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Jacob, A.

Publications and source records attributed to Jacob, A..

17 recordsLinked to original sources

The PSD-95 interactome of hippocampal synapses potentiated in response to an in vivo learning task

Changes in the molecular composition of synapses underlie the functional changes in synaptic strength after learning. These phenomena have been studied either via imaging of individual candidate proteins, or via the global analysis of the synaptic proteome, lumping together all synapses, regardless of their activation or potentiation status. As a step towards the characterization of the proteome of synapses that have undergone potentiation following a learning paradigm, we have designed SynActive-PSD95-FLAG, a genetically encoded probe consisting of a FLAG-tagged PSD-95 endowed with activity-dependent local translation and expression enrichment at potentiating dendritic spines. SynActive-PSD95-FLAG was expressed via Adeno Associated Viral vectors (AAVs) in the hippocampus of mice which were exposed to contextual fear conditioning. Then, PSD95-FLAG immunoprecipitation from hippocampal extracts, followed by mass spectrometry, was used to characterize the changes in the PSD-95 interactome caused by in vivo synaptic potentiation. This revealed extensive rearrangements in the stoichiometry between PSD-95 and its direct and indirect interactors, highlighting proteins involved in peptide translation, including ribosomal components, and vesicle trafficking. Our results, obtained with a selectively expressed proteomic handle, provide new insight into the molecular substrates of hippocampal learning and a novel tool to study the proteome of potentiated synapses.

neuroscience↗

A Glucan Synthase-Remodeler Module Organizes Branched Glucan Assembly in the Fungal Cell Wall

The fungal cell wall is an essential extracellular matrix that underpins growth, morphogenesis, and pathogenesis. Cell wall construction requires numerous enzymes that synthesize and remodel extracellular polymers, yet the principles governing their spatial and functional organization remain unclear. In the fission yeast Schizosaccharomyces pombe, we identify Ghs2, a predicted glycoside hydrolase 16 (GH16) domain-containing transmembrane protein, as an obligate binding partner of the {beta}-1,3-glucan synthase Bgs3. Ghs2 and Bgs3 co-localize at sites of polarized growth and physically associate in vivo. Structure-guided modeling positions the Ghs2 GH16 domain proximal to the predicted Bgs3 glucan extrusion pore, suggesting coordinated polymer synthesis and remodeling. Solid-state NMR analyses demonstrate that both Ghs2 and Bgs3 are required for the proper accumulation of branched {beta}-1,3-glucan. Together with genetic and cell biological evidence, these findings support a model in which Bgs3 synthesizes linear {beta}-1,3-glucan and Ghs2 subsequently introduces {beta}-1,6-linked branch points onto the nascent polymer. More broadly, we propose that synthase-modifier pairs may act together to shape polymer architecture during cell wall assembly.

cell biology↗

Oxidative Stress-Responsive Cell Wall Remodeling Depends on Phosphate in Candida albicans

The growing number of patients susceptible to invasive Candida albicans infections has intensified the need for new antifungal targets in pathways essential for fungal growth and pathogenesis. Among these pathways, phosphate homeostasis has emerged as a significant determinant of virulence, yet how phosphate availability shapes cell wall structure in response to host-derived oxidative stress remains unclear. During commensal growth, C. albicans cells typically enjoy phosphate repletion and a neutral redox environment. Transitioning to invade host tissues, they simultaneously experience phosphate deprivation and intense extrinsic oxidative stress. Here, we employ solid-state NMR to render details of cell wall remodeling in response to oxidative stress, in its dependence on phosphate. Phosphate deprived cells remodel the rigid wall core and reduce hydration and polymer mobility in the absence of oxidative stress. During hydrogen peroxide exposure, highly mobile outer polysaccharides are primary interactors. In wildtype cells, some of these polymers are recruited into the rigid core, reinforcing the wall scaffold, whereas phosphate transport mutants fail to undergo this remodeling. These findings establish phosphate acquisition as a component of oxidative defense and link nutrient sensing and -availability to the mechanical resilience of the fungal cell wall, revealing an architectural vulnerability with relevance for antifungal development.

microbiology↗

Alveolar Type II Cell-derived MMP1high basal cells promote destructive microcysts in idiopathic pulmonary fibrosis.

