scholarly journals Biochemical and genetic characterization of multiple splice variants of the Flt3 ligand

Blood ◽  
1996 ◽  
Vol 88 (9) ◽  
pp. 3371-3382 ◽  
Author(s):  
T McClanahan ◽  
J Culpepper ◽  
D Campbell ◽  
J Wagner ◽  
K Franz-Bacon ◽  
...  
Keyword(s):  
Cell Lines ◽  
Splice Variant ◽  
Splice Variants ◽  
Expression Patterns ◽  
Cell Contact ◽  
Flt3 Ligand ◽  
Stromal Cell Line ◽  
Membrane Bound ◽  
Macrophage Colony Stimulating Factor ◽  
Macrophage Colony

We have performed a comprehensive analysis of cell lines and tissues to compare and contrast the expression patterns of Flt3 ligand (FL), c-Kit ligand (KL), and macrophage colony-stimulating factor as well as their receptors, Flt3, c-Kit, and c-Fms. The message for FL is unusually ubiquitous, whereas that of its receptor is quite restricted, apparently limiting the function of the ligand to fetal development and early hematopoiesis. We have also sequenced a mouse FL genomic clone, revealing how the three splice variant FL mRNAs that we have isolated arise. The chromosomal location of the FL gene has been mapped, by in situ hybridization, to chromosome 7 in mouse and chromosome 19 in human. Natural FL protein has been purified from a stromal cell line and shown to be a 65 kD nondisulfide-linked homodimeric glycoprotein comprised of 30 kD subunits, each containing 12 kD of N- and O-linked sugars. Pulse-chase experiments show that one of the splice variants (T110) is responsible for producing the bulk of soluble FL, but only after it has first been expressed at the cell surface as a membrane-bound form. The other splice-variant forms produce molecules that are either obligatorily soluble (T169) or membrane-bound but released only very slowly (T118). Finally, even though most cell lines express some amount of FL mRNA, we found that very little FL protein is actually made, with T cells and stromal cells being the major producers. The data suggests that FL plays its roles over very short distances, perhaps requiring cell-cell contact.

scholarly journals Expression of Activated Mutants of the Human Interleukin-3/Interleukin-5/Granulocyte-Macrophage Colony-Stimulating Factor Receptor Common β Subunit in Primary Hematopoietic Cells Induces Factor-Independent Proliferation and Differentiation

Blood ◽  
1997 ◽  
Vol 90 (4) ◽  
pp. 1471-1481 ◽  
Author(s):  
Matthew P. McCormack ◽  
Thomas J. Gonda
Keyword(s):  
Amino Acid ◽  
Cell Lines ◽  
Amino Acid Substitution ◽  
Single Amino Acid ◽  
Colony Stimulating Factor ◽  
Interleukin 5 ◽  
Proliferation And Differentiation ◽  
Macrophage Colony Stimulating Factor ◽  
Macrophage Colony ◽  
Stimulating Factor

Abstract To date, several activating mutations have been discovered in the common signal-transducing subunit (hβc) of the receptors for human granulocyte-macrophage colony-stimulating factor, interleukin-3, and interleukin-5. Two of these, FIΔ and I374N, result in a 37 amino acid duplication and a single amino acid substitution in the extracellular domain of hβc, respectively. A third, V449E, results in a single amino acid substitution in the transmembrane domain. Previous studies comparing the activity of these mutants in different hematopoietic cell lines imply that the transmembrane and extracellular mutations act by different mechanisms and suggest the requirement for cell type-specific molecules in signalling. To characterize the ability of these mutant hβc subunits to mediate growth and differentiation of primary cells and hence investigate their oncogenic potential, we have expressed all three mutants in primary murine hematopoietic cells using retroviral transduction. It is shown that, whereas expression of either extracellular hβc mutant confers factor-independent proliferation and differentiation on cells of the neutrophil and monocyte lineages only, expression of the transmembrane mutant does so on these lineages as well as the eosinophil, basophil, megakaryocyte, and erythroid lineages. Factor-independent myeloid precursors expressing the transmembrane mutant display extended proliferation in liquid culture and in some cases yielded immortalized cell lines.

