Showing papers on "Transdifferentiation published in 2012"
TL;DR: It is concluded that a single glial transcription factor is essential for restoration of damaged nerves, acting to control the transdifferentiation of myelin and Remak Schwann cells to dedicated repair cells in damaged tissue.
608 citations
TL;DR: This study provides a method for generating patient-specific airway epithelial cells for disease modeling and in vitro drug testing and reports an in vitro directed differentiation protocol for generating functional CFTR-expressingAirway epithelia from human embryonic stem cells.
Abstract: Cystic fibrosis (CF) is a fatal genetic disease caused by mutations in the CFTR (cystic fibrosis transmembrane conductance regulator) gene, which regulates chloride and water transport across all epithelia and affects multiple organs, including the lungs. Here we report an in vitro directed differentiation protocol for generating functional CFTR-expressing airway epithelia from human embryonic stem cells. Carefully timed treatment by exogenous growth factors that mimic endoderm developmental pathways in vivo followed by air-liquid interface culture results in maturation of patches of tight junction–coupled differentiated airway epithelial cells that demonstrate active CFTR transport function. As a proof of concept, treatment of CF patient induced pluripotent stem cell–derived epithelial cells with a small-molecule compound to correct for the common CF processing mutation resulted in enhanced plasma membrane localization of mature CFTR protein. Our study provides a method for generating patient-specific airway epithelial cells for disease modeling and in vitro drug testing.
383 citations
TL;DR: This work strongly suggests that genes associated with EMT may play a significant role in cisplatin resistance in ovarian cancer, therefore potentially leading to the development of predictive biomarkers of drug response or novel therapeutic strategies for overcoming drug resistance.
Abstract: The epithelial to mesenchymal transition (EMT) is a molecular process through which an epithelial cell undergoes transdifferentiation into a mesenchymal phenotype. The role of EMT in embryogenesis is well-characterized and increasing evidence suggests that elements of the transition may be important in other processes, including metastasis and drug resistance in various different cancers. Agilent 4 × 44 K whole human genome arrays and selected reaction monitoring mass spectrometry were used to investigate mRNA and protein expression in A2780 cisplatin sensitive and resistant cell lines. Invasion and migration were assessed using Boyden chamber assays. Gene knockdown of snail and slug was done using targeted siRNA. Clinical relevance of the EMT pathway was assessed in a cohort of primary ovarian tumours using data from Affymetrix GeneChip Human Genome U133 plus 2.0 arrays. Morphological and phenotypic hallmarks of EMT were identified in the chemoresistant cells. Subsequent gene expression profiling revealed upregulation of EMT-related transcription factors including snail, slug, twist2 and zeb2. Proteomic analysis demonstrated up regulation of Snail and Slug as well as the mesenchymal marker Vimentin, and down regulation of E-cadherin, an epithelial marker. By reducing expression of snail and slug, the mesenchymal phenotype was largely reversed and cells were resensitized to cisplatin. Finally, gene expression data from primary tumours mirrored the finding that an EMT-like pathway is activated in resistant tumours relative to sensitive tumours, suggesting that the involvement of this transition may not be limited to in vitro drug effects. This work strongly suggests that genes associated with EMT may play a significant role in cisplatin resistance in ovarian cancer, therefore potentially leading to the development of predictive biomarkers of drug response or novel therapeutic strategies for overcoming drug resistance.
332 citations
TL;DR: An obligate function for TRPC6 and calcineurin in promoting myofibroblast differentiation is demonstrated, suggesting a comprehensive pathway for myofIBroblast formation in conjunction with TGF-β, p38 MAPK, and SRF.
291 citations
TL;DR: Precise characterization of the deregulated extracellular and intracellular signaling pathways, mediators and cellular differentiation programs that contribute to fibrosis in SSc will facilitate the development of selective, targeted therapeutic strategies.
