| 1. |
- Ahlenius, Henrik, et al.
(author)
-
Adaptor Protein LNK Is a Negative Regulator of Brain Neural Stem Cell Proliferation after Stroke.
- 2012
-
In: The Journal of Neuroscience : the official journal of the Society for Neuroscience. - 1529-2401. ; 32:15, s. 5151-5164
-
Journal article (peer-reviewed)abstract
- Ischemic stroke causes transient increase of neural stem and progenitor cell (NSPC) proliferation in the subventricular zone (SVZ), and migration of newly formed neuroblasts toward the damaged area where they mature to striatal neurons. The molecular mechanisms regulating this plastic response, probably involved in structural reorganization and functional recovery, are poorly understood. The adaptor protein LNK suppresses hematopoietic stem cell self-renewal, but its presence and role in the brain are poorly understood. Here we demonstrate that LNK is expressed in NSPCs in the adult mouse and human SVZ. Lnk(-/-) mice exhibited increased NSPC proliferation after stroke, but not in intact brain or following status epilepticus. Deletion of Lnk caused increased NSPC proliferation while overexpression decreased mitotic activity of these cells in vitro. We found that Lnk expression after stroke increased in SVZ through the transcription factors STAT1/3. LNK attenuated insulin-like growth factor 1 signaling by inhibition of AKT phosphorylation, resulting in reduced NSPC proliferation. Our findings identify LNK as a stroke-specific, endogenous negative regulator of NSPC proliferation, and suggest that LNK signaling is a novel mechanism influencing plastic responses in postischemic brain.
|
|
| 2. |
- Braun, Sebastian, et al.
(author)
-
Pharmacological interference with the glucocorticoid system influences symptoms and lifespan in a mouse model of Rett syndrome.
- 2012
-
In: Human Molecular Genetics. - : Oxford University Press (OUP). - 0964-6906 .- 1460-2083. ; 21:8, s. 1673-1680
-
Journal article (peer-reviewed)abstract
- Rett syndrome (RTT) is caused by loss-of-function mutations in the X-linked gene MECP2 coding for methyl CpG-binding protein 2 (MeCP2). This protein can act as transcriptional repressor and we showed in a previous study that glucocorticoid-inducible genes are up-regulated in a RTT mouse model and that these genes are direct MeCP2 targets. Here, we report that pharmacological intervention with the glucocorticoid system has an impact on the symptoms and lifespan in a RTT mouse model. Our data support a functional implication of the stress hormone system in RTT and suggest this hormone system as potential therapeutic target.
|
|
| 3. |
- Chickarmane, Vijay, et al.
(author)
-
Transcriptional dynamics of the embryonic stem cell switch
- 2006
-
In: PLoS Computational Biology. - : Public Library of Science (PLoS). - 1553-7358. ; 2:9, s. 1080-1092
-
Journal article (peer-reviewed)abstract
- Recent ChIP experiments of human and mouse embryonic stem cells have elucidated the architecture of the transcriptional regulatory circuitry responsible for cell determination, which involves the transcription factors OCT4, SOX2, and NANOG. In addition to regulating each other through feedback loops, these genes also regulate downstream target genes involved in the maintenance and differentiation of embryonic stem cells. A search for the OCT4-SOX2-NANOG network motif in other species reveals that it is unique to mammals. With a kinetic modeling approach, we ascribe function to the observed OCT4-SOX2-NANOG network by making plausible assumptions about the interactions between the transcription factors at the gene promoter binding sites and RNA polymerase (RNAP), at each of the three genes as well as at the target genes. We identify a bistable switch in the network, which arises due to several positive feedback loops, and is switched ON/OFF by input environmental signals. The switch stabilizes the expression levels of the three genes, and through their regulatory roles on the downstream target genes, leads to a binary decision: when OCT4, SOX2, and NANOG are expressed and the switch is ON, the self-renewal genes are ON and the differentiation genes are OFF. The opposite holds when the switch is OFF. The model is extremely robust to parameter changes. In addition to providing a self-consistent picture of the transcriptional circuit, the model generates several predictions. Increasing the binding strength of NANOG to OCT4 and SOX2, or increasing its basal transcriptional rate, leads to an irreversible bistable switch: the switch remains ON even when the activating signal is removed. Hence, the stem cell can be manipulated to be self-renewing without the requirement of input signals. We also suggest tests that could discriminate between a variety of feedforward regulation architectures of the target genes by OCT4, SOX2, and NANOG.
|
|
| 4. |
- Colecchia, Federico, et al.
