26 results on '"Kritzik M"'
Search Results
2. Growth factor-induced signaling of the pancreatic epithelium
- Author
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Kayali, A G, primary, Stotland, A, additional, Gunst, K V, additional, Kritzik, M, additional, Liu, G, additional, Dabernat, S, additional, Zhang, Y-Q, additional, Wu, W, additional, and Sarvetnick, N, additional
- Published
- 2005
- Full Text
- View/download PDF
3. Transcription factor expression during pancreatic islet regeneration
- Author
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Kritzik, M, primary
- Published
- 2000
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4. Expression of ErbB receptors during pancreatic islet development and regrowth.
- Author
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Kritzik, M. R., Krahl, T., Good, A., Gu, D., Lai, C., Fox, H., and Sarvetnick, N.
- Published
- 2000
5. PDX-1 and Msx-2 expression in the regenerating and developing pancreas.
- Author
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Kritzik, M. R., Jones, E., Chen, Z., Krakowski, M., Krahl, T., Good, A., Wright, C., Fox, H., and Sarvetnick, N.
- Published
- 1999
6. Transgenic expression of epidermal growth factor and keratinocyte growth factor in β-cells results in substantial morphological changes.
- Author
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Krakowski, M. L., Kritzik, M. R., Jones, E. M., Krahl, T., Lee, J., Arnush, M., Gu, D., Mroczkowski, B., and Sarvetnick, N.
- Published
- 1999
7. Imaging Approaches in Cancer Biology.
- Author
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Rajbhandari N, Diaz E, Kritzik M, and Reya T
- Subjects
- Humans, Animals, Diagnostic Imaging methods, Neoplasms pathology, Neoplasms diagnostic imaging, Tumor Microenvironment
- Abstract
A majority of cancer research is focused on defining the cellular and molecular basis of cancer cells and the signals that control oncogenic transformation; as a consequence, we know very little about the dynamic behavior of cancer cells in vivo. To begin to view and understand the mechanisms and interactions that control cancer initiation, growth, and metastatic progression and how these processes are influenced by the microenvironment and the signals derived from it, it is essential to develop strategies that allow imaging of the cancer cells in the context of the living microenvironment. Here, we discuss emerging work designed to visualize how cancer cells function within the microenvironment to discover how these interactions act coordinately to enable aberrant growth and to understand how they could be targeted to design new approaches to intercept the disease., (Copyright © 2024 Cold Spring Harbor Laboratory Press; all rights reserved.)
- Published
- 2024
- Full Text
- View/download PDF
8. Identification of a Musashi2 translocation as a novel oncogene in myeloid leukemia.
- Author
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Spinler K, Hamilton M, Bajaj J, Shima Y, Diaz E, Kritzik M, and Reya T
- Abstract
Myeloid leukemias, diseases marked by aggressiveness and poor outcomes, are frequently triggered by oncogenic translocations. In the case of chronic myelogenous leukemia (CML) the BCR-ABL fusion initiates chronic phase disease with second hits allowing progression to blast crisis. Although Gleevec has been transformative for CML, blast crisis CML remains relatively drug resistant. Here we show that MSI2-HOXA9, a translocation with an unknown role in cancer, can serve as a second hit in driving bcCML. Compared to BCR-ABL, BCR-ABL/MSI2-HOXA9 led to a more aggressive disease in vivo with decreased latency, increased lethality and a differentiation blockade that is a hallmark of blast crisis. Domain mapping revealed that the MSI2 RNA binding domain RRM1 had a preferential impact on growth and lethality of bcCML relative to RRM2 or the HOXA9 domain. Mechanistically, MSI2-HOXA9 triggered global downstream changes with a preferential upregulation of mitochondrial components. Consistent with this, BCR-ABL/MSI2-HOXA9 cells exhibited a significant increase in mitochondrial respiration. These data suggest that MSI2-HOXA9 acts, at least in part, by increasing expression of the mitochondrial polymerase Polrmt and augmenting mitochondrial function and basal respiration in blast crisis. Collectively, our findings demonstrate for the first time that translocations involving the stem and developmental signal MSI2 can be oncogenic, and suggest that MSI, which we found to be a frequent partner for an array of translocations, could also be a driver mutation across solid cancers., Competing Interests: COMPETING INTERESTS T.R. is a founder, and member of the Board of Directors, and holds executive roles at Tiger Hill Therapeutics.
- Published
- 2023
- Full Text
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9. Single-cell mapping identifies MSI + cells as a common origin for diverse subtypes of pancreatic cancer.
