Membrane-associated and soluble granulocyte/macrophage-colony-stimulating factor receptor α subunits are independently regulated in HL-60 cells Journal Article

   

Authors:	Heaney, M. L.; Vera, J. C.; Raines, M. A.; Golde, D. W.
Article Title:	Membrane-associated and soluble granulocyte/macrophage-colony-stimulating factor receptor α subunits are independently regulated in HL-60 cells
Abstract:	The effects of granulocyte/macrophage-colony-stimulating factor (GM-CSF) are mediated by interaction with its composite receptor (GMR), which consists of a unique a subunit (GMRα) and a β subunit (GMRβ) that is common to the receptors for GM-CSF, interleukin 3, and interleukin 5. GMRβ is required for high-affinity binding, cell proliferation, and protein phosphorylation but has no intrinsic GM-CSF-binding activity. GMRα in isolation binds to GM-CSF with low affinity and can signal for increased glucose uptake. In addition to the membrane-bound receptor (mGMRα), there is a naturally occurring soluble isoform (sGMRα) that is released free into the pericellular milieu. Analysis of genomic sequences reveals that the soluble GMRα isoform comes about by alternative mRNA splicing. To examine GMRα expression, we developed a quantitative reverse transcription-polymerase chain reaction assay based on serial dilutions of in vitro transcribed GMRα RNA. This assay provides a strict log-log measure of GMRα RNA expression, distinguishes transcripts related to the soluble and membrane-associated isoforms, and quantitatively detects 0.1 fg of GMRα-related mRNA. There was little or no GMRα expression in two human lymphoid cell lines and in the erythroblastic leukemia cell line K562, but all myeloid cell lines tested expressed both the membrane- associated and soluble isoforms of GMRα. Baseline level of expression of both isoforms varied >20-fold among the myeloid cell lines studied. Differentiation of HL-60 cells to neutrophils with dimethyl sulfoxide led to a 2-fold downregulation of sGMRα and a 20-fold upregulation of mGMRα. These differentiation-induced transcriptional changes were unrelated to changes in mRNA stability. These findings indicate that sGMRα is differentially expressed from mGMRα in human hematopoietic cells and that programmed downregulation of sGMRα may be important in myeloid maturation.
Keywords:	controlled study; leukemia; human cell; comparative study; polymerase chain reaction; reverse transcription polymerase chain reaction; granulocyte macrophage colony stimulating factor; cell line; tumor cells, cultured; leukemia, promyelocytic, acute; gene expression regulation, neoplastic; amino acid sequence; molecular sequence data; rna, messenger; cell membrane; alternative rna splicing; base sequence; hematopoiesis; neutrophils; receptor affinity; dna primers; cytosol; rna splicing; dna, complementary; receptor upregulation; growth factor receptor; membrane receptor; cell strain hl 60; receptors, granulocyte-macrophage colony-stimulating factor; receptor subunit; genomic library; receptors, interleukin; mrna stability; human; priority journal; article; support, non-u.s. gov't; support, u.s. gov't, p.h.s.; macromolecular systems; receptors, interleukin-3; human leukemia cell lines
Journal Title:	Proceedings of the National Academy of Sciences of the United States of America
Volume:	92
Issue:	6
ISSN:	0027-8424
Publisher:	National Academy of Sciences
Date Published:	1995-03-14
Start Page:	2365
End Page:	2369
Language:	English
DOI:	10.1073/pnas.92.6.2365
PUBMED:	7892272
PROVIDER:	scopus
PMCID:	PMC42484
DOI/URL:	https://www.scopus.com/inward/record.uri?eid=2-s2.0-0028931430&doi=10.1073%2fpnas.92.6.2365&partnerID=40&md5=833bf3ee3137f0c901c99b6b260d1ecd
Notes:	Article -- Export Date: 28 August 2018 -- Source: Scopus

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