Quiescent State Research Articles

An alternative way to break the matrix barrier: an experimental study of a LIFU-mediated, visualizable targeted nanoparticle synergistic amplification for the treatment of malignant fibroblasts

Malignant fibroblasts (MFs) are widely present in various diseases and are characterized by connective tissue proliferation; these cells act as a physical barrier that severely limits drug delivery and affects disease outcomes. Based on this, we constructed the smart, integrated, theranostic, targeted lipid nanoprobe HMME-RG3@PFH to overcome the bottleneck in the early diagnosis and treatment of MF-related diseases. The protein glucose transporter protein 1 (GLUT-1) is overexpressed on MFs, and its ideal substrate, ginsenoside RG3 (RG3), significantly enhances the targeted uptake of HMME-RG3@PFH by MFs in a hypoxic environment and endows the nanomaterial with stealthiness to prolong its circulation. Perfluorohexane (PFH), a substance that can undergo phase change, was encapsulated in the lipid core and vaporized for ultrasound-enhanced imaging under low-intensity focused ultrasound (LIFU) irradiation. Moreover, hematoporphyrin monomethyl ether (HMME) was loaded into the lipid bilayer for photoacoustic molecular imaging and sonodynamic therapy (SDT) of MFs under the combined effects of LIFU. Additionally, HMME-RG3@PFH instantaneously burst during visualization to promote targeted drug delivery. In addition, the increased number of exposed RG3 fragments can regulate the MFs to enter a quiescent state. Overall, this nanoplatform ultimately achieves dual-modal imaging with targeted and precise drug release for visualization and synergistic amplification therapy, providing a new possibility for the early diagnosis and precise treatment of MF-related diseases.

Bach2 repression of CD36 regulates lipid-metabolism-linked effector functions in follicular B cells

The transcription repressor Bach2 plays a crucial role in shaping humoral immunity, but its cell-autonomous function remains elusive. Here, we reveal the mechanism by which Bach2 regulates effector cell maturation in peripheral B cells. In response to Toll-like receptor (TLR) agonists, Bach2 deficiency promotes the differentiation of follicular, but not marginal zone, B cells into effector cells, producing interleukin (IL)-6 and antibodies. This phenomenon is associated with changes in lipid metabolism, such as increases in CD36 expression, lipid influx, and fatty acid oxidation. Consistent with this, Bach2-deficient B cells exhibit elevated levels of mitochondrial oxidative stress, lipid peroxidation, and p38 activation. Mechanistically, Bach2 acts as a repressor of Cd36, and inhibition of CD36 or fatty acid oxidation reduces the differentiation of naive B cells into IL-6- and antibody-secreting cells. These results indicate Bach2 as a key metabolic checkpoint regulator crucial for maintaining a functionally quiescent state of follicular B cells.

A kidney-specific fasting-mimicking diet induces podocyte reprogramming and restores renal function in glomerulopathy.

Cycles of a fasting-mimicking diet (FMD) promote regeneration and reduce damage in the pancreases, blood, guts, and nervous systems of mice, but their effect on kidney disease is unknown. In addition, a FMD has not been tested in rats. Here, we show that cycles of a newly developed low-salt FMD (LS-FMD) restored normal proteinuria and nephron structure and function in rats with puromycin-induced nephrosis compared with that in animals with renal damage that did not receive the dietary intervention. LS-FMD induced modulation of a nephrogenic gene program, resembling renal developmental processes in multiple kidney structures. LS-FMD also activated podocyte-lineage reprogramming pathways and promoted a quiescent state in mature podocytes in the rat kidney damage model. In a pilot clinical study in patients with chronic kidney disease, FMD cycles of 5 days each month for 3 months promoted renoprotection, including reduction of proteinuria and improved endothelial function, compared with that in patients who did not receive the FMD cycles. These results show that FMD cycles, which promote the reprogramming of multiple renal cell types and lead to glomerular damage reversal in rats, should be tested further for the treatment of progressive kidney diseases.

