Biology subjects

Aube, J.

Publications and source records attributed to Aube, J..

At least 19 recordsLinked to original sources

bioRxiv2026

Two new gastropod holobionts from Atlantic hydrothermal vents showing different levels of endosymbiosis dependence

Chemosynthetic symbioses underpin animal life at deep-sea hydrothermal vents, encompassing substantial variabilities in symbiont identity, metabolic capacity, and host dependence. Here, we characterise symbioses in two peltospirid snails from Mid-Atlantic Ridge vents, Peltospira gargantua and P. smaragdina, using 3D anatomical reconstruction, stable isotope analyses, fluorescence in situ hybridization, transmission electron microscopy, and metagenomics. Both species hosted abundant intracellular Campylobacterota within bacteriocytes of a hypertrophied oesophageal gland. Their dominant symbionts belonged to genus Sulfurimonas, but the two hosts were associated with distinct symbiont lineages. Symbiont genomes encoded carbon fixation through the rTCA cycle, sulfide oxidation, and Group I Ni-Fe hydrogenases, indicating combined thiotrophic and hydrogenotrophic capacities. Hydrogenase copy number varied across vent fields from one to three copies. The P. gargantua symbiont from the hydrogen-enriched Hydra vent field carried two divergent copies, including one with a truncated catalytic region, potentially reflecting local adaptation to vent geochemistry. Anatomical and isotopic comparisons further revealed contrasting host dependence, with P. gargantua having a proportionally larger oesophageal gland and ventricle coupled with a reduced radula, as well as a greater nitrogen-isotope enrichment between symbiotic and non-symbiotic tissues. The smaller oesophageal gland and larger feeding apparatus of P. smaragdina point to it being mixotrophic. Previously, all known peltospirid symbioses have partnered with Gammaproteobacteria, and we expand the known diversity of peltospirid symbioses. Our findings underscore how closely related hosts can exhibit different degrees of dependence on symbiosis, and that mixotrophic symbiosis may be prevalent in small vent species previously thought to be non-symbiotic.

ecology↗

bioRxiv2026

Dynamic view of an allosteric intermediate in a positively cooperative dimer

Positive cooperativity in ligand binding is a hallmark of allosteric oligomers, yet how the first binding event enhances the second remains obscure, because the pivotal singly-bound intermediate (lig) is thermodynamically disfavored and rarely accumulates. Distinguishing concerted (MWC) from sequential (KNF) mechanisms turns on one question: when a ligand binds one protomer, does its empty partner change conformation? Here we resolve this for the allosteric homodimer chorismate mutase (CM) using mixed-labeled dimers (MLDs), in which a single maleimide crosslink stabilizes a heterodimer carrying one NMR-labeled and one active-site-inactivated subunit, trapping lig for prolonged study. Isothermal titration calorimetry shows that inhibitor binding to CM is positively cooperative and entirely entropy-driven, with the second event carrying far larger enthalpic and entropic swings than the first. Protomer-resolved NMR reveals that the first binding event switches both subunits to the relaxed (R) state--a concerted, MWC-like transition that rules out a strictly sequential model--yet the empty subunit is not a clean R conformer but a "fuzzy", dynamically heterogeneous ensemble, with extensive microsecond- millisecond motion focused at the dimer interface, and a raft of residues surrounding the empty active site. Backbone probes confirm that both critical 11-12 loops adopt their active posture upon first ligand binding. The mismatch between the chemical-shift picture (MWC-like) and the thermodynamics (weighted toward the second event) argues that cooperativity is not encoded by a simple two-state switch, but by activated dynamics that a purely structural model cannot capture. Significance StatementCooperative ligand binding underlies allosteric control across biology, but mechanisms have been hard to pin down because the crucial half-bound intermediate of a cooperative dimer barely exists at equilibrium. We stabilize this intermediate in the enzyme chorismate mutase by chemically linking one NMR-visible subunit to one that cannot bind ligand, letting us watch each subunit independently. Binding the first ligand flips both subunits to the active state, yet the empty subunit becomes highly dynamic rather than rigidly active. Combined with calorimetry, this shows that the free energy of cooperativity must be stored in ensemble dynamics, not merely in a switch between two structures. The linkage method further opens the door to additional solution-based studies required to better understand allostery and benchmark tools of the future.