Abstract: Fibrosis in multiple organs is a prominent pathological finding and distinguishing hallmark of systemic sclerosis (SSc). Findings during the past 5 years have contributed to a more complete understanding of the complex cellular and molecular underpinning of fibrosis in SSc. Fibroblasts, the principal effector cells, are activated in the profibrotic cellular milieu by cytokines and growth factors, developmental pathways, endothelin 1 and thrombin. Innate immune signaling via Toll-like receptors, matrix-generated biomechanical stress signaling via integrins, hypoxia and oxidative stress seem to be implicated in perpetuating the process. Beyond chronic fibroblast activation, fibrosis represents a failure to terminate tissue repair, coupled with an expanded population of mesenchymal cells originating from bone marrow and transdifferentiation of epithelial cells, endothelial cells and pericytes. In addition, studies have identified intrinsic alterations in SSc fibroblasts resulting from epigenetic changes, as well as altered microRNA expression that might underlie the cell-autonomous, persistent activation phenotype of these cells. Precise characterization of the deregulated extracellular and intracellular signaling pathways, mediators and cellular differentiation programs that contribute to fibrosis in SSc will facilitate the development of selective, targeted therapeutic strategies. Effective antifibrotic therapy will ultimately involve novel compounds and repurposing of drugs that are already approved for other indications.
288 citations
TL;DR: It is suggested that Lgr5 marks sensory precursors and that Wnt signaling can promote their proliferation and provide mechanistic insights into Wnt-responsive progenitor cells during sensory organ development.
Abstract: Inner ear hair cells are specialized sensory cells essential for auditory function. Previous studies have shown that the sensory epithelium is postmitotic, but it harbors cells that can behave as progenitor cells in vitro, including the ability to form new hair cells. Lgr5, a Wnt target gene, marks distinct supporting cell types in the neonatal cochlea. Here, we tested the hypothesis that Lgr5+ cells are Wnt-responsive sensory precursor cells. In contrast to their quiescent in vivo behavior, Lgr5+ cells isolated by flow cytometry from neonatal Lgr5EGFP-CreERT2/+ mice proliferated and formed clonal colonies. After 10 d in culture, new sensory cells formed and displayed specific hair cell markers (myo7a, calretinin, parvalbumin, myo6) and stereocilia-like structures expressing F-actin and espin. In comparison with other supporting cells, Lgr5+ cells were enriched precursors to myo7a+ cells, most of which formed without mitotic division. Treatment with Wnt agonists increased proliferation and colony-formation capacity. Conversely, small-molecule inhibitors of Wnt signaling suppressed proliferation without compromising the myo7a+ cells formed by direct differentiation. In vivo lineage tracing supported the idea that Lgr5+ cells give rise to myo7a+ hair cells in the neonatal Lgr5EGFP-CreERT2/+ cochlea. In addition, overexpression of β-catenin initiated proliferation and led to transient expansion of Lgr5+ cells within the cochlear sensory epithelium. These results suggest that Lgr5 marks sensory precursors and that Wnt signaling can promote their proliferation and provide mechanistic insights into Wnt-responsive progenitor cells during sensory organ development.
263 citations
TL;DR: The results indicated that, even under highly standardized culture conditions, donor age and long-term passage have effects on hMSC characteristics, which should be taken into account prior to stem cell-based therapies.
Abstract: Bone marrow-derived human mesenchymal stem cells (BM-hMSCs) represent a promising cell-based therapy for a number of degenerative conditions. Many applications require cell expansion and involve the treatment of diseases and conditions found in an aging population. Therefore, the effects of donor age and long-term passage must be clarified. In this study, the effects of donor age and long-term passage on the morphology, proliferation potential, characteristics, mesodermal differentiation ability, and transdifferentiation potential of hMSCs towards neurogenic lineage were evaluated. Cells from child donors (0–12 years, n = 6) maintained their fibroblast-like morphology up to higher passages and proliferated in a greater number than those from adult (25–50 years, n = 6) and old (over 60 years, n = 6) donors. Adipogenic, osteogenic, and neurogenic differentiation potential decreased with age, while chondrogenic potential did not change. Long-term passage affected the morphology and proliferation of hMSCs from all ages. With increasing passage number, proliferation rate decreased and cells lost their typical morphology. Expression levels of neural markers (β III tubulin and NSE) and topo II isoforms in populations of nondifferentiated hMSCs were investigated by reverse transcription polymerase chain reaction analysis. While neural marker and topo IIβ expression levels increased due to increasing passage number in adult hMSCs compared to child hMSCs, topo IIα decreased in both. These results indicated that, even under highly standardized culture conditions, donor age and long-term passage have effects on hMSC characteristics, which should be taken into account prior to stem cell-based therapies.