(author)
-
Tissue-specific regulatory network extractor (TS-REX): a database and software resource for the tissue and cell type-specific investigation of transcription factor-gene networks.
- 2009
-
In: Nucleic Acids Research. - : Oxford University Press (OUP). - 1362-4962 .- 0305-1048. ; 37:11, s. 82-82
-
Journal article (peer-reviewed)abstract
- The prediction of transcription factor binding sites in genomic sequences is in principle very useful to identify upstream regulatory factors. However, when applying this concept to genomes of multicellular organisms such as mammals, one has to deal with a large number of false positive predictions since many transcription factor genes are only expressed in specific tissues or cell types. We developed TS-REX, a database/software system that supports the analysis of tissue and cell type-specific transcription factor-gene networks based on expressed sequence tag abundance of transcription factor-encoding genes in UniGene EST libraries. The use of expression levels of transcription factor-encoding genes according to hierarchical anatomical classifications covering different tissues and cell types makes it possible to filter out irrelevant binding site predictions and to identify candidates of potential functional importance for further experimental testing. TS-REX covers ESTs from H. sapiens and M. musculus, and allows the characterization of both presence and specificity of transcription factors in user-specified tissues or cell types. The software allows users to interactively visualize transcription factor-gene networks, as well as to export data for further processing. TS-REX was applied to predict regulators of Polycomb group genes in six human tumor tissues and in human embryonic stem cells.
|
|
| 5. |
-
DNA Microarrays
- 2005
-
Editorial collection (other academic/artistic)abstract
- DNA Microarrays introduces all up-to-date microarray platforms and their various applications. It is written for scientists who are entering the field of DNA microarrays as well as those already familiar with the technology, but interested in new applications and methods.
|
|
| 6. |
- Franke, W W, et al.
(author)
-
Desmosomes--dual junctional principles of intra- and supracellular order in epithelial differentiation and tissue formation
- 1994
-
In: Verhandlungen der Deutschen Gesellschaft fur Pathologie. - 0070-4113. ; 78, s. 8-14
-
Journal article (peer-reviewed)abstract
- The cells of most normal and malignantly growing tissues are connected by "adhering junctions", i.e. distinct sites of "homotypic" contact between the plasma membranes of two cells of the same or a similar kind, associated on the cytoplasmic side by a dense plaque at which often bundles of cytoskeletal filaments anchor. Of the various types of adhering junctions desmosomes are characteristic of epithelia and carcinomas but also occur in some other cell types. Their molecular components have recently been identified and characterized by cDNA-cloning and sequencing. Unexpectedly, the molecular complement of desmosomes has been found to show certain differences in different epithelia, with particularly complex patterns in stratified squamous epithelia as well as in tumors and cultured cell lines derived therefrom. In addition, molecular principles important in the assembly of desmosomes and in the specific anchorage of intermediate-sized filaments (IFs) at desmosomal plaques have been elucidated. The possible value of cell type-specific isoforms of desmosomal components as markers for the subtyping of carcinomas and the role of desmosomal cadherins during invasion and metastasis of carcinomas are discussed.
|
|
| 7. |
|
|
| 8. |
- Hamidouche, Zahia, et al.
(author)
-
Autocrine Fibroblast Growth Factor 18 Mediates Dexamethasone-Induced Osteogenic Differentiation of Murine Mesenchymal Stem Cells
- 2010
-
In: Journal of Cellular Physiology. - : Wiley. - 1097-4652 .- 0021-9541. ; 224:2, s. 509-515
-
Journal article (peer-reviewed)abstract
- The potential of mesenchymal stem cells (MSC) to differentiate into functional bone forming cells provides an important tool for bone regeneration. The identification of factors capable of promoting osteoblast differentiation in MSCs is therefore critical to enhance the osteogenic potential of MSCs. Using microarray analysis combined with biochemical and molecular approach, we found that FGF18, a member of the FGF family, is upregulated during osteoblast differentiation induced by dexamethasone in murine MSCs. We showed that overexpression of FGF18 by lentiviral (LV) infection, or treatment of MSCs with recombinant human (rh)FGF18 increased the expression of the osteoblast specific transcription factor Runx2, and enhanced osteoblast phenotypic marker gene expression and in vitro osteogenesis. Molecular silencing using lentiviral shRNA demonstrated that downregulation of FGFR1 or FGFR2 abrogated osteoblast gene expression induced by either LV-FGF18 or rhFGF18, indicating that FGF18 enhances osteoblast differentiation in MSCs via activation of FGFR1 or FGFR2 signaling. Biochemical and pharmacological analyses showed that the induction of phenotypic osteoblast markers by LV-FGF18 is mediated by activation of ERK1/2-MAPKs and PI3K signaling in MSCs. These results reveal that FGF18 is an essential autocrine positive regulator of the osteogenic differentiation program in murine MSCs and indicate that osteogenic differentiation induced by FGF18 in MSCs is triggered by FGFR1/FGFR2-mediated ERK1/2-MAPKs and PI3K signaling. J. Cell. Physiol. 224: 509-515, 2010. (C) 2010 Wiley-Liss, Inc.
