Biology subjects

Moreira, S.

Publications and source records attributed to Moreira, S..

13 recordsLinked to original sources

bioRxiv2026

Aberrant oxidative metabolism selects for TET2-deficient hematopoietic stem and progenitor cells

The mechanism(s) driving selective expansion of mutant hematopoietic stem and progenitor cells (HSPC) in clonal hematopoiesis (CH) are incompletely understood. Here, we address the role of metabolism in selection for HSPC with loss of function mutations in TET2. Loss of Tet2 in murine HSPC triggers overexpression of glycolysis and oxidative phosphorylation genes and increased oxidative metabolism via an enlarged mitochondrial network. However, Tet2-deficient HSPC maintain a normal redox state. Strikingly, compound loss of the rate-limiting pentose phosphate pathway (PPP) enzyme glucose-6-phosphate dehydrogenase (G6PD) triggers increased reactive oxygen species and impairs the fitness of Tet2-deficient HSPC. We find that aberrant oxidative metabolism is also a feature of HSPC in human CH and clonal cytopenia of unknown significance (CCUS). Overall, our data point to aberrant metabolism as a critical and conserved driver of selection in TET2-deficient CH and identify the PPP as a crucial compensatory pathway needed to maintain their selective advantage. Statement of SignificanceThis study identifies oxidative metabolism as a critical driver of selection for TET2-deficient HSPC in clonal hematopoiesis (CH). It also demonstrates that cellular redox state is a vulnerability that impairs their fitness. These insights establish targetable metabolic pathway(s) that could be exploited in the setting of TET2 mutant CH.

cancer biology↗

bioRxiv2025

Stress Granules Underlie Acute Myeloid Leukemia Stem Cell Survival and Stress Adaptation

The link between cancer maintenance and an ability to sustain continued growth through stresses conferred by the cancer state itself is growing. However, there are significant gaps in our understanding of how this stress is managed, particularly at the level of cancer initiating cells. Here, we identify proteins comprising the dynamic, stress-adaptive ribonucleoprotein complexes known as stress granules (SG) to be enriched among the factors essential for leukemic stem cell (LSC)-driven leukemic propagation. Focusing on core SG nucleator G3BP1, we dissect the role of SGs in human acute myeloid leukemia (AML), their targetability, and the mechanisms they govern to uncover a novel propensity for AML, and in particular LSC-enriched fractions, to prime the expression of SG components, form SGs with greater fidelity and to be reliant on their establishment and continued integrity for LSC maintenance. We further unveil the transcript and protein interactome of G3BP1 in the AML context and show that consolidated control of innate immune signaling, and apoptosis repression is executed through regional binding specificity of G3BP1 to highly structured 3UTRs and cooperation with the RNA helicase UPF1 to mediate transcript decay in SGs. Altogether our findings advance novel fundamental principles of stress adaptation exploited in AML and LSCs that may extend to other cancers and uncover SGs as a novel axis for therapy development.

cancer biology↗

bioRxiv2022

Intra-host viral populations of SARS-CoV-2 in immunosuppressed patients with hematologic cancers

Throughout the SARS-CoV-2 pandemic, several variants of concern (VOC) have been identified, many of which share recurrent mutations in the spike proteins receptor binding domain (RBD). This region coincides with known epitopes and can therefore have an impact on immune escape. Protracted infections in immunosuppressed patients have been hypothesized to lead to an enrichment of such mutations and therefore drive evolution towards VOCs. Here, we show that immunosuppressed patients with hematologic cancers develop distinct populations with immune escape mutations throughout the course of their infection. Notably, by investigating the co-occurrence of substitutions on individual sequencing reads in the RBD, we found quasispecies harboring mutations that confer resistance to known monoclonal antibodies (mAbs) such as S:E484K and S:E484A. Furthermore, we provide the first evidence for a viral reservoir based on intra-host phylogenetics. Our results on viral reservoirs can shed light on protracted infections interspersed with periods where the virus is undetectable as well as an alternative explanation for some long-COVID cases. Our findings also highlight that protracted infections should be treated with combination therapies rather than by a single mAbs to clear pre-existing resistant mutations.