biophysics↗

bioRxiv2026

Loss of riboflavin biosynthesis leads to accumulation of select aromatic amino acids and loss of infectivity in Mycobacterium tuberculosis

Riboflavin biosynthesis is required for in vitro survival of the human pathogen Mycobacterium tuberculosis (Mtb). However, despite the lack of a known transporter, growth can be rescued by exogenous riboflavin. The riboflavin biosynthesis pathway is also predicted essential in vivo, but whether riboflavin levels available in the host can support survival has not been directly tested. Here we constructed a set of inducible CRISPR interference (CRISPRi) knockdown and targeted gene deletion strains for known riboflavin biosynthesis genes (ribA2, ribG, ribH, ribC) as tools to characterize riboflavin requirements, uptake, and metabolite changes and to assess in vivo essentiality. We found that riboflavin, but not flavin adenine dinucleotide or flavin mononucleotide, rescued auxotrophy for all strains tested. Further, riboflavin uptake did not show strong evidence of being dependent on active or facilitated transport, supporting the mechanism of passive diffusion. Targeted metabolite profiling after removal of riboflavin from growth medium confirmed reduced riboflavin levels. While other riboflavin intermediates were not detected, significant accumulation of aromatic amino acids (Phe, Tyr) was observed across all assayed strains, as well as alteration in a vitamin B9 metabolite. Selecting the ribC knockout as a representative strain, we found that riboflavin depletion had a bacteriostatic effect as late as 3 weeks after removal. Unexpectedly, {Delta}ribC lacked infectivity in an aerosol mouse infection, suggesting that the potential to scavenge riboflavin from the host is not sufficient to survive in vivo. Overall, our results show that altered metabolism upon loss of riboflavin biosynthesis leads to compromised Mtb infectivity. IMPORTANCETuberculosis remains one of the worlds most deadly infectious diseases, underscoring the need to explore new drug targets. Riboflavin (vitamin B2) biosynthesis has emerged as a promising target because Mycobacterium tuberculosis (Mtb) depends on this pathway for survival. The riboflavin pathway also produces metabolites that modulate host mucosal-associated invariant T (MAIT) cell activity, towards understanding potential strategies for host-directed therapies. Here we found that disrupting riboflavin biosynthesis led to not only compromised survival, but also widespread changes to metabolism and loss of the ability to establish infection in an animal model. These findings improve our understanding of how Mtb adapts to metabolic stress, with implications for developing drugs that target riboflavin biosynthesis and for alterations in host immunity to be explored in future studies.