|
|
| 9. |
|
|
| 10. |
- Hertwig, Falk, et al.
(author)
-
Definition of Genetic Events Directing the Development of Distinct Types of Brain Tumors from Postnatal Neural Stem/Progenitor Cells.
- 2012
-
In: Cancer Research. - 1538-7445. ; 72:13, s. 3381-3392
-
Journal article (peer-reviewed)abstract
- Although brain tumors are classified and treated based upon their histology, the molecular factors involved in the development of various tumor types remain unknown. In this study, we show that the type and order of genetic events directs the development of gliomas, central nervous system primitive neuroectodermal tumors, and atypical teratoid/rhabdoid-like tumors from postnatal mouse neural stem/progenitor cells (NSC/NPC). We found that the overexpression of specific genes led to the development of these three different brain tumors from NSC/NPCs, and manipulation of the order of genetic events was able to convert one established tumor type into another. In addition, loss of the nuclear chromatin-remodeling factor SMARCB1 in rhabdoid tumors led to increased phosphorylation of eIF2α, a central cytoplasmic unfolded protein response (UPR) component, suggesting a role for the UPR in these tumors. Consistent with this, application of the proteasome inhibitor bortezomib led to an increase in apoptosis of human cells with reduced SMARCB1 levels. Taken together, our findings indicate that the order of genetic events determines the phenotypes of brain tumors derived from a common precursor cell pool, and suggest that the UPR may represent a therapeutic target in atypical teratoid/rhabdoid tumors. Cancer Res; 72(13); 3381-92. ©2012 AACR.
|
|
| 11. |
- Kalscheuer, Vera M, et al.
(author)
-
Mutations in the polyglutamine binding protein 1 gene cause X-linked mental retardation
- 2003
-
In: Nature Genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 35:4, s. 313-315
-
Journal article (peer-reviewed)abstract
- We found mutations in the gene PQBP1 in 5 of 29 families with nonsyndromic (MRX) and syndromic (MRXS) forms of X-linked mental retardation (XLMR). Clinical features in affected males include mental retardation, microcephaly, short stature, spastic paraplegia and midline defects. PQBP1 has previously been implicated in the pathogenesis of polyglutamine expansion diseases. Our findings link this gene to XLMR and shed more light on the pathogenesis of this common disorder.
|
|
| 12. |
- Leefa, Isabelle, et al.
(author)
-
High Podocalyxin levels promote cell viability partially through up-regulation of Annexin A2
- 2016
-
In: Biochemical and Biophysical Research Communications. - : Elsevier BV. - 0006-291X. ; 478:2, s. 573-579
-
Journal article (peer-reviewed)abstract
- Podocalyxin (PODXL) is a highly glycosylated and sialylated transmembrane protein that is up-regulated in various types of tumors and whose expression levels positively correlate with tumor grade. We previously found Podxl to be highly expressed in murine tumorigenic neural stem/progenitor cells (NSPs). Here we investigated the effects of elevated Podxl levels in these cells. NSPs overexpressing Podxl did not form brain tumors upon intracranial transplantations, indicating that high levels of this gene alone are not sufficient for tumor initiation. However, Podxl overexpression had a positive effect on cell number, sphere formation and cell viability, indicating that it might in this way contribute to the development and/or maintenance of tumors. Proteome analyses of Podxl-overexpressing and control NSPs revealed increased levels of Annexin A2 (ANXA2). We also found increased transcript levels, indicating that PODXL stimulates expression of the Anxa2 gene. Lack of Anxa2 in Podxl-overexpressing NSPs resulted in reduced viability of these cells, suggesting that PODXL-mediated pro-survival effects can at least in part be explained by increased ANXA2 levels. Finally, our data indicate that Podxl overexpression activates the MAP kinase (MAPK) pathway which in turn up-regulates Anxa2 expression. Our data indicate a novel molecular connection between PODXL and ANXA2: both exert pro-survival effects in NSPs, and PODXL positively regulates ANXA2 expression through the MAPK pathway.
|
|
| 13. |
- Mazur, Magdalena, et al.