247 citations
TL;DR: Hh signaling reduced numbers of glycolytic myofibroblasts and liver fibrosis in mice and similar effects were observed following administration of pharmacologic inhibitors of Hh, which might be applied to diagnosis and treatment of patients with cirrhosis.
204 citations
TL;DR: Recent findings are reviewed that delineate the pathophysiological mechanisms whereby EMT stimulated by TGF-β promotes metastatic progression and disease recurrence in human carcinomas.
Abstract: Transforming growth factor-β (TGF-β) is a potent pleiotropic cytokine that regulates mammalian development, differentiation, and homeostasis in essentially all cell types and tissues. TGF-β normally exerts anticancer activities by prohibiting cell proliferation and by creating cell microenvironments that inhibit cell motility, invasion, and metastasis. However, accumulating evidence indicates that the process of tumorigenesis, particularly that associated with metastatic progression, confers TGF-β with oncogenic activities, a functional switch known as the "TGF-β paradox." The molecular determinants governing the TGF-β paradox are complex and represent an intense area of investigation by researchers in academic and industrial settings. Recent findings link genetic and epigenetic events in mediating the acquisition of oncogenic activity by TGF-β, as do aberrant alterations within tumor microenvironments. These events coalesce to enable TGF-β to direct metastatic progression via the stimulation of epithelial-mesenchymal transition (EMT), which permits carcinoma cells to abandon polarized epithelial phenotypes in favor of apolar mesenchymal-like phenotypes. Attempts to deconstruct the EMT process induced by TGF-β have identified numerous signaling molecules, transcription factors, and microRNAs operant in mediating the initiation and resolution of this complex transdifferentiation event. In addition to its ability to enhance carcinoma cell invasion and metastasis, EMT also endows transitioned cells with stem-like properties, including the acquisition of self-renewal and tumor-initiating capabilities coupled to chemoresistance. Here, we review recent findings that delineate the pathophysiological mechanisms whereby EMT stimulated by TGF-β promotes metastatic progression and disease recurrence in human carcinomas.
198 citations
TL;DR: It is shown that down-regulating crucial tumor suppressor functions, EMT inducers make cells particularly prone to malignant conversion, and that cooperation between an EMT inducer and an active form of RAS is sufficient to trigger transformation of mammary epithelial cells into malignant cells.
Abstract: The epithelial-mesenchymal transition (EMT) is an embryonic transdifferentiation process consisting of conversion of polarized epithelial cells to motile mesenchymal ones. EMT–inducing transcription factors are aberrantly expressed in multiple tumor types and are known to favor the metastatic dissemination process. Supporting oncogenic activity within primary lesions, the TWIST and ZEB proteins can prevent cells from undergoing oncogene-induced senescence and apoptosis by abolishing both p53- and RB-dependent pathways. Here we show that they also downregulate PP2A phosphatase activity and efficiently cooperate with an oncogenic version of H-RAS in malignant transformation of human mammary epithelial cells. Thus, by down-regulating crucial tumor suppressor functions, EMT inducers make cells particularly prone to malignant conversion. Importantly, by analyzing transformed cells generated in vitro and by characterizing novel transgenic mouse models, we further demonstrate that cooperation between an EMT inducer and an active form of RAS is sufficient to trigger transformation of mammary epithelial cells into malignant cells exhibiting all the characteristic features of claudin-low tumors, including low expression of tight and adherens junction genes, EMT traits, and stem cell–like characteristics. Claudin-low tumors are believed to be the most primitive breast malignancies, having arisen through transformation of an early epithelial precursor with inherent stemness properties and metaplastic features. Challenging this prevailing view, we propose that these aggressive tumors arise from cells committed to luminal differentiation, through a process driven by EMT inducers and combining malignant transformation and transdifferentiation.
184 citations
TL;DR: A new method for efficient conditional hair cell ablation in adult mouse utricles is introduced and it is demonstrated that hair cells are spontaneously regenerated in vivo in regions where there may be ongoing hair cell turnover.