microbiology↗

bioRxiv2026

HuR inhibition attenuates hypertension and fibrosis in chronic kidney disease

BackgroundElevated RNA-binding protein HuR has been reported in patients with chronic kidney disease (CKD), but its specific pathogenic role remains unclear. Here, we investigated HuR involvement in progressive CKD induced by deoxycorticosterone acetate (DOCA) plus angiotensin II (Ang II) in mice and evaluated the therapeutic efficacy and mechanisms of the HuR inhibitor KH3. MethodsAdult male mice underwent uninephrectomy and were subjected to DOCA + Ang II infusion with 1% NaCl in drinking water. Mice were then treated with KH3 or vehicle for 3 weeks. Control mice received saline injections without DOCA and Ang II infusion. ResultsDOCA + Ang II infusion markedly increased HuR expression in circulating exosomes and kidney tissues, which was attenuated by KH3. KH3 halted the progression of albuminuria and improved renal function, and reduced kidney hypertrophy and glomerular and tubulointerstitial fibrosis compared with untreated DOCA + Ang II mice. These improvements were associated with reduced podocyte and tubular injury. KH3 also decreased renal macrophage infiltration and suppressed NF-{kappa}Bp65, Nox2, AKT phosphorylation, TGF-{beta}1, and Wisp1, consistent with reduced inflammation, oxidative stress, and fibrosis. In addition, KH3 partially lowered arterial blood pressure in DOCA + Ang II-infused mice, an effect that may involve suppression of SGLT2-associated profibrotic vascular responses, as supported by studies in cultured VSMCs and mesenteric resistance arteries. ConclusionsHuR is upregulated in DOCA + Ang II-induced renal and vascular injury and contributes to hypertensive, inflammatory, oxidative, and fibrotic responses in CKD. Pharmacologic inhibition of HuR-RNA interactions represents a promising therapeutic strategy for CKD. NOVELTY AND RELEVANCEO_ST_ABSWhat Is New?C_ST_ABSThis study identifies the RNA-binding protein HuR (ELAVL1) as a previously unrecognized upstream post-transcriptional regulator of blood pressure in hypertensive chronic kidney disease. We demonstrate for the first time that pharmacologic disruption of HuR-RNA interactions lowers arterial blood pressure in vivo. In addition, we uncover a novel HuR-SGLT2-vascular smooth muscle cell (VSMC) signaling axis, revealing that HuR regulates inducible vascular SGLT2 expression and Ang II-mediated vasoconstrictive responses. What Is Relevant?Hypertension in CKD arises from integrated renal and vascular dysfunction that is incompletely controlled by current therapies. Our findings are highly relevant because we identify HuR as a nodal post-transcriptional regulator that coordinates renal injury, vascular inflammation, and smooth muscle contractility, rather than acting within a single cell type or signaling pathway. Clinical and Pathophysiological ImplicationThese data support a model in which HuR-driven RNA regulatory programs amplify Ang II-dependent vascular hypercontractility and hypertension in CKD. Therapeutic targeting of HuR-RNA interactions represents a novel antihypertensive strategy that may complement renin-angiotensin-aldosterone system (RAAS) blockade and provides mechanistic insight into the blood pressure-lowering and vascular protective effects of SGLT2 inhibitors, including in non-diabetic CKD.

pathology↗

bioRxiv2025

MAIT cell responses to intracellular and extracellular pathogens are mediated by distinct antigen presenting cells

Mucosal-associated invariant T (MAIT) cells recognize microbial derivatives of riboflavin synthesis presented by the MHC class I-related (MR1) molecule. Although these metabolites are highly conserved among bacteria, the cells that present them remain unknown. Here, we show type-17 MAIT cells respond to diverse isolates of the extracellular pathogen Acinetobacter baumannii and promote bacterial clearance. Both hematopoietic and non-hematopoietic cells mediate MR1 presentation within the lungs and mediastinal lymph nodes (meLNs). Conversely, the type-1 MAIT cell response to the intracellular pathogen Francisella tularensis requires MR1 presentation by type-2 conventional dendritic cells (cDC2s) within meLNs and ablation of these cells or their expression of MR1 renders animals more susceptible to the infection. Although MR1 is broadly expressed at homeostasis, A. baumannii enhances MR1 on macrophages and fibroblasts, while F. tularensis increases expression on cDC2s. These results demonstrate that microbial tropism dictates which APCs mediate MR1 presentation of metabolites, revealing alternative therapeutic approaches.

immunology↗

bioRxiv2025

Triazole 187 is a biased KOR agonist that suppresses itch without sedation and induces anxiolytic-like behaviors in mice.

Kappa opioid receptor agonists are clinically used to treat pruritis and have therapeutic potential for the treatment of pain and neuropsychiatric disorders. We have previously shown that triazole 1.1 is a G protein signaling-biased KOR agonist, that can suppress itch without producing signs of sedation in mice. This profile was recapitulated in rats and non-human primates however, triazole 1.1 had limited potency as an antipruritic. Here we describe a more potent, G protein signaling-biased agonist, triazole 187. Triazole 187 is a potent antipruritic agent and does not decrease spontaneous locomotor activity; interestingly, it produces anxiolytic-like behaviors in mice, an effect not observed for triazole 1.1. In addition to curbing sedation, triazole 187 produces only mild diuresis, resulting in 30% of urine output induced by U50,488H at dose that is 188-fold the antipruritic potency dose. Compounds like triazole 187 may present a means to treat anxiety accompanied by persistent chronic itch while avoiding sedation and diuresis accompanied by typical KOR agonists. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=107 SRC="FIGDIR/small/638680v1_ufig1.gif" ALT="Figure 1"> View larger version (27K): org.highwire.dtl.DTLVardef@17e9e6aorg.highwire.dtl.DTLVardef@1d27741org.highwire.dtl.DTLVardef@9389dcorg.highwire.dtl.DTLVardef@3fd825_HPS_FORMAT_FIGEXP M_FIG Graphic Abstract C_FIG

