scholarly journals Biosynthesis of spectrin and its assembly into the cytoskeletal system of Friend erythroleukemia cells.

1986 ◽  
Vol 103 (1) ◽  
pp. 103-113 ◽  
Author(s):  
S R Pfeffer ◽  
T Huima ◽  
C M Redman
Keyword(s):  
Dimethyl Sulfoxide ◽  
Soluble Fraction ◽  
Insoluble Fraction ◽  
Cell Fraction ◽  
Erythroleukemia Cells ◽  
Alpha Spectrin ◽  
Membrane Bound ◽  
Friend Erythroleukemia Cells ◽  
Cytoskeletal System ◽  
In Cells

Friend erythroleukemia cells, grown in the presence of dimethyl sulfoxide for 3 d, synthesize unequal amounts of the two chains (alpha and beta) of spectrin with approximately 15-30% more beta than alpha spectrin. When cells were ruptured by nitrogen cavitation, nascent alpha and beta spectrin were found to be associated with a membranous cell fraction and were not detected in the soluble cytoplasmic cell fraction. Nascent membrane-bound spectrin appeared not to be protected by membranes, since it was susceptible to trypsin degradation in the absence of detergent. On fractionation of cells with 1% Triton X-100, more (1.75-fold) nascent spectrin was found in the Triton-soluble fraction than in the Triton-insoluble fraction (cytoskeleton). In the Triton-soluble fraction, there was 55% more nascent beta spectrin than alpha spectrin, while the cytoskeleton contained nearly equal amounts of alpha and beta spectrin. Cells were pulse-labeled with L-[35S]methionine for 2 min and chase incubated for varying periods of time from 15 to 90 min with nonradioactive L-methionine. Radioactive spectrin accumulated in the Triton-soluble fraction for the first 15 min of chase incubation and then dropped by 25% in the next hour. By contrast, the amount of radioactive spectrin in the Triton-insoluble fraction rose gradually for 1 h of the chase period. This indicates that, in Friend erythroleukemia cells, a pool of membrane-bound spectrin containing an excess of the beta polypeptide is used to form the cytoskeletal system which is composed of equal molar amounts of alpha and beta spectrin. The location of spectrin was determined by immunoelectron microscopy. Small amounts of spectrin were detected in cells not treated with dimethyl sulfoxide and in these cells it was located on the surface membrane and within the cytoplasm. On treatment with dimethyl sulfoxide, complex vacuolar structures containing viruses appeared in the cells. In cells treated with dimethyl sulfoxide for 3 d 30% of the spectrin was near the outer membrane and 25% was associated with vacuolar structures, whereas in cells treated for 5 and 7 d the majority of spectrin (57-61%) was located in the vacuolar areas.

scholarly journals Rapid capping in alpha-spectrin-deficient MEL cells from mice afflicted with hereditary hemolytic anemia.

1994 ◽  
Vol 125 (5) ◽  
pp. 1057-1065 ◽  
Author(s):  
S C Dahl ◽  
R W Geib ◽  
M T Fox ◽  
M Edidin ◽  
D Branton
Keyword(s):  
Membrane Structure ◽  
Membrane Skeleton ◽  
Wild Type ◽  
Membrane Glycoproteins ◽  
Erythroleukemia Cells ◽  
Alpha Spectrin ◽  
Erythroleukemia Cell ◽  
The Stability ◽  
In Cells

A spectrin-based membrane skeleton is important for the stability and organization of the erythrocyte. To study the role of spectrin in cells that possess complex cytoskeletons, we have generated alpha-spectrin-deficient erythroleukemia cell lines from sph/sph mice. These cells contain beta-spectrin, but lack alpha-spectrin as determined by immunoblot and Northern blot analyses. The effects of alpha-spectrin deficiency are apparent in the cells' irregular shape and fragility in culture. Capping of membrane glycoproteins by fluorescent lectin or antibodies occurs more rapidly in sph/sph than in wild-type erythroleukemia cells, and the caps appear more concentrated. The data support the idea that spectrin plays an important role in organizing membrane structure and limiting the lateral mobility of integral membrane glycoproteins in cells other than mature erythrocytes.

scholarly journals Hypomethylation of DNA during differentiation of friend erythroleukemia cells

1980 ◽  
Vol 86 (2) ◽  
pp. 366-370 ◽  
Author(s):  
JK Christman ◽  
N Weich ◽  
B Schoenbrun ◽  
N Schneiderman ◽  
G Acs
Keyword(s):  
Dimethyl Sulfoxide ◽  
Mammalian Cells ◽  
Dna Methyltransferases ◽  
Methyl Groups ◽  
Close Link ◽  
Erythroleukemia Cells ◽  
Chemically Induced ◽  
Methyl Cytosine ◽  
Friend Erythroleukemia Cells

DNA from mammalian cells has been shown to contain significant amounts of 5-methyl cytosine resulting from enzymatic transfer of methyl groups from s-adenosylmethionine to cytosine residues in the DNA polymer. The function of this modification is not known. We have found that DNA synthesized during chemically induced differentiation of friend erythroleukemia cells is hypomethylated, as measured by its ability to accept methyl groups transferred by homologous DNA methyltransferases in vitro. The extent of hypomethylation detected by this sensitive method is small, a decrease of less than 1.6 percent in 5-methylcytosine content. Hypomethylated DNA can be isolated from friend erythroleukemia cells grown in the presence of dimethyl sulfoxide, butyrate, hexamethylene-bis- acetamide, pentamethylene-bis acetamide, and ethionine. However, hypomethylated DNA is found only under conditions where differentiation is actually induced. DNA isolated from cells of a dimethyl sulfoxide- resistant subclone grown in the presence of that agent is not hypomethylated, although DNA of these cells becomes hypomethylated after growth in the presence of inducers that can trigger their differentiation. We also find that the DNA of friend erythroleukemia cells does not become hypomethylated when the cells are exposed to inducing agents in the presence of substances that inhibit differentiation. These results suggest a close link between genome modification by methylation and differentiation of friend erythroleukemia cells.

15-Lipoxygenase products affect protein phosphorylation in Friend erythroleukemia cells

1990 ◽  
Vol 68 (7-8) ◽  
pp. 1052-1056 ◽  
Author(s):  
B. S. Beckman ◽  
J. R. Jeter Jr.
Keyword(s):  
Arachidonic Acid ◽  
Protein Phosphorylation ◽  
Dimethyl Sulfoxide ◽  
Arachidonic Acid Metabolism ◽  
Hexamethylene Bisacetamide ◽  
Differentiated Cells ◽  
Erythroleukemia Cells ◽  
Acid Protein ◽  
Undifferentiated Cells ◽  
Friend Erythroleukemia Cells

Endogenous arachidonic acid metabolism and protein phosphorylation have been examined in Friend erythroleukemia cells in response to the induction of differentiation by dimethyl sulfoxide and hexamethylene bisacetamide. 15-Hydroxyeicosatetraenoic acid levels were elevated in cells differentiated with hexamethylene bisacetamide or dimethyl sulfoxide compared with undifferentiated cells. Protein phosphorylation decreased markedly in differentiated cells compared with undifferentiated cells and the addition of 15-hydroperoxyeicosatetraenoic acid specifically decreased the phosphorylation of a 28-kilodalton protein. These findings indicate that products of 15-lipoxygenase may act as intracellular messengers in Friend erythroleukemia cells by affecting protein phosphorylation.Key words: arachidonic acid, protein phosphorylation, proliferation, differentiation, 15-lipoxygenase.

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