(author)
-
Microphthalmia transcription factor regulates pancreatic β-cell function
- 2013
-
In: Diabetes. - : American Diabetes Association. - 1939-327X .- 0012-1797. ; 62:8, s. 2834-2842
-
Journal article (peer-reviewed)abstract
- Precise regulation of β-cell function is crucial for maintaining blood glucose homeostasis. Pax6 is an essential regulator of β-cell-specific factors like insulin and Glut2. Studies in the developing eye suggest that Pax6 interacts with Mitf to regulate pigment cell differentiation. Here, we show that Mitf, like Pax6, is expressed in all pancreatic endocrine cells during mouse postnatal development and in the adult islet. A Mitf loss-of-function mutation results in improved glucose tolerance and enhanced insulin secretion but no increase in β-cell mass in adult mice. Mutant β-cells secrete more insulin in response to glucose than wild-type cells, suggesting that Mitf is involved in regulating β-cell function. In fact, the transcription of genes critical for maintaining glucose homeostasis (insulin and Glut2) and β-cell formation and function (Pax4 and Pax6) is significantly upregulated in Mitf mutant islets. The increased Pax6 expression may cause the improved β-cell function observed in Mitf mutant animals, as it activates insulin and Glut2 transcription. Chromatin immunoprecipitation analysis shows that Mitf binds to Pax4 and Pax6 regulatory regions, suggesting that Mitf represses their transcription in wild-type β-cells. We demonstrate that Mitf directly regulates Pax6 transcription and controls β-cell function.
|
|
| 14. |
- Noack, Sandra, et al.
(author)
-
Periostin Secreted by Mesenchymal Stem Cells Supports Tendon Formation in an Ectopic Mouse Model
- 2014
-
In: Stem Cells and Development. - : Mary Ann Liebert Inc. - 1557-8534 .- 1547-3287. ; 23:16, s. 1844-1857
-
Journal article (peer-reviewed)abstract
- True tendon regeneration in human patients remains a vision of musculoskeletal therapies. In comparison to other mesenchymal lineages the biology of tenogenic differentiation is barely understood. Specifically, easy and efficient protocols are lacking that might enable tendon cell and tissue differentiation based on adult (stem) cell sources. In the murine mesenchymal progenitor cell line C3H10T1/2 overexpression of the growth factor bone morphogenetic protein 2 (BMP2) and a constitutively active transcription factor, Smad8 L + MH2, mediates tendon cell differentiation in vitro and the formation of tendon-like tissue in vivo. We hypothesized that during this differentiation secreted factors involved in extracellular matrix formation exert a major impact on tendon development. Gene expression analyses revealed four genes encoding secreted factors that are notably upregulated: periostin, C-type lectin domain family 3 (member b), RNase A4, and follistatin-like 1. These factors have not previously been implicated in tendon biology. Among these, periostin showed a specific expression in tenocytes of adult mouse Achilles tendon and in chondrocytes within the nonmineralized fibrocartilage zone of the enthesis with the calcaneus. Overexpression of periostin alone or in combination with constitutively active BMP receptor type in human mesenchymal stem cells and subsequent implantation into ectopic sites in mice demonstrated a reproducible moderate tenogenic capacity that has not been described before. Therefore, periostin may belong to the factors contributing to the development of tenogenic tissue.
|
|
| 15. |
- Nuber, Ulrike, et al.