- Author
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Rajbhandari N, Hamilton M, Quintero CM, Ferguson LP, Fox R, Schürch CM, Wang J, Nakamura M, Lytle NK, McDermott M, Diaz E, Pettit H, Kritzik M, Han H, Cridebring D, Wen KW, Tsai S, Goggins MG, Lowy AM, Wechsler-Reya RJ, Von Hoff DD, Newman AM, and Reya T
- Subjects
- Mice, Animals, Carcinoma, Pancreatic Ductal pathology, Pancreatic Neoplasms pathology
- Abstract
Identifying the cells from which cancers arise is critical for understanding the molecular underpinnings of tumor evolution. To determine whether stem/progenitor cells can serve as cells of origin, we created a Msi2-Cre
ERT2 knock-in mouse. When crossed to CAG-LSL-MycT58A mice, Msi2-CreERT2 mice developed multiple pancreatic cancer subtypes: ductal, acinar, adenosquamous, and rare anaplastic tumors. Combining single-cell genomics with computational analysis of developmental states and lineage trajectories, we demonstrate that MYC preferentially triggers transformation of the most immature MSI2+ pancreas cells into multi-lineage pre-cancer cells. These pre-cancer cells subsequently diverge to establish pancreatic cancer subtypes by activating distinct transcriptional programs and large-scale genomic changes, and enforced expression of specific signals like Ras can redirect subtype specification. This study shows that multiple pancreatic cancer subtypes can arise from a common pool of MSI2+ cells and provides a powerful model to understand and control the programs that shape divergent fates in pancreatic cancer., Competing Interests: Declaration of interests T.R. is a founder and member of the Board of Directors, and holds executive roles at Tiger Hill Therapeutics., (Copyright © 2023 Elsevier Inc. All rights reserved.)- Published
- 2023
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10. A stem cell reporter based platform to identify and target drug resistant stem cells in myeloid leukemia.
- Author
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Spinler K, Bajaj J, Ito T, Zimdahl B, Hamilton M, Ahmadi A, Koechlein CS, Lytle N, Kwon HY, Anower-E-Khuda F, Sun H, Blevins A, Weeks J, Kritzik M, Karlseder J, Ginsberg MH, Park PW, Esko JD, and Reya T
- Subjects
- Animals, Antineoplastic Agents therapeutic use, Blast Crisis genetics, Blast Crisis pathology, Chemoradiotherapy methods, Disease Models, Animal, Drug Resistance, Neoplasm drug effects, Gene Knock-In Techniques, Gene Knockout Techniques, Genes, Reporter genetics, Green Fluorescent Proteins chemistry, Green Fluorescent Proteins genetics, High-Throughput Screening Assays, Humans, Imatinib Mesylate pharmacology, Imatinib Mesylate therapeutic use, Integrin beta Chains metabolism, Leukemia, Myeloid, Acute genetics, Leukemia, Myeloid, Acute pathology, Mice, Transgenic, Neoplastic Stem Cells drug effects, Neoplastic Stem Cells radiation effects, RNA-Seq, Signal Transduction drug effects, Syndecan-1 genetics, Syndecan-1 metabolism, Blast Crisis therapy, Leukemia, Myeloid, Acute therapy, Neoplastic Stem Cells pathology, RNA-Binding Proteins genetics, Syndecan-1 antagonists & inhibitors
- Abstract
Intratumoral heterogeneity is a common feature of many myeloid leukemias and a significant reason for treatment failure and relapse. Thus, identifying the cells responsible for residual disease and leukemia re-growth is critical to better understanding how they are regulated. Here, we show that a knock-in reporter mouse for the stem cell gene Musashi 2 (Msi2) allows identification of leukemia stem cells in aggressive myeloid malignancies, and provides a strategy for defining their core dependencies. Specifically, we carry out a high throughput screen using Msi2-reporter blast crisis chronic myeloid leukemia (bcCML) and identify several adhesion molecules that are preferentially expressed in therapy resistant bcCML cells and play a key role in bcCML. In particular, we focus on syndecan-1, whose deletion triggers defects in bcCML growth and propagation and markedly improves survival of transplanted mice. Further, live imaging reveals that the spatiotemporal dynamics of leukemia cells are critically dependent on syndecan signaling, as loss of this signal impairs their localization, migration and dissemination to distant sites. Finally, at a molecular level, syndecan loss directly impairs integrin β
7 function, suggesting that syndecan exerts its influence, at least in part, by coordinating integrin activity in bcCML. These data present a platform for delineating the biological underpinnings of leukemia stem cell function, and highlight the Sdc1-Itgβ7 signaling axis as a key regulatory control point for bcCML growth and dissemination.- Published
- 2020
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11. A Multiscale Map of the Stem Cell State in Pancreatic Adenocarcinoma.