Abstract: We developed a transgenic mouse to permit conditional and selective ablation of hair cells in the adult mouse utricle by inserting the human diphtheria toxin receptor (DTR) gene into the Pou4f3 gene, which encodes a hair cell-specific transcription factor. In adult wild-type mice, administration of diphtheria toxin (DT) caused no significant hair cell loss. In adult Pou4f3(+/DTR) mice, DT treatment reduced hair cell numbers to 6% of normal by 14 days post-DT. Remaining hair cells were located primarily in the lateral extrastriola. Over time, hair cell numbers increased in these regions, reaching 17% of untreated Pou4f3(+/DTR) mice by 60 days post-DT. Replacement hair cells were morphologically distinct, with multiple cytoplasmic processes, and displayed evidence for active mechanotransduction channels and synapses characteristic of type II hair cells. Three lines of evidence suggest replacement hair cells were derived via direct (nonmitotic) transdifferentiation of supporting cells: new hair cells did not incorporate BrdU, supporting cells upregulated the pro-hair cell gene Atoh1, and supporting cell numbers decreased over time. This study introduces a new method for efficient conditional hair cell ablation in adult mouse utricles and demonstrates that hair cells are spontaneously regenerated in vivo in regions where there may be ongoing hair cell turnover.
TL;DR: Using in vitro and in vivo infection models, it is demonstrated that the S. Typhimurium type III effector protein SopB induces an epithelial-mesenchymal transition (EMT) of FAE enterocytes into M cells to promote host colonization and invasion.
TL;DR: To explore the signaling mechanisms of EndMT, which are believed to function as fibroblasts in damaged tissue and may therefore have an important role in pathological process, may provide novel therapeutic strategies for treating cancer.
Abstract: Epithelial-mesenchymal transition is an important developmental process, participates in tumor's formation, invasion, and metastasis and has been extensively studied. Recently, endothelial-mesenchymal transition (EndMT), a newly recognized type of cellular transdifferentiation, has been demonstrated to participate in a number of diseases by causing morphology changes and pathological processes. Previous studies showed that EndMT was a critical process of embryonic cardiac development. Not only that recent advances also suggested that EndMT occurred postnatally in cancer and cardiac fibrosis and emerged as a possible source of cancer-associated fibroblasts (CAFs). CAFs were found to acquire properties that promoted tumor development and metastasis formation. Resident endothelial cells undergoing EndMT lose their endothelial markers, acquire a mesenchymal or myofibroblastic phenotype, express mesenchymal cell products such as α-smooth muscle actin and type I collagen and develop invasive and migratory abilities. EndMT-derived cells are believed to function as fibroblasts in damaged tissue and may therefore have an important role in pathological process. However, little is known about the signaling mechanisms that cause endothelial cells to transform into mesenchymal cells. Transforming growth factor-β, Notch, or other signaling pathways could direct or interact to mediate EndMT. Therefore, to explore the signaling mechanisms of EndMT may provide novel therapeutic strategies for treating cancer.
TL;DR: Recent achievements in the maintenance of stem cells, including pluripotent and lineage-specific stem cells and in the control of cell fate conversions, including iPSC reprogramming, conversion of primed to naïve pluripotency, and transdifferentiation are examined, with an emphasis on manipulation with small molecules.
Abstract: Despite the great potential of stem cells for basic research and clinical applications, obstacles - such as their scarce availability and difficulty in controlling their fate - need to be addressed to fully realize their potential. Recent achievements of cellular reprogramming have enabled the generation of induced pluripotent stem cells (iPSCs) or other lineage-committed cells from more accessible and abundant somatic cell types by defined genetic factors. However, serious concerns remain about the efficiency and safety of current genetic approaches to cell reprogramming and traditional culture systems that are used for stem cell maintenance. As a complementary approach, small molecules that target specific signaling pathways, epigenetic processes and other cellular processes offer powerful tools for manipulating cell fate to a desired outcome. A growing number of small molecules have been identified to maintain the self-renewal potential of stem cells, to induce lineage differentiation and to facilitate reprogramming by increasing the efficiency of reprogramming or by replacing genetic reprogramming factors. Furthermore, mechanistic investigations of the effects of these chemicals also provide new biological insights. Here, we examine recent achievements in the maintenance of stem cells, including pluripotent and lineage-specific stem cells, and in the control of cell fate conversions, including iPSC reprogramming, conversion of primed to naive pluripotency, and transdifferentiation, with an emphasis on manipulation with small molecules.