pharmacology and toxicology↗

bioRxiv2025

CD4+ Mucosal-associated Invariant T (MAIT) cells express highly diverse T cell receptors

Mucosal-associated invariant T cells are highly conserved innate-like T cells in mammals recognized for their high baseline frequency in human blood and cytotoxic effector functions during infectious diseases, autoimmunity, and cancer. While the majority of these cells express a conserved CD8{beta}+ TRAV1-2 T cell receptor recognizing microbially-derived Vitamin B2 intermediates presented by the evolutionarily conserved major histocompatibility complex I-related molecule, MR1, there is an emerging appreciation for diverse subsets that may be selected for in humans with distinct functions, including subpopulations that co-express CD4. Prior work has not examined T cell receptor (TCR) heterogeneity in CD4+ MAIT cells, largely due to bias of identifying human MAIT cells as CD8+ TRAV1-2+ cells. In this study, we adopted an unbiased single-cell TCR-sequencing approach of total MR1-5-OP-RU-tetramer-reactive T cells and discovered that CD4+ MAIT cells express highly diverse TRAV1-2 negative TCRs. To specifically characterize this TCR repertoire, we analyzed VDJ sequences of single MR1-5-OP-RU tetramer+ MAIT cells across two datasets and identified distinct TCR usage among CD4+ MAIT cells including TRAV21, TRAV8 (TRAV8-1, TRAV8-2, TRAV8-3), and TRAV12 families (TRAV12-2, TRAV12-3), as well as more variable J chain and CDR3 sequences. Non-TRAV1-2 MAIT cell TCRs were also enriched after in vitro expansion, including with Mycobacterial tuberculosis. These results indicate that mature human CD4+ MAIT cells adopt distinct TCR usage from the canonical TRAV1-2+ CD8+ subset and suggest that alternative MR1 ligands in addition to riboflavin intermediates may select them.

genomics↗

bioRxiv2024

FISH, a new tool for in situ preservation of RNA in tissues of deep-sea mobile fauna.

Accessing the metabolic functioning of deep-sea animals in situ remains a technological challenge as the recovery time of samples is incompatible with the short lifespan of such molecules as mRNAs. Tools able to preserve RNA in situ exist but they are incompatible with the study of mobile fauna. Here we describe a new sampling tool, named FISH (Fixer In situ of Homogenized Substrates), implemented on a submersible and equipped with a number of new specific features to collect and preserve in situ tissue of mobile fauna. Connected to the suction pump of a submersible, FISH incorporates a sampling bowl to which two bottles of a preservative reagent are attached, a suction hose, and a support containing a motor connected to the sampling bowl by a magnetic coupling system. We used the deep-sea hydrothermal shrimp Rimicaris exoculata from the Mid-Atlantic Ridge as a model to test the suitability of our new tool. FISH was compared to two other sampling methods, which use a metatranscriptomic approach targeting microbial communities associated with cephalothorax symbionts. RNA quality, gene assignment and taxonomic and gene function diversity showed differences between in situ and on-board preservation of tissues. Of the alternative sampling methods tested, the suction sampler was clearly not suitable for RNA-based studies, while pressurized recovery showed results closer to the sample quality obtained with FISH sampling. The FISH sampler has therefore demonstrated to be a cost-effective and reliable tool to efficiently preserve RNA recovered from deep-sea environments.