The Developmental Cycle of Spirodela polyrhiza Turions: A Model for Turion-Based Duckweed Overwintering?

Duckweeds are widely distributed small, simply constructed aquatic higher plants (the Lemnaceae) found on quiet freshwater surfaces. Species inhabiting temperate climates may have to cope with long periods of severe cold during the winter season. Several duckweeds form compact resting structures from the assimilatory fronds of the growing season that can bridge inhospitable conditions in a quiescent state. Of these, turions separate from the mother fronds and overwinter on the water body bottom in a dormant state. They can surface, germinate, and sprout to resume active growth upon warming in the spring. The turions of the largest duckweed, Spirodela polyrhiza, have been intensively examined as to ultrastructure, the factors governing their formation and release from dormancy, and the signals driving their germination and sprouting and the accompanying starch degradation. Comparative transcriptomics of assimilatory fronds and dormant turions are revealing the molecular features of this developmental cycle. The results illustrate an elegant sequence of reactions that ensures aquatic survival of even severe winters by frost avoidance in a vegetative mode. Since little is known about other duckweed resting fronds, the S. polyrhiza turion developmental cycle cannot be considered to be representative of duckweed resting fronds in general but can serve as a reference for corresponding investigations.

New orbital periods of high-inclination dwarf novae based on Gaia Alerts photometry

The orbital period of a cataclysmic variable stands as a crucial parameter for investigating the structure and physics of these binary systems, as well as understanding their evolution. We use photometric Gaia data for dwarf novae (DNe) in the quiescent state ---which are available for a number of years--- to determine new orbital periods and improve or modify previously suggested period values. Two approaches are implemented for selecting high-inclination targets, either eclipsing or with ellipsoidal variations. We determine new orbital periods for 75 DNe and improve ephemerides for 27 more (three of which change significantly), contributing 9.4<!PCT!> of the known DNe periods of between 0.05 and 2.0 days, and doubling the number of known periods exceeding 0.44 days. Their phase-folded light curves are presented and arranged by orbital period, illustrating the transition from short-period systems, dominated by radiation from the accretion disc and the hot spot, to longer-period DNe, where the Roche-lobe-filling secondary star is the primary visual flux source. This transition ---which occurs around the well-known period gap (between sim 2 and 3 hours)--- is expected, as DNe with larger orbital periods typically harbour more massive donors, which contribute to the visible flux. However, this transition is not abrupt. Within the same range of periods, we observe systems dominated by ellipsoidal variations, where the companion star is clearly visible, as well as others dominated by the disc and the hot spot. The presence of some DNe with ellipsoidal variations near the lower edge of the period gap is striking, as the companions in these systems are expected to be cool low-mass M-dwarfs not visible in the light curve. This could indicate that we are observing systems where the donor star was originally much more massive and underwent significant nuclear evolution before mass-transfer began, as has been suggested previously for QZ Ser.

Autophagy is required for mammary tumor recurrence by promoting dormant tumor cell survival following therapy