(author)
-
The widespread human desmocollin Dsc2 and tissue-specific patterns of synthesis of various desmocollin subtypes
- 1995
-
In: European Journal of Cell Biology. - 0171-9335. ; 66:1, s. 69-74
-
Journal article (peer-reviewed)abstract
- By comparison of the cDNA-derived amino acid sequences and the cell type-specific patterns of synthesis we have identified desmocollin Dsc2 as the most widespread, perhaps ubiquitous desmocollin subtype. Using Northern blot analyses and ribonuclease protection assays we have found an approximately 5.6 kb mRNA encoding Dsc2 in all the diverse human tissues, tumors and cell lines examined that are known to possess desmosomes, i.e. not only epithelial cells but also myocardiac cells and lymph nodes. By contrast, desmocollin subtypes Dsc1 and Dsc3 have been detected only in certain stratified squamous epithelia, with the most conspicuous restriction of Dsc1 to epidermis and--remarkably, but unexplained--lymph nodes, and in certain carcinomas and cell lines derived therefrom. We have also determined that both Dsc2 mRNA splice forms, the one encoding the larger polypeptide a and the one coding for the shorter Dsc2b, occur in all the diverse tissues and cell lines examined. We also show that certain cells such as the epidermal keratinocyte line HaCaT and the vulvar carcinoma-derived line A-431 continually synthesize more than one Dsc subtype. The cell type-specific patterns of synthesis of the various Dsg and Dsc subtypes are discussed in relation to tissue development during embryogenesis and to malignant transformations, and the utilization of reagents for the specific Dsg and Dsc subtypes in tumor diagnosis is proposed.
|
|
| 16. |
- Pfenninger, Cosima, et al.
(author)
-
CD133 is not present on neurogenic astrocytes in the adult subventricular zone, but on embryonic neural stem cells, ependymal cells, and glioblastoma cells
- 2007
-
In: Cancer Research. - 1538-7445. ; 67:12, s. 5727-5736
-
Journal article (peer-reviewed)abstract
- Human brain tumor stem cells have been enriched using antibodies against the surface protein CD133. An antibody recognizing CD133 also served to isolate normal neural stem cells from fetal human brain, suggesting a possible lineage relationship between normal neural and brain tumor stem cells. Whether CD133-positive brain tumor stem cells can be derived from CD133-positive neural stem or progenitor cells still requires direct experimental evidence, and an important step toward such investigations is the identification and characterization of normal CD133-presenting cells in neurogenic regions of the embryonic and adult brain. Here, we present evidence that CD133 is a marker for embryonic neural stem cells, an intermediate radial glial/ependymal cell type in the early postnatal stage, and for ependymal cells in the adult brain, but not for neurogenic astrocytes in the adult subventricular zone. Our findings suggest two principal possibilities for the origin of brain tumor stem cells: a derivation from CD133-expressing cells, which are normally not present in the adult brain (embryonic neural stem cells and an early postnatal intermediate radial glial/ependymal cell type), or from CD133-positive ependymal cells in the adult brain, which are, however, generally regarded as postmitotic. Alternatively, brain tumor stem cells could be derived from proliferative but CD133-negative neurogenic astrocytes in the adult brain. In the latter case, brain tumor development would involve the production of CD133.
|
|
| 17. |
- Pfenninger, Cosima, et al.
(author)
-
Prospectively isolated CD133/CD24-positive ependymal cells from the adult spinal cord and lateral ventricle wall differ in their long-term in vitro self-renewal and in vivo gene expression.
- 2011
-
In: GLIA. - : Wiley. - 1098-1136 .- 0894-1491. ; 59:1, s. 68-81
-
Journal article (peer-reviewed)abstract
- In contrast to ependymal cells located above the subventricular zone (SVZ) of the adult lateral ventricle wall (LVW), adult spinal cord (SC) ependymal cells possess certain neural stem cell characteristics. The molecular basis of this difference is unknown. In this study, antibodies against multiple cell surface markers were applied to isolate pure populations of SC and LVW ependymal cells, which allowed a direct comparison of their in vitro behavior and in vivo gene expression profile. Isolated CD133(+)/CD24(+)/CD45(-)/CD34(-) ependymal cells from the SC displayed in vitro self-renewal and differentiation capacity, whereas those from the LVW did not. SC ependymal cells showed a higher expression of several genes involved in cell division, cell cycle regulation, and chromosome stability, which is consistent with a long-term self-renewal capacity, and shared certain transcripts with neural stem cells of the embryonic forebrain. They also expressed several retinoic acid (RA)-regulated genes and responded to RA exposure. LVW ependymal cells showed higher transcript levels of many genes regulated by transforming growth factor-β family members. Among them were Dlx2, Id2, Hey1, which together with Foxg1 could explain their potential to turn into neuroblasts under certain environmental conditions. © 2010 Wiley-Liss, Inc.
|
|
| 18. |
- Prost, Gaëlle, et al.
