are specifically and constitutively devoid of pDCs by expressing diphtheria toxin under coordinated control of the Siglech and Pacsin1 genes, uniquely co-expressed in pDCs. pDC-less mice mounted protective immunity against systemic infection with mouse Cytomegalovirus and showed higher survival and less lung immunopathology to intranasal infection with influenza virus and SARS-CoV2. Thus, contrary to the prevailing dogma, we revealed that pDCs and their interferons are dispensable or deleterious during several viral infections. pDC-less mice will enable rigorously reassessing the roles of pDCs in health and disease.

immunology↗

bioRxiv2022

Induction of telomerase in p21-positive cells counteracts capillaries rarefaction in aging mice lung

Telomerase is required for long-term cell proliferation and linked to stem cells. This is evident in the lung where short telomeres are associated with lung dysfunction. We constructed a mouse model in which the telomerase (Tert) is expressed from the p21Cdkn1a promoter. We found that this peculiar Tert expression curb age-related emphysema and pulmonary perivascular fibrosis in old mice. In old mice lungs, such Tert expression preferentially occurs in endothelial cells where it reduces the number of senescent endothelial cells. Remarkably, we report that Tert counteracts the age-related decline in capillary density. This was associated with an increased number of Cd34+ cells identified as a subclass of capillary cells with proliferative capacity. Expression of catalytically inactive Tert neither prevents the decline of capillary density in old mice nor protects against age-related emphysema and fibrosis. These findings reveal that telomerase decreases age-decline of pulmonary functions by sustaining microvasculature regeneration and outgrowth.

molecular biology↗

bioRxiv2022

Norepinephrine regulates Ca2+ signals and fate of oligodendrocyte progenitor cells in the cortex

Oligodendrocyte precursor cells (OPCs) represent the most abundant group of proliferating cells in the adult central nervous system. OPCs serve as progenitors for oligodendrocyte (OLs) throughout the life, and contribute to developmental and adaptive myelination, and myelin repair during diseased state. OPCs make synaptic and extra-synaptic contacts with axons, and detect and respond to neuronal activity. How OPCs translate the information relayed by the neuronal activity into Ca2+ signals, which in turn influence their fate and survival, is less understood. We developed novel transgenic mouse lines expressing a cytosolic and membrane anchored variants of genetically encoded Ca2+ sensors (GCaMP6f or mGCaMP6s) in OPCs, performed 2-photon microscopy in the somatosensory cortex of the awake behaving mice, and simultaneously monitored intracellular Ca2+ signals and their cell-fate progression. We found Ca2+ signals in OPCs mainly occur within processes and confine to micrometer-size segments called Ca2+ microdomains. Microdomain Ca2+ signals enhanced in OPCs when mice engage in exploratory behavior. OPCs exhibit distinct Ca2+ signals while they proliferate to maintain their precursor pool or differentiate to generate new OL. When mice engaged in exploratory behavior, the cortical projections of noradrenergic neurons in locus coeruleus showed increased firing rate and norepinephrine release. Norepinephrine activated all three subtypes of alpha1 adrenergic receptor expressed by OPCs and evoked intracellular Ca2+ increase in OPCs. A chemogenetic activation of noradrenergic neurons, promoted differentiation of cortical OPCs into OL, and at the same time suppressed OPC proliferation rate. Hence, we uncovered that various cell types of oligodendrocyte lineage exhibits unique signatures of Ca2+ activity, which these cells might integrate for making their fate decisions, and norepinephrine signaling can be a potent regulator of OPC fate.

neuroscience↗

bioRxiv2021

Cellular selectivity of STING stimulation determines priming of tumor-specific T cell responses

T cells that recognize tumor antigens are crucial for anti-tumor immune responses. Induction of anti-tumor T cells in immunogenic tumors depends on STING, the intracellular innate immune receptor for cyclic guanosine monophosphate-adenosine monophosphate (cGAMP) and related cyclic dinucleotides (CDNs). However, the optimal way to leverage STING activation in non-immunogenic tumors is still unclear. Here, we show that cGAMP delivery by intra-tumoral injection of virus-like particles (cGAMP-VLP) leads to differentiation of tumor-specific T cells, decrease in tumor regulatory T cells (Tregs) and anti-tumoral responses that synergize with PD1 blockade. By contrast, intra-tumoral injection of synthetic CDN leads to tumor necrosis and systemic T cell activation but no differentiation of tumor-specific T cells, and a demise of immune cells in injected tumors. Analyses of cytokine responses and genetic models revealed that cGAMP-VLP preferentially targets STING in dendritic cells at a 1000-fold less dose than synthetic CDN. Sub-cutaneous administration of cGAMP-VLP showed synergy when combined with a tumor Treg-depleting antibody to elicit systemic tumor-specific T cells, leading to complete and lasting tumor eradication. These finding show that cell targeting of STING stimulation shapes the anti-tumor T cell response and reveal a therapeutic strategy with T cell modulators.

immunology↗