- Author
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Lytle NK, Ferguson LP, Rajbhandari N, Gilroy K, Fox RG, Deshpande A, Schürch CM, Hamilton M, Robertson N, Lin W, Noel P, Wartenberg M, Zlobec I, Eichmann M, Galván JA, Karamitopoulou E, Gilderman T, Esparza LA, Shima Y, Spahn P, French R, Lewis NE, Fisch KM, Sasik R, Rosenthal SB, Kritzik M, Von Hoff D, Han H, Ideker T, Deshpande AJ, Lowy AM, Adams PD, and Reya T
- Subjects
- Adenocarcinoma genetics, Adenocarcinoma metabolism, Animals, Cell Adhesion Molecules genetics, Cell Adhesion Molecules metabolism, Cell Differentiation, Epigenesis, Genetic, Gene Library, Humans, Mice, Mice, Knockout, Mice, SCID, Neoplastic Stem Cells cytology, Nuclear Receptor Subfamily 1, Group F, Member 3 antagonists & inhibitors, Nuclear Receptor Subfamily 1, Group F, Member 3 genetics, Nuclear Receptor Subfamily 1, Group F, Member 3 metabolism, Pancreatic Neoplasms genetics, Pancreatic Neoplasms metabolism, RNA Interference, RNA, Small Interfering metabolism, Receptors, G-Protein-Coupled antagonists & inhibitors, Receptors, G-Protein-Coupled genetics, Receptors, G-Protein-Coupled metabolism, Receptors, Interleukin-10 antagonists & inhibitors, Receptors, Interleukin-10 genetics, Receptors, Interleukin-10 metabolism, T-Lymphocytes cytology, T-Lymphocytes immunology, T-Lymphocytes metabolism, Transcriptome, Tumor Cells, Cultured, Adenocarcinoma pathology, Neoplastic Stem Cells metabolism, Pancreatic Neoplasms pathology
- Abstract
Drug resistance and relapse remain key challenges in pancreatic cancer. Here, we have used RNA sequencing (RNA-seq), chromatin immunoprecipitation (ChIP)-seq, and genome-wide CRISPR analysis to map the molecular dependencies of pancreatic cancer stem cells, highly therapy-resistant cells that preferentially drive tumorigenesis and progression. This integrated genomic approach revealed an unexpected utilization of immuno-regulatory signals by pancreatic cancer epithelial cells. In particular, the nuclear hormone receptor retinoic-acid-receptor-related orphan receptor gamma (RORγ), known to drive inflammation and T cell differentiation, was upregulated during pancreatic cancer progression, and its genetic or pharmacologic inhibition led to a striking defect in pancreatic cancer growth and a marked improvement in survival. Further, a large-scale retrospective analysis in patients revealed that RORγ expression may predict pancreatic cancer aggressiveness, as it positively correlated with advanced disease and metastasis. Collectively, these data identify an orthogonal co-option of immuno-regulatory signals by pancreatic cancer stem cells, suggesting that autoimmune drugs should be evaluated as novel treatment strategies for pancreatic cancer patients., (Copyright © 2019 Elsevier Inc. All rights reserved.)
- Published
- 2019
- Full Text
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12. Image-based detection and targeting of therapy resistance in pancreatic adenocarcinoma.
- Author
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Fox RG, Lytle NK, Jaquish DV, Park FD, Ito T, Bajaj J, Koechlein CS, Zimdahl B, Yano M, Kopp J, Kritzik M, Sicklick J, Sander M, Grandgenett PM, Hollingsworth MA, Shibata S, Pizzo D, Valasek M, Sasik R, Scadeng M, Okano H, Kim Y, MacLeod AR, Lowy AM, and Reya T
- Subjects
- Animals, Carcinoma in Situ genetics, Carcinoma in Situ pathology, Carcinoma, Pancreatic Ductal genetics, Carcinoma, Pancreatic Ductal metabolism, Carcinoma, Pancreatic Ductal pathology, Cell Transformation, Neoplastic genetics, Disease Models, Animal, Disease Progression, Drug Resistance, Neoplasm genetics, Female, Gene Deletion, Genes, Reporter genetics, Humans, Male, Mice, Models, Genetic, Neoplastic Cells, Circulating metabolism, Nerve Tissue Proteins deficiency, Nerve Tissue Proteins metabolism, Oligonucleotides, Antisense administration & dosage, Oligonucleotides, Antisense genetics, Oligonucleotides, Antisense pharmacokinetics, Oligonucleotides, Antisense therapeutic use, Pancreatic Neoplasms genetics, Pancreatic Neoplasms metabolism, Pancreatic Neoplasms pathology, RNA-Binding Proteins metabolism, Signal Transduction drug effects, Survival Rate, Xenograft Model Antitumor Assays, Carcinoma, Pancreatic Ductal drug therapy, Drug Resistance, Neoplasm drug effects, Molecular Imaging, Nerve Tissue Proteins genetics, Pancreatic Neoplasms drug therapy, RNA-Binding Proteins genetics
- Abstract
Pancreatic intraepithelial neoplasia is a pre-malignant lesion that can progress to pancreatic ductal adenocarcinoma, a highly lethal malignancy marked by its late stage at clinical presentation and profound drug resistance. The genomic alterations that commonly occur in pancreatic cancer include activation of KRAS2 and inactivation of p53 and SMAD4 (refs 2-4). So far, however, it has been challenging to target these pathways therapeutically; thus the search for other key mediators of pancreatic cancer growth remains an important endeavour. Here we show that the stem cell determinant Musashi (Msi) is a critical element of pancreatic cancer progression both in genetic models and in patient-derived xenografts. Specifically, we developed Msi reporter mice that allowed image-based tracking of stem cell signals within cancers, revealing that Msi expression rises as pancreatic intraepithelial neoplasia progresses to adenocarcinoma, and that Msi-expressing cells are key drivers of pancreatic cancer: they preferentially harbour the capacity to propagate adenocarcinoma, are enriched in circulating tumour cells, and are markedly drug resistant. This population could be effectively targeted by deletion of either Msi1 or Msi2, which led to a striking defect in the progression of pancreatic intraepithelial neoplasia to adenocarcinoma and an improvement in overall survival. Msi inhibition also blocked the growth of primary patient-derived tumours, suggesting that this signal is required for human disease. To define the translational potential of this work we developed antisense oligonucleotides against Msi; these showed reliable tumour penetration, uptake and target inhibition, and effectively blocked pancreatic cancer growth. Collectively, these studies highlight Msi reporters as a unique tool to identify therapy resistance, and define Msi signalling as a central regulator of pancreatic cancer.