Idiopathic Pulmonary Fibrosis (IPF) is a fatal lung disease characterized by progressive epithelial metaplasia and widespread fibrosis. Alveolar microcysts develop near terminal airways in IPF and are linked to poor outcome. Using HTII-280 as a short-term lineage marker of AT2-derived AT0 (SFTPC+/SCGB3A2+) and basaloid (KRT17) cells, together with organoids and spatial transcriptomics (Xenium), we highlight epithelial similarities between respiratory bronchioles (RBs) and alveolar microcysts both having AT0, SCGB3A2+, and basaloid/basal cells (BCs), albeit with expanded BCs in IPF microcysts. The AT0- and AT2-derived BCs strongly express the collagenase, matrix metalloproteinase protein-1, MMP1 in organoids -- mirroring in situ BCs lining IPF microcysts, but distinct from MMP1low BCs in large airways or normal lungs. Expression of MMP1 correlates with basal cell hypoxia pathway activity. MMP1high AT2-derived BCs and IPF BCs promoted type 1 collagen degradation ex vivo and in vivo after xenotransplantation, forming microcystic structures that were abrogated by concurrent MMP inhibitor treatment. Notably, a Frizzled 5 WNT agonist antibody reversed the MMP1high state of AT2-derived BCs, raising a possible therapeutic approach. These findings suggest AT2 transdifferentiation to basaloid/basal cells is uncommon in normal lungs but can expand as a potential source of alveolar destruction, likely contributing to the pernicious course of IPF.

cell biology↗

Distinct spatial distribution of potentiated dendritic spines in encoding- and recall-activated hippocampal neurons

Experimental advancements in neuroscience have identified cellular engrams -- ensembles of neurons whose activation is necessary and sufficient for memory retrieval. Synaptic plasticity, including long-term potentiation, is key to memory encoding and recall, but the relationship between learning-induced dendritic spine potentiation and neuron-wide activation remains unclear. Here, we employ a post-synaptic translation-dependent potentiation reporter (SA-PSD{Delta}Venus) and a neuronal activation reporter (ESARE-dTurquoise) to determine their spatiotemporal correlation in the mouse hippocampal CA1 following contextual fear conditioning (CFC). Potentiated spines were enriched in activated neurons, with distribution varying across CA1 layers at different phases of memory: potentiated spines were more frequent in activated neurons in stratum oriens and stratum lacunosum moleculare after CFC (encoding), while recall-activated neurons showed a larger number of potentiated spines in the stratum radiatum. These findings demonstrate that the relative weight and spatial distribution of potentiated synaptic inputs to hippocampal CA1 pyramidal neurons changes between the encoding and retrieval phases of memory.

neuroscience↗

A stem cell-based platform for functional analysis of genetic variants in lung disease

Advances in genetic and transcriptomic technologies have identified large numbers of genes and variants of potential importance to human disease. Determining the function of these genes and variants is a critical bottleneck in understanding disease etiology. Variants of uncertain significance (VUS) are highly prevalent in our genomes, but our ability to identify them significantly outpaces our ability to determine their molecular and clinical consequences. We developed a genetically tractable induced pluripotent stem cell (iPSC) based platform to investigate gene variant pathogenicity in lung disease, using primary ciliary dyskinesia (PCD) as a model. We identified an individual with a clinical diagnosis of PCD and a VUS in the gene Multiciliate differentiation and DNA synthesis associated cell cycle protein (MCIDAS). Through gene-editing of iPSC-derived airway basal stem cells (iBCs), we precisely defined the molecular and cellular pathogenicity of the variant providing a successful application of the iPSC system to diagnose a lung disease.

cell biology↗

Engineering lung-sensing T cells using synthetic receptors targeting RAGE

Our goal was to leverage synthetic biology approaches to engineer lung-sensing T cells that trigger synthetic transcriptional programs only when in the lung. First, we identified a lung-specific cell surface protein, receptor for advanced glycation endproducts (RAGE), expressed at high levels exclusively in the lung. Then, we engineered chimeric antigen receptors (CAR) and synthetic notch receptors (SynNotch) to bind this protein. We showed that anti-RAGE CAR-T cells traffic to and proliferate in the lung exclusively. Anti-RAGE SynNotch receptors activate transcription of a fluorescent reporter only when co-cultured with RAGE+ cell lines or primary lung cells. Finally, we tested an anti-RAGE SynNotch to anti-CD19 CAR circuit in vivo in mice implanted with lung and flank tumors and found that this approach cleared CD19-expressing lung tumors without affecting CD19-expressing flank tumors. Thus, we demonstrate that RAGE is a lung-specific target and that T cells expressing anti-RAGE receptors can sense and activate lung-specific therapeutic transcriptional programs. This approach could be extended to allow cell-based therapies that target and deliver genetically encoded payloads to treat lung diseases while avoiding systemic toxicity.

