scholarly journals Hematopoietic lineage-specific heterogeneity in the 5'-terminal region of the chicken proto-myb transcript.

1989 ◽  
Vol 9 (9) ◽  
pp. 3771-3776 ◽  
Author(s):  
W K Kim ◽  
M A Baluda

Comparison of the nucleotide sequence of the upstream c-myb exon UE3 with the sequences of a thymus c-myb cDNA and of a B-lymphoma c-myb cDNA suggested the existence of T- and B-cell-specific heterogeneity in the 5'-terminal region of the c-myb coding sequence. This possibility was investigated with T-cell-specific and B-cell-specific DNA probes in a Northern (RNA) blot analysis of mRNAs from different hematopoietic cell types and from chicken embryo fibroblasts. The hematopoietic tissues analyzed were bone marrow, bursa of Fabricius, and thymus from 1-day-old chicks, 13-day yolk sac, and spleen from 16-day embryos. At least three different c-myb mRNA species were found to have 5'-terminal heterogeneity that was specific for either B cells, T cells, or the other hematopoietic cells and chicken embryo fibroblasts. This lineage-specific heterogeneity in the c-myb transcript was found to be expressed in the bone marrow precursors of B and T cells before they migrated to their definitive differentiation sites. S1 nuclease protection analysis of the UE3 exon, part of which appeared to be coding sequences for thymic c-myb mRNA, revealed that this exon is utilized either in its entirety or partially in a cell-lineage-specific manner by all six tissues analyzed. Also, the 5'-terminal exon(s) present in the thymus cDNA was absent in c-myb mRNAs from the other cell types analyzed.

1989 ◽  
Vol 9 (9) ◽  
pp. 3771-3776
Author(s):  
W K Kim ◽  
M A Baluda

Comparison of the nucleotide sequence of the upstream c-myb exon UE3 with the sequences of a thymus c-myb cDNA and of a B-lymphoma c-myb cDNA suggested the existence of T- and B-cell-specific heterogeneity in the 5'-terminal region of the c-myb coding sequence. This possibility was investigated with T-cell-specific and B-cell-specific DNA probes in a Northern (RNA) blot analysis of mRNAs from different hematopoietic cell types and from chicken embryo fibroblasts. The hematopoietic tissues analyzed were bone marrow, bursa of Fabricius, and thymus from 1-day-old chicks, 13-day yolk sac, and spleen from 16-day embryos. At least three different c-myb mRNA species were found to have 5'-terminal heterogeneity that was specific for either B cells, T cells, or the other hematopoietic cells and chicken embryo fibroblasts. This lineage-specific heterogeneity in the c-myb transcript was found to be expressed in the bone marrow precursors of B and T cells before they migrated to their definitive differentiation sites. S1 nuclease protection analysis of the UE3 exon, part of which appeared to be coding sequences for thymic c-myb mRNA, revealed that this exon is utilized either in its entirety or partially in a cell-lineage-specific manner by all six tissues analyzed. Also, the 5'-terminal exon(s) present in the thymus cDNA was absent in c-myb mRNAs from the other cell types analyzed.


1976 ◽  
Vol 155 (2) ◽  
pp. 297-301 ◽  
Author(s):  
P J. Anderson

The isolation and quantification of an 18-residue peptide from the N-terminal region of chicken actin was used to quantify the amount of actin in acetone-dried powders of chicken breast muscle and chicken-embryo fibroblasts. Either isotope dilution or double labelling can be used for peptide quantification. About 17% of the protein of chicken breast muscle was estimated to be actin. However, only 0.25% of the protein of chicken-embryo fibroblasts was determined to be actin by quantification of this peptide. The actin content of fibroblasts may be low or the amino acid sequences of muscle and fibroblast actin may differ in the N-terminal region. The methodology used can be extended to examine whether other regions of muscle actin sequence are present in fibroblasts or other cell types.


Author(s):  
Gary E. Korte

Four types of specialized epithelial cells have been observed in the fish tastebud, within the capsule formed by the flattened epidermal cells. However, only two or three of these have been previously noted in any one species, including the glass catfish Kryptopterus bicirrhis, the subject of this investigation (1,2). For the first time, all four types of specialized cells have been observed,and an artifact of fixation relevant to the identification of these cell types has been uncovered.A single basal, or B cell lies on the basement membrane of the epidermis (Fig. 1). It makes many synapses with the afferent nerve plexus, which lies just above it. The other three cell types, designated S,L and T cells (Fig. 2A) are external to the nerve plexus, and only rarely make synapses onto nerves, confirming the observations of several other investigations.


