Reflux esophagitis damages the squamous epithelium that normally lines the esophagus, and promotes replacement of the damaged squamous lining by the intestinal metaplasia of Barrett’s esophagus, the ...precursor of esophageal adenocarcinoma. Therefore, to prevent the development of Barrett’s metaplasia and esophageal adenocarcinoma, the pathogenesis of reflux esophagitis must be understood. We have reported that reflux esophagitis, both in a rat model and in humans, develops as a cytokine-mediated inflammatory injury (i.e., cytokine sizzle), not as a caustic chemical injury (i.e., acid burn), as traditionally has been assumed. Moreover, reflux induces activation of hypoxia inducible factor (HIF)-2α, which enhances the transcriptional activity of nuclear factor kappa-light-chain-enhancer of activated B cells
(
NF-κB) causing increases in pro-inflammatory cytokines and in migration of T lymphocytes, an underlying molecular mechanism for this cytokine-mediated injury. In some individuals, reflux esophagitis heals with Barrett’s metaplasia. A number of possibilities exist for the origin of the progenitor cells that give rise to this intestinal metaplasia including those of the esophagus, the proximal stomach, or the bone marrow. However, intestinal cells are not normally found in the esophagus, the stomach, or the bone marrow. Thus, the development of Barrett’s intestinal metaplasia must involve some molecular reprogramming of key developmental transcription factors within the progenitor cell, a process termed transcommitment, which may be initiated by the noxious components of the gastric refluxate. This review will highlight recent studies on the pathogenesis of reflux esophagitis and on reflux-related molecular reprogramming of esophageal squamous epithelial cells in the pathogenesis of Barrett’s metaplasia.
Reprogramming of cardiac fibroblasts into induced cardiomyocyte-like cells in situ represents a promising strategy for cardiac regeneration. A combination of 3 cardiac transcription factors, Gata4, ...Mef2c, and Tbx5 (GMT), can convert fibroblasts into induced cardiomyocyte-like cells, albeit with low efficiency in vitro.
We screened 5500 compounds in primary cardiac fibroblasts to identify the pathways that can be modulated to enhance cardiomyocyte reprogramming.
We found that a combination of the transforming growth factor-β inhibitor SB431542 and the WNT inhibitor XAV939 increased reprogramming efficiency 8-fold when added to GMT-overexpressing cardiac fibroblasts. The small molecules also enhanced the speed and quality of cell conversion; we observed beating cells as early as 1 week after reprogramming compared with 6 to 8 weeks with GMT alone. In vivo, mice exposed to GMT, SB431542, and XAV939 for 2 weeks after myocardial infarction showed significantly improved reprogramming and cardiac function compared with those exposed to only GMT. Human cardiac reprogramming was similarly enhanced on transforming growth factor-β and WNT inhibition and was achieved most efficiently with GMT plus myocardin.
Transforming growth factor-β and WNT inhibitors jointly enhance GMT-induced direct cardiac reprogramming from cardiac fibroblasts in vitro and in vivo and provide a more robust platform for cardiac regeneration.
Identification of the thyroid transcription factors (TTFs), NKX2-1, FOXE1, PAX8 and HHEX, has considerably advanced our understanding of thyroid development, congenital thyroid disorders and thyroid ...cancer. The TTFs are fundamental to proper formation of the thyroid gland and for maintaining the functional differentiated state of the adult thyroid; however, they are not individually required for precursor cell commitment to a thyroid fate. Although knowledge of the mechanisms involved in thyroid development has increased, the full complement of genes involved in thyroid gland specification and the signals that trigger expression of the genes that encode the TTFs remain unknown. The mechanisms involved in thyroid organogenesis and differentiation have provided clues to identifying the genes that are involved in human congenital thyroid disorders and thyroid cancer. Mutations in the genes that encode the TTFs, as well as polymorphisms and epigenetic modifications, have been associated with thyroid pathologies. Here, we summarize the roles of the TTFs in thyroid development and the mechanisms by which they regulate expression of the genes involved in thyroid differentiation. We also address the implications of mutations in TTFs in thyroid diseases and in diseases not related to the thyroid gland.