genomics↗

bioRxiv2022

A two-step in vivo CRISPR screen unveils pervasive RNA binding protein dependencies for leukemic stem cells and identifies ELAVL1 as a therapeutic target

Acute myeloid leukemia (AML) progression and relapse is fueled by self-renewing leukemic stem cells (LSCs) whose molecular determinants have been difficult to discern from normal hematopoietic stem cells (HSCs) or to uncover in screening approaches focused on general AML cell properties. We have identified a unique set of RNA binding proteins (RBPs) that are enriched in human AML LSCs but repressed in HSCs. Using an in vivo two step CRISPR-Cas9-mediated screening approach to specifically score for cancer stem cell functionality, we found 32 RBPs essential for LSC propagation and self-renewal in MLL-AF9 translocated AML. Using knockdown or small molecule approaches we show that targeting key hit RBP ELAVL1 impaired LSC-driven in vivo leukemic reconstitution and selectively depleted primitive AML cells vs. normal hematopoietic stem and progenitors. Importantly, knockdown of Elavl1 spared HSCs while significantly reducing LSC numbers across genetically diverse leukemias. Integrative RNA-seq and eCLIP-seq profiling revealed hematopoietic differentiation, RNA splicing and mitochondrial metabolism as key features defining the leukemic ELAVL1-mRNA interactome with the mitochondrial import protein TOMM34 being a direct ELAVL1-stabilized target whose inhibition impairs AML propagation. Altogether, through the use of a stem cell-adapted in vivo CRISPR dropout screening strategy, this work demonstrates that a wide variety of post-transcriptionally acting RBPs are important regulators of LSC-survival and self-renewal and, as exemplified by ELAVL1, highlights their potential as therapeutic targets in AML.

cancer biology↗

bioRxiv2021

SARS-CoV-2 Omicron Spike recognition by plasma from individuals receiving BNT162b2 mRNA vaccination with a 16-weeks interval between doses

Continuous emergence of SARS-CoV-2 variants of concern (VOC) is fueling the COVID-19 pandemic. Omicron (B.1.1.529), is rapidly spreading worldwide. The large number of mutations in its Spike raised concerns about a major antigenic drift that could significantly decrease vaccine efficacy and infection-induced immunity. A long interval between BNT162b2 mRNA doses was shown to elicit antibodies that efficiently recognize Spikes from different VOCs. Here we evaluated the recognition of Omicron Spike by plasma from a cohort of SARS-CoV-2 naive and previously-infected individuals that received their BNT162b2 mRNA vaccine 16-weeks apart. Omicron Spike was recognized less efficiently than D614G, Alpha, Beta, Gamma and Delta Spikes. We compared to plasma activity from participants receiving a short (4-weeks) interval regimen. Plasma from individuals of the long interval cohort recognized and neutralized better the Omicron Spike compared to those that received a short interval. Whether this difference confers any clinical benefit against Omicron remains unknown.

microbiology↗

bioRxiv2021

Stretch-induced endogenous electric fields drive neural crest directed collective cell migration in vivo

Directed collective cell migration (dCCM) is essential for morphogenesis1, 2. Cell clusters migrate in inherently complex in vivo environments composed of chemical, electrical, mechanical as well as topological features. While these environmental factors have been shown to allow dCCM in vitro, our understanding of dCCM in vivo is mostly limited to chemical guidance3. Thus, despite its wide biological relevance, the mechanisms that guide dCCM in vivo remain unclear. To address this, we study endogenous electric fields in relation to the migratory environment of the Xenopus laevis cephalic neural crest, an embryonic cell population that collectively and directionally migrates in vivo4, and whose migratory mode has been linked to cancer invasion and metastasis5. Combining bioelectrical, biomechanical and molecular tools, we show that endogenous electric fields drive neural crest dCCM via electrotaxis in vivo. Moreover, we identify the voltage-sensitive phosphatase 1 (Vsp1) as a key component of the molecular mechanism used by neural crest cells to transduce electric fields into a directional cue in vivo. Furthermore, Vsp1 function is specifically required for electrotaxis, being dispensable for cell motility and chemotaxis. Finally, we reveal that endogenous electric fields are mechanoelectrically established. Mechanistically, convergent extension movements of the neural fold generate membrane tension, which in turn opens stretch-activated channels to mobilise the ions required to fuel electric fields. Overall, our results reveal a mechanism of cell guidance, where electrotaxis emerges from the mechanoelectrical and molecular interplay between neighbouring tissues. More broadly, our data contribute to validate the, otherwise understudied, functions of endogenous bioelectrical stimuli in morphogenetic processes6.