molecular biology↗

bioRxiv2024

MAIT Cells Modulate Innate Immune Cells and Inhibit Colon Cancer Growth

Mucosal-associated invariant T (MAIT) cells are innate-like T cells that can be activated by microbial antigens and cytokines and are abundant in mucosal tissues including the colon. MAIT cells have cytotoxic and pro-inflammatory functions and have potentials for use as adoptive cell therapy. However, studies into their anti-cancer activity, including their role in colon cancer, are limited. Using an animal model of colon cancer, we show that peritumoral injection of in vivo-expanded MAIT cells into RAG1-/- mice with MC38-derived tumors inhibits tumor growth compared to control. Multiplex cytokine analyses show that tumors from the MAIT cell-treated group have higher expression of markers for eosinophil-activating cytokines, suggesting an association between eosinophil recruitment and tumor inhibition. In a human peripheral leukocyte co-culture model, we show that leukocytes stimulated with MAIT ligand show an increase in eotaxin-1 production and activation of eosinophils, associated with increased cancer cell killing. In conclusion, we show that MAIT cells have a protective role in a murine colon cancer model, associated with modulation of the immune response to cancer, potentially involving eosinophil-associated mechanisms. Our results highlight the potential of MAIT cells for non-donor restricted colon cancer immunotherapy. Brief summaryIn models of colon cancer, MAIT cells have anti-tumor activity, associated with increased production of proinflammatory and eosinophil-modulating cytokines.

cancer biology↗

bioRxiv2023

SETD2 maintains nuclear lamina stability to safeguard the genome

Histone methyltransferases play essential roles in the organization and function of chromatin. They are also frequently mutated in human diseases including cancer1. One such often mutated methyltransferase, SETD2, associates co-transcriptionally with RNA polymerase II and catalyzes histone H3 lysine 36 trimethylation (H3K36me3) - a modification that contributes to gene transcription, splicing, and DNA repair2. While studies on SETD2 have largely focused on the consequences of its catalytic activity, the non-catalytic functions of SETD2 are largely unknown. Here we report a catalysis-independent function of SETD2 in maintaining nuclear lamina stability and genome integrity. We found that SETD2, via its intrinsically disordered N-terminus, associates with nuclear lamina proteins including lamin A/C, lamin B1, and emerin. Depletion of SETD2, or deletion of its N-terminus, resulted in widespread nuclear morphology abnormalities and genome stability defects that were reminiscent of a defective nuclear lamina. Mechanistically, the N-terminus of SETD2 facilitates the association of the mitotic kinase CDK1 with lamins, thereby promoting lamin phosphorylation and depolymerization required for nuclear envelope disassembly during mitosis. Taken together, our findings reveal an unanticipated link between the N-terminus of SETD2 and nuclear lamina organization that may underlie how SETD2 acts as a tumor suppressor.

cell biology↗

bioRxiv2023

HuR inhibition reduces post-ischemic cardiac remodeling by dampening acute inflammatory gene expression and the innate immune response

Myocardial ischemia/reperfusion (I/R) injury and the resulting cardiac remodeling is a common cause of heart failure. The RNA binding protein Human Antigen R (HuR) has been previously shown to reduce cardiac remodeling following both I/R and cardiac pressure overload, but the full extent of the HuR-dependent mechanisms within cells of the myocardium have yet to be elucidated. In this study, we applied a novel small molecule inhibitor of HuR to define the functional role of HuR in the acute response to I/R injury and gain a better understanding of the HuR-dependent mechanisms during post-ischemic myocardial remodeling. Our results show an early (two hours post-I/R) increase in HuR activity that is necessary for early inflammatory gene expression by cardiomyocytes in response to I/R. Surprisingly, despite the reductions in early inflammatory gene expression at two hours post-I/R, HuR inhibition has no effect on initial infarct size at 24-hours post-I/R. However, in agreement with previously published work, we do see a reduction in pathological remodeling and preserved cardiac function at two weeks post-I/R upon HuR inhibition. RNA-sequencing analysis of neonatal rat ventricular myocytes (NRVMs) at two hours post-LPS treatment to model damage associated molecular pattern (DAMP)-mediated activation of toll like receptors (TLRs) demonstrates a broad HuR-dependent regulation of pro-inflammatory chemokine and cytokine gene expression in cardiomyocytes. We show that conditioned media from NRVMs pre-treated with HuR inhibitor loses the ability to induce inflammatory gene expression in bone marrow derived macrophages (BMDMs) compared to NRVMs treated with LPS alone. Functionally, HuR inhibition in NRVMs also reduces their ability to induce endocrine migration of peripheral blood monocytes in vitro and reduces post-ischemic macrophage infiltration to the heart in vivo. In summary, these results suggest a HuR-dependent expression of pro-inflammatory gene expression by cardiomyocytes that leads to subsequent monocyte recruitment and macrophage activation in the post-ischemic myocardium.

