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Kirill V Tarasov

Publications and source records attributed to Kirill V Tarasov.

8 recordsLinked to original sources
PubMed2006

Signals from embryonic fibroblasts induce adult intestinal epithelial cells to form nestin-positive cells with proliferation and multilineage differentiation capacity in vitro.

The intestinal epithelium has one of the greatest regenerative capacities in the body; however, neither stem nor progenitor cells have been successfully cultivated from the intestine. In this study, we applied an "artificial niche" of mouse embryonic fibroblasts to derive multipotent cells from the intestinal epithelium. Cocultivation of adult mouse and human intestinal epithelium with fibroblast feeder cells led to the generation of a novel type of nestin-positive cells (intestinal epithelium-derived nestin-positive cells [INPs]). Transcriptome analyses demonstrated that mouse embryonic fibroblasts expressed relatively high levels of Wnt/bone morphogenetic protein (BMP) transcripts, and the formation of INPs was specifically associated with an increase in Lef1, Wnt4, Wnt5a, and Wnt/BMP-responsive factors, but a decrease of BMP4 transcript abundance. In vitro, INPs showed a high but finite proliferative capacity and readily differentiated into cells expressing neural, pancreatic, and hepatic transcripts and proteins; however, these derivatives did not show functional properties. In vivo, INPs failed to form chimeras following injection into mouse blastocysts but integrated into hippocampal brain slice cultures in situ. We conclude that the use of embryonic fibroblasts seems to reprogram adult intestinal epithelial cells by modulation of Wnt/BMP signaling to a cell type with a more primitive embryonic-like stage of development that has a high degree of flexibility and plasticity.

Animals↗
PubMed2006

Newly expressed SUR1-regulated NC(Ca-ATP) channel mediates cerebral edema after ischemic stroke.

Pathological conditions in the central nervous system, including stroke and trauma, are often exacerbated by cerebral edema. We recently identified a nonselective cation channel, the NC(Ca-ATP) channel, in ischemic astrocytes that is regulated by sulfonylurea receptor 1 (SUR1), is opened by depletion of ATP and, when opened, causes cytotoxic edema. Here, we evaluated involvement of this channel in rodent models of stroke. SUR1 protein and mRNA were newly expressed in ischemic neurons, astrocytes and capillaries. Upregulation of SUR1 was linked to activation of the transcription factor Sp1 and was associated with expression of functional NC(Ca-ATP) but not K(ATP) channels. Block of SUR1 with low-dose glibenclamide reduced cerebral edema, infarct volume and mortality by 50%, with the reduction in infarct volume being associated with cortical sparing. Our findings indicate that the NC(Ca-ATP) channel is crucially involved in development of cerebral edema, and that targeting SUR1 may provide a new therapeutic approach to stroke.

ATP-Binding Cassette Transporters↗
PubMed2006

SAGE analysis to identify embryonic stem cell-predominant transcripts.

The Human Genome Consortium has successfully sequenced the entire human genome (http://www.genome.gov/11006945), but an unfinished goal remains the identification of specific genes responsible for unique cellular processes. With respect to embryonic stem (ES) cells, this includes the identification of factors that govern self-renewal and pluripotentiality. One technique that facilitates this last goal is serial analysis of gene expression (SAGE), a functional genomics technique that identifies and quantifies mRNA transcripts. This technique relies on the preparation and sequencing of complementary DNA concatemers to rapidly generate a comprehensive profile of gene expression within a cell, and unlike microarrays, it does not require prior knowledge of the genes to be assayed. Because SAGE is a sequence-based technique, it can be used to search for ES-restricted genes (i.e., markers) by sequence comparisons among stem cells, differentiated cells, and tissues. These markers can then be genetically manipulated to understand the molecular basis for stem cell biology to help define how transcriptional mechanisms distinguish ES cells from other, less-pluripotent cell types. SAGE is, thus, a powerful technique that permits a comprehensive analysis of mRNA abundance that can define, at a molecular level, fundamental characteristics of ES cells. In this chapter, we illustrate the basic principles of SAGE, describe a complete protocol for the generation of SAGE libraries, and show how this technique can be employed to analyze embryonic stem cells.

Animals↗
PubMed2002

SAGE identification of gene transcripts with profiles unique to pluripotent mouse R1 embryonic stem cells.