synthetic biology↗

Proton-Detected Solid-State NMR for Deciphering Structural Polymorphism and Dynamic Heterogeneity of Cellular Carbohydrates in Pathogenic Fungi

Carbohydrate polymers in their cellular context display highly polymorphic structures and dynamics essential to their diverse functions, yet they are challenging to analyze biochemically. Proton-detection solid-state NMR spectroscopy offers high isotopic abundance and sensitivity, enabling rapid and high-resolution structural characterization of biomolecules. Here, an array of 2D/3D 1H-detection solid-state NMR techniques are tailored to investigate polysaccharides in fully protonated or partially deuterated cells of three prevalent pathogenic fungi: Rhizopus delemar, Aspergillus fumigatus, and Candida albicans, representing filamentous species and yeast forms. Selective detection of acetylated carbohydrates reveals fifteen forms of N-acetylglucosamine units in R. delemar chitin, which coexists with chitosan as separate domains or polymers and associates with proteins only at limited sites. This is supported by distinct order parameters and effective correlation times of their motions, analyzed through relaxation measurements and model-free analysis. Five forms of -1,3-glucan with distinct structural origins and dynamics were identified in A. fumigatus, important for this buffering polysaccharide to perform diverse roles of supporting wall mechanics and regenerating soft matrix under antifungal stress. Eight -1,2-mannan sidechain variants in C. albicans were resolved, highlighting the crucial role of mannan sidechains in maintaining interactions with other cell wall polymers to preserve structural integrity. These methodologies provide novel insights into the functional structures of key fungal polysaccharides and create new opportunities for exploring carbohydrate biosynthesis and modifications across diverse organisms.

biochemistry↗

Solid-State NMR Analysis of Schizosaccharomyces pombe Reveals Role of α-Amylase Family Enzymes in Cell Wall Structure and Function

The fission yeast Schizosaccharomyces pombe is a widely employed model organism for studying the eukaryotic cell cycle. Like plants and bacteria, S. pombe must build a cell wall in concert with its cell cycle, but how cell wall-synthesizing and remodeling enzymes mediate this process remains unclear. Here we characterize the functions of Aah1 and Aah3, two related S. pombe -amylases that are putative members of this evolutionarily conserved family of cell wall-modifying proteins. We found that unlike rod-shaped wildtype S. pombe cells, aah1{Delta} aah3{Delta} cells are nearly spherical, grow slowly, have thickened cell walls, and have severe defects in cell separation following cytokinesis. Solid-state NMR spectroscopy analyses of intact wildtype and aah1{Delta} aah3{Delta} cells revealed that aah1{Delta} aah3{Delta} cell walls are rigidified with a significant reduction in the -glucan matrix, characterized by reduced amounts of the major -1,3-glucan and the minor -1,4-glucan within the rigid and mobile phases; this reduction was compensated for by a two-fold increase in {beta}-glucan content. Indeed, viability of aah1{Delta} aah3{Delta} cells depended on {beta}-glucan upregulation and the cell wall integrity pathway that mediates it. While aah1{Delta} aah3{Delta} cells resemble cells with impaired function of the transglycosylation domain of -glucan synthase 1 (Ags1), increased expression of Aah3 does not compensate for impaired Ags1 function or vice-versa. Overall, our data suggest that Aah1 and Aah3 are required in addition to Ags1, likely downstream, for the transglycosylation of -glucan chains to generate fibers of appropriate dimensions to support proper cell morphology, growth, and division. Significance StatementThis study utilized a range of imaging techniques and high-resolution solid-state NMR spectroscopy of intact S. pombe cells to refine our understanding of S. pombe cell wall composition. This study also determined that two related GPI-anchored -amylase family proteins, Aah1 and Aah3, likely act as transglycosylases non-redundantly with an -glucan synthase in the synthesis of -glucan chains of appropriate content and size to support polarized growth and cell division. Our results also highlight the anti-fungal therapeutic potential of GPI-anchored enzymes acting in concert with glucan synthases.

