Home About us Contact
|
Home About us Contact | ||
|
|
||
One Cell Type (one + cell_type)
Selected AbstractsTransdifferentiation in developmental biology, disease, and in therapyDEVELOPMENTAL DYNAMICS, Issue 12 2007Shifaan Thowfeequ Abstract 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. Developmental Dynamics 236:3208,3217, 2007. © 2007 Wiley-Liss, Inc. [source] Acute activation of Erk1/Erk2 and protein kinase B/akt proceed by independent pathways in multiple cell typesFEBS JOURNAL, Issue 17 2005Doris Chiu We used two inhibitors of the signaling enzyme phosphatidylinositol 3-kinase (PtdIns3K), wortmannin and LY294002, to evaluate the potential involvement of PtdIns3K in the activation of the MAP kinases (MAPK), Erk1 and Erk2. In dose,response studies carried out on six different cell lines and a primary cell culture, we analyzed the ability of the inhibitors to block phosphorylation of protein kinase B/akt (PKB/akt) at Ser473 as a measure of PtdIns3K activity, or the phosphorylation of Erk1/2 at activating Thr/Tyr sites as a measure of the extent of activation of MAPK/Erk kinase (MEK/Erk). In three different hemopoietic cell lines stimulated with cytokines, and in HEK293 cells, stimulated with serum, either wortmannin or LY294002, but never both, could partially block phosphorylation of Erks. The same observations were made in a B-cell line and in primary fibroblasts. In only one cell type, the A20 B cells, was there a closer correlation between the PtdIns3K inhibition by both inhibitors, and their corresponding effects on Erk phosphorylation. However, this stands out as an exception that gives clues to the mechanism by which cross-talk might occur. In all other cells, acute activation of the pathway leading to Erk phosphorylation could proceed independently of PtdIns3K activation. In a biological assay comparing these two pathways, the ability of LY294002 and the MEK inhibitor, U0126, to induce apoptosis were tested. Whereas LY294002 caused death of cytokine-dependent hemopoietic cells, U0126 had little effect, but both inhibitors together had a synergistic effect. The data show that these two pathways are regulating very different downstream events involved in cell survival. [source] Co-culture in cartilage tissue engineeringJOURNAL OF TISSUE ENGINEERING AND REGENERATIVE MEDICINE, Issue 3 2007Jeanine Hendriks Abstract For biotechnological research in vitro in general and tissue engineering specifically, it is essential to mimic the natural conditions of the cellular environment as much as possible. In choosing a model system for in vitro experiments, the investigator always has to balance between being able to observe, measure or manipulate cell behaviour and copying the in situ environment of that cell. Most tissues in the body consist of more than one cell type. The organization of the cells in the tissue is essential for the tissue's normal development, homeostasis and repair reaction. In a co-culture system, two or more cell types brought together in the same culture environment very likely interact and communicate. Co-culture has proved to be a powerful in vitro tool in unravelling the importance of cellular interactions during normal physiology, homeostasis, repair and regeneration. The first co-culture studies focused mainly on the influence of cellular interactions on oocytes maturation to a pre-implantation blastocyst. Therefore, a brief overview of these studies is given here. Later on in the history of co-culture studies, it was applied to study cell,cell communication, after which, almost immediately as the field of tissue engineering was recognized, it was introduced in tissue engineering to study cellular interactions and their influence on tissue formation. This review discusses the introduction and applications of co-culture systems in cell biology research, with the emphasis on tissue engineering and its possible application for studying cartilage regeneration. Copyright © 2007 John Wiley & Sons, Ltd. [source] Polycomb, trithorax and the decision to differentiateBIOESSAYS, Issue 4 2006Leonie Ringrose For stem cells, life is full of potential: they have a high capacity to proliferate and a wide choice of future identities. When they differentiate, cells leave behind this freedom and become ever more committed to a single fate. Intriguingly, the Polycomb and Trithorax groups of proteins are vital to the very different natures of both stem cells and differentiated cells, but little is known about how they make the transition from one cell type to the other. A recent paper1 throws light on this mystery, showing that the Polycomb proteins dramatically change their behaviour at a crucial moment of differentiation. BioEssays 28: 330,334, 2006. © 2006 Wiley Periodicals, Inc. [source] | ||||||||||