(author)
-
The putative tumor suppressor gene EphA7 is a novel BMI-1 target
- 2016
-
In: Oncotarget. - : Impact Journals, LLC. - 1949-2553. ; 7:36, s. 58203-58217
-
Journal article (peer-reviewed)abstract
- Bmi1 was originally identified as a gene that contributes to the development of mouse lymphoma by inhibiting MYC-induced apoptosis through repression of Ink4a and Arf. It codes for the Polycomb group protein BMI-1 and acts primarily as a transcriptional repressor via chromatin modifications. Although it binds to a large number of genomic regions, the direct BMI-1 target genes described so far do not explain the full spectrum of BMI-1-mediated effects. Here we identify the putative tumor suppressor gene EphA7 as a novel direct BMI-1 target in neural cells and lymphocytes. EphA7 silencing has been reported in several different human tumor types including lymphomas, and our data suggest BMI1 overexpression as a novel mechanism leading to EphA7 inactivation via H3K27 trimethylation and DNA methylation.
|
|
| 19. |
- Roloff, Tim C, et al.
(author)
-
Chromatin, epigenetics and stem cells
- 2005
-
In: European Journal of Cell Biology. - : Elsevier BV. - 0171-9335. ; 84:2-3, s. 123-135
-
Journal article (peer-reviewed)abstract
- Epigenetics is a term that has changed its meaning with the increasing biological knowledge on developmental processes. However, its current application to stem cell biology is often imprecise and is conceptually problematic. This article addresses two different subjects, the definition of epigenetics and chromatin states of stem and differentiated cells. We describe mechanisms that regulate chromatin changes and provide an overview of chromatin states of stem and differentiated cells. Moreover, a modification of the current epigenetics definition is proposed that is not restricted by the heritability of gene expression throughout cell divisions and excludes translational gene expression control.
|
|
| 20. |
- Roloff, Tim C, et al.
(author)
-
Comparative study of methyl-CpG-binding domain proteins
- 2003
-
In: BMC Genomics. - 1471-2164. ; 4:1
-
Journal article (peer-reviewed)abstract
- BACKGROUND: Methylation at CpG dinucleotides in genomic DNA is a fundamental epigenetic mechanism of gene expression control in vertebrates. Proteins with a methyl-CpG-binding domain (MBD) can bind to single methylated CpGs and most of them are involved in transcription control. So far, five vertebrate MBD proteins have been described as MBD family members: MBD1, MBD2, MBD3, MBD4 and MECP2. RESULTS: We performed database searches for new proteins containing an MBD and identified six amino acid sequences which are different from the previously described ones. Here we present a comparison of their MBD sequences, additional protein motifs and the expression of the encoding genes. A calculated unrooted dendrogram indicates the existence of at least four different groups of MBDs within these proteins. Two of these polypeptides, KIAA1461 and KIAA1887, were only present as predicted amino acid sequences based on a partial human cDNA. We investigated their expression by Northern blot analysis and found transcripts of ~8 kb and ~5 kb respectively, in all eight normal tissues studied. CONCLUSIONS: Eleven polypeptides with a MBD could be identified in mouse and man. The analysis of protein domains suggests a role in transcriptional regulation for most of them. The knowledge of additional existing MBD proteins and their expression pattern is important in the context of Rett syndrome.
|
|
| 21. |
- Schmidt, A, et al.