BackgroundMortality from breast cancer is principally due to tumor recurrence. Recurrent breast cancers arise from the pool of residual tumor cells, termed minimal residual disease, that survive treatment and may exist in a dormant state for 20 years or more following treatment of the primary tumor. As recurrent breast cancer is typically incurable, understanding the mechanisms underlying dormant tumor cell survival is a critical priority in breast cancer research. The importance of this goal is further underscored by emerging evidence suggesting that targeting dormant residual tumor cells in early-stage breast cancer patients may be a means to prevent tumor recurrence and its associated mortality. In this regard, the role of autophagy in dormant tumor cell survival and recurrence remains unresolved, with conflicting reports of both pro-survival/recurrence-promoting and pro-death/recurrence-suppressing effects of autophagy inhibition in dormant tumor cells. Resolving this question has important clinical implications.MethodsWe used genetically engineered mouse models that faithfully recapitulate key features of human breast cancer progression, including minimal residual disease, tumor dormancy, and recurrence. We used genetic and pharmacological approaches to inhibit autophagy, including treatment with chloroquine, genetic knockdown of ATG5 or ATG7, or deletion of BECN and determined their effects on dormant tumor cell survival and recurrence.ResultsWe demonstrate that the survival and recurrence of dormant mammary tumor cells following therapy is dependent upon autophagy. We find that autophagy is induced in vivo following HER2 downregulation and remains activated in dormant residual tumor cells. Using genetic and pharmacological approaches we show that inhibiting autophagy by chloroquine administration, ATG5 or ATG7 knockdown, or deletion of a single allele of the tumor suppressor Beclin 1 is sufficient to inhibit mammary tumor recurrence, and that autophagy inhibition results in the death of dormant mammary tumor cells in vivo.ConclusionsOur findings demonstrate a pro-tumorigenic role for autophagy in tumor dormancy and recurrence following therapy, reveal that dormant tumor cells are uniquely reliant upon autophagy for their survival, and indicate that targeting dormant residual tumor cells by inhibiting autophagy impairs tumor recurrence. These studies identify a pharmacological target for a cellular state that is resistant to commonly used anti-neoplastic agents and suggest autophagy inhibition as an approach to reduce dormant minimal residual disease in order to prevent lethal tumor recurrence.

On the origin of star formation quenching in massive galaxies at ≳ in the cosmological simulations IllustrisTNG

ABSTRACT Using the cosmological simulations IllustrisTNG, we perform a comprehensive analysis of quiescent, massive galaxies at $z \gtrsim 3$. The goal is to understand what suppresses their star formation so early in cosmic time, and how other similar mass galaxies remain highly star forming. As a first-order result, the simulations are able to produce massive, quiescent galaxies in this high-redshift regime. We find that active galactic nucleus (AGN) feedback is the primary cause of halting star formation in early, massive galaxies. Not only do the central, supermassive black holes (SMBHs) of the quenched galaxies have earlier seed times, but they also grow faster than in star-forming galaxies. As a result, the quenched galaxies are exposed to AGN feedback for longer, and experience the kinetic, jet mode of the AGN feedback earlier than the star-forming galaxies. The release of kinetic energy reduces inflows of gas while likely maintaining outflows, which keeps a low cold gas fraction and decreases the star formation of the galaxies down to a state of quiescence. In addition to AGN feedback, we also investigate the influence of the large-scale environment. While mergers do not play a significant role in the quenching process, the quenched galaxies tend to reside in more massive haloes and denser regions during their evolution. As this provides a greater initial amount of infalling gas to the galaxies, the large-scale environment can mildly affect the fate of the central SMBH growth and, via AGN feedback, contribute to star formation quenching.

Heterogeneity in oligodendrocyte precursor cell proliferation is dynamic and driven by passive bioelectrical properties

Oligodendrocyte precursor cells (OPCs) generate myelinating oligodendrocytes and are the main proliferative cells in the adult central nervous system. OPCs are a heterogeneous population, with proliferation and differentiation capacity varying with brain region and age. We demonstrate that during early postnatal maturation, cortical, but not callosal, OPCs begin to show altered passive bioelectrical properties, particularly increased inward potassium (K+) conductance, which correlates with G1 cell cycle stage and affects their proliferation potential. Neuronal activity-evoked transient K+ currents in OPCs with high inward K+ conductance potentially release OPCs from cell cycle arrest. Eventually, OPCs in all regions acquire high inward K+ conductance, the magnitude of which may underlie differences in OPC proliferation between regions, with cells being pushed into a dormant state as they acquire high inward K+ conductance and released from dormancy by synchronous neuronal activity. Age-related accumulation of OPCs with high inward K+ conductance might contribute to differentiation failure.

