Expansion Of Progenitors Research Articles

Fibro-Adipogenic Progenitor Isolation, Expansion, and Differentiation from the Spiny Mouse Model

Fibro-Adipogenic Progenitor Isolation, Expansion, and Differentiation from the Spiny Mouse Model

TMOD-12. DEFINING THE ROLE OF THE DAAM2 R414W GERMLINE VARIANT IN FAMILIAL GLIOMA

Abstract Malignant glioma is the most common primary brain tumor in adults, leading to high morbidity and mortality due to its aggressive nature and limited efficacious treatment options. To improve this prognosis, research has focused on genetic factors that may contribute to glioma. While most glioma cases arise from sporadic somatic mutations, approximately 5-10% are classified as familial glioma, stemming from inherited genetic variations. Although several studies have explored mechanisms behind somatic mutations in glioma, less is known about hereditary variants that promote glioma susceptibility. We recently discovered five germline mutations in Daam2 (Dishevelled associated activator of morphogenesis 2) from familial glioma patients. To examine the role of these mutations in familial glioma, we overexpressed these mutations in patient-derived glioma stem-like cells, which were subsequently orthotopically xenografted into immunodeficient mice. We identified that one of these mutations, Daam2-R414W, promotes tumor cell proliferation both in vitro and in vivo. To further understand the role of the Daam2-R414W mutation in familial glioma, we generated a knock-in immunocompetent mouse model with the Daam2-R414W mutation. In these mutant mice, we found an increased number of proliferating glial progenitor cells in the subventricular zone compared to Daam2 wildtype mice, suggesting the potential of the Daam2-R414W mutation to influence glial progenitor expansion to stimulate glioma initiation. Furthermore, to establish a potential mechanism, we performed proteomic profiling of Daam2 wildtype and Daam2-R414W overexpression tumors and found enrichment of Git1, a GTPase-activating protein involved in cytoskeletal remodeling, suggesting that the Daam2-R414W variant may interact with Git1 to promote tumor invasion. Our findings thus far identify a hereditary genetic variant with the potential to increase the risk of glioma, shedding light on the repercussions of a human developmental gene variant and its potential to disrupt normal cellular machinery to promote malignancy and glioma development.

Molecular Lineages and Spatial Distributions of Subplate Neurons in the Human Fetal Cerebral Cortex.

The expansion of neural progenitors and production of distinct neurons are crucial for architectural assembly and formation of connectivity in human brains. Subplate neurons (SPNs) are among the firstborn neurons in the human fetal cerebral cortex, and play a critical role in establishing intra- and extracortical connections. However, little is known about SPN origin and developmental lineages. In this study, spatial landscapes and molecular trajectories of SPNs in the human fetal cortices from gestational weeks (GW) 10 to 25 are created by performing spatial transcriptomics and single-cell RNA sequencing. Genes known to be evolutionarily human-specific and genes associated with extracellular matrices (ECMs) are found to maintain stable proportions of subplate neurons among other neuronal types. Enriched ECM gene expression in SPNs varies in distinct cortical regions, with the highest level in the frontal lobe of human fetal brains. This study reveals molecular origin and lineage specification of subplate neurons in the human fetal cerebral cortices, and highlights underpinnings of SPNs to cortical neurogenesis and early structural folding.

P53 mutation biases squamocolumnar junction progenitor cells towards dysplasia rather than metaplasia in Barrett’s oesophagus

BackgroundWhile p53 mutations occur early in Barrett’s oesophagus (BE) progression to oesophageal adenocarcinoma (EAC), their role in gastric cardia stem cells remains unclear.ObjectiveThis study investigates the impact of p53 mutation...

Expansion of the neocortex and protection from neurodegeneration by invivo transient reprogramming.