microbiology↗

Myomatrix arrays for high-definition muscle recording

Neurons coordinate their activity to produce an astonishing variety of motor behaviors. Our present understanding of motor control has grown rapidly thanks to new methods for recording and analyzing populations of many individual neurons over time. In contrast, current methods for recording the nervous systems actual motor output - the activation of muscle fibers by motor neurons - typically cannot detect the individual electrical events produced by muscle fibers during natural behaviors and scale poorly across species and muscle groups. Here we present a novel class of electrode devices ("Myomatrix arrays") that record muscle activity at unprecedented resolution across muscles and behaviors. High-density, flexible electrode arrays allow for stable recordings from the muscle fibers activated by a single motor neuron, called a "motor unit", during natural behaviors in many species, including mice, rats, primates, songbirds, frogs, and insects. This technology therefore allows the nervous systems motor output to be monitored in unprecedented detail during complex behaviors across species and muscle morphologies. We anticipate that this technology will allow rapid advances in understanding the neural control of behavior and in identifying pathologies of the motor system.

neuroscience↗

IRIS: Integrated Retinal Functionality in Image Sensors

Neuromorphic image sensors draw inspiration from the biological retina to implement visual computations in electronic hardware. Gain control in phototransduction and temporal differentiation at the first retinal synapse inspired the first generation of neuromorphic sensors, but processing in downstream retinal circuits, much of which has been discovered in the past decade, has not been implemented in image sensor technology. We present a technology-circuit co-design solution that implements two motion computations occurring at the output of the retina that could have wide applications for vision based decision making in dynamic environments. Our simulations on Globalfoundries 22nm technology node show that, by taking advantage of the recent advances in semiconductor chip stacking technology, the proposed retina-inspired circuits can be fabricated on image sensing platforms in existing semiconductor foundries. Integrated Retinal Functionality in Image Sensors (IRIS) technology could drive advances in machine vision applications that demand robust, high-speed, energy-efficient and low-bandwidth real-time decision making.

bioengineering↗

Editing the core region in HPFH deletions alters fetal and adult globin expression for treatment of β-hemoglobinopathies

Reactivation of fetal hemoglobin (HbF) is the commonly adapted strategy to ameliorate {beta}-hemoglobinopathies. However, the continued production of defective adult hemoglobin (HbA) limits the HbF tetramer production affecting the therapeutic benefits. Here, we tested various deletional hereditary persistence of fetal hemoglobin (HPFH) mutations and identified a 11 kb sequence, encompassing Putative Repressor Region (PRR) to {beta}-globin Exon-1 ({beta}E1), as the core deletion that ablates HbA and exhibit superior production of HbF compared to HPFH or other well-established targets. The PRR-{beta}E1 edited hematopoietic stem and progenitor cells (HSPCs) retained engraftment potential to repopulate for long-term hematopoiesis in immunocompromised mice generating HbF+ cells in vivo. Importantly, the editing induces therapeutically relevant levels of HbF to reverse the phenotypes of both sickle cell disease and {beta}-thalassemia major. These results indicate that the PRR-{beta}E1 gene editing in patient HSPCs can potentially lead to superior therapeutic outcomes for {beta}-hemoglobinopathies gene therapy.

biochemistry↗

Sexual deprivation induces a CRF independent stress response and decreases resistance to stressors in Drosophila via a subpopulation of Neuropeptide F receptor-expressing neurons