TL;DR: It is hypothesized that autophagy mediates PCa NED in the bone and identified interleukin-6 (IL-6), a cytokine more highly expressed in HS5 cells than in HS27a cells, as a paracrine factor that regulates PCa Autophagy.
Abstract: Autophagy reallocates nutrients and clears normal cells of damaged proteins and organelles. In the context of metastatic disease, invading cancer cells hijack autophagic processes to survive and adapt in the host microenvironment. We sought to understand how autophagy is regulated in the metastatic niche for prostate cancer (PCa) cells where bone marrow stromal cell (BMSC) paracrine signaling induces PCa neuroendocrine differentiation (NED). In PCa, this transdifferentiation of metastatic PCa cells to neuronal-like cells correlates with advanced disease. Because autophagy provides a survival advantage for cancer cells and promotes cell differentiation, we hypothesized that autophagy mediates PCa NED in the bone. Thus, we determined the ability of paracrine factors in conditioned media (CM) from two separate BMSC subtypes, HS5 and HS27a, to induce autophagy in C4-2 and C4-2B bone metastatic PCa cells by characterizing the autophagy marker, LC3. Unlike HS27a CM, HS5 CM induced LC3 accumulation in PCa cells, suggesting autophagy was induced and indicating that HS5 and HS27a secrete a different milieu of paracrine factors that influence PCa autophagy. We identified interleukin-6 (IL-6), a cytokine more highly expressed in HS5 cells than in HS27a cells, as a paracrine factor that regulates PCa autophagy. Pharmacological inhibition of STAT3 activity did not attenuate LC3 accumulation, implying that IL-6 regulates NED and autophagy through different pathways. Finally, chloroquine inhibition of autophagic flux blocked PCa NED; hence autophagic flux maintains NED. Our studies imply that autophagy is cytoprotective for PCa cells in the bone, thus targeting autophagy is a potential therapeutic strategy.
TL;DR: The antidiabetic effect of MSCs intravenously administered is unrelated to their transdifferentiation potential but to their capability to restore the balance between Th1 and Th2 immunological responses along with the modification of the pancreatic microenvironment.
Abstract: Type 1 diabetes mellitus (T1DM) is a chronic metabolic disease that results from cell-mediated autoimmune destruction of insulin-producing cells. In T1DM animal models, it has been shown that the systemic administration of multipotent mesenchymal stromal cells, also referred as to mesenchymal stem cells (MSCs), results in the regeneration of pancreatic islets. Mechanisms underlying this effect are still poorly understood. Our aims were to assess whether donor MSCs (a) differentiate into pancreatic β-cells and (b) modify systemic and pancreatic pathophysiologic markers of T1DM. After the intravenous administration of 5 × 10(5) syngeneic MSCs, we observed that mice with T1DM reverted their hyperglycemia and presented no donor-derived insulin-producing cells. In contrast, 7 and 65 days post-transplantation, MSCs were engrafted into secondary lymphoid organs. This correlated with a systemic and local reduction in the abundance of autoaggressive T cells together with an increase in regulatory T cells. Additionally, in the pancreas of mice with T1DM treated with MSCs, we observed a cytokine profile shift from proinflammatory to antinflammatory. MSC transplantation did not reduce pancreatic cell apoptosis but recovered local expression and increased the circulating levels of epidermal growth factor, a pancreatic trophic factor. Therefore, the antidiabetic effect of MSCs intravenously administered is unrelated to their transdifferentiation potential but to their capability to restore the balance between Th1 and Th2 immunological responses along with the modification of the pancreatic microenvironment. Our data should be taken into account when designing clinical trials aimed to evaluate MSC transplantation in patients with T1DM since the presence of endogenous precursors seems to be critical in order to restore glycemic control.
TL;DR: Fibrosis progression both in vitro and in vivo (animal models and patients) is accompanied by increased NOX4 expression, which mediates acquisition and maintenance of the MFB phenotype, as well as TGF-β-induced death of hepatocytes.