Yamanaka factors (YFs) can reverse some aging features in mammalian tissues, but their effects on the brain remain largely unexplored. Here, we induced YFs in the mouse brain in a controlled spatiotemporal manner in two different scenarios: brain development and adult stages in the context of neurodegeneration. Embryonic induction of YFs perturbed cell identity of both progenitors and neurons, but transient and low-level expression is tolerated by these cells. Under these conditions, YF induction led to progenitor expansion, an increased number of upper cortical neurons and glia, and enhanced motor and social behavior in adult mice. Additionally, controlled YF induction is tolerated by principal neurons in the adult dorsal hippocampus and prevented the development of several hallmarks of Alzheimer's disease, including cognitive decline and altered molecular signatures, in the 5xFAD mouse model. These results highlight the powerful impact of YFs on neural proliferation and their potential use in brain disorders.

Generation of human expandable limb-bud-like progenitors via chemically induced dedifferentiation.

In certain highly regenerative animals, cellular dedifferentiation occurs after injury, allowing specialized cells to become progenitor cells for regeneration. However, this capacity is restricted in human cells due to reduced plasticity. Here, we introduce a chemical-induced dedifferentiation approach that reverts the differentiated cells to a progenitor-like state, conferring the features of human limb bud cells from human adult somatic cells. These chemically induced human limb-bud-like progenitors (hCiLBP cells) show a high degree of transcriptomic similarity to human embryonic limb bud progenitors. Importantly, we established culture conditions that allow hCiLBP cells to undergo extensive expansion while maintaining population homogeneity and long-term self-renewal capacity. Moreover, hCiLBP cells exhibit increased osteochondrogenic differentiation ability, providing an innovative platform for generation of skeletal lineage cell types. These results highlight a potential therapeutic approach for repairing damaged human tissues through reversal of developmental pathways from mature cells to expandable progenitor cells.

Further biological characterization of small molecules UM171 and SR1: In vitro effects on three hematopoietic cell populations from human cord blood

Small molecules UM171 and SR1 have already been taken into clinically-oriented protocols for the ex vivo expansion of hematopoietic stem (HSCs) and progenitor (HPCs) cells. In order to gain further insight into their biology, in the present study we have assessed their effects, both individually and in combination, on the in vitro long-term proliferation and expansion of HSCs and HPCs contained within three different cord blood-derived cell populations: MNCs (CD34+ cells = 0.8 %), LIN− cells (CD34+ cells = 41 %), and CD34+ cells (CD34+ cells >98 %). Our results show that when added to cultures in the absence of recombinant stimulatory cytokines, neither molecule had any effect. In contrast, when added in the presence of hematopoietic cytokines, UM171 and SR1 had significant stimulatory effects on cell proliferation and expansion in cultures of LIN− and CD34+ cells. No significant effects were observed in cultures of MNCs. The effects of both molecules were more pronounced in cultures with the highest proportion of CD34+ cells, and the greatest effects were observed when both molecules were added in combination. In the absence of small molecules, cell numbers reached a peak by days 25–30, and then declined; whereas in the presence of UM171 or/and SR1 cell numbers were sustained up to day 45 of culture. Our results indicate that besides CD34+ cells, LIN− cells could also be used as input cells in clinically-oriented expansion protocols, and that using both molecules simultaneously would be a better approach than using only one of them.

Lamellipodia-Mediated Osteoblast Haptotaxis Guided by Fibronectin Ligand Concentrations on a Multiplex Chip.

Skull morphogenesis is a complex, dynamic process involving two different germ layers and progressing to the coordinated, directional growth of individual bones. The mechanisms underlying directional growth toward the apex are not completely understood. Here, a microfluidic chip-based approach is utilized to test whether calvarial osteoblast progenitors undergo haptotaxis on a gradient of Fibronectin1 (FN1) via lamellipodia. Mimicking the embryonic cranial mesenchyme's FN1 pattern, FN1 gradients is established in the chip using computer modeling and fluorescent labeling. Primary mouse calvarial osteoblast progenitors are plated in the chip along an array of segmented gradients of adsorbed FN1. The study performs single-cell tracking and measures protrusive activity. Haptotaxis is observed at an intermediate FN1 concentration, with an average directional migration index (yFMI) of 0.07, showing a significant increase compared to the control average yFMI of -0.01. A significant increase in protrusive activity is observed during haptotaxis. Haptotaxis is an Arp2/3-dependent, lamellipodia-mediated process. Calvarial osteoblast progenitors treated with the Arp2/3 (Actin Related Protein 2/3 complex) inhibitor CK666 show significantly diminished haptotaxis, with an average yFMI of 0.01. Together, these results demonstrate haptotaxis on an FN1 gradient as a new mechanism in the apical expansion of calvarial osteoblast progenitors during development and shed light on the etiology of calvarial defects.