The identification of signals that regulate pluripotentiality and self-renewal is fundamental to the understanding of stem cell biology. To quantify the functionally active genome of pluripotent R1 embryonic stem (ES) cells, we used the method of serial analysis of gene expression (SAGE) to sequence a total of 140,313 SAGE tags. Of 44,569 unique transcripts, 9% matched known genes in the nonredundant GenBank database, whereas >35% of the unique tags did not match any known mouse sequence. Comparisons of relatively abundant (> or = 20) tags in the ES cell SAGE catalog with publicly available SAGE data sets identified 16 transcripts with an abundance profile unique to pluripotent R1 ES cells. We confirmed 12 by RT-PCR including those encoding KLF2, a transcription factor; galanin, a hypothalamic neurohormone; BAX, a proapoptotic signaling factor; and CDK4 and PAL31, cell cycle progression associated proteins. The data from this study provide a starting point for detailed transcriptome analyses of stem cells.

Animals↗
PubMed2002

A quantitative and validated SAGE transcriptome reference for adult mouse heart.

Transcriptome comparisons facilitate the identification of developmental, aging, and disease-related genes. To quantify the functionally active genome of adult C57BL/6 mouse heart (AMH), we used serial analysis of gene expression (SAGE) to sequence a total of 88,860 tags or 23,941 unique tags. Over 66% of the unique tags matched either known genes or ESTs. Mitochondrial transcripts accounted for 18.7% of the total transcripts, whereas sarcomeric proteins accounted for 3.2% of all tags. After comparison of AMH expression profiles obtained by SAGE and cDNA arrays, we observed numerous quantitative discrepancies (for example: arrays, mt-Co1 > mt-Co2 > mt-Co3; SAGE, mt-Co1 >> mt-Co3 >or= mt-Co2). We carried out quantitative PCR analyses as an independent test of transcript abundance and determined that SAGE yielded quantitatively reliable data. These SAGE results thus represent the first quantitative expression profile of AMH and serve as a reliable transcriptome reference to identify dynamic changes in cardiac gene expression.

Animals↗
PubMed2002

SAGE identification of differentiation responsive genes in P19 embryonic cells induced to form cardiomyocytes in vitro.

Transcriptome profiling facilitates the identification of developmentally regulated genes. To quantify the functionally active genome of P19 embryonic carcinoma (EC) cells induced to form cardiomyocytes, we employed serial analysis of gene expression (SAGE) to sequence and compare a total of 171,735 SAGE tags from three libraries (undifferentiated P19 EC cells, differentiation days 3 + 0.5 and 3 + 3.0). After in vitro differentiation, only 3.1% of the gene products demonstrated significant (P < 0.05) changes in expression. The most highly significant changes (P < 0.01) involved altered expression of 410 genes encoding predominantly transcription factors, differentiation factors and growth regulators. Quantitative polymerase chain reaction analysis and in situ hybridization revealed five growth regulators (Dlk1, Igfbp5, Hmga2, Podxl and Ptn) and two unknown ESTs with expression profiles similar to known cardiac transcription factors, implicating these growth regulators in cardiac differentiation. These SAGE libraries thus serve as a reference resource for understanding the role of differentiation-dependent genes in embryonic stem cell models induced to form cardiomyocytes in vitro.

Animals↗
PubMedDate not supplied

Somatic stem cell marker prominin-1/CD133 is expressed in embryonic stem cell-derived progenitors.

Prominin-1/CD133 is a plasma membrane marker found in several types of somatic stem cells, including hematopoietic and neural stem cells. To study its role during development and with differentiation, we analyzed its temporal and spatial expression (mRNA and protein) in preimplantation embryos, undifferentiated mouse embryonic stem (ES) cells, and differentiated ES cell progeny. In early embryos, prominin-1 was expressed in trophoblast but not in cells of the inner cell mass; however, prominin-1 transcripts were detected in undifferentiated ES cells. Both ES-derived cells committed to differentiation and early progenitor cells coexpressed prominin-1 with early lineage markers, including the cytoskeletal markers (nestin, cytokeratin 18, desmin), fibulin-1, and valosin-containing protein. After spontaneous differentiation at terminal stages, prominin-1 expression was downregulated and no coexpression with markers characteristic for neuroectodermal, mesodermal, and endodermal cells was found. Upon induction of neuronal differentiation, some prominin-1-positive cells, which coexpressed nestin and showed the typical morphology of neural progenitor cells, persisted until terminal stages of differentiation. However, no coexpression of prominin-1 with markers of differentiated neural cells was detected. In conclusion, we present the somatic stem cell marker prominin-1 as a new parameter to define ES-derived committed and early progenitor cells.

AC133 Antigen↗