developmental biology↗

bioRxiv2021

Impact of temperature on the affinity of SARS-CoV-2 Spike for ACE2

The seasonal nature in the outbreaks of respiratory viral infections with increased transmission during low temperatures has been well established. The current COVID-19 pandemic makes no exception, and temperature has been suggested to play a role on the viability and transmissibility of SARS-CoV-2. The receptor binding domain (RBD) of the Spike glycoprotein binds to the angiotensin-converting enzyme 2 (ACE2) to initiate viral fusion. Studying the effect of temperature on the receptor-Spike interaction, we observed a significant and stepwise increase in RBD-ACE2 affinity at low temperatures, resulting in slower dissociation kinetics. This translated into enhanced interaction of the full Spike to ACE2 receptor and higher viral attachment at low temperatures. Interestingly, the RBD N501Y mutation, present in emerging variants of concern (VOCs) that are fueling the pandemic worldwide, bypassed this requirement. This data suggests that the acquisition of N501Y reflects an adaptation to warmer climates, a hypothesis that remains to be tested.

microbiology↗

bioRxiv2021

A single BNT162b2 mRNA dose elicits antibodies with Fc-mediated effector functions and boost pre-existing humoral and T cell responses

The standard dosing of the Pfizer/BioNTech BNT162b2 mRNA vaccine validated in clinical trials includes two doses administered three weeks apart. While the decision by some public health authorities to space the doses because of limiting supply has raised concerns about vaccine efficacy, data indicate that a single dose is up to 90% effective starting 14 days after its administration. We analyzed humoral and T cells responses three weeks after a single dose of this mRNA vaccine. Despite the proven efficacy of the vaccine at this time point, no neutralizing activity were elicited in SARS-CoV-2 naive individuals. However, we detected strong anti-receptor binding domain (RBD) and Spike antibodies with Fc-mediated effector functions and cellular responses dominated by the CD4+ T cell component. A single dose of this mRNA vaccine to individuals previously infected by SARS-CoV-2 boosted all humoral and T cell responses measured, with strong correlations between T helper and antibody immunity. Neutralizing responses were increased in both potency and breadth, with distinctive capacity to neutralize emerging variant strains. Our results highlight the importance of vaccinating uninfected and previously-infected individuals and shed new light into the potential role of Fc-mediated effector functions and T cell responses in vaccine efficacy. They also provide support to spacing the doses of two-vaccine regimens to vaccinate a larger pool of the population in the context of vaccine scarcity against SARS-CoV-2.

immunology↗

bioRxiv2019

Lgl cortical dynamics are independent of binding to the Scrib-Dlg complex but require Dlg-dependent restriction of aPKC

Apical-basal polarity underpins the formation of specialized epithelial barriers that are critical for metazoan physiology. Although apical-basal polarity is long known to require the basolateral determinants Lethal Giant Larvae (Lgl), Discs Large (Dlg) and Scribble (Scrib), mechanistic understanding of their function is limited. Lgl plays a role as an aPKC inhibitor, but it remains unclear whether Lgl also forms a complex with Dlg or Scrib. Using fluorescence recovery after photobleaching, we show that Lgl does not form immobile complexes at the lateral domain of Drosophila follicle cells. Optogenetic depletion of plasma membrane phosphatidylinositol 4,5-biphosphate (PIP2) or Dlg removal accelerate Lgl cortical dynamics. However, whereas Lgl turnover relies on PIP2 binding, Dlg and Scrib are only required for Lgl localization and dynamic behavior in the presence of aPKC function. Furthermore, light-induced oligomerization of basolateral proteins indicate that Lgl is not part of the Scrib-Dlg complex in vivo. Thus, Scrib-Dlg are necessary to repress aPKC activity in the lateral domain but do not provide cortical binding sites for Lgl. Our work therefore highlights that Lgl does not act in a complex but in parallel with Scrib-Dlg to antagonize apical determinants.