Physiological adaptations of red blood cells during aestivation in the south American lungfish Lepidosiren paradoxa

The South American lungfish Lepidosiren paradoxa inhabits areas with variable pluvial regimes. During aestivation (dormancy state observed in some species during dry seasons), the prolonged period of dryness imposes osmotic stress. We aimed to investigate the physiological and morphological adaptations of RBCs in Lepidosiren paradoxa during aestivation. Here, the lungfish were subjected to aestivation for 20 and 40 days and compared to a control group in an active period. The osmotic fragility, blood osmolality, and pH were measured. Blood smears were performed to assess morphological changes in the RBCs. Lepidosiren paradoxa presented lower hemolysis when compared with a teleost fish and tegu lizard. Hemolysis increased when the lungfish was subjected to 40 days of aestivation (from 6.04 % to 16.51 %; control vs 40-day aestivation). Hematocrit rose in both aestivation groups compared to the control (26.36 %, 41.36 % and 41 %, control, 20 and 40 days, respectively; p < 0.05) indicating changes in RBC volume and hydration status. Moreover, the results revealed increased osmolality in the 40-day aestivation group (244.4 vs 372.1 mmol/Kg; control vs 40-day aestivation). 40 days of aestivation led to a decrease in blood pH when compared to the control and 20-day aestivation groups. Both aestivation durations resulted in a reduction in the perimeter and cell diameters in at least one direction of the RBCs (24 % mean reduction in size from control to 40 days aestivation). These findings suggest that South American lungfish possess remarkable physiological and morphological adaptations in their RBCs during aestivation.

Quiescent cancer cells induced by high-density cultivation reveals cholesterol-mediated survival and lung metastatic traits.

The metastatic cascade, a multifaceted and highly aggressive process, is the primary cause of mortality. The survival of quiescent cancer cells in circulatory system during metastasis is crucial, yet our comprehension is constrained by the absence of universally accepted quiescent cancer models. We developed a quiescent cancer cell model using high-density cultivation. Based on the scRNA-seq analysis, IP-MS, metabolomics, mouse lung metastasis models, cholesterol assay, PLA and other molecular experiments, we explored the molecular mechanism. Immunofluorescence, atomic force microscope, FluidFM, and shear stress stimulation were used to analyze the cytoskeleton and membrane properties contributing to mechanical force resistance. We established a quiescent cancer cell model induced by high-density cultivation. Single-cell RNA sequencing (scRNA-seq) analysis reveals that CDC25A plays a crucial role in the transition to quiescence, with its expression significantly elevated in the quiescent state. Depletion of CDC25A leads to an increased proliferative capacity, and reduced metastasis under high-density conditions. Mechanistically, upregulated CDC25A in quiescent cells enhances cholesterol metabolism via endosome pathways, leading to cell cycle arrest. This increase in cholesterol reinforces the cytoskeleton, alters membrane properties, and improves resistance to mechanical forces in circulatory system. CDC25A significantly increased the cholesterol metabolism through endosome pathway in quiescent cancer cells, leading to the significant changes in cytoskeleton and membrane properties so as to enhance the resistance of mechanical force in circulatory system, facilitating lung metastasis. In high-density cultivation, quiescent cancer cells, up-regulate cholesterol metabolism by CDC25A through endosome pathway, enhancing the resistance to mechanical force in circulatory system, facilitating lung metastasis.

YAP Overcomes Mechanical Barriers to Induce Mitotic Rounding and Adult Cardiomyocyte Division.