Abstract: A role for the NADPH oxidases NOX1 and NOX2 in liver fibrosis has been proposed, but the implication of NOX4 is poorly understood yet. The aim of this work was to study the functional role of NOX4 in different cell populations implicated in liver fibrosis: hepatic stellate cells (HSC), myofibroblats (MFBs) and hepatocytes. Two different mice models that develop spontaneous fibrosis (Mdr2−/−/p19ARF−/−, Stat3Δhc/Mdr2−/−) and a model of experimental induced fibrosis (CCl4) were used. In addition, gene expression in biopsies from chronic hepatitis C virus (HCV) patients or non-fibrotic liver samples was analyzed. Results have indicated that NOX4 expression was increased in the livers of all animal models, concomitantly with fibrosis development and TGF-β pathway activation. In vitro TGF-β-treated HSC increased NOX4 expression correlating with transdifferentiation to MFBs. Knockdown experiments revealed that NOX4 downstream TGF-β is necessary for HSC activation as well as for the maintenance of the MFB phenotype. NOX4 was not necessary for TGF-β-induced epithelial-mesenchymal transition (EMT), but was required for TGF-β-induced apoptosis in hepatocytes. Finally, NOX4 expression was elevated in patients with hepatitis C virus (HCV)-derived fibrosis, increasing along the fibrosis degree. In summary, fibrosis progression both in vitro and in vivo (animal models and patients) is accompanied by increased NOX4 expression, which mediates acquisition and maintenance of the MFB phenotype, as well as TGF-β-induced death of hepatocytes.
TL;DR: The results suggest that careful manipulation of the Pax6 regulatory circuit may facilitate the generation of retinal and pigment epithelium cells from embryonic or induced pluripotent stem cells.
Abstract: The separation of the optic neuroepithelium into future retina and retinal pigment epithelium (RPE) is a critical event in early eye development in vertebrates. Here we show in mice that the transcription factor PAX6, well-known for its retina-promoting activity, also plays a crucial role in early pigment epithelium development. This role is seen, however, only in a background genetically sensitized by mutations in the pigment cell transcription factor MITF. In fact, a reduction in Pax6 gene dose exacerbates the RPE-to-retina transdifferentiation seen in embryos homozygous for an Mitf null allele, and it induces such a transdifferentiation in embryos that are either heterozygous for the Mitf null allele or homozygous for an RPE–specific hypomorphic Mitf allele generated by targeted mutation. Conversely, an increase in Pax6 gene dose interferes with transdifferentiation even in homozygous Mitf null embryos. Gene expression analyses show that, together with MITF or its paralog TFEC, PAX6 suppresses the expression of Fgf15 and Dkk3. Explant culture experiments indicate that a combination of FGF and DKK3 promote retina formation by inhibiting canonical WNT signaling and stimulating the expression of retinogenic genes, including Six6 and Vsx2. Our results demonstrate that in conjunction with Mitf/Tfec Pax6 acts as an anti-retinogenic factor, whereas in conjunction with retinogenic genes it acts as a pro-retinogenic factor. The results suggest that careful manipulation of the Pax6 regulatory circuit may facilitate the generation of retinal and pigment epithelium cells from embryonic or induced pluripotent stem cells.
TL;DR: This study establishes mural-like tumor cells differentiated from GSCs as a significant contributor to microvasculature of glioblastoma and points to Flk-1 as a potential target for therapeutic intervention that could complement current anti-angiogenic treatment.
Abstract: Recent evidence has shown that glioblastoma stem-like cells (GSCs) can transdifferentiate into endothelial cells and vascular-like tumor cells. The latter pattern of vascularization indicates an alternative microvascular circulation known as vasculogenic mimicry (VM). However, it remains to be clarified how the GSC-driven VM makes a significant contribution to tumor vasculature. Here, we investigated 11 cases of glioblastomas and found that most of them consisted of blood-perfused vascular channels that coexpress mural cell markers smooth muscle α-actin and platelet-derived growth factor receptor β, epidermal growth factor receptor, and vascular endothelial growth factor receptor 2 (Flk-1), but not CD31 or VE-cadherin. This microvasculature coexisted with endothelial cell-associated vessels. GSCs derived from patients with glioblastomas developed vigorous mural cell-associated vascular channels but few endothelial cell vessels in orthotopic animal models. Suppression of Flk-1 activity and gene expression abrogated GSC transdifferentiation and vascularization in vitro, and inhibited VM in animal models. This study establishes mural-like tumor cells differentiated from GSCs as a significant contributor to microvasculature of glioblastoma and points to Flk-1 as a potential target for therapeutic intervention that could complement current anti-angiogenic treatment.