- Published
- 2016
- Full Text
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13. Musashi signaling in stem cells and cancer.
- Author
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Fox RG, Park FD, Koechlein CS, Kritzik M, and Reya T
- Subjects
- Animals, Carcinogenesis metabolism, Drosophila metabolism, Drosophila Proteins metabolism, Neoplasms metabolism, RNA-Binding Proteins metabolism, Signal Transduction physiology, Stem Cells metabolism
- Abstract
How a single cell gives rise to an entire organism is one of biology's greatest mysteries. Within this process, stem cells play a key role by serving as seed cells capable of both self-renewal to sustain themselves as well as differentiation to generate the full diversity of mature cells and functional tissues. Understanding how this balance between self-renewal and differentiation is achieved is crucial to defining not only the underpinnings of normal development but also how its subversion can lead to cancer. Musashi, a family of RNA binding proteins discovered originally in Drosophila and named after the iconic samurai, Miyamoto Musashi, has emerged as a key signal that confers and protects the stem cell state across organisms. Here we explore the role of this signal in stem cells and how its reactivation can be a critical element in oncogenesis. Relative to long-established developmental signals such as Wnt, Hedgehog, and Notch, our understanding of Musashi remains in its infancy; yet all evidence suggests that Musashi will emerge as an equally powerful paradigm for regulating development and cancer and may be destined to have a great impact on biology and medicine.
- Published
- 2015
- Full Text
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14. Nodal and lefty signaling regulates the growth of pancreatic cells.
- Author
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Zhang YQ, Sterling L, Stotland A, Hua H, Kritzik M, and Sarvetnick N
- Subjects
- Activins metabolism, Animals, Apoptosis, Cell Line, Cell Proliferation, Enzyme Activation, Interferon-gamma genetics, Interferon-gamma metabolism, Left-Right Determination Factors, Mice, Mice, Inbred C57BL, Mice, Transgenic, Mitogen-Activated Protein Kinases metabolism, Nodal Protein, Proto-Oncogene Proteins c-akt metabolism, Regeneration, Transforming Growth Factor beta genetics, Gene Expression Regulation, Developmental, Islets of Langerhans cytology, Islets of Langerhans embryology, Signal Transduction physiology, Transforming Growth Factor beta metabolism
- Abstract
Nodal and its antagonist, Lefty, are important mediators specifying the laterality of the organs during embryogenesis. Nodal signals through activin receptors in the presence of its co-receptor, Cripto. In the present study, we investigated the possible roles of Nodal and Lefty signaling during islet development and regeneration. We found that both Nodal and Lefty are expressed in the pancreas during embryogenesis and islet regeneration. In vitro studies demonstrated that Nodal inhibits, whereas Lefty enhances, the proliferation of a pancreatic cell line. In addition, we showed that Lefty-1 activates MAPK and Akt phosphorylation in these cells. In vivo blockade of endogenous Lefty using neutralizing Lefty-1 monoclonal antibody results in a significantly decreased proliferation of duct epithelial cells during islet regeneration. This is the first study to decipher the expression and function of Nodal and Lefty in pancreatic growth. Importantly, our results highlight a novel function of Nodal-Lefty signaling in the regulation of expansion of pancreatic cells.
- Published
- 2008
- Full Text
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15. FGFR3 is a negative regulator of the expansion of pancreatic epithelial cells.
- Author
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Arnaud-Dabernat S, Kritzik M, Kayali AG, Zhang YQ, Liu G, Ungles C, and Sarvetnick N
- Subjects
- Aging, Animals, Animals, Newborn, Cell Line, Epithelial Cells drug effects, Islets of Langerhans cytology, Mice, Mice, Inbred NOD, Mice, Knockout, Pancreas embryology, Receptor, Fibroblast Growth Factor, Type 3 deficiency, Receptor, Fibroblast Growth Factor, Type 3 genetics, Regeneration, Signal Transduction physiology, Epithelial Cells cytology, Islets of Langerhans physiology, Pancreas cytology, Receptor, Fibroblast Growth Factor, Type 3 physiology
- Abstract
Fibroblast growth factors (FGFs) and their receptors (FGFRs) are key signaling molecules for pancreas development. Although FGFR3 is a crucial developmental gene, acting as a negative regulator of bone formation, its participation remains unexplored in pancreatic organogenesis. We found that FGFR3 was expressed in the epithelia in both mouse embryonic and adult regenerating pancreata but was absent in normal adult islets. In FGFR3 knockout mice, we observed an increase in the proliferation of epithelial cells in neonates, leading to a marked increase in islet areas in adults. In vitro studies showed that FGF9 is a very potent ligand for FGFR3 and activates extracellular signal-related kinases (ERKs) in pancreatic cell lines. Moreover, FGFR3 blockade or FGFR3 deficiency led to increased proliferation of pancreatic epithelial cells in vivo. This was accompanied by an increase in the proportion of potential islet progenitor cells. Thus, our results show that FGFR3 signaling inhibits the expansion of the immature pancreatic epithelium. Consequently, this study suggests that FGFR3 participates in regulating pancreatic growth during the emergence of mature islet cells.
- Published
- 2007
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16. BMP4 regulates pancreatic progenitor cell expansion through Id2.