Induction of Thymus Atrophy and Disruption of Thymocyte Development by Fipronil through Dysregulation of IL-7-Associated Genes.

The susceptibility of the immune system to immunotoxic chemicals is evident, particularly in the thymus, a vital primary immune organ prone to atrophy due to exposure to toxicants. Fipronil (FPN), a widely used insecticide, is of concern due to its potential neurotoxicity, hepatotoxicity, and immunotoxicity. Our previous study showed that FPN disturbed the antigen-specific T-cell functionality in vivo. As T-cell lineage commitment and thymopoiesis are closely interconnected with the normal function of the T-cell-mediated immune responses, this study aims to further examine the toxic effects of FPN on thymocyte development. In this study, 4-week-old BALB/c mice received seven doses of FPN (1, 5, 10 mg/kg) by gavage. Thymus size, medulla/cortex ratio, total thymocyte counts, double-positive thymocyte population, and IL-7-positive cells decreased dose-dependently. IL-7 aids the differentiation of early T-cell precursors into mature T cells, and several essential genes contribute to the maturation of T cells in the thymus. Foxn1 ensures that the thymic microenvironment is suitable for the maturation of T-cell precursors. Lyl1 is involved in specifying lymphoid cells and maintaining T-cell development in the thymus. The c-Kit/SCF collaboration fosters a supportive thymic milieu to promote the formation of functional T cells. The expression of IL-7, IL-7R, c-Kit, SCF, Foxn1, and Lyl1 genes in the thymus was significantly diminished in FPN-treated groups with the concordance with the reduction of IL-7 signaling proteins (IL-7, IL-7R, c-KIT, SCF, LYL1, FOXO3A, and GABPA), suggesting that the dysregulation of T-cell lineage-related genes may contribute to the thymic atrophy induced by FPN. In addition, FPN disturbed the functionality of thymocytes with an increase of IL-4 and IFN-γ production and a decrease of IL-2 secretion after T-cell mitogen stimulation ex vivo. Collectively, FPN significantly deregulated genes related to T-cell progenitor differentiation, survival, and expansion, potentially leading to impaired thymopoiesis.

Loss of Dnajc21 leads to cytopenia and altered nucleotide metabolism in zebrafish

Mutations in the DNAJC21 gene were recently described in Shwachman–Diamond syndrome (SDS), a bone marrow failure syndrome with high predisposition for myeloid malignancies. To study the underlying biology in hematopoiesis regulation and disease, we generated the first in vivo model of Dnajc21 deficiency using the zebrafish. Zebrafish dnajc21 mutants phenocopy key SDS patient phenotypes such as cytopenia, reduced growth, and defective protein synthesis. We show that cytopenia results from impaired hematopoietic differentiation, accumulation of DNA damage, and reduced cell proliferation. The introduction of a biallelic tp53 mutation in the dnajc21 mutants leads to the development of myelodysplastic neoplasia-like features defined by abnormal erythroid morphology and expansion of hematopoietic progenitors. Using transcriptomic and metabolomic analyses, we uncover a novel role for Dnajc21 in nucleotide metabolism. Exogenous nucleoside supplementation restores neutrophil counts, revealing an association between nucleotide imbalance and neutrophil differentiation, suggesting a novel mechanism in dnajc21-mutant SDS biology.