Many specialized cells in adult organs acquire a state of cell cycle arrest and quiescence through unknown mechanisms. Our limited understanding of mammalian cell cycle arrest is derived primarily from cell culture models. Adult mammalian cardiomyocytes, a classic example of cell cycle arrested cells, exit the cell cycle postnatally and remain in an arrested state for the life of the organism. Cardiomyocytes can be induced to re-enter the cell cycle by YAP5SA, an active form of the Hippo signaling pathway effector YAP. We performed clonal analyses to determine the cell kinetics of YAP5SA cardiomyocytes. We also performed single-cell RNA sequencing, marker gene analysis, and functional studies to examine how YAP5SA cardiomyocytes progress through the cell cycle. We discovered that YAP5SA-expressing cardiomyocytes divided efficiently, with >20% of YAP5SA cardiomyocyte clones containing ≥2 cardiomyocytes. YAP5SA cardiomyocytes re-entered cell cycle at the G1/S transition and had an S phase lasting ≈48 hours. Sarcomere disassembly is required for cardiomyocyte progression from S to G2 phase and the induction of mitotic rounding. Although oscillatory Cdk expression was induced in YAP5SA cardiomyocytes, these cells inefficiently progressed through G2 phase. This is improved by inhibiting P21 function, implicating checkpoint activity as an additional barrier to YAP5SA-induced cardiomyocyte division. Our data reveal that YAP5SA overcomes the mechanically constrained myocardial microenvironment to induce mitotic rounding with cardiomyocyte division, thus providing new insights into the in vivo mechanisms that maintain cell cycle quiescence in adult mammals.

H2AK119ub dynamics controls hair follicle stem cell quiescence.

The transition of stem cells from a quiescent state to an active state is a finely tuned process that requires the dismantling of the quiescence program and the establishment of a cell cycle-promoting transcriptional landscape. Whether epigenetic processes control stem cell states to promote the regeneration of adult tissues remains elusive. In this study, we show that a repressive histone modification, H2AK119ub, is dynamic between quiescent and active hair follicle stem cells (HFSCs) in the adult murine skin. Ablation of H2AK119ub in HFSCs leads to impaired quiescence leading to premature activation and an eventual exhaustion of HFSC pool. Transcriptional and chromatin studies revealed that H2AK119ub directly represses a proliferation promoting transcriptional program in the HFSCs to preserve quiescence. Lastly, we identify that the inhibitory FGF signaling produced by the hair follicle niche keratinocytes maintains H2AK119ub in quiescent HFSCs. Together, these findings reveal that a repressive histone mark, H2AK119ub, is under the dynamic regulation of inhibitory niche signaling to prevent the untimely establishment of an activated state to preserve SC function and longevity.

Epigenetic Regulation in Myocardial Fibroblasts and Its Impact on Cardiovascular Diseases

Myocardial fibroblasts play a crucial role in heart structure and function. In recent years, significant progress has been made in understanding the epigenetic regulation of myocardial fibroblasts, which is essential for cardiac development, homeostasis, and disease progression. In healthy hearts, cardiac fibroblasts (CFs) play a crucial role in synthesizing the extracellular matrix (ECM) when in a dormant state. However, under pathological and environmental stress, CFs transform into activated fibroblasts known as myofibroblasts. These myofibroblasts produce an excess of ECM, which promotes cardiac fibrosis. Although multiple molecular mechanisms are associated with CF activation and myocardial dysfunction, emerging evidence highlights the significant involvement of epigenetic regulation in this process. Epigenetics refers to the heritable changes in gene expression that occur without altering the DNA sequence. These mechanisms have emerged as key regulators of myocardial fibroblast function. This review focuses on recent advancements in the understanding of the role of epigenetic regulation and emphasizes the impact of epigenetic modifications on CF activation. Furthermore, we present perspectives and prospects for future research on epigenetic modifications and their implications for myocardial fibroblasts.

Maltodextrin-derived nanoparticles resensitize intracellular dormant Staphylococcus aureus to rifampicin