Living in a changing environment composed of other behaving animals entails both opportunities and challenges to obtain resources and mating partners. Actions that promote survival and reproduction are reinforced by the brain reward systems, whereas coping with the challenges associated with obtaining these rewards are mediated by stress response pathways. The activation of the latter can impair health and shorten lifespan. Although similar responses to social opportunity and challenge exist across the animal kingdom, little is known about the mechanisms that process reward and stress under different social conditions. Here, we studied the interplay between deprivation of sexual reward and stress response in Drosophila melanogaster and discovered that repeated failures to obtain sexual reward induces a frustration-like state that is characterized by increased arousal, persistent sexual motivation, and impaired ability to cope with starvation and oxidative stressors. We show that this increased arousal and sensitivity to starvation is mediated by disinhibition of neurons that express receptors for the fly homologue of neuropeptide Y (neuropeptide F, NPF). We furthermore demonstrate the existence of an anatomical overlap between stress and reward systems in the fly brain in the form of neurons that co-express receptors for NPF (NPFR) and the corticotropin-releasing factor (CRF)-like homologue Diuretic hormone 44 (Dh44), and that deprivation of sexual reward leads to translocation of forkhead box-subgroup O (FoxO) to the cytoplasm in these neurons. Nevertheless, the activity of Dh44 neurons alone does not mediate sensitivity to starvation and aroused behavior following sexual deprivation, instead, these responses are mediated by disinhibition of ~12-16 NPFR-expressing neurons via a dynamin-independent synaptic signaling mechanism, suggesting the existence of a NPFR mediated stress pathway which is Dh44-independent. This paves the path for using simple model organisms to dissect mechanisms behind anticipation of reward, and more specifically, to determine what happens when expectations to obtain natural and drug rewards are not met.

animal behavior and cognition↗

HNRNPK is retained in the cytoplasm by Keratin 19 to stabilize target mRNAs

Heterogeneous nuclear ribonucleoprotein K (HNRNPK) regulates pre-mRNA processing and long non-coding RNA localization in the nucleus. It was previously shown that shuttling of HNRNPK to the cytoplasm promotes cell proliferation and cancer metastasis. However, the mechanism of HNRNPK cytoplasmic localization, its cytoplasmic RNA ligands, and impact on posttranscriptional gene regulation remain uncharacterized. Here we show that the intermediate filament protein Keratin 19 (K19) directly interacts with HNRNPK and sequesters it in the cytoplasm. Correspondingly, in K19 knockout breast cancer cells, HNRNPK does not localize in the cytoplasm, resulting in reduced cell proliferation. We mapped cytoplasmic HNRNPK target mRNAs using PAR-CLIP where transcriptome data to show that, in the cytoplasm, HNRNPK stabilizes target mRNAs bound to the 3 untranslated region at the expected C-rich sequence elements. Furthermore, these mRNAs are typically involved in cancer progression and include the p53 signaling pathway that is dysregulated upon HNRNPK knockdown or K19 knockout. This study identifies how a cytoskeletal protein can directly regulate gene expression by controlling subcellular localization of RNA binding proteins to support pathways involved in cancer progression.

molecular biology↗

Lytic Reactivation of the Kaposis sarcoma-associated herpesvirus (KSHV) is Accompanied by Major Nucleolar Alterations

The nucleolus is a sub-nuclear compartment whose primary function is the biogenesis of ribosomal subunits. Certain viral infections affect the morphology and composition of the nucleolar compartment and influence ribosomal RNA (rRNA) transcription and maturation. However, no description of nucleolar morphology and function during infection with Kaposis sarcoma-associated herpesvirus (KSHV) is available to date. Using immunofluorescence microscopy, we documented extensive destruction of the nuclear and nucleolar architecture during lytic reactivation of KSHV. This was manifested by redistribution of key nucleolar proteins, including the rRNA transcription factor, UBF, the essential pre-rRNA processing factor Fibrillarin, and the nucleolar multifunctional phosphoproteins Nucleophosmin (NPM1) and Nucleolin. Distinct delocalization patterns were evident; certain nucleolar proteins remained together whereas others dissociated, implying that nucleolar proteins undergo nonrandom programmed dispersion. Of note, neither Fibrillarin nor UBF colocalized with promyelocytic leukemia (PML) nuclear bodies or with the viral protein LANA-1, and their redistribution was not dependent on viral DNA replication or late viral gene expression. No significant changes in pre-rRNA levels and no accumulation of pre-rRNA intermediates were found by RT-qPCR and Northern blot analysis, respectively. Furthermore, fluorescent in situ hybridization (FISH), combined with immunofluorescence, revealed an overlap between Fibrillarin and internal transcribed spacer 1 (ITS1), which represents the primary product of the pre-rRNA, suggesting that the processing of rRNA proceeds during lytic reactivation. Finally, small changes in the levels of pseudouridylation were documented across the rRNA. Taken together, our results suggest that rRNA transcription and processing persist during lytic reactivation of KSHV, yet they may become uncoupled. Whether the observed nucleolar alterations favor productive infection or signify cellular anti-viral responses remains to be determined. Author SummaryWe describe the extensive destruction of the nuclear and nucleolar architecture during lytic reactivation of KSHV. Distinct delocalization patterns are illustrated: certain nucleolar proteins remained associated with each other whereas others dissociated, implying that nucleolar proteins undergo nonrandom programmed dispersion. Of note, no significant changes in pre-rRNA levels and no accumulation of pre-rRNA intermediates were found, suggesting that pre-RNA transcription and processing continue and could be uncoupled during lytic reactivation. Small changes in the levels of pseudouridylation were documented across the rRNA. Previous studies showed that the different forms of KSHV infection are controlled through cellular and viral functions, which reprogram host epigenetic, transcriptomic, post-transcriptomic and proteomic landscapes. The ability of KSHV to affect the nucleolus and rRNA modifications constitutes a novel interaction network between viral and cellular components. The study of rRNA modifications is still in its infancy; however, the notion of altering cell fate by regulating rRNA modifications has recently begun to emerge, and its significance in viral infection is intriguing.