scholarly journals Real-Time RT-PCR Quantification of Human Telomerase Reverse Transcriptase Splice Variants in Tumor Cell Lines and Non–Small Cell Lung Cancer

2007 ◽  
Vol 53 (1) ◽  
pp. 53-61 ◽  
Author(s):  
Eleni Mavrogiannou ◽  
Areti Strati ◽  
Aliki Stathopoulou ◽  
Emily G Tsaroucha ◽  
Loukas Kaklamanis ◽  
...  
Keyword(s):  
Tumor Cell ◽  
Real Time ◽  
Cell Lines ◽  
Splice Variant ◽  
Splice Variants ◽  
Telomerase Activity ◽  
Tumor Cell Lines ◽  
Rt Pcr ◽  
Human Telomerase Reverse Transcriptase ◽  
Tissue Samples

Abstract Background: We developed and validated a real-time reverse transcription (RT)–PCR for the quantification of 4 individual human telomerase reverse transcriptase (TERT) splice variants (α+β+, α−β+, α+β−, α−β−) in tumor cell lines and non–small cell lung cancer (NSCLC). Methods: We used in silico designed primers and a common TaqMan probe for highly specific amplification of each TERT splice variant, PCR transcript–specific DNA external standards as calibrators, and the MCF-7 cell line for the development and validation of the method. We then quantified TERT splice variants in 6 tumor cell lines and telomerase activity and TERT splice variant expression in cancerous and paired noncancerous tissue samples from 28 NSCLC patients. Results: In most tumor cell lines, we observed little variation in the proportion of TERT splice variants. The α+β− splice variant showed the highest expression and α−β+ and α−β− the lowest. Quantification of the 4 TERT splice variants in NSCLC and surrounding nonneoplastic tissues showed the highest expression percentage for the α+β− variant in both NSCLC and adjacent nonneoplastic tissue samples, followed by α+β+, with the α−β+ and α−β− splice variants having the lowest expression. In the NSCLC tumors, the α+β+ variant had higher expression than other splice variants, and its expression correlated with telomerase activity, overall survival, and disease-free survival. Conclusions: Real-time RT-PCR quantification is a specific, sensitive, and rapid method that can elucidate the biological role of TERT splice variants in tumor development and progression. Our results suggest that the expression of the TERT α+β+ splice variant may be an independent negative prognostic factor for NSCLC patients.

Perverted responses of the human granulocyte-macrophage colony-stimulating factor receptor in mouse cell lines due to cross-species β-subunit association

Blood ◽  
2001 ◽  
Vol 98 (10) ◽  
pp. 3165-3168 ◽  
Author(s):  
Barbara McClure ◽  
Frank Stomski ◽  
Angel Lopez ◽  
Joanna Woodcock
Keyword(s):  
Cell Lines ◽  
Underlying Mechanism ◽  
Mouse Cell ◽  
Colony Stimulating Factor ◽  
Murine Cell ◽  
Gm Csf ◽  
Murine Cell Line ◽  
Macrophage Colony Stimulating Factor ◽  
Macrophage Colony ◽  
Stimulating Factor

Abstract Transfected murine cell lines are commonly used to study the function of many human cytokine or receptor mutants. This study reports the inappropriate activation of the human granulocyte-macrophage colony-stimulating factor (hGM-CSF) receptor by the human GM-CSF antagonist, E21R, when the human receptor is introduced into the murine cell line BaF-B03. E21R-induced proliferation of the BaF-B03 cells is dependent on transfection with both hGM-CSF receptor α and βc subunits. Studies on the underlying mechanism revealed constitutive association between human and mouse βc and GM-CSF receptor-α, tyrosine phosphorylation of mouse and human βc, and association of phosphorylated mouse βc into an activated human GM-CSF receptor complex in response to E21R and GM-CSF. This interspecies receptor cross-talk of receptor signaling subunits may produce misleading results and emphasizes the need to use cell lines devoid of the cognate endogenous receptors for functional analysis of ligand and receptor mutants.