TL;DR: It is demonstrated that miR-29 is under negative regulation by TGF-beta (TGF-β)–Smad3 signaling via dual mechanisms of both inhibiting MyoD binding and enhancing Yin Yang 1 (YY1)-recruited Polycomb association.
Abstract: MicroRNAs (miRNAs) are non-coding RNAs that regulate gene expression in post-transcriptional fashion, and emerging studies support their importance in regulating many biological processes, including myogenic differentiation and muscle development. miR-29 is a promoting factor during myogenesis but its full spectrum of impact on muscle cells has yet to be explored. Here we describe an analysis of miR-29 affected transcriptome in C2C12 muscle cells using a high throughput RNA-sequencing platform. The results reveal that miR-29 not only functions to promote myogenic differentiation but also suppresses the transdifferentiation of myoblasts into myofibroblasts. miR-29 inhibits the fibrogenic differentiation through down-regulating both extracellular matrix genes and cell adhesion genes. We further demonstrate that miR-29 is under negative regulation by TGF-beta (TGF-β)–Smad3 signaling via dual mechanisms of both inhibiting MyoD binding and enhancing Yin Yang 1 (YY1)-recruited Polycomb association. Together, these results identify miR-29 as a pleiotropic molecule in both myogenic and fibrogenic differentiation of muscle cells.
TL;DR: In vivo study showed that PU-PEI-mediated miR145 delivery to xenograft tumors reduced tumor growth and metastasis, sensitized tumors to chemoradiotherapies, and prolonged the survival times of tumor-bearing mice.
TL;DR: Using expression profiling of epigenetic regulators in quiescent and activated primary HSCs, ASH1 is found to be a key transcriptional activator component of the MeCP2 epigenetic relay pathway that orchestrates coordinated induction of multiple profibrogenic genes.
TL;DR: It is demonstrated that miR-29 expression is downregulated in dystrophic muscles of mdx mice, a model of DMD, and TGF-β-miR- 29 as a novel regulatory axis during myoblasts conversion into myofibroblasts constitutes a novel contributing route to muscle fibrogenesis of D MD.
TL;DR: This review makes a summary on current understanding of the roles of miRNAs in the development of liver fibrosis, HSC functions and their potential as novel drug targets.
TL;DR: The transformed cells secrete insulin and are capable of relieving diabetes in streptozotocin-treated NOD-SCID (non-obese diabetic severe combined immunodeficiency) mice however the transformation is not complete and lacks critical aspects of the beta cell phenotype.
Abstract: Pdx1 (pancreatic and duodenal homeobox 1), Ngn3 (neurogenin 3) and MafA (v-maf musculoaponeurotic fibrosarcoma oncogene family, protein A) have been reported to bring about the transdifferentiation of pancreatic exocrine cells to beta (β) cells in vivo. We have investigated the mechanism of this process using a standard in vitro model of pancreatic exocrine cells, the rat AR42j-B13 cell line. We constructed a new adenoviral vector encoding all three genes, called Ad-PNM (adenoviral Pdx1, Ngn3, MafA construct). When introduced into AR42j-B13 cells, Ad-PNM caused a rapid change to a flattened morphology and a cessation of cell division. The expression of exocrine markers is suppressed. Both insulin genes are up-regulated as well as a number of transcription factors normally characteristic of beta cells. At the chromatin level, histone tail modifications of the Pdx1, Ins1 (insulin 1) and Ins2 (insulin 2) gene promoters are shifted in a direction associated with gene activity, and the level of DNA CpG methylation is reduced at the Ins1 promoter. The transformed cells secrete insulin and are capable of relieving diabetes in streptozotocin-treated NOD-SCID (non-obese diabetic severe combined immunodeficiency) mice. However the transformation is not complete. The cells lack expression of several genes important for beta cell function and they do not show glucose-sensitive insulin secretion. We conclude that, for this exocrine cell model, although the transformation is dramatic, the reprogramming is not complete and lacks critical aspects of the beta cell phenotype.