The cellular-level effects of low/high frequency oscillating magnetic field on excitable cells such as neurons are well established. In contrast, the effects of a homogeneous, static magnetic field ...(SMF) on Central Nervous System (CNS) glial cells are less investigated. Here, we have developed an in vitro SMF stimulation set-up to investigate the genomic effects of SMF exposure on oligodendrocyte differentiation and neurotrophic factors secretion. Human oligodendrocytes precursor cells (OPCs) were stimulated with moderate intensity SMF (0.3 T) for a period of two weeks (two hours/day). The differential gene expression of cell activity marker (c-fos), early OPC (Olig1, Olig2. Sox10), and mature oligodendrocyte markers (CNP, MBP) were quantified. The enhanced myelination capacity of the SMF stimulated oligodendrocytes was validated in a dorsal root ganglion microfluidics chamber platform. Additionally, the effects of SMF on the gene expression and secretion of neurotrophic factors- BDNF and NT3 was quantified. We also report that SMF stimulation increases the intracellular calcium influx in OPCs as well as the gene expression of L-type channel subunits-CaV1.2 and CaV1.3. Our findings emphasize the ability of glial cells such as OPCs to positively respond to moderate intensity SMF stimulation by exhibiting enhanced differentiation, functionality as well as neurotrophic factor release.
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•Cholangiocarcinomas are rich in stroma containing cancer-associated fibroblasts and lymphatic vessels.•PDGF-D released by tumoral ducts attracts and activates liver fibroblasts to ...secrete VEGF-C/VEGF-A.•Lymphangiogenesis and lymphatic invasion are driven by VEGF-A/-C released by liver myofibroblasts.•Targeting liver myofibroblasts in vivo inhibits tumor-associated lymphangiogenesis and lymph node metastases.•These studies identify new possible molecular targets for the treatment of cholangiocarcinoma.
In cholangiocarcinoma, early metastatic spread via lymphatic vessels often precludes curative therapies. Cholangiocarcinoma invasiveness is fostered by an extensive stromal reaction, enriched in cancer-associated fibroblasts (CAFs) and lymphatic endothelial cells (LECs). Cholangiocarcinoma cells recruit and activate CAFs by secreting PDGF-D. Herein, we investigated the role of PDGF-D and liver myofibroblasts in promoting lymphangiogenesis in cholangiocarcinoma.
Human cholangiocarcinoma specimens were immunostained for podoplanin (LEC marker), α-SMA (CAF marker), VEGF-A, VEGF-C, and their cognate receptors (VEGFR2, VEGFR3). VEGF-A and VEGF-C secretion was evaluated in human fibroblasts obtained from primary sclerosing cholangitis explants. Using human LECs incubated with conditioned medium from PDGF-D-stimulated fibroblasts we assessed migration, 3D vascular assembly, transendothelial electric resistance and transendothelial migration of cholangiocarcinoma cells (EGI-1). We then studied the effects of selective CAF depletion induced by the BH3 mimetic navitoclax on LEC density and lymph node metastases in vivo.
In cholangiocarcinoma specimens, CAFs and LECs were closely adjacent. CAFs expressed VEGF-A and VEGF-C, while LECs expressed VEGFR2 and VEGFR3. Upon PDGF-D stimulation, fibroblasts secreted increased levels of VEGF-C and VEGF-A. Fibroblasts, stimulated by PDGF-D induced LEC recruitment and 3D assembly, increased LEC monolayer permeability, and promoted transendothelial EGI-1 migration. These effects were all suppressed by the PDGFRβ inhibitor, imatinib. In the rat model of cholangiocarcinoma, navitoclax-induced CAF depletion, markedly reduced lymphatic vascularization and reduced lymph node metastases.
PDGF-D stimulates VEGF-C and VEGF-A production by fibroblasts, resulting in expansion of the lymphatic vasculature and tumor cell intravasation. This critical process in the early metastasis of cholangiocarcinoma may be blocked by inducing CAF apoptosis or by inhibiting the PDGF-D-induced axis.
Cholangiocarcinoma is a highly malignant cancer affecting the biliary tree, which is characterized by a rich stromal reaction involving a dense population of cancer-associated fibroblasts that promote early metastatic spread. Herein, we show that cholangiocarcinoma-derived PDGF-D stimulates fibroblasts to secrete vascular growth factors. Thus, targeting fibroblasts or PDGF-D-induced signals may represent an effective tool to block tumor-associated lymphangiogenesis and reduce the invasiveness of cholangiocarcinoma.