developmental biology↗

bioRxiv2019

Comparison Between Normobaric Hypoxia Altitude Simulation Test and Altitude Hypoxia Predictive Equations in Cystic Fibrosis Patients

BackgroundThe Hypoxia Altitude Simulation Test (HAST) is the Gold Standard to evaluate hypoxia in response to altitude and to decide on in-flight requirements for oxygen supplementation. Several equations are available to predict PaO2 in altitude (PaO2alt), but it remains unclear whether their predictive value is equivalent. We aimed to compare the results obtained by the available methods in a population of cystic fibrosis (CF) adults.\n\nMethodsEighty-eight adults (58 healthy controls and 30 CF patients) performed a spirometry followed by an HAST. HAST results were compared with the predicted PaO2alt made by five equations: 1st: PaO2alt= 0,410 x PaO2ground + 1,7652; 2nd: PaO2alt= 0,519 x PaO2ground + 11,855 x FEV1 (L) - 1,760; 3rd: PaO2alt= 0,453 x PaO2ground + 0,386 x FEV1 (%) + 2,44; 4th: PaO2alt= 0,88 + 0,68 x PaO2ground; 5th: PaO2alt= PaO2ground - 26,6.\n\nResultsNone of the controls required in-flight oxygen neither by HAST or by the five predictive equations. Eleven CF-patients had PaO2alt < 50 mmHg, accessed by HAST. The positive predictive value was 50% (1st), 87.5% (2nd and 3rd), 77.78% (4th) and 58.33% (5th). Areas under the curve were 78.95% (1st), 84.69% (2nd), 88.04% (3rd) and 78.95% (4th and 5th). FEV1 and PaO2ground were correlated with HAST results.\n\nConclusionsThe 3rd equation gave the best predictions in comparison with results obtained by HAST. However, because the individual differences found were substantial for all equations, we still recommend performing a HAST whenever possible to confidently access in-flight hypoxia and the need for oxygen.

pathology↗

bioRxiv2018

TCF7L1 and TCF7 differentially regulate specific mouse ES cell genes in response to GSK-3 inhibition

The genome-wide chromatin occupancy of the TCF/LEF factors and its modulation by Wnt pathway activation remain poorly defined. Here, we describe mouse ES cell (mESC) lines expressing a single copy knock-in of the 3xFLAG epitope at the N-terminus of TCF7L1 and TCF7, the two most-highly expressed TCF/LEF factors in mESCs. TCF7L1 protein levels, detected by immunoblotting with a FLAG antibody, were much higher than TCF7 in mESCs maintained in standard serum- and LIF-supplemented medium, even in the presence of the GSK-3 inhibitor, CHIR99021 (CHIR). We used FLAG antibody-mediated ChIP-seq to determine TCF7 and TCF7L1 chromatin occupancy in mESCs cultured in standard medium with or without CHIR for 14 hours. TCF7 and TCF7L1 displayed very few overlapping ChIP peaks across the genome, with TCF7L1 binding significantly more genes than TCF7 in both culture conditions. Despite a reduction in total TCF7L1 protein after CHIR treatment, the TCF7L1 ChIP peak profiles were not uniformly attenuated. Our data demonstrate that TCF7L1 chromatin occupancy upon short-term CHIR treatment is modulated in a target-specific manner. Our findings also suggest that Wnt target genes in mESCs are not regulated by TCF/LEF switching, and TCF7L1, although often called a constitutive repressor, may serve as a transcriptional activator of certain target genes in CHIR-treated mESCs.\n\nHighlightsO_LIChIP and cytometry data suggest that TCF7L1 does not directly regulate mESC Nanog expression.\nC_LIO_LITCF7L1 remains associated with {beta}-catenin in the presence of CHIR99021.\nC_LIO_LITCF7 and TCF7L1 display different chromatin occupancies in mESCs.\nC_LIO_LITCF7L1 binding at specific genomic sites is variably altered by CHIR99021.\nC_LI