- Author
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Hua H, Zhang YQ, Dabernat S, Kritzik M, Dietz D, Sterling L, and Sarvetnick N
- Subjects
- Animals, Basic Helix-Loop-Helix Transcription Factors metabolism, Bone Morphogenetic Protein 4, Bone Morphogenetic Proteins genetics, Gene Expression Regulation, Developmental, Inhibitor of Differentiation Protein 2 genetics, Leukemia, Plasma Cell, Mice, Nerve Tissue Proteins metabolism, Pancreas growth & development, Pancreatic Ducts cytology, Pancreatic Ducts growth & development, Signal Transduction, Bone Morphogenetic Proteins metabolism, Inhibitor of Differentiation Protein 2 metabolism, Insulin-Secreting Cells metabolism, Stem Cells metabolism
- Abstract
Inhibitor of DNA binding (Id) proteins bind to and inhibit the function of basic helix-loop-helix (bHLH) transcription factors including those that regulate pancreatic development. Moreover, bone morphogenetic proteins (BMPs) regulate the expression of Ids. We hypothesized that BMP4 and Id proteins play a role in the expansion and differentiation of epithelial progenitor cells. We demonstrate that BMP4 induces the expression of Id2 along with the expansion of AR42J pancreatic epithelial cells. Furthermore, neutralization of BMP4 significantly reduced duct epithelial cell expansion in a mouse model of islet regeneration. BMP4 stimulation promotes Id2 binding to the bHLH transcription factor NeuroD, which is required for the differentiation of pancreatic islet cells. Therefore, our results indicate that BMP4 stimulation blocks the differentiation of endocrine progenitor cells and instead promotes their expansion thereby revealing a novel paradigm of signaling explaining the balance between expansion and differentiation of pancreatic duct epithelial progenitors. Understanding the mechanisms of BMP and Id function elucidates a key step during pancreas embryogenesis, which is important knowledge for expanding pancreatic progenitors in vitro.
- Published
- 2006
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17. Identification and expansion of pancreatic stem/progenitor cells.
- Author
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Zhang YQ, Kritzik M, and Sarvetnick N
- Subjects
- Animals, Cell Differentiation physiology, Embryo, Mammalian cytology, Humans, Insulin metabolism, Islets of Langerhans cytology, Islets of Langerhans metabolism, Models, Biological, Pancreas physiology, Pancreatic Ducts cytology, Pancreatic Ducts metabolism, Regeneration physiology, Stem Cells physiology, Cell Proliferation, Pancreas cytology, Stem Cells cytology
- Abstract
Pancreatic islet transplantation represents an attractive approach for the treatment of diabetes. However, the limited availability of donor islets has largely hampered this approach. In this respect, the use of alternative sources of islets such as the ex vivo expansion and differentiation of functional endocrine cells for treating diabetes has become the major focus of diabetes research. Adult pancreatic stem cells /progenitor cells have yet to be recognized because limited markers exist for their identification. While the pancreas has the capacity to regenerate under certain circumstances, questions where adult pancreatic stem/progenitor cells are localized, how they are regulated, and even if the pancreas harbors a stem cell population need to be resolved. In this article, we review the recent achievements both in the identification as well as in the expansion of pancreatic stem/progenitor cells.
- Published
- 2005
- Full Text
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18. Inhibition of activin signaling induces pancreatic epithelial cell expansion and diminishes terminal differentiation of pancreatic beta-cells.
- Author
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Zhang YQ, Cleary MM, Si Y, Liu G, Eto Y, Kritzik M, Dabernat S, Kayali AG, and Sarvetnick N
- Subjects
- Activin Receptors physiology, Activins antagonists & inhibitors, Activins pharmacology, Animals, Cell Differentiation drug effects, Cell Differentiation physiology, Cell Division drug effects, Cell Division physiology, Epithelial Cells drug effects, Follistatin pharmacology, Humans, Interferon-gamma genetics, Islets of Langerhans drug effects, Mice, Mice, Inbred NOD, Mice, Transgenic, Recombinant Proteins pharmacology, Activins physiology, Epithelial Cells cytology, Islets of Langerhans physiology, Pancreas cytology
- Abstract
Activins regulate the growth and differentiation of a variety of cells. During pancreatic islet development, activins are required for the specialization of pancreatic precursors from the gut endoderm during midgestation. In this study, we probed the role of activin signaling during pancreatic islet cell development and regeneration. Indeed, we found that both activins and activin receptors are upregulated in duct epithelial cells during islet differentiation. Interestingly, the expression of endogenous cellular inhibitors of activin signaling, follistatin and Cripto, were also found to be augmented. Inhibition of activins significantly enhanced survival and expansion of pancreatic epithelial cells but decreased the numbers of differentiated beta-cells. Our results suggest that the homeostasis of growth and terminal differentiation requires a precise context-dependent regulation of activin signaling. Follistatin participates in this process by promoting expansion of precursor cells during pancreas growth.
- Published
- 2004
- Full Text
- View/download PDF
19. The stromal cell-derived factor-1alpha/CXCR4 ligand-receptor axis is critical for progenitor survival and migration in the pancreas.
