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Title: Reprogramming of fibroblasts by the Piwil2 gene
Author: Elyaderani, Parisa Javadian
Awarding Body: University of Newcastle Upon Tyne
Current Institution: University of Newcastle upon Tyne
Date of Award: 2012
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The Piwil2 gene belongs to the Piwi family of genes conserved during evolution from Arabidopsis to human. The Piwi family genes are considered as stem cell modulators functioning in meristem cell division in Arabidopsis and germ stem cell propagation in C.elegans and in mammals. Although some essential functions such as germ cell development, transposition repression, epigenetic modification and translational regulation, as well as stem cell and cancer stem cell maintenance, are attributed to this family of genes, the detailed mechanism of the function of these genes still remains elusive. In this study, by taking advantage of the gam of function technique, the coding sequence of the Piwil2 gene was introduced into fibroblasts and stable Piwil2 expressing fibroblasts were established. These cells were evaluated for expression of germ cell specific markers, since the Piwil2 gene is well known as a regulator of spermatogenesis. Piwil2 transfected cells did not express specific markers of spermatogenesis, except Stra8 and Fragilis, but they did express the pluripotent markers of Oct4, Nanog, c-Myc and Klf4 instead. Furthermore, Piwil2 transfected cells exhibited a high tendency to form colony-like structures, partial staining for alkaline phosphatise (AP) activity, expression of germ layer markers and markers of the blood lineage. In terms of teratoma formation, Piwil2 transfected cells showed tumour outgrowth when injected subcutaneously in SCID mice. However, histological observations of the tumour sections revealed that tumours were not teratomas; instead, they were highly malignant tumours with rare signs of differentiation. This result is consistent with the suggestion that the Piwil2 gene is a cancer stem cell gene that is ectopically expressed in a variety of mammalian tumours. Although these results do not show full germ cell or i~S cell conversion of fibroblasts, the dramatic changes that were induced in the Piwil2 transfected cells, compared to the control cells, suggest this gene can act as a modulator of fundamental pathways such as proliferation and differentiation and bestow an unusual phenotype on fibroblasts. It is worth pointing out that some of the findings of this study, such as Oct4 and Terl19 expression in transfected fibroblasts, were not stable in spite of stable expression of the Piwil2 gene. The underlying reason for this might be some sort of dynamic effect of the Piwil2 gene on cell behaviour
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available