microbiology↗

Loss of Complement Factor H impairs antioxidant capacity and energy metabolism of human RPE cells

Age-related macular degeneration (AMD) is the leading cause of blindness in the elderly population. About 50% of AMD patients present polymorphisms in the Complement Factor H (CFH) gene, coding for Factor H protein (FH). AMD-associated CFH risk variants, Y402H in particular, impair FH function leading to complement overactivation. In AMD, retinal homeostasis is compromised due to dysfunction of retinal pigment epithelium (RPE) cells. Whether FH contributes to AMD pathogenesis only via complement system dysregulation remains unclear. To investigate the potential role of FH on energy metabolism and oxidative stress in RPE cells, we silenced CFH in human hTERT-RPE1 cells. FH-deprived RPE cells exposed to oxidative insult, showed altered metabolic homeostasis, including reduction of glycolysis and mitochondrial respiration, paralleled by an increase in lipid peroxidation. Our data suggest that FH protects RPE cells from oxidative stress and metabolic reprogramming, highlighting a novel function for FH in AMD pathogenesis. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=148 SRC="FIGDIR/small/898551v1_ufig1.gif" ALT="Figure 1"> View larger version (47K): org.highwire.dtl.DTLVardef@32644borg.highwire.dtl.DTLVardef@569cf4org.highwire.dtl.DTLVardef@5a8aa2org.highwire.dtl.DTLVardef@43cc55_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗

Single-cell time-series mapping of cell fate trajectories reveals an expanded developmental potential for human PSC-derived distal lung progenitors

Alveolar epithelial type 2 cells (AEC2s) are the facultative progenitors responsible for maintaining lung alveoli throughout life, yet are difficult to access from patients for biomedical research or lung regeneration applications. Here we engineer AEC2s from human induced pluripotent stem cells (iPSCs) in vitro and use single cell RNA sequencing (scRNA-seq) to profile the detailed kinetics of their differentiation over time. We focus on both the desired target cells as well as those that appear to diverge to alternative endodermal fates. By combining scRNA-seq with lentiviral barcoding to trace differentiating clones, we reveal the bifurcating cell fate trajectories followed as primordial lung progenitors differentiate into mature AEC2s. We define the global transcriptomic signatures of primary developing human AEC2s from fetal through adult stages in order to identify the subset of in vitro differentiating cells that appear to recapitulate the path of in vivo development. In addition, we develop computational methods based on Continuous State Hidden Markov Models (CSHMM) to identify the precise timing and type of signals, such as over-exuberant Wnt responses, that induce some early multipotent NKX2-1+ progenitors to lose lung fate as they clonally diverge into a variety of non-lung endodermal lineages. Finally, we find that this initial developmental plasticity is regulatable via Wnt modulation, and subsides over time, ultimately resulting in iPSC-derived AEC2s that exhibit a stable phenotype and nearly limitless self-renewal capacity in vitro. Our methods and computational approaches can be widely applied to study and control directed differentiation, producing an inexhaustible supply of mature lineages, exemplified here by the generation of AEC2s.

developmental biology↗