The c-fms proto-oncogene product is related to the receptor for the mononuclear phagocyte growth factor, CSF-1

The feline c-fms proto-oncogene product is a 170 kd glycoprotein with associated tyrosine kinase activity. This glycoprotein was expressed on mature cat macrophages from peritoneal inflammatory exudates and spleen. Similarly, the receptor for the murine colony-stimulating factor, CSF-1, is restricted to cells of the mononuclear phagocytic lineage and is a 165 kd glycoprotein with an associated tyrosine kinase. Rabbit antisera to a recombinant v-fms-coded polypeptide precipitated the feline c-fms product and specifically cross-reacted with a 165 kd glycoprotein from mouse macrophages. This putative product of the murine c-fms gene exhibited an associated tyrosine kinase activity in immune complexes, specifically bound murine CSF-1, and, in the presence of the growth factor, was phosphorylated on tyrosine in membrane preparations. The murine c-fms proto-oncogene product and the CSF-1 receptor are therefore related, and possibly identical, molecules.     

Genetic mapping of the mouse c-fms proto-oncogene to chromosome 18.

Chinese hamster X mouse somatic cell hybrids were analyzed by Southern blot hybridization with a probe specific for the cellular c-fms proto-oncogene. Results demonstrate that Fms, the genetic locus containing this sequence, maps to mouse chromosome 18. Mouse Fms is thus not linked to the same set of genes involved in growth regulation that human FMS is linked to.     

A point mutation in the extracellular domain of the human CSF-1 receptor (c-fms proto-oncogene product) activates its transforming potential

A human CSF-1 receptor containing an "activating" mutation in its extracellular domain (serine for leucine 301) induced morphologic transformation, anchorage-independent growth, and tumorigenicity in mouse NIH 3T3 cells. A second regulatory mutation within the receptor's intracytoplasmic carboxy-terminal tail (phenylalanine for tyrosine 969) augmented transforming efficiency but was itself insufficient to induce transformation. Like the v-fms oncogene product, receptors bearing the activating mutation retained high-affinity binding sites for CSF-1 but were retarded in transport to the cell surface and were phosphorylated on tyrosine in the absence of ligand. Although the activating mutation does not affect the CSF-1 binding site in the receptor extracellular domain, it must induce a conformational change that mimics the effect of ligand binding, resulting in CSF-1-independent signals for cell growth.     

Expression of fascin-1, the gene encoding the actin-bundling protein fascin-1, during mouse embryogenesis

Fascin-1 is an actin-bundling protein that contributes to the architecture and function of cell protrusions and microfilaments in cell adhesion, interactions and motility. Fascin-1 has been studied in cultured cells and by biophysical methods, but little is known about its distribution and functions in vertebrate development. As a first step to understanding the role of fascin-1 in embryogenesis, we have characterised the expression pattern of fascin-1 by in situ hybridisation on whole-mount and sectioned mouse embryos from embryonic day (E)8.0-E16.5. Fascin-1 was widely expressed throughout the embryo and the developing nervous system and mesenchymal tissues represented major sites of expression. Intense signals were observed in different regions of the brain, in the spinal cord and retina, and the cranial and dorsal root ganglia (DRG) appeared strongly positive. This neural expression remained strong throughout development. Fascin-1 