1987 ◽  
Vol 7 (9) ◽  
pp. 3147-3155 ◽  
Author(s):  
E Erikson ◽  
D Stefanovic ◽  
J Blenis ◽  
R L Erikson ◽  
J L Maller

Ribosomal protein S6 becomes highly phosphorylated during progesterone- or insulin-induced maturation of Xenopus laevis oocytes. We have previously purified an Mr 92,000 protein as one of the major S6 kinases from Xenopus unfertilized eggs. In this paper we confirm by renaturation of activity from a sodium dodecyl sulfate-polyacrylamide gel that this protein is an S6 kinase. This enzyme, termed S6 kinase II (S6 K II), was used for the preparation of polyclonal antiserum. Immunocomplexes formed with the antiserum and purified S6 K II were able to express kinase activity with the same substrate specificity as that of the purified enzyme, including autophosphorylation of S6 K II itself. The antiserum did not react with S6 kinase I, another major S6 kinase present in Xenopus eggs, which is chromatographically distinct from S6 K II. The administration of progesterone to oocytes resulted in a 20- to 25-fold increase in S6 kinase activity in extracts of these cells. Immunocomplex kinase assays done on extracts revealed that anti-S6 K II serum reacted with S6 kinase from progesterone-treated oocytes. This antiserum also reacted with the activated S6 kinase from insulin-stimulated oocytes. In addition, anti-S6 K II serum reacted with activated S6 kinase from chicken embryo fibroblasts stimulated with serum or transformed by Rous sarcoma virus. These results indicate that S6 K II or an antigenically related S6 kinase(s) is subject to regulation by mitogenic stimuli in various cell types.


1987 ◽  
Vol 7 (9) ◽  
pp. 3147-3155
Author(s):  
E Erikson ◽  
D Stefanovic ◽  
J Blenis ◽  
R L Erikson ◽  
J L Maller

Ribosomal protein S6 becomes highly phosphorylated during progesterone- or insulin-induced maturation of Xenopus laevis oocytes. We have previously purified an Mr 92,000 protein as one of the major S6 kinases from Xenopus unfertilized eggs. In this paper we confirm by renaturation of activity from a sodium dodecyl sulfate-polyacrylamide gel that this protein is an S6 kinase. This enzyme, termed S6 kinase II (S6 K II), was used for the preparation of polyclonal antiserum. Immunocomplexes formed with the antiserum and purified S6 K II were able to express kinase activity with the same substrate specificity as that of the purified enzyme, including autophosphorylation of S6 K II itself. The antiserum did not react with S6 kinase I, another major S6 kinase present in Xenopus eggs, which is chromatographically distinct from S6 K II. The administration of progesterone to oocytes resulted in a 20- to 25-fold increase in S6 kinase activity in extracts of these cells. Immunocomplex kinase assays done on extracts revealed that anti-S6 K II serum reacted with S6 kinase from progesterone-treated oocytes. This antiserum also reacted with the activated S6 kinase from insulin-stimulated oocytes. In addition, anti-S6 K II serum reacted with activated S6 kinase from chicken embryo fibroblasts stimulated with serum or transformed by Rous sarcoma virus. These results indicate that S6 K II or an antigenically related S6 kinase(s) is subject to regulation by mitogenic stimuli in various cell types.


1985 ◽  
Vol 100 (3) ◽  
pp. 692-703 ◽  
Author(s):  
J J Lin ◽  
D M Helfman ◽  
S H Hughes ◽  
C S Chou