(author)
-
Desmosomes and cytoskeletal architecture in epithelial differentiation: cell type-specific plaque components and intermediate filament anchorage
- 1994
-
In: European Journal of Cell Biology. - 0171-9335. ; 65:2, s. 229-245
-
Journal article (peer-reviewed)abstract
- Among the diverse kinds of intercellular, plaque-bearing, cadherin-containing junctions, desmosomes (maculae adhaerentes) represent a major type characterized by the presence of specific transmembrane glycoproteins, i.e. desmosomal cadherins of the desmoglein and desmocollin categories, and the cytoplasmic plaque proteins, desmoplakin I and plakoglobin. Recent studies, however, have shown that the composition of desmosomes is not identical in the various normal and tumorous desmosome-forming tissues and cell cultures, including diverse forms of epithelia and carcinomas, meningothelia and meningiomas, myocardium and the lymph node follicle reticulum. Desmosomes can differ in their specific complement of desmogleins, Dsg1-3, and desmocollins, Dsc1a-3b, as well as in the additional presence and in their relative amounts of certain accessory plaque proteins such as desmoplakin II and plakophilin 1, a basic member of the larger plakoglobin family of proteins ("band 6 protein"). Assembly and function of desmosomes are effected by the interaction of the specific complement of desmosomal cadherins with certain cytoplasmic proteins. In particular, the cytoplasmic portions ("tails") of the desmosomal cadherins contain certain domains and amino acid sequence motifs, identified by mutagenesis and transfection assays, that are essential elements in desmosome formation, notably the assembly of plaque proteins, and in the site-specific anchorage of intermediate-sized filaments (IFs) of the cytoskeleton, thereby contributing to the specific intracellular as well as supracellular, i.e. tissue, architecture.
|
|
| 22. |
- Singh, Umashankar, et al.
(author)
-
Expression and Functional Analysis of Genes Deregulated in Mouse Placental Overgrowth Models: Car2 and Ncam1
- 2005
-
In: Developmental Dynamics. - : Wiley. - 1058-8388 .- 1097-0177. ; 234:4, s. 1034-1045
-
Journal article (peer-reviewed)abstract
- Different causes, such as maternal diabetes, cloning by nuclear transfer, interspecific hybridization, and deletion of some genes such as Esx1, Ipl, or Cdkn1c, may underlie placental overgrowth. In a previous study, we carried out comparative gene expression analysis in three models of placental hyperplasias, cloning, interspecies hybridization (IHPD), and Esx1 deletion. This study identified a large number of genes that exhibited differential expression between normal and enlarged placentas; however, it remained unclear how altered expression of any specific gene was related to any specific placental phenotype. In the present study, we focused on two genes, Car2 and Ncam1, which both exhibited increased expression in interspecies and cloned hyperplastic placentas. Apart from a detailed expression analysis of both genes during normal murine placentation, we also assessed morphology of placentas that were null for Car2 or Ncam1. Finally, we attempted to rescue placental hyperplasia in a congenic model of IHPD by decreasing transcript levels of Car2 or Ncam1. In situ analysis showed that both genes are expressed mainly in the spongiotrophoblast, however, expression patterns exhibited significant variability during development. Contrary to expectations, homozygous deletion of either Car2 or Ncam1 did not result in placental phenotypes. However, expression analysis of Car3 and Ncam2, which can take over the function of Car2 and Ncam1, respectively, indicated a possible rescue mechanism, as Car3 and Ncam2 were expressed in spongiotrophoblast of Car2 and Ncam1 mutant placentas. On the other hand, downregulation of either Car2 or Ncam1 did not rescue any of the placental phenotypes of AT24 placentas, a congenic model for interspecies hybrid placentas. This strongly suggested that altered expression of Car2 and Ncam1 is a downstream event in placental hyperplasia.
|
|
| 23. |
- Stock, Kristin, et al.
(author)
-
Neural precursor cells induce cell death of high-grade astrocytomas through stimulation of TRPV1
- 2012
-
In: Nature Medicine. - : Springer Science and Business Media LLC. - 1546-170X .- 1078-8956. ; 18:8, s. 1232-1232
-
Journal article (peer-reviewed)abstract
- Primary astrocytomas of grade 3 or 4 according to the classification system of the World Health Organization (high-grade astrocytomas or HGAs) are preponderant among adults and are almost invariably fatal despite the use of multimodal therapy. Here we show that the juvenile brain has an endogenous defense mechanism against HGAs. Neural precursor cells (NPCs) migrate to HGAs, reduce glioma expansion and prolong survival time by releasing endovanilloids that activate the vanilloid receptor (transient receptor potential vanilloid subfamily member-1 or TRPV1) on HGA cells. TRPV1 is highly expressed in tumor and weakly expressed in tumor-free brain. TRPV1 stimulation triggers tumor cell death through the branch of the endoplasmic reticulum stress pathway that is controlled by activating transcription factor-3 (ATF3). The antitumorigenic response of NPCs is lost with aging. NPC-mediated tumor suppression can be mimicked in the adult brain by systemic administration of the synthetic vanilloid arvanil, suggesting that TRPV1 agonists have potential as new HGA therapeutics.
|
|
