Induction of erythroid differentiation in rat erythroleukaemic (REL) cells

Alcorn, Michael Joseph (1995) Induction of erythroid differentiation in rat erythroleukaemic (REL) cells. PhD thesis, University of Glasgow.

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Abstract

The work presented here was an attempt to characterise some properties of a rat erythroleukaemic cell line (REL), in particular, the ability of these cells to undergo erytliroid differentiation following exposure to dimethylsulphoxide (DMSO). Erythroid differentiation was readily demonstrated by the appearance of haemoglobin in REL cells, using the benzidine reaction. Although it required some 72 hours exposure to DMSO before significant numbers of haemoglobinized cells could be detected, it appeared that some cells became committed to differentiate after as little as 8 hours exposure. It was possible to propose a sequence of events when REL cells were exposed to DMSO. After 4 hours of DMSO, DNA synthesis was down- regulated and REL cells started to shift out of S-phase of the cell cycle (i.e. proliferative) and started to accumulate in G0/G1(i.e. quiescent). This loss of proliferative ability was reflected in a reduction in cloning efficiency, i.e. some cells could no longer divide. Cells became committed to differentiation by 8 hours and by 24 hours, gross morphological changes could be observed, e.g. a significant reduction in cell size, cells adopting a smooth surface appearance as demonstrated by scanning electron microscopy (SEM). Cells producing haemoglobin could be detected by 72 hours of DMSO and the number of cells rose to a maximum after about 96 hours. It would appear that haemoglobin production is a relatively late event in DMSO-induced erytliroid differentiation of REL cells. To try to identify the biological activities that regulate differentiation, REL cells were adapted to a chemically defined, serum-free (SF) medium. Although the growth and division of these cells was not significantly different from cells grown in serum-containing medium, without serum, REL cells could not be induced to differentiate. Even when SF medium was supplemented with combinations of known growth factors / cytokines, no significant erythroid differentiation was obtained. It is because of this ability to differentiate along an erythroid pathway that the REL cells are regarded as erythroleukaemic. However, under certain culture conditions, REL cells developed characteristics associated with monocyte / macrophage maturation as demonstrated by morphology, appearance under SEM, cytochemical analyses, and expression of a macrophage-associated surface antigen. It would appear that REL cells are not restricted to the erythroid lineage, but, in fact, they retain the potential to mature along additional lineages. Brief cytogenetic analysis revealed the presence of a chromosomal abberation, namely, the translocation of the major portion of chromosome 3 to the terminal region of chromosome 1. The area of the breakpoint on chromosome 3 contains the protooncogene, c-abl. It may be that this translocation subverts the normal expression of c-abl and this aberrant expression contributes to the unregulated growth of REL cells.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Additional Information: Adviser: K Alan Burnett
Keywords: Cellular biology
Date of Award: 1995
Depositing User: Enlighten Team
Unique ID: glathesis:1995-71710
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 17 May 2019 09:31
Last Modified: 17 May 2019 09:31
URI: http://theses.gla.ac.uk/id/eprint/71710

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