Seven polypeptides (a, b, c, 1, 2, 3a, and 3b) have been previously identified as tropomyosin isoforms in chicken embryo fibroblasts (CEF) (Lin, J. J.-C., Matsumura, F., and Yamashiro-Matsumura, S., 1984, J. Cell. Biol., 98:116-127). Spots a and c had identical mobility on two-dimensional gels with the slow-migrating and fast-migrating components, respectively, of chicken gizzard tropomyosin. However, the remaining isoforms of CEF tropomyosin were distinct from chicken skeletal and cardiac tropomyosins on two-dimensional gels. The mixture of CEF tropomyosin has been isolated by the combination of Triton/glycerol extraction of monolayer cells, heat treatment, and ammonium sulfate fractionation. The yield of tropomyosin was estimated to be 1.4% of total CEF proteins. The identical set of tropomyosin isoforms could be found in the antitropomyosin immunoprecipitates after the cell-free translation products of total poly(A)+ RNAs isolated from CEF cells. This suggested that at least seven mRNAs coding for these tropomyosin isoforms existed in the cell. Purified tropomyosins (particularly 1, 2, and 3) showed different actin-binding abilities in the presence of 100 mM KCl and no divalent cation. Under this condition, the binding of tropomyosin 3 (3a + 3b) to actin filaments was significantly weaker than that of tropomyosin 1 or 2. CEF tropomyosin 1, and probably 3, could be cross-linked to form homodimers by treatment with 5,5'-dithiobis-(2-nitrobenzoate), whereas tropomyosin a and c formed a heterodimer. These dimer species may reflect the in vivo assembly of tropomyosin isoforms, since dimer formation occurred not only with purified tropomyosin but also with microfilament-associated tropomyosin. The expression of these tropomyosin isoforms in Rous sarcoma virus-transformed CEF cells has also been investigated. In agreement with the previous report by Hendricks and Weintraub (Proc. Natl. Acad. Sci. USA., 78:5633-5637), we found that major tropomyosin 1 was greatly reduced in transformed cells. We have also found that the relative amounts of tropomyosin 3a and 3b were increased in both the total cell lysate and the microfilament fraction of transformed cells. Because of the different actin-binding properties observed for CEF tropomyosins, changes in the expression of these isoforms may, in part, be responsible for the reduction of actin cables and the alteration of cell shape found in transformed cells.


1991 ◽  
Vol 11 (9) ◽  
pp. 4448-4454
Author(s):  
M K White ◽  
T B Rall ◽  
M J Weber

The increase in glucose transport that occurs when chicken embryo fibroblasts (CEFs) are transformed by src is associated with an increase in the amount of type 1 glucose transporter protein, and we have previously shown that this effect is due to a decrease in the degradation rate of this protein. The rate of CEF type 1 glucose transporter biosynthesis and the level of its mRNA are unaffected by src transformation. To study the molecular basis of this phenomenon, we have been isolating chicken glucose transporter cDNAs by hybridization to a rat type 1 glucose transporter probe at low stringency. Surprisingly, these clones corresponded to a message encoding a protein which has most sequence similarity to the human type 3 glucose transporter and which we refer to as CEF-GT3. CEF-GT3 is clearly distinct from the CEF type 1 transporter that we have previously described. Northern (RNA) analysis of CEF RNA with CEF-GT3 cDNA revealed two messages of 1.7 and 3.3 kb which were both greatly induced by src transformation. When the CEF-GT3 cDNA was expressed in rat fibroblasts, a three-to fourfold enhancement of 2-deoxyglucose uptake was observed, indicating that CEF-GT3 is a functional glucose transporter. Northern analyses using a CEF-GT3 and a rat type 1 probe demonstrated that there is no hybridization between different isoforms but that there is cross-species hybridization between the rat type 1 probe and the chicken homolog. Southern blot analyses confirmed that the chicken genomic type 1 and type 3 transporters are encoded by distinct genes. We conclude that CEFs express two types of transporter, type 1 (which we have previously reported to be regulated posttranslationally by src) and a novel type 3 isoform which, unlike type 1, shows mRNA induction upon src transformation. We conclude that src regulates glucose transport in CEFs simultaneously by two different mechanisms.


1986 ◽  
Vol 6 (12) ◽  
pp. 4602-4610
Author(s):  
U Bond ◽  
M J Schlesinger

A chicken genomic library was screened to obtain genomic clones for ubiquitin genes. Two genes that differ in their genomic location and organization were identified. One gene, designated Ub I, contains four copies of the protein-coding sequence arranged in tandem, while the second gene, Ub II, contains three. The origin of the two major mRNAs that are induced after heat shock in chicken embryo fibroblasts was determined by generating DNA probes from the 5'-and 3'-noncoding regions of the two genes. Both mRNAs are transcribed from Ub I, the larger being the unspliced precursor of the smaller. A 674-base-pair intron was located within the 5'-noncoding region of Ub I. The second gene, Ub II, does not appear to code for an RNA species in normal or heat-shocked chicken embryo fibroblasts. The expression of ubiquitin mRNA during heat shock and recovery was examined. Addition of actinomycin D before heat shock completely abolished the response of ubiquitin mRNA to the stress. Analysis of the stability of the mRNA during recovery revealed that the mRNA accumulated during the heat shock is rapidly degraded with a half-life of approximately 1.5 h, suggesting a specialized but transient role for ubiquitin during heat shock.


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