Publications by authors named "Shifaan Thowfeequ"

8 Publications

  • Page 1 of 1

Hepatocyte-ductal transdifferentiation is mediated by reciprocal repression of SOX9 and C/EBPα.

Cell Reprogram 2014 Oct 25;16(5):314-23. Epub 2014 Aug 25.

1 Centre for Regenerative Medicine, Department of Biology & Biochemistry University of Bath , Claverton Down, Bath, BA2 7AY, United Kingdom .

Primary hepatocytes rapidly dedifferentiate when cultured in vitro. We have studied the mechanism of hepatocyte dedifferentiation by using two culture media: one that maintains hepatocytes in a differentiated state and another that allows dedifferentiation. We show that dedifferentiation involves partial transformation of hepatocytes into cells that resemble biliary epithelial cells. Lineage labeling and time-lapse filming confirm that the dedifferentiated cells are derived from hepatocytes and not from contaminating ductal or fibroblastic cells in the original culture. Furthermore, we establish that the conversion of hepatocytes to biliary-like cells is regulated by mutual antagonism of CCAAT/enhancer binding protein alpha (C/EBPα) and SOX9, which have opposing effects on the expression of hepatocyte and ductal genes. Thus, hepatocyte dedifferentiation induces the biliary gene expression program by alleviating C/EBPα-mediated repression of Sox9. We propose that reciprocal antagonism of C/EBPα and SOX9 also operates in the formation of hepatocytes and biliary ducts from hepatoblasts during normal embryonic development. These data demonstrate that reprogramming of differentiated cells can be used to model the acquisition and maintenance of cell fate in vivo.
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http://dx.doi.org/10.1089/cell.2014.0032DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4172464PMC
October 2014

Isolation of high quality RNA from embryonic kidney and cells.

Methods Mol Biol 2012 ;886:203-10

Department of Genetics and Development, Columbia University, New York, NY, USA.

All the mRNAs within a cell and their relative levels are indicative of gene expression within that cell, which is essential for its structure and function in its differentiated state. Therefore, methods for the identification of the specific mRNAs and the quantitation of their levels are invaluable tools for understanding gene expression. Due to high endogenous RNase activity within virtually all living cells, the isolation of good quality RNA with minimal degradation is not a trivial task. This protocol outlines a tried and tested methodology for isolating high quality RNA from embryonic kidneys for various applications including microarray analysis and quantitative reverse transcription PCR (qRT-PCR).
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http://dx.doi.org/10.1007/978-1-61779-851-1_18DOI Listing
September 2012

Generation of hepatocyte-like cells from in vitro transdifferentiated human fetal pancreas.

Cell Transplant 2009 ;18(2):183-93

Division of Transplantation Surgery, Karolinska University Hospital-Huddinge, Karolinska Institutet, Stockholm, Sweden.

Although the appearance of hepatic foci in the pancreas has been described in animal experiments and in human pathology, evidence for the conversion of human pancreatic cells to liver cells is still lacking. We therefore investigated the developmental plasticity between human embryonic pancreatic cells and liver cells. Cells were isolated and expanded from 7-8-week-old human fetal pancreata (HFP) and were characterized for the absence and presence of pancreatic and hepatic markers. In vitro expanded HFP were treated with fibroblast growth factor 2 (FGF2) and dexamethasone (DX) to induce a liver phenotye in the cells. These treated cells in various passages were further studied for their capacity to be functional in hepatic parenchyma following retrorsine-induced injury in nude C57 black mice. Amylase- and EPCAM-positive-enriched cells isolated from HFP and treated with FGF2 and DX lost expression of pancreatic markers and gained a liver phenotype. Hepatic differentiation was based on the expression (both at the mRNA and protein level) of liver markers albumin and cytokeratin 19. When transplanted in vivo into nude mice treated with retrorsine, both cell types successfully engrafted and functionally differentiated into hepatic cells expressing human albumin, glycogen, dipeptidyl peptidase, and gamma-glutamyltranspeptidase. These data indicate that human fetal pancreatic cells have a capacity to alter their gene expression profile in response to exogenous treatment with FGF2 and DX. It may be possible to generate an unlimited supply of hepatocytes in vitro for cell therapy.
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http://dx.doi.org/10.3727/096368909788341333DOI Listing
August 2009

Reprogramming of liver to pancreas.