Independent expansion, selection, and hypervariability of the TBC1D3 gene family in humans.

TBC1D3 is a primate-specific gene family that has expanded in the human lineage and has been implicated in neuronal progenitor proliferation and expansion of the frontal cortex. The gene family and its expression have been challenging to investigate because it is embedded in high-identity and highly variable segmental duplications. We sequenced and assembled the gene family using long-read sequencing data from 34 humans and 11 nonhuman primate species. Our analysis shows that this particular gene family has independently duplicated in at least five primate lineages, and the duplicated loci are enriched at sites of large-scale chromosomal rearrangements on Chromosome 17. We find that all human copy-number variation maps to two distinct clusters located at Chromosome 17q12 and that humans are highly structurally variable at this locus, differing by as many as 20 copies and ∼1 Mbp in length depending on haplotypes. We also show evidence of positive selection, as well as a significant change in the predicted human TBC1D3 protein sequence. Last, we find that, despite multiple duplications, human TBC1D3 expression is limited to a subset of copies and, most notably, from a single paralog group: TBC1D3-CDKL These observations may help explain why a gene potentially important in cortical development can be so variable in the human population.

Missense Mutations in Myc Box I Influence Nucleocytoplasmic Transport to Promote Leukemogenesis.

Somatic missense mutations in the phosphodegron domain of the MYC gene (MYC Box I or MBI) are detected in the dominant clones of a subset of patients with acute myeloid leukemia (AML), but the mechanisms by which they contribute to AML are unknown. To investigate the effects of MBI MYC mutations on hematopoietic cells, we employed a multi-omic approach to systematically compare the cellular and molecular consequences of expressing oncogenic doses of wild type, threonine-58 and proline-59 mutant MYC proteins in hematopoietic cells, and we developed a knockin mouse harboring the germline MBI mutation p.T58N in the Myc gene. Both wild-type and MBI mutant MYC proteins promote self-renewal programs and expand highly selected subpopulations of progenitor cells in the bone marrow. Compared with their wild-type counterparts, mutant cells display decreased cell death and accelerated leukemogenesis in vivo, changes that are recapitulated in the transcriptomes of human AML-bearing MYC mutations. The mutant phenotypes feature decreased stability and translation of mRNAs encoding proapoptotic and immune-regulatory genes, increased translation of RNA binding proteins and nuclear export machinery, and distinct nucleocytoplasmic RNA profiles. MBI MYC mutant proteins also show a higher propensity to aggregate in perinuclear regions and cytoplasm. Like the overexpression model, heterozygous p.T58N knockin mice displayed similar changes in subcellular MYC localization, progenitor expansion, transcriptional signatures, and develop hematopoietic tumors. This study uncovers that MBI MYC mutations alter RNA nucleocytoplasmic transport mechanisms to contribute to the development of hematopoietic malignancies.

SMCHD1 activates the expression of genes required for the expansion of human myoblasts.

SMCHD1 is an epigenetic regulatory protein known to modulate the targeted repression of large chromatin domains. Diminished SMCHD1 function in muscle fibers causes Facioscapulohumeral Muscular Dystrophy (FSHD2) through derepression of the D4Z4 chromatin domain, an event which permits the aberrant expression of the disease-causing gene DUX4. Given that SMCHD1 plays a broader role in establishing the cellular epigenome, we examined whether loss of SMCHD1 function might affect muscle homeostasis through additional mechanisms. Here we show that acute depletion of SMCHD1 results in a DUX4-independent defect in myoblast proliferation. Genomic and transcriptomic experiments determined that SMCHD1 associates with enhancers of genes controlling cell cycle to activate their expression. Amongst these cell cycle regulatory genes, we identified LAP2 as a key target of SMCHD1 required for the expansion of myoblasts, where the ectopic expression of LAP2 rescues the proliferation defect of SMCHD1-depleted cells. Thus, the epigenetic regulator SMCHD1 can play the role of a transcriptional co-activator for maintaining the expression of genes required for muscle progenitor expansion. This DUX4-independent role for SMCHD1 in myoblasts suggests that the pathology of FSHD2 may be a consequence of defective muscle regeneration in addition to the muscle wasting caused by spurious DUX4 expression.