Increasing membrane-bound MCSF does not enhance OPGL-driven osteoclastogenesis from marrow cells

2001 ◽  
Vol 280 (1) ◽  
pp. E103-E111 ◽  
Author(s):  
X. Fan ◽  
D. Fan ◽  
H. Gewant ◽  
C. L. Royce ◽  
M. S. Nanes ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Chinese Hamster ◽  
Osteoclast Formation ◽  
Local Bone ◽  
Cell Layers ◽  
Membrane Bound ◽  
Macrophage Colony Stimulating Factor ◽  
Macrophage Colony ◽  
Osteoprotegerin Ligand ◽  
Fixed Cell

Macrophage colony-stimulating factor (MCSF) and osteoprotegerin ligand (OPGL), both produced by osteoblasts/stromal cells, are essential factors for osteoclastogenesis. Whether local MCSF levels regulate the amount of osteoclast formation is unclear. Two culture systems, ST-2 and Chinese hamster ovary-membrane-bound MCSF (CHO-mMCSF)-Tet-OFF cells, were used to study the role of mMCSF in osteoclast formation. Cells from bone marrow (BMM) or spleen were cultured with soluble OPGL on glutaraldehyde-fixed cell layers; osteoclasts formed after 7 days. Osteoclast number was proportional to the amount of soluble OPGL added. In contrast, varying mMCSF levels in the ST-2 or CHO-mMCSF-Tet-OFF cell layers, respectively by variable plating or by addition of doxycycline, did not affect BMM osteoclastogenesis: 20–450 U of mMCSF per well generated similar osteoclast numbers. In contrast, spleen cells were resistant to mMCSF: osteoclastogenesis required ≥250 U per well and further increased as mMCSF rose higher. Our results demonstrate that osteoclast formation in the local bone environment is dominated by OPGL. Increasing mMCSF above basal levels does not further enhance osteoclast formation from BMMs, indicating that mMCSF does not play a dominant regulatory role in the bone marrow.

scholarly journals Identification and characterization of a low-affinity granulocyte- macrophage colony-stimulating factor receptor on primary and cultured human melanoma cells

Blood ◽  
1991 ◽  
Vol 78 (3) ◽  
pp. 609-615 ◽  
Author(s):  
GC Baldwin ◽  
DW Golde ◽  
GF Widhopf ◽  
J Economou ◽  
JC Gasson
Keyword(s):  
Cell Lines ◽  
Melanoma Cell ◽  
Melanoma Cells ◽  
Human Melanoma ◽  
Colony Stimulating Factor ◽  
Gm Csf ◽  
Macrophage Colony Stimulating Factor ◽  
Macrophage Colony ◽  
Stimulating Factor ◽  
Melanoma Cell Lines

Abstract Hematopoietic growth factor receptors are present on cells of normal nonhematopoietic tissues such as endothelium and placenta. We previously demonstrated functional human granulocyte-macrophage colony- stimulating factor (GM-CSF) receptors on small cell carcinoma of the lung cell lines, and others have reported that certain solid tumor cell lines respond to GM-CSF in clonogenic assays. In the current study, we examine human melanoma cell lines and fresh specimens of melanoma to determine whether they have functional GM-CSF receptors. Scatchard analyses of 125I-GM-CSF equilibrium binding to melanoma cell lines showed a mean of 542 +/- 67 sites per cell with a kd of 0.72 +/- 0.14 nmol/L. Cross-linking studies in the melanoma cell line, M14, showed a major GM-CSF receptor species of 84,000 daltons. Under the conditions tested, the M14 cells did not have a proliferative response to GM-CSF in vitro, nor was any induction of primary response genes detected by Northern analysis in response to GM-CSF. Studies to determine internal translocation of the receptor-ligand complex indicated less than 10% of the 125I-GM-CSF internalized was specifically bound to receptors. Primary melanoma cells from five surgical specimens had GM-CSF receptors; Scatchard analysis was performed on one sample, showing 555 sites/cell with a kd of 0.23 nmol/L. These results indicate that human tumor cells may express a low-affinity GM-CSF receptor protein that localizes to the cell surface and binds ligand, but lacks functional components or accessory factors needed to transduce a signal.

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