Intracellular bacteria are recognized as a crucial factor in the persistence and recurrence of infections. The efficacy of current antibiotic treatments faces substantial challenges due to the dormant state formation of intracellular bacteria. In this study, we devised a strategy aimed at reverting intracellular dormant bacteria to a metabolically active state, thereby increasing their vulnerability to antibiotics. We found that oligosaccharides, especially maltodextrin (MD), can be absorbed by dormant S. aureus, leading to their revival and restoration of sensitivity to rifampicin (Rif). We then synthesized a reactive oxygen species (ROS)-responsive MD-prodrug by covalently binding MD with 4-(hydroxymethyl) phenylboronic acid pinacol ester (MD-PBAP) and prepared a ROS-responsive nanoparticles (MDNP) using a nanoprecipitation and self-assembly method. Once internalized by host cells, MDNP was degraded to MD, reactivating dormant S. aureus, and enhancing their susceptibility to Rif. More importantly, MDNP treatment restored the sensitivity of intracellular persistent S. aureus to Rif in both a reservoir transfer model and whole-body infection model. Additionally, MDNP have demonstrated excellent biocompatibility in both in vitro and in vivo settings. These results offer a promising therapeutic avenue for managing persistent intracellular bacterial infections by reviving and resensitizing intracellular dormant bacteria to conventional antibiotics.

Protein aggregation is a consequence of the dormancy-inducing membrane toxin TisB in Escherichia coli.

Protein aggregates occur in all living cells due to misfolding of proteins. In bacteria, protein aggregation is associated with cellular inactivity, which is related to dormancy and tolerance to stressful conditions, including exposure to antibiotics. In Escherichia coli, the membrane toxin TisB is an important factor for dormancy and antibiotic tolerance upon DNA damage mediated by the fluoroquinolone antibiotic ciprofloxacin. Here, we show that TisB provokes protein aggregation, which, in turn, promotes an extended state of cellular dormancy. Our study suggests that protein aggregation is a consequence of membrane toxins with the potential to affect the duration of dormancy and the outcome of antibiotic therapy.

Microtubule reorganization and quiescence: an intertwined relationship.

Quiescence is operationally defined as a reversible proliferation arrest. This cellular state is central for both organism development and homeostasis, its dysregulation causing many pathologies. The quiescent state encompasses very diverse cellular situations depending on the cell type and its environment. Further, quiescent cell properties evolve with time, a process that is thought to be at the origin of aging in multicellular organisms. Microtubules are found in all eukaryotes, and are essential for cell proliferation as they support chromosome segregation and intracellular trafficking. Upon proliferation cessation and quiescence establishment, the microtubule cytoskeleton was shown to undergo significant remodeling. The purpose of this review is to examine the literature in search of evidence to determine whether the observed microtubule reorganizations are merely a consequence of quiescence establishment or if they somehow participate in this cell fate decision.

Evidence for biomolecular condensates of MatP in spatiotemporal regulation of the bacterial cell division cycle.

An increasing number of proteins involved in bacterial cell cycle events have been recently shown to undergo phase separation. The resulting biomolecular condensates play an important role in cell cycle protein function and may be involved in development of persister cells tolerant to antibiotics. Here we report that the E. coli chromosomal Ter macrodomain organizer MatP, a division site selection protein implicated in the coordination of chromosome segregation with cell division, forms biomolecular condensates in cytomimetic systems. These condensates are favored by crowding and preferentially localize at the membrane of microfluidics droplets, a behavior probably mediated by MatP-lipid binding. Condensates are negatively regulated and partially dislodged from the membrane by DNA sequences recognized by MatP ( matS ), which partition into them. Unexpectedly, MatP condensation is enhanced by FtsZ, a core component of the division machinery previously described to undergo phase separation. Our biophysical analyses uncover a direct interaction between the two proteins, disrupted by matS sequences. This binding might have implications for FtsZ ring positioning at mid-cell by the Ter linkage, which comprises MatP and two other proteins that bridge the canonical MatP/FtsZ interaction. FtsZ/MatP condensates interconvert with bundles in response to GTP addition, providing additional levels of regulation. Consistent with discrete foci reported in cells, MatP biomolecular condensates may facilitate MatP's role in chromosome organization and spatiotemporal regulation of cytokinesis and DNA segregation. Moreover, sequestration of MatP in these membraneless compartments, with or without FtsZ, could promote cell entry into dormant states that are able to survive antibiotic treatments.