Condensate-Promoting ENL Mutation Drives Tumorigenesis In Vivo Through Dynamic Regulation of Histone Modifications and Gene Expression.

Gain-of-function mutations in the histone acetylation "reader" eleven-nineteen-leukemia (ENL), found in acute myeloid leukemia (AML) and Wilms tumor, are known to drive condensate formation and gene activation in cellular systems. However, their role in tumorigenesis remains unclear. Using a conditional knock-in mouse model, we show that mutant ENL perturbs normal hematopoiesis, induces aberrant expansion of myeloid progenitors, and triggers rapid onset of aggressive AML. Mutant ENL alters developmental and inflammatory gene programs in part by remodeling histone modifications. Mutant ENL forms condensates in hematopoietic stem/progenitor cells at key leukemogenic genes, and disrupting condensate formation via mutagenesis impairs its chromatin and oncogenic function. Moreover, treatment with an acetyl-binding inhibitor of the mutant ENL displaces these condensates from target loci, inhibits mutant ENL-induced chromatin changes, and delays AML initiation and progression in vivo. Our study elucidates the function of ENL mutations in chromatin regulation and tumorigenesis and demonstrates the potential of targeting pathogenic condensates in cancer treatment. Significance: A direct link between ENL mutations, condensate formation, and tumorigenesis is lacking. This study elucidates the function and mechanism of ENL mutations in leukemogenesis, establishing these mutations as bona fide oncogenic drivers. Our results also support the role of condensate dysregulation in cancer and reveal strategies to target pathogenic condensates.

Extracellular vesicles originating from melanoma cells promote dysregulation in haematopoiesis as a component of cancer immunoediting.

Haematopoiesis dysregulation with the presence of immature myeloid and erythroid immunosuppressive cells are key characteristics of the immune escape phase of tumour development. Here, the role of in vitro generated B16F10 tumour cell-derived extracellular vesicles (tEVs) as indirect cellular communicators, participating in tumour-induced dysregulation of haematopoiesis, was explored. The isolated tEVs displayed features of small EVs with a size range of 100-200nm, expressed the common EV markers CD63, CD9, and Alix, and had a spherical shape with a lipid bilayer membrane. Proteomic profiling revealed significant levels of angiogenic factors, particularly vascular endothelial growth factor (VEGF), osteopontin, and tissue factor, associated with the tEVs. Systemic administration of these tEVs in syngeneic mice induced splenomegaly and disrupted haematopoiesis, leading to extramedullary haematopoiesis, expansion of splenic immature erythroid progenitors, reduced bone marrow cellularity, medullary expansion of granulocytic myeloid suppressor cells, and the development of anaemia. These effects closely mirrored those observed in tumour-bearing mice and were not seen after heat inactivating the tEVs. In vitro studies demonstrated that tEVs independently induced the expansion of bone marrow granulocytic myeloid suppressor cells and B cells while reducing the frequency of cells in the erythropoietic lineage. These effects of tEVs were significantly abrogated by the blockade of VEGF or heat inactivation. Our findings underscore the important role of tEVs in dysregulating haematopoiesis during the immune escape phase of cancer immunoediting, suggesting their potential as targets for addressing immune evasion and reinstating normal hematopoietic processes.

Mesenchymal Wnts are required for morphogenetic movements of calvarial osteoblasts during apical expansion.