molecular biology↗

bioRxiv2022

Enhancing Mucosal-Associated Invariant T (MAIT) cell function and expansion with human selective serum

Mucosal-associated invariant T (MAIT) cells are promising innate-like lymphocytes with potential for use in anti-tumor immunotherapy. Existing MAIT cell expansion protocols are associated with potentially decremental phenotypic changes, including increased frequency of CD4+ MAIT cells and higher inhibitory receptor expression. In this study, we compared the effect on expansion of human MAIT cells of a serum replacement, Physiologix XF SR (Phx), with traditional serum fetal bovine serum (FBS) for supplementing RPMI-1640 media. Using flow cytometry, we found that Phx supported a significantly higher proliferative capacity for MAIT cells and resulted in a lower frequency of CD4+ MAIT cells, which have been associated with reduced Th1 effector and cytolytic functions. We saw that culturing MAIT cells in Phx led to better survival of MAIT cells and lower frequency of PD-1+ MAIT cells compared to FBS-supplemented media. Functionally, we saw that Phx supplementation was associated with a higher frequency of IFN-{gamma}+ MAIT cells after stimulation with E. coli compared to FBS-supplemented RPMI. In conclusion, we show that MAIT cells cultured in Phx have higher proliferative capacity, lower expression of inhibitory receptors, and have higher capacity to produce IFN-{gamma} after E. coli stimulation, compared to FBS-supplemented RPMI. This work shows that expanding MAIT cells with Phx compared to FBS-supplemented RPMI result in a more functionally desirable MAIT cell for future anti-tumor immunotherapy.

immunology↗

bioRxiv2022

AGC Kinase Inhibitors Regulate STING Signaling Through SGK-Dependent and SGK-Independent Mechanisms

The STING signaling pathway is essential for the innate immune response to DNA viruses and bacteria and is important in tumor immunity. STING binding to cGAMP or to synthetic agonists leads to the activation of the kinase TBK1 which phosphorylates the transcription factor IRF3 which promotes expression of type 1 interferons such as IFN{beta} to block viral activity. Aberrant type 1 IFN expression is associated with human diseases including autoimmunity, HIV, and cancer. Here we identify N-[4-(1H-pyrazolo[3,4-b] pyrazin-6-yl)-phenyl]-sulfonamide (Sanofi-14h), a compound with preference for inhibition of the AGC family kinase SGK3, as an inhibitor of IFN{beta} gene expression in response to STING stimulation of macrophages. Sanofi-14h abrogated SGK activity and also impaired activation of the critical TBK1/IRF3 pathway downstream of STING activation, notably blocking the ligand-induced interaction of STING with TBK1. Deletion of SGK1 and SGK3 in macrophages suppressed activation of IFN{beta} transcription but did not block TBK1/IRF3 activation downstream of STING. Gene and protein expression analysis revealed that deletion of SGK1/3 in a macrophage cell line decreases basal expression of critical transcription factors required for the innate immune response, such as IRF7 and STAT1. Additional studies reveal that other AGC kinase inhibitors block TBK1 and IRF3 activation suggesting common action on a critical regulatory node in the STING pathway. Thus, studies with Sanofi-14h have revealed both SGK-dependent and SGK-independent effects in the STING pathway and suggest a mechanism to alter type 1 IFN transcription through small molecule therapy.

immunology↗

bioRxiv2022

Use of a MAIT activating ligand, 5-OP-RU, as a mucosal adjuvant in a murine model of Vibrio cholerae O1 vaccination.