- Author
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Kayali AG, Van Gunst K, Campbell IL, Stotland A, Kritzik M, Liu G, Flodström-Tullberg M, Zhang YQ, and Sarvetnick N
- Subjects
- Animals, Apoptosis physiology, Cell Division physiology, Cell Movement physiology, Cell Survival physiology, Cells, Cultured, Chemokine CXCL12, Disease Models, Animal, Epithelial Cells cytology, Epithelial Cells metabolism, Fetus, Ligands, Mice, Mice, Inbred NOD, Mice, Transgenic, Mitogen-Activated Protein Kinases metabolism, Pancreas cytology, Pancreas metabolism, Pancreatic Ducts cytology, Pancreatic Ducts growth & development, Pancreatic Ducts metabolism, Proto-Oncogene Proteins metabolism, Proto-Oncogene Proteins c-akt, Regeneration physiology, Stem Cells cytology, src-Family Kinases metabolism, Chemokines, CXC metabolism, Pancreas growth & development, Protein Serine-Threonine Kinases, Receptors, CXCR4 metabolism, Stem Cells metabolism
- Abstract
The SDF-1alpha/CXCR4 ligand/chemokine receptor pair is required for appropriate patterning during ontogeny and stimulates the growth and differentiation of critical cell types. Here, we demonstrate SDF-1alpha and CXCR4 expression in fetal pancreas. We have found that SDF-1alpha and its receptor CXCR4 are expressed in islets, also CXCR4 is expressed in and around the proliferating duct epithelium of the regenerating pancreas of the interferon (IFN) gamma-nonobese diabetic mouse. We show that SDF-1alpha stimulates the phosphorylation of Akt, mitogen-activated protein kinase, and Src in pancreatic duct cells. Furthermore, migration assays indicate a stimulatory effect of SDF-1alpha on ductal cell migration. Importantly, blocking the SDF-1alpha/CXCR4 axis in IFNgamma-nonobese diabetic mice resulted in diminished proliferation and increased apoptosis in the pancreatic ductal cells. Together, these data indicate that the SDF-1alpha-CXCR4 ligand receptor axis is an obligatory component in the maintenance of duct cell survival, proliferation, and migration during pancreatic regeneration.
- Published
- 2003
- Full Text
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20. Allele-dependent transcriptional regulation of the human integrin alpha2 gene.
- Author
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Jacquelin B, Tarantino MD, Kritzik M, Rozenshteyn D, Koziol JA, Nurden AT, and Kunicki TJ
- Subjects
- 5' Untranslated Regions, Blood Platelets metabolism, DNA-Binding Proteins metabolism, Down-Regulation, Genes, Regulator, Humans, Integrin alpha2, Integrins metabolism, Leukocytes, Mononuclear metabolism, Linkage Disequilibrium, Pregnancy Proteins metabolism, Protein Binding, Receptors, Collagen, Sp1 Transcription Factor metabolism, Transcription, Genetic genetics, Alleles, Antigens, CD genetics, Gene Expression Regulation genetics
- Abstract
Genetically controlled variation in alpha2beta1 expression by human blood platelets was previously described. Sixty-two haplotype sequences corresponding to the proximal 5' regulatory region (-1096 to +1) of the alpha2 gene were compared, and a dimorphic sequence -52C>T was identified that is located precisely between 2 tandem Sp1/Sp3 binding elements previously shown to be absolutely required for transcriptional activity of this gene in epithelial cell lines and the erythroleukemic cell line K562. The gene frequency of -52T in a random Caucasian population is approximately 0.35, and the expression of -52T correlates directly with reduced densities of platelet alpha2beta1. In mobility shift analyses, the -52T substitution attenuates complex formation with both Sp1 and Sp3. When transfected into the erythroleukemia cell line Dami, promoter-luciferase constructs bearing the -52T sequence exhibit a 5-fold decrease in activity relative to the -52C construct. In transfected CHRF-288-11 megakaryocytic cells, the corresponding activity decreases by 10-fold. The -52T sequence appears to be in linkage disequilibrium with the previously defined allele A3 (807C; HPA-5b), known to be associated with diminished expression of platelet alpha2beta1. In summary, a natural dimorphism has been identified within the proximal 5' regulatory region of the human integrin alpha2 gene that is responsible for decreased expression levels of the integrin alpha2beta1 on blood platelets through a mechanism that is probably mediated by the nuclear regulatory proteins Sp1 and Sp3.
- Published
- 2001
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21. Transgenic expression of epidermal growth factor and keratinocyte growth factor in beta-cells results in substantial morphological changes.
- Author
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Krakowski ML, Kritzik MR, Jones EM, Krahl T, Lee J, Arnush M, Gu D, Mroczkowski B, and Sarvetnick N
- Subjects
- Animals, Blood Glucose metabolism, Fibroblast Growth Factor 10, Fibroblast Growth Factor 7, Humans, Islets of Langerhans cytology, Islets of Langerhans metabolism, Mice, Mice, Transgenic, Pancreas anatomy & histology, Transforming Growth Factor beta metabolism, Epidermal Growth Factor metabolism, Fibroblast Growth Factors, Growth Substances metabolism, Pancreas metabolism, Regeneration physiology
- Abstract
The upregulation of a limited number of growth factors in our interferon-gamma transgenic model for regeneration within the pancreas lead us to propose that these factors are important during pancreatic regeneration. In this study, we have assessed the influence of two growth factors within the pancreas, epidermal growth factor (EGF) and keratinocyte growth factor (KGF), by ectopically expressing these proteins under the control of the human insulin promoter in transgenic mice. This beta-cell-targeted expression of either EGF or KGF resulted in significant morphological changes, including cellular proliferation and disorganized islet growth. Intercrossing the individual Ins-EGF and Ins-KGF transgenic mice resulted in more profound changes in pancreatic morphology including proliferation of pancreatic cells and extensive intra-islet fibrosis. Insulin-producing beta-cells were found in some of the ducts of older Ins-EGF and Ins-EGFxKGF transgenic mice, and amylase-producing cells were observed within the islet structures of the double transgenic mice. These data suggest that both EGF and KGF are capable of affecting pancreatic differentiation and growth, and that co-expression of these molecules in islets has a more substantial impact on the pancreas than does expression of either growth factor alone.