Apical expansion of calvarial osteoblast progenitors from the cranial mesenchyme (CM) above the eye is integral to calvarial growth and enclosure of the brain. The cellular behaviors and signals underlying the morphogenetic process of calvarial expansion are unknown. Time-lapse light-sheet imaging of mouse embryos revealed calvarial progenitors intercalate in 3D in the CM above the eye, and exhibit protrusive and crawling activity more apically. CM cells express non-canonical Wnt/planar cell polarity (PCP) core components and calvarial osteoblasts are bidirectionally polarized. We found non-canonical ligand Wnt5a-/- mutants have less dynamic cell rearrangements and protrusive activity. Loss of CM-restricted Wntless (CM-Wls), a gene required for secretion of all Wnt ligands, led to diminished apical expansion of Osx+ calvarial osteoblasts in the frontal bone primordia in a non-cell autonomous manner without perturbing proliferation or survival. Calvarial osteoblast polarization, progressive cell elongation and enrichment for actin along the baso-apical axis were dependent on CM-Wnts. Thus, CM-Wnts regulate cellular behaviors during calvarial morphogenesis for efficient apical expansion of calvarial osteoblasts. These findings also offer potential insights into the etiologies of calvarial dysplasias.

Alpha-6 integrin deletion delays the formation of Brca1/p53-deficient basal-like breast tumors by restricting luminal progenitor cell expansion

BackgroundThe aberrant amplification of mammary luminal progenitors is at the origin of basal-like breast cancers associated with BRCA1 mutations. Integrins mediate cell–matrix adhesion and transmit mechanical and chemical signals that drive epithelial stem cell functions and regulate tumor progression, metastatic reactivation, and resistance to targeted therapies. Consistently, we have recently shown that laminin-binding integrins are essential for the expansion and differentiation of mammary luminal progenitors in physiological conditions. As over-expression of the laminin-binding α6 integrin (Itgα6) is associated with poor prognosis and reduced survival in breast cancer, we here investigate the role of Itgα6 in mammary tumorigenesis.MethodsWe used Blg-Cre; Brca1F/F; Trp53F/F mice, a model that phenocopies human basal-like breast cancer with BRCA1 mutations. We generated mutant mice proficient or deficient in Itgα6 expression and followed tumor formation. Mammary tumors and pretumoral tissues were characterized by immunohistochemistry, flow cytometry, RT-qPCR, Western blotting and organoid cultures. Clonogenicity of luminal progenitors from preneoplastic glands was studied in 3D Matrigel cultures.ResultsWe show that Itga6 deletion favors activation of p16 cell cycle inhibitor in the preneoplastic tissue. Subsequently, the amplification of luminal progenitors, the cell of origin of Brca1-deficient tumors, is restrained in Itgα6-deficient gland. In addition, the partial EMT program operating in Brca1/p53-deficient epithelium is attenuated in the absence of Itgα6. As a consequence of these events, mammary tumor formation is delayed in Itgα6-deficient mice. After tumor formation, the lack of Itgα6 does not affect tumor growth but rather alters their differentiation, resulting in reduced expression of basal cell markers.ConclusionsOur data indicate that Itgα6 has a pro-tumorigenic role in Blg-Cre; Brca1F/F; Trp53F/F mice developing basal-like mammary tumors. In particular, we reveal that Itgα6 is required for the luminal progenitor expansion and the aberrant partial EMT program that precedes the formation of BRCA1 deficient tumors.

Conditionally immortalized cell lines with mast cell potential

Abstract Prior to the establishment of definitive hematopoiesis, mast cells (MCs) derived from the yolk sac and fetal liver colonize diverse tissues, maintaining a presence throughout life. Following the establishment of definitive hematopoiesis, hematopoietic stem cells from the bone marrow (BM) also contribute to the MC pool. The diverse origins and tissue-resident nature of MCs complicate their study. Therefore, a system facilitating the expansion of MC progenitors and their controlled differentiation becomes crucial. This report outlines the development of conditionally immortalized MC progenitor cell lines based on two tissue sources, i.e. mouse fetal liver and adult bone marrow. To obtain cell lines, retroviral vectors encoding an estrogen-regulated Hox gene were introduced into progenitor cells derived from both tissues. These transduced cells can be expanded in their non-differentiated state for extended periods and upon estrogen removal, these cells differentiate into MCs in the presence of IL-3 and SCF. Resulting mast cells are functionally comparable to BM-derived MCs, initiating degranulation upon IgE cross-linking. Likewise, these MCs express MC-specific proteases such as chymase 1 and MCPT4. In conclusion, our findings highlight the efficacy of estrogen-regulated Hox genes in targeting MC progenitors in both fetal liver and adult BM. The established cell lines serve as reliable tools for studying MC biology, ontogeny and, possibly, disease conditions, such as allergies.