BackgroundMucosal-associated invariant T (MAIT) cells are innate-like T cells enriched in the mucosa with capacity for B cell help. We hypothesize that targeting MAIT cells, using a MAIT activating ligand as an adjuvant, could improve mucosal vaccine responses to bacterial pathogens. MethodsWe utilized murine models of Vibrio cholerae vaccination to test the adjuvant potential of the MAIT activating ligand, 5-(2-oxopropylideneamino)-6-D-ribitylaminouracil (5-OP-RU). We measured V. cholerae-specific antibody and antibody-secreting cell responses, and used flow cytometry to examine MAIT cell and B cell phenotype, in blood, bronchoalveolar lavage fluid (BALF), and mucosal tissues, following intranasal vaccination with live V. cholerae O1 or a V. cholerae O1 polysaccharide conjugate vaccine. ResultsWe report significant expansion of MAIT cells in the lungs of 5-OP-RU treated mice, and increases in BALF V. cholerae O-specific-polysaccharide IgG responses in our conjugate vaccine model adjuvanted with low-dose 5-OP-RU. No significant differences in humoral responses were found in our live V. cholerae vaccination model. ConclusionsUsing a murine model, we demonstrate the potential, as well as the limitations, of targeting MAIT cells to improve antibody responses to a mucosal cholera vaccine. Our study highlights the need for future research optimizing MAIT cell targeting for improving mucosal vaccines. One Sentence SummaryTargeting mucosal-associated invariant T (MAIT) cells with a mucosal adjuvant in an intranasal cholera vaccine model resulted in significant expansion of lung MAIT cells, but limited improvements in cholera-specific antibody responses.

immunology↗

bioRxiv2022

HuR-dependent expression of Wisp1 is necessary for TGF????-induced cardiac myofibroblast activity

Cardiac fibrosis is regulated by the activation and phenotypic switching of quiescent cardiac fibroblasts to active myofibroblasts, which have extracellular matrix (ECM) remodeling and contractile functions which play a central role in cardiac remodeling in response to injury. Here, we show that expression and activity of the RNA binding protein HuR is increased in cardiac fibroblasts upon transformation to an active myofibroblast. Pharmacological inhibition of HuR significantly blunts the TGF{beta}-dependent increase in ECM remodeling genes, total collagen secretion, in vitro scratch closure, and collagen gel contraction in isolated primary cardiac fibroblasts, suggesting a suppression of TGF{beta}-induced myofibroblast activation upon HuR inhibition. To delineate HuR-dependent mechanisms, we used photoactivatable ribonucleoside-enhanced crosslinking and immunoprecipitation (PAR-CLIP) to identify eleven mRNA transcripts that showed enriched HuR binding following TGF{beta} treatment as well as significant co-expression correlation with HuR, SMA, and periostin using single-cell RNA-sequencing from ischemic-zone isolated fibroblasts. Of these, Wnt1-inducible signaling pathway protein-1 (Wisp1; Ccn4), was the most significantly associated with HuR expression in fibroblasts. Accordingly, we found Wisp1 expression to be increased in cardiac fibroblasts isolated from the ischemic-zone of mouse hearts following ischemia/reperfusion, and confirmed Wisp1 expression to be HuR-dependent in isolated fibroblasts. Finally, addition of exogenous recombinant Wisp1 is able to partially rescue myofibroblast contractile function following HuR inhibition, demonstrating that HuR-dependent Wisp1 expression plays a functional role in HuR-dependent MF activity downstream of TGF{beta}. In conclusion, HuR activity is necessary for the functional activation of primary cardiac fibroblasts in response to TGF{beta}, in part through post-transcriptional regulation of Wisp1. HIGHLIGHTSO_LIThe RNA binding protein HuR is highly expressed in cardiac fibroblasts and its expression strongly correlates with markers of active myofibroblasts C_LIO_LIHuR inhibition reduces migration, contraction, and ECM production activity of cardiac fibroblasts C_LIO_LIExpression of the secreted matricellular protein, Wisp1, is increased in a HuR-dependent manner following TGF{beta} treatment C_LIO_LIRecombinant Wisp1 rescues myofibroblast contractile function following HuR inhibition C_LIO_LIHuR-dependent expression of Wisp1 is necessary for myofibroblast activation C_LI