Recent studies indicate that DNA methylation can be used to identify transcriptional enhancers, but no systematic approach has been developed for genome-wide identification and analysis of enhancers ...based on DNA methylation. We describe ELMER (Enhancer Linking by Methylation/Expression Relationships), an R-based tool that uses DNA methylation to identify enhancers and correlates enhancer state with expression of nearby genes to identify transcriptional targets. Transcription factor motif analysis of enhancers is coupled with expression analysis of transcription factors to infer upstream regulators. Using ELMER, we investigated more than 2,000 tumor samples from The Cancer Genome Atlas. We identified networks regulated by known cancer drivers such as GATA3 and FOXA1 (breast cancer), SOX17 and FOXA2 (endometrial cancer), and NFE2L2, SOX2, and TP63 (squamous cell lung cancer). We also identified novel networks with prognostic associations, including RUNX1 in kidney cancer. We propose ELMER as a powerful new paradigm for understanding the cis-regulatory interface between cancer-associated transcription factors and their functional target genes.
Merkel cells are innervated mechanosensory cells responsible for light-touch sensations. In murine dorsal skin, Merkel cells are located in touch domes and found in the epidermis around primary ...hairs. While it has been shown that Merkel cells are skin epithelial cells, the progenitor cell population that gives rise to these cells is unknown. Here, we show that during embryogenesis, SOX9-positive (+) cells inside hair follicles, which were previously known to give rise to hair follicle stem cells (HFSCs) and cells of the hair follicle lineage, can also give rise to Merkel Cells. Interestingly, while SOX9 is critical for HFSC specification, it is dispensable for Merkel cell formation. Conversely, FGFR2 is required for Merkel cell formation but is dispensable for HFSCs. Together, our studies uncover SOX9(+) cells as precursors of Merkel cells and show the requirement for FGFR2-mediated epithelial signalling in Merkel cell specification.
This book focuses on issues regarding the learning of a foreign language in older adults (aged 60 and over). It details a multidisciplinary study on Japanese older learners of Spanish and discusses ...the influence of learning experiences on vocabulary learning strategy use. It also proposes concrete techniques for teachers of older learners.
This study investigated the immunostimulatory effects of laminarin with respect to inflammatory mediators such as hydrogen peroxide, calcium, nitric oxide, various cytokines, transcription factors, ...and immune response gene in RAW 264.7 mouse macrophages. Laminarin did not reduce the cell proliferation of RAW 264.7 mouse macrophages at concentrations up to 500 µg/mL. Laminarin significantly increased the release of hydrogen peroxide, calcium, nitric oxide, monocyte chemotactic protein-1, vascular endothelial growth factor, leukemia inhibitory factor, and granulocyte-colony stimulating factor with enhancing expression of Signal Transducer and Activator of Transcription 1 (STAT1), STAT3, c-Jun, c-Fos, and cyclooxygenase-2 mRNA in RAW 264.7 cells. The results suggest that laminarin has immunostimulatory properties, strengthening immune reactions via the transcription factor pathway in macrophages.
To identify pathways involved in adult lung regeneration, we employ a unilateral pneumonectomy (PNX) model that promotes regenerative alveolarization in the remaining intact lung. We show that PNX ...stimulates pulmonary capillary endothelial cells (PCECs) to produce angiocrine growth factors that induce proliferation of epithelial progenitor cells supporting alveologenesis. Endothelial cells trigger expansion of cocultured epithelial cells, forming three-dimensional angiospheres reminiscent of alveolar-capillary sacs. After PNX, endothelial-specific inducible genetic ablation of
Vegfr2 and
Fgfr1 in mice inhibits production of MMP14, impairing alveolarization. MMP14 promotes expansion of epithelial progenitor cells by unmasking cryptic EGF-like ectodomains that activate the EGF receptor (EGFR). Consistent with this, neutralization of MMP14 impairs EGFR-mediated alveolar regeneration, whereas administration of EGF or intravascular transplantation of MMP14
+ PCECs into pneumonectomized
Vegfr2/Fgfr1-deficient mice restores alveologenesis and lung inspiratory volume and compliance function. VEGFR2 and FGFR1 activation in PCECs therefore increases MMP14-dependent bioavailability of EGFR ligands to initiate and sustain alveologenesis.
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► Pulmonary capillary endothelial cells (PCECs) support alveologenesis ► Autocrine VEGFR2 and FGFR1 activation in PCECs induces MMP14 expression ► MMP14 unmasks EGF receptor ligands, enhancing epithelial cell proliferation ► Injection of activated PCECs or angiocrine factors accelerates lung regeneration
Capillary endothelial cells support the regeneration of alveolar epithelial cells by secreting a matrix metalloprotease that unmasks cryptic epidermal growth factor receptor ligands.
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