TL;DR: Understanding the effects of matrix components on infarct fibroblasts may guide the design of peptides that reproduce, or inhibit, specific matricellular functions, attenuating adverse remodeling.
Abstract: Cardiac fibroblasts are key cellular effectors of cardiac repair; their phenotype and function are modulated by interactions with extracellular matrix proteins. This review manuscript discusses the effects of the extracellular matrix on the inflammatory and reparative properties of fibroblasts in the infarcted myocardium. Early generation of matrix fragments in the infarct induces a pro-inflammatory and matrix-degrading fibroblast phenotype. Formation of a fibrin/fibronectin-rich provisional matrix serves as a conduit for migration of fibroblasts into the infarcted area. Induction of ED-A fibronectin and nonfibrillar collagens may contribute to myofibroblast transdifferentiation. Upregulation of matricellular proteins promotes transduction of growth factor and cytokine-mediated signals. As the scar matures, matrix cross-linking, clearance of matricellular proteins, and reduced growth factor signaling cause deactivation and apoptosis of reparative infarct fibroblasts. Understanding the effects of matrix components on infarct fibroblasts may guide the design of peptides that reproduce, or inhibit, specific matricellular functions, attenuating adverse remodeling.
TL;DR: It is suggested that Oct4 is the gatekeeper into a reprogramming expressway that can be directed by altering the experimental conditions, including Oct4.
Abstract: Through cellular differentiation, a single cell eventually gives rise to all the various lineages of an organism. This process has traditionally been viewed as irreversible. However, nuclear transfer experiments have demonstrated that differentiated cells can be reprogrammed to form even an entire organism. Yamanaka electrified the world with the discovery that expression of only four transcription factors was sufficient to induce pluripotency in differentiated somatic cells of mammals. Expansion of this work has shown that expression of the master pluripotency gene Oct4 is sufficient to induce pluripotency in neural stem cells. In contrast to somatic cells, germline cells express Oct4 and can acquire pluripotency without the addition of exogenous transcription factors. More recently, it has been possible to also induce an alternative cell fate directly by the transdifferentiation of cells mediated by the introduction of specific transcription factors, including Oct4. Therefore, we suggest that Oct4 is the gatekeeper into a reprogramming expressway that can be directed by altering the experimental conditions.
TL;DR: Observations indicate that Tet2 helps CEBPα rapidly derepress myeloid genes during the conversion of pre-B cells into macrophages.
TL;DR: The results suggest that epigenetically reprogrammed EPCs display a safe, more plastic phenotype and improve postinfarct cardiac repair by both neocardiomyogenesis and neovascularization.
Abstract: Rationale:Although bone marrow endothelial progenitor cell (EPC)-based therapies improve the symptoms in patients with ischemic heart disease, their limited plasticity and decreased function in patients with existing heart disease limit the full benefit of EPC therapy for cardiac regenerative medicine. Objective:We hypothesized that reprogramming mouse or human EPCs, or both, using small molecules targeting key epigenetic repressive marks would lead to a global increase in active gene transcription, induce their cardiomyogenic potential, and enhance their inherent angiogenic potential. Method and Results:Mouse Lin-Sca1+CD31+ EPCs and human CD34+ cells were treated with inhibitors of DNA methyltransferases (5-Azacytidine), histone deacetylases (valproic acid), and G9a histone dimethyltransferase. A 48-hour treatment led to global increase in active transcriptome, including the reactivation of pluripotency-associated and cardiomyocyte-specific mRNA expression, whereas endothelial cell–specific genes were si...
TL;DR: It is found that loss of Rbpj depletes the pancreas of Hes1-expressing CACs, abrogating their ongoing contribution to growth and homeostasis of more proximal duct structures, and provides direct evidence of an endogenous genetic program to control interconversion of cell fates in the adult Pancreas.