molecular biology↗

bioRxiv2021

AD Informer Set: Chemical tools to facilitate Alzheimer's disease drug discovery

IntroductionThe portfolio of novel targets to treat Alzheimers disease (AD) has been enriched by the AMP-AD program. MethodsA cheminformatics-driven effort enabled identification of existing small molecule modulators for many protein targets nominated by AMP-AD and suitable positive control compounds to be included in the set. ResultsWe have built an annotated set of 171 small molecule modulators, including mostly inhibitors, targeting 98 unique proteins that have been nominated by AMP-AD consortium members as novel targets for AD treatment. These small molecules vary in their quality and should be considered chemical tools that can be used in efforts to validate therapeutic hypotheses, but which would require further optimization. A physical copy of the AD Informer Set can be ordered via the AD Knowledge Portal. DiscussionSmall molecule tools that enable target validation are important tools for the translation of novel hypotheses into viable therapeutic strategies for AD.

neuroscience↗

bioRxiv2021

Role of Ori in Thermococcus barophilus

The mechanisms underpinning replication of genomic DNA in Archaea have recently been challenged. Species belonging to two different taxonomic orders grow well in the absence of an origin of replication, challenging the role of the replication origin in these organisms. Here, we pursue the investigation of the particular way some archaea manage their DNA replication with Thermococcus barophilus and the role of Ori in this Archaea. Surprisingly we discovered that T. barophilus uses its Ori all along the growth curve with marked increase at the end of exponential phase. Through gene deletion, we show that Ori utilization requires Cdc6, and that origin deletion results in increased time in lag phase and a moderate decrease of growth rate in mutants. The number of chromosomes are quite similar between both strains during exponential and early stationary phases but differs after 24h of growth where {Delta}TbOriC has only 6 chromosomes/cell compared to 10 for the reference strain (WT). Following 1hr of growth in fresh media, {Delta}TbOriC strains contains 3 chromosome copies/cell, whereas the WT contains only 1. We hypothesize that the T. barophilus might degrade DNA to obtain energy to start replication and cell division, whereas the {Delta}TbOriC must maintain more chromosomal copies in order to initiate DNA replication in the absence of an origin or replication. Finally, we analyzed the role of Ori at temperatures above or below the optimal temperature, revealing that Ori is important to start growth at those temperatures, suggesting that replication origins may be involved in stress response.

microbiology↗

bioRxiv2020

Single cell transcriptional profiling reveals helper, effector, and regulatory MAIT cell populations enriched during homeostasis and activation

Mucosal-associated invariant T (MAIT) cells are innate-like lymphocytes that recognize microbial vitamin B metabolites and have emerging roles in infectious disease, autoimmunity, and cancer. Although MAIT cells are identified by a semi-invariant T cell receptor, their phenotypic and functional heterogeneity is not well understood. Here we present an integrated single cell transcriptomic analysis of over 76,000 human MAIT cells during acute and chronic antigen-specific activation with the MR1 ligand 5-OP-RU and non-specific TCR stimulation. We show that MAIT cells span a broad range of homeostatic, effector, helper, tissue-infiltrating, regulatory, and exhausted phenotypes, with distinct gene expression programs associated with CD4+ or CD8+ co-expression. During acute activation, MAIT cells rapidly adopt a cytotoxic phenotype characterized by high expression of GZMB, IFNG and TNF. In contrast, chronic stimulation induces heterogeneous states defined by proliferation, cytotoxicity, immune modulation, and exhaustion. These scRNAseq-defined MAIT cell subtypes were also detected in individuals recently exposed to Mycobacterium tuberculosis infection, confirming their presence during human infection. Our study provides the first comprehensive atlas of human MAIT cells in activation conditions and defines substantial functional heterogeneity, suggesting complex roles in health and disease.

immunology↗