BMP2 and BMP7 cooperate with H3.3K27M to promote quiescence and invasiveness in pediatric diffuse midline gliomas.

Pediatric diffuse midline gliomas (pDMG) are an aggressive type of childhood cancer with a fatal outcome. Their major epigenetic determinism has become clear, notably with the identification of K27M mutations in histone H3. However, the synergistic oncogenic mechanisms that induce and maintain tumor cell phenotype have yet to be deciphered. In 20 to 30% of cases, these tumors have an altered BMP signaling pathway with an oncogenic mutation on the BMP type I receptor ALK2, encoded by ACVR1. However, the potential impact of the BMP pathway in tumors non-mutated for ACVR1 is less clear. By integrating bulk, single-cell, and spatial transcriptomic data, we show here that the BMP signaling pathway is activated at similar levels between ACVR1 wild-type and mutant tumors and identify BMP2 and BMP7 as putative activators of the pathway in a specific subpopulation of cells. By using both pediatric isogenic glioma lines genetically modified to overexpress H3.3K27M and patients-derived DIPG cell lines, we demonstrate that BMP2/7 synergizes with H3.3K27M to induce a transcriptomic rewiring associated with a quiescent but invasive cell state. These data suggest a generic oncogenic role for the BMP pathway in gliomagenesis of pDMG and pave the way for specific targeting of downstream effectors mediating the K27M/BMP crosstalk.

BMP2 and BMP7 cooperate with H3.3K27M to promote quiescence and invasiveness in pediatric diffuse midline gliomas

Pediatric diffuse midline gliomas (pDMG) are an aggressive type of childhood cancer with a fatal outcome. Their major epigenetic determinism has become clear, notably with the identification of K27M mutations in histone H3. However, the synergistic oncogenic mechanisms that induce and maintain tumor cell phenotype have yet to be deciphered. In 20 to 30% of cases, these tumors have an altered BMP signaling pathway with an oncogenic mutation on the BMP type I receptor ALK2, encoded by ACVR1. However, the potential impact of the BMP pathway in tumors non-mutated for ACVR1 is less clear. By integrating bulk, single-cell, and spatial transcriptomic data, we show here that the BMP signaling pathway is activated at similar levels between ACVR1 wild-type and mutant tumors and identify BMP2 and BMP7 as putative activators of the pathway in a specific subpopulation of cells. By using both pediatric isogenic glioma lines genetically modified to overexpress H3.3K27M and patients-derived DIPG cell lines, we demonstrate that BMP2/7 synergizes with H3.3K27M to induce a transcriptomic rewiring associated with a quiescent but invasive cell state. These data suggest a generic oncogenic role for the BMP pathway in gliomagenesis of pDMG and pave the way for specific targeting of downstream effectors mediating the K27M/BMP crosstalk.

Relevance of charged and polar amino acids for functionality of membrane toxin TisB

Bacterial dormancy is marked by reduced cellular activity and the suspension of growth. It represents a valuable strategy to survive stressful conditions, as exemplified by the long-term tolerance towards antibiotics that is attributable to a fraction of dormant cells, so-called persisters. Here, we investigate the membrane toxin TisB (29 amino acids) from the chromosomal toxin-antitoxin system tisB/istR-1 in Escherichia coli. TisB depolarizes the inner membrane in response to DNA damage, which eventually promotes a stress-tolerant state of dormancy within a small fraction of the population. Using a plasmid-based system for moderate tisB expression and single amino acid substitutions, we dissect the importance of charged and polar amino acids. We observe that the central amino acids lysine 12 and glutamine 19 are of major importance for TisB functionality, which is further validated for lysine 12 in the native context upon treatment with the DNA-damaging antibiotic ciprofloxacin. Finally, we apply a library-based approach to test additional TisB variants in higher throughput, revealing that at least one positive charge at the C-terminus (either lysine 26 or 29) is mandatory for TisB-mediated dormancy. Our study provides insights into the molecular basis for TisB functionality and extends our understanding of bacterial membrane toxins.