- Published
- 1999
- Full Text
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22. Low platelet alpha2beta1 levels in type I von Willebrand disease correlate with impaired platelet function in a high shear stress system.
- Author
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Di Paola J, Federici AB, Mannucci PM, Canciani MT, Kritzik M, Kunicki TJ, and Nugent D
- Subjects
- Alleles, Blood Platelets pathology, Cells, Cultured, Humans, Integrins metabolism, Platelet Adhesiveness genetics, Receptors, Collagen, Stress, Mechanical, von Willebrand Diseases genetics, Blood Platelets physiology, Integrins genetics, von Willebrand Diseases blood, von Willebrand Diseases physiopathology
- Abstract
Platelet adhesion to collagen-coated surfaces in whole blood under flow conditions is mediated by both von Willebrand factor (vWF)-dependent recruitment of the platelet glycoprotein Ib-IX receptor complex and collagen interaction with the integrin alpha2beta1. In type 1 von Willebrand disease (vWD), platelet adhesive functions are impaired due to the decrease in vWF levels in plasma and platelets. There are at least three alleles of the human alpha2 gene, distinguishable by a cluster of silent or noncoding sequence differences within a segment of the gene. Two alleles, associated with low receptor density can be distinguished by nucleotide 807C, while the third allele associated with high receptor density, expresses nucleotide 807T. Gene frequencies of these alleles in a normal population (n = 167) are 0.58 for 807C and 0.42 for 807T. We measured the frequencies of these alleles in symptomatic patients with five types of vWD (type 1, n = 78; type 2A, n = 25, type 2B, n = 14; type 2M, n = 10; and type 3, n = 20). Compared with the normal group, no significant difference in allele frequencies was observed among individuals with types 2A, 2B, 2M, or 3 vWD. However, the frequency of the 807C allele, associated with low collagen receptor density, among type 1 vWD patients (807C =.71; 807T =.29) was significantly higher than that of the normal population (P =.007). Also, in patients with vWD type 1 and borderline to normal ristocetin-cofactor (vWF:RCo) activity values, collagen receptor density correlates inversely with closure time in a high shear stress system (platelet function analyzer [PFA-100]). We propose that low platelet alpha2beta1 density results in less efficient primary platelet adhesion and may result in increased tendency to bleed, as evidenced by the high frequency of this polymorphism in patients with type 1 vWD compared with normal individuals. In addition, this may account for the variability between patients with similar levels of vWF antigen, but strikingly different bleeding histories.
- Published
- 1999
23. Pancreatic expression of keratinocyte growth factor leads to differentiation of islet hepatocytes and proliferation of duct cells.
- Author
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Krakowski ML, Kritzik MR, Jones EM, Krahl T, Lee J, Arnush M, Gu D, and Sarvetnick N
- Subjects
- Aging physiology, Animals, Cell Differentiation physiology, Fibroblast Growth Factor 10, Fibroblast Growth Factor 7, Growth Substances genetics, Insulin genetics, Mice, Mice, Transgenic genetics, Promoter Regions, Genetic genetics, Fibroblast Growth Factors, Growth Substances metabolism, Islets of Langerhans cytology, Liver cytology, Pancreas metabolism, Pancreatic Ducts cytology
- Abstract
Keratinocyte growth factor, (KGF), a member of the fibroblast growth factor (FGF) family, is involved in wound healing. It also promotes the differentiation of many epithelial tissues and proliferation of epithelial cells as well as pancreatic duct cells. Additionally, many members of the highly homologous FGF family (including KGF), influence both growth and cellular morphology in the developing embryo. We have previously observed elevated levels of KGF in our interferon-gamma transgenic mouse model of pancreatic regeneration. To understand the role of KGF in pancreatic differentiation, we generated insulin promoter-regulated KGF transgenic mice. Remarkably, we have found that ectopic KGF expression resulted in the emergence of hepatocytes within the islets of Langerhans in the pancreas. Additionally, significant intra-islet duct cell proliferation in the pancreata of transgenic KGF mice was observed. The unexpected appearance of hepatocytes and proliferation of intra-islet duct cells in the pancreata of these mice evidently stemmed directly from local exposure to KGF.
- Published
- 1999
- Full Text
- View/download PDF
24. Nucleotide polymorphisms in the alpha2 gene define multiple alleles that are associated with differences in platelet alpha2 beta1 density.
- Author
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Kritzik M, Savage B, Nugent DJ, Santoso S, Ruggeri ZM, and Kunicki TJ
- Subjects
- Antigens, CD chemistry, Codon genetics, Collagen metabolism, DNA Mutational Analysis, Humans, Integrin alpha2, Integrins metabolism, Introns genetics, Isoantigens immunology, Polymerase Chain Reaction, Polymorphism, Restriction Fragment Length, Receptors, Collagen, Stress, Mechanical, Structure-Activity Relationship, Alleles, Antigens, CD genetics, Integrins analysis, Platelet Adhesiveness genetics, Point Mutation, Polymorphism, Genetic
- Abstract
Three allelic differences in the alpha2 gene are associated with expression levels of the alpha2beta1 integrin on the platelet surface. We have previously defined two linked silent polymorphisms in the alpha2 gene coding region at nucleotides 807 (C or T) and 873 (G or A). We have now identified one rarer nucleotide polymorphism in the coding region at nucleotide 837 (T or C) and four additional linked polymorphisms within the introns that flank these coding sequences. Moreover, we have determined that the alloantigenic Br polymorphism, which resides in a distal coding region at nucleotide 1648, is also linked to the 837 polymorphism. Thus, three alpha2 gene alleles, defined by eight nucleotide polymorphisms, have now been discovered. Allele 1 (807T/837T/873A/Brb) is associated with increased levels of alpha2beta1; allele 2 (807C/837T/873G/Brb) and allele 3 (807C/837C/873G/Bra) are each associated with lower levels of alpha2beta1. Finally, we also show here that the rate of platelet attachment to type I collagen in whole blood under conditions of high shear rate (1,500/s) is proportional to the density of alpha2beta1 receptors on the platelet surface. Thus, the density of platelet alpha2beta1 could have an important impact on platelet adhesion to collagen in whole blood and therefore on platelet function in vivo, contributing to an increased risk of thrombosis or to bleeding in relevant disease states.
- Published
- 1998
25. Characterization and sequence of an additional 15-lipoxygenase transcript and of the human gene.
- Author
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Kritzik MR, Ziober AF, Dicharry S, Conrad DJ, and Sigal E
- Subjects
- Base Sequence, Cloning, Molecular, DNA, Complementary isolation & purification, Humans, Interleukin-4, Molecular Sequence Data, Polymerase Chain Reaction, RNA isolation & purification, Arachidonate 15-Lipoxygenase genetics, DNA, Complementary genetics, Monocytes enzymology, RNA genetics
- Abstract
15-lipoxygenase is a lipid-peroxidating enzyme that oxidizes fatty acids, such as those esterified to cellular membranes. It has been implicated in the oxidative modification of low-density lipoprotein and is thus thought to contribute to the development of atherosclerosis. The enzyme has also been shown to be specifically induced by interleukin-4 in human blood monocytes. Two 15-lipoxygenase-hybridizing messages were detected in these cells; one (2.7 kb) corresponds to the previously isolated cDNA for 15-lipoxygenase, while the other (4 kb) was of unknown origin. We have isolated and characterized this 4 kb transcript. Our experiments show that it has 1.2 kb additional sequence in its 3' untranslated region, and that it is generated from genomic sequences through differential polyA site selection. We present studies to address the functional significance of the extended 3'UTR. Selection of an upstream polyadenylation signal results in production of the 2.7 kb transcript. In addition, we present here for the first time the cloning and sequence of the human 15-lipoxygenase gene, as well as the identification of regulatory elements in the promoter region of this gene.
- Published
- 1997
- Full Text
- View/download PDF
26. Hereditary variation in platelet integrin alpha 2 beta 1 density is associated with two silent polymorphisms in the alpha 2 gene coding sequence.
- Author
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Kunicki TJ, Kritzik M, Annis DS, and Nugent DJ
- Subjects
- Alleles, Blood Platelets physiology, Collagen physiology, Female, Flow Cytometry, Genetic Variation, Humans, Male, Platelet Adhesiveness, Receptors, Collagen, Blood Platelets metabolism, Codon genetics, Integrins blood, Integrins genetics, Polymorphism, Genetic
- Abstract
The integrin alpha 2 beta 1 is a receptor for collagen that plays a fundamental role in the adhesion of blood platelets to the extracellular matrix. We previously reported that platelet alpha 2 beta 1 levels among randomly selected individuals can vary up to 10-fold and that this correlates with differences in adhesiveness to type-I or type-III collagens. We have now found two linked, allelic polymorphisms within the coding sequence of the alpha 2 gene that correlate with receptor density, TTT/TTC at codon Phe224 and ACA/ACG at codon Thr246. By Southern blot hybridization of specific antisense DNA probes to segments of genomic DNA that encompass each coding region, we have determined the gene frequencies of each allele in a random donor population (n = 65) to be 0.585 (TTC...ACG) and 0.415 (TTT...ACA). There is a statistically significant correlation between the alleles TTT...ACA (codons 224...246) and high receptor density (n = 30; P < .002), whereas the complimentary alleles TTC...ACG are associated with low receptor density. Heterozygous individuals express intermediate levels of this receptor, and familial studies confirm that these allelic polymorphisms are inherited characteristics. These findings prove that the level of platelet alpha 2 beta 1 is an inherited trait. The molecular basis for receptor density remains to be determined, but our findings establish that these silent alleles within the coding sequence of the alpha 2 gene are linked to the genetic basis for variation in receptor density.
- Published
- 1997
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