cell biology↗

bioRxiv2018

Endogenous BioID elucidates TCF7L1 interactome modulation upon GSK-3 inhibition in mouse ESCs

Modulation of Wnt target gene expression via the TCF/LEFs remains poorly understood. We employ proximity-based biotin labeling (BioID) to examine GSK-3 inhibitor effects on the TCF7L1 interactome in mouse ESCs. We generated ESC lines with biotin ligase BirA* fused to TCF7L1 by knocking it into the endogenous TCF7L1 locus or by inserting a doxinducible BirA*-TCF7L1 transgene into the Rosa26 locus. Induction yielded BirA*-TCF7L1 levels 3-fold higher than in the endogenous system, but substantial overlap in biotinylated proteins with high peptide counts were detected by each method. Known TCF7L1 interactors TLE3/4 and {beta}-catenin, and numerous proteins not previously associated with TCF7L1, were identified in both systems. Despite reduced BirA*-TCF7L1 levels, the number of hits identified with both BioID approaches increased after GSK-3 inhibition. We elucidate the network of TCF7L1 proximal proteins regulated by GSK-3 inhibition, validate the utility of endogenous BioID, and provide mechanistic insights into TCF7L1 target gene regulation.\n\nHighlightsO_LIBirA*-TCF7L1 at single-copy physiological levels generates robust BioID data\nC_LIO_LICHIR99021 reduces TCF7L1 levels but increases detectable TCF7L1-proximal proteins\nC_LIO_LIThe TCF7L1 interactome of largely epigenetic/transcription factors fluctuates with GSK-3 inhibition\nC_LIO_LIJMJD1C, SALL4 and BRG1/SMARCA4 are validated as TCF7L-interacting proteins\nC_LI

cell biology↗

bioRxiv2018

Anthropometric and functional profiles of elite athletes from different categories at ABADA Capoeira World Championship

This study aimed to characterize the anthropometric and functional profiles of 50 male elite competitors at the 2017 Capoeira World Championship organized by ABADA Capoeira School in the city of Rio de Janeiro. The competitors were divided into different weight categories: lightweight (VIOLA, [≤]76.9 kg; n = 15), intermediate weight (MEDIO, 77.0-85.9 kg; n = 25), and heavyweight (GUNGA, [≥]86.0 kg; n = 10). Two evaluation batteries were performed: 1) anthropometry and somatotype determination and 2) functional performance on push-up, sit-up, and sit-and-reach tests; quadrant jump test (QJT); squat jump (SJ); and countermovement jump (CMJ). Results reveal that the mesomorphic component of the somatotype differed between the GUNGA subgroup and other groups (F[2,47] = 7.617; p = 0.001), while ectomorphy differed between the VIOLA and GUNGA subgroups (F[2,47] = 3.899; p = 0.027). The \"endo-mesomorph\" classification predominated in the three investigated categories. For functional performance, there was a difference in QJT between the VIOLA and GUNGA subgroups (F[2,47] = 4.299; p = 0.019). The endomorphism had a negative correlation (p < 0.01) with the performance in the sit-up (r = -0.51), push -up (r = -0.39), SJ (r = -0.45), and CMJ (r = -0.49). We concluded that at the international level, male elite competitors show predominance in the mesomorphic component of the somatotype. Furthermore, the endomorphic component correlated inversely with functional performance in trunk and upper limb resistance tests and lower limb explosive strength tests. These results can help coaches in targeting specific training programs for Capoeira athletes who aim for a high competitive level.

physiology↗