Differentiation of murine erythroleukemia cells results in the rapid repression of vimentin gene expression.

Abstract

We show that vimentin filaments are present in undifferentiated Friend murine erythroleukemia cells, but are lost progressively to undetectable levels by 96 h of dimethyl sulfoxide-mediated differentiation. The amount of newly synthesized cytoskeletal vimentin is decreased dramatically by 24 h of induction, and is paralleled by a rapid loss of vimentin mRNA (approximately 25-fold reduction at 96 h). Hence, disappearance of vimentin filaments in these cells appears to be regulated at the level of vimentin mRNA abundance. On the other hand, the levels of actin synthesis and actin mRNA remain essentially unchanged. The kinetics of vimentin mRNA reduction during dimethyl sulfoxide-mediated differentiation, and the levels of vimentin mRNA observed in the presence of hexamethylene-bisacetamide or hemin as inducers suggest that the cessation of vimentin expression precedes, but may be associated with commitment to terminal differentiation. Our results demonstrate the dynamic regulation of vimentin expression in mammalian erythropoiesis.

Coding sequence and growth regulation of the human vimentin gene.

“…On the contrary, vimentin RNA levels decreased when HL-60 cells were induced to differentiate with retinoic acid. Vimentin synthesis also decreases in the morphological differentiation of 3T3 adipocytes (53) and in differentiating erythroleukemia cells (39). This ambivalence of vimentin expression, by which its RNA levels increase both after stimulation of cellular proliferation and after induction of differentiation, should not be surprising.…”

Changes in nuclear morphology during apoptosis correlate with vimentin cleavage by different caspases located either upstream or downstream of Bcl‐2 action

“…Immunoelectron microscopic studies of avian erythrocytes suggested that vimentin is involved in anchoring the nucleus to the plasma membrane (Granger & Lazarides 1982). During erythroid differentiation of cultured erythroid precursor cells, vimentin expression is down-regulated, suggesting that removal of the vimentin network may be necessary for enucleation (Dellagi et al 1983;Ngai et al 1984;Sangiorgi et al 1990). Over-expression of vimentin in transgenic mice resulted in cataracts in the eye lens, possibly because the enucleation of lens cells during development was hampered (Capetanaki et al 1989).…”

Expression of transfected vimentin genes in differentiating murine erythroleukemia cells reveals divergent cis-acting regulation of avian and mammalian vimentin sequences.

“…[35S]methionine for 1 h as described previously (69). Equivalent amounts of protein-incorporated [35S] radioactivity in Triton X-100-insoluble residues (5, 62) from each sample were loaded on two-dimensional isoelectric focusing-SDSpolyacrylamide gels (70); gels were stained with Coomassie blue to visualize total protein and then impregnated with 2,5-diphenyloxazole for fluorography (7).…”

“…Equivalent amounts of protein-incorporated [35S] radioactivity in Triton X-100-insoluble residues (5, 62) from each sample were loaded on two-dimensional isoelectric focusing-SDSpolyacrylamide gels (70); gels were stained with Coomassie blue to visualize total protein and then impregnated with 2,5-diphenyloxazole for fluorography (7). Immunofluorescence microscopy with an anti-chicken vimentin antiserum (33) was performed exactly as described previously (69 57-nt extension products, corresponding to correctly initiated hamster vimentin mRNA, were quantitated by Cerenkov radiation determination of excised gel slices. Serial dilution of BHK-21 RNA (a source of high levels of hamster vimentin RNA) over a 20-fold range yielded a commensurate decrease in radioactive extension products (data not shown).…”

“…In chicken embryonic erythropoiesis, vimentin mRNA is found at low levels in immature, mitotic primitive cells and accumulates to increasingly higher levels during terminal differentiation of the definitive erythroid lineage, apparently underlying similar changes at the protein level (10). During differentiation of murine erythroleukemia (MEL) cells in vitro, vimentin mRNA levels rapidly and extensively decline (-25-fold reduction), rendering a concomitant decrease in vimentin synthesis and a subsequent loss of vimentin filaments (69). The striking difference in the changes of vimentin mRNA abundances (and, ultimately, vimentin filaments) during mammalian and avian erythropoiesis presents an opportunity to study not only the factors responsible for the dynamic positive and negative regulation of the vimentin gene but also the basis for the evolutionary divergence of the two erythropoietic programs with regard to vimentin expression.…”