Abstract 2018: The Role Of Interleukin 27 Receptor Signaling In Regulation Of Intestinal Barrier, Gut Microbiota And Abdominal Aortic Aneurysm.

Abdominal aortic aneurysm (AAA) is a cardiovascular disease characterized by accumulation of immune cells, inflammation, and degradation of medial layer of the abdominal aorta. Angiotensin II (Ang II) plays a key role in controlling blood pressure but is also able to regulate various immune and non-immune cells. While some studies suggested the role of Ang II in dysbiosis, the link between alteration of intestinal microbiota and AAA is largely unexplored. Cytokines are established regulators of inflammatory milieu in the aortic wall in AAA, but their distant contribution, for example via control of intestinal microbial homeostasis and cooperation with Ang II, has never been explored. Interleukin (IL)27 is a member of the IL6/IL12 superfamily that regulates various immune and non-immune cells. We previously showed that IL27R signaling cooperates with Ang II in the regulation of myelopoiesis thereby promoting AAA. Myeloid progenitor expansion and myeloid cell production driven by AngII are blunted in Apoe -/- Il27ra -/- mice. Here we found that Apoe -/- Il27ra -/- mice were also protected from gut dysbiosis and contain less pro-inflammatory bacterial genera in their colons. Unexpectedly, microbiota depletion accelerated AAA development in Apoe -/- Il27ra -/- mice, while Apoe -/- controls were protected from the disease. RNA seq analysis revealed upregulation of inflammatory pathways and downregulation in tight junctions and collagen in colons of Apoe -/- Il27ra -/- mice with ablated microbiota. Transcriptomic analysis of Apoe -/- colonic organoids stimulated with recIL27 shows upregulation of pathways linked to cell proliferation, cell cycle, and junction genes, indicating direct role of IL27. The analysis of the bone marrow revealed elevation of early myeloid progenitors which correlated with heightened circulating monocytes and neutrophils in Apoe -/- Il27ra -/- mice with ablated microbiota. Non-targeted metabolomics revealed microbiota and IL27R signaling-dependent alteration of serum metabolites likely mediating the effect on myeloid cells and AAA. Overall, our work uncovers novel role of IL27R signaling in the regulation of AAA, mechanistically connecting intestinal barrier and microbiota to the pathogenesis of this CVD.

Thrombopoietin, the Primary Regulator of Platelet Production: From Mythos to Logos, a Thirty-Year Journey.

Thrombopoietin, the primary regulator of blood platelet production, was postulated to exist in 1958, but was only proven to exist when the cDNA for the hormone was cloned in 1994. Since its initial cloning and characterization, the hormone has revealed many surprises. For example, instead of acting as the postulated differentiation factor for platelet precursors, megakaryocytes, it is the most potent stimulator of megakaryocyte progenitor expansion known. Moreover, it also stimulates the survival, and in combination with stem cell factor leads to the expansion of hematopoietic stem cells. All of these growth-promoting activities have resulted in its clinical use in patients with thrombocytopenia and aplastic anemia, although the clinical development of the native molecule illustrated that "it's not wise to mess with mother nature", as a highly engineered version of the native hormone led to autoantibody formation and severe thrombocytopenia. Finally, another unexpected finding was the role of the thrombopoietin receptor in stem cell biology, including the development of myeloproliferative neoplasms, an important disorder of hematopoietic stem cells. Overall, the past 30 years of clinical and basic research has yielded many important insights, which are reviewed in this paper.