Methods Mol Biol 2009 ;482:407-18

Centre for Regenerative Medicine, Department of Biology, University of Bath, Bath, UK.

Islet grafts have demonstrated that patients with diabetes would benefit greatly by beta-cell therapy. However, the paucity of available islets for transplantation as well as the immunological barriers faced in allogeneic transplantation represent a tremendous barrier to regenerative approaches to the treatment of diabetes. Here, we present a strategy and protocols to transdifferentiate developmentally related hepatocytes into beta-cells by the ectopic expression of critical beta-cell transcription factors.
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http://dx.doi.org/10.1007/978-1-59745-060-7_25DOI Listing
February 2009

Erythropoietin mediates hepcidin expression in hepatocytes through EPOR signaling and regulation of C/EBPalpha.

Blood 2008 Jun 7;111(12):5727-33. Epub 2008 Mar 7.

Iron Genes and Immune System, Instituto de Biologia Molecular e Celular, University of Porto, Porto, Portugal.

Hepcidin is the principal iron regulatory hormone, controlling the systemic absorption and remobilization of iron from intracellular stores. Recent in vivo studies have shown that hepcidin is down-regulated by erythropoiesis, anemia, and hypoxia, which meets the need of iron input for erythrocyte production. Erythropoietin (EPO) is the primary signal that triggers erythropoiesis in anemic and hypoxic conditions. Therefore, a direct involvement of EPO in hepcidin regulation can be hypothesized. We report here the regulation of hepcidin expression by EPO, in a dose-dependent manner, in freshly isolated mouse hepatocytes and in the HepG2 human hepatocyte cell model. The effect is mediated through EPOR signaling, since hepcidin mRNA levels are restored by pretreatment with an EPOR-blocking antibody. The transcription factor C/EBPalpha showed a pattern of expression similar to hepcidin, at the mRNA and protein levels, following EPO and anti-EPOR treatments. Chromatin immunoprecipitation experiments showed a significant decrease of C/EBPalpha binding to the hepcidin promoter after EPO supplementation, suggesting the involvement of this transcription factor in the transcriptional response of hepcidin to EPO.
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http://dx.doi.org/10.1182/blood-2007-08-106195DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2597200PMC
June 2008

Transdifferentiation in developmental biology, disease, and in therapy.

Dev Dyn 2007 Dec;236(12):3208-17

Centre for Regenerative Medicine, Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath, United Kingdom.

Transdifferentiation (or metaplasia) refers to the conversion of one cell type to another. Because transdifferentiation normally occurs between cells that arise from the same region of the embryo, understanding the molecular and cellular events in cell type transformations may help to explain the mechanisms underlying normal development. Here we review examples of transdifferentiation in nature focusing on the possible role of cell type switching in metamorphosis and regeneration. We also examine transdifferentiation in mammals in relation to disease and the use of transdifferentiated cells in cellular therapy.
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http://dx.doi.org/10.1002/dvdy.21336DOI Listing
December 2007

Stem cells in the adult pancreas and liver.

Biochem J 2007 Jun;404(2):169-78

Centre for Regenerative Medicine, Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath BA2 7AY, UK.

Stem cells are undifferentiated cells that can self-renew and generate specialized (functional) cell types. The remarkable ability of stem cells to differentiate towards functional cells makes them suitable modalities in cellular therapy (which means treating diseases with the body's own cells). Potential targets for cellular therapy include diabetes and liver failure. However, in order for stem cells to be clinically useful, we must learn to identify them and to regulate their differentiation. We will use the intestine as a classical example of a stem cell compartment, and then examine the evidence for the existence of adult stem cells in two endodermally derived organs: pancreas and liver. We will review the characteristics of the putative stem cells in these tissues and the transcription factors controlling their differentiation towards functional cell types.
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http://dx.doi.org/10.1042/BJ20070167DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2715288PMC
June 2007

Liver specification: a new role for Wnts in liver development.

Curr Biol 2006 Sep;16(17):R688-90

Centre for Regenerative Medicine, Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath BA2 7AY, UK.

Secreted Wnt proteins control a diverse array of developmental decisions. A recent analysis of the zebrafish mutant prometheus points to a previously unknown role for Wnts during liver specification.
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http://dx.doi.org/10.1016/j.cub.2006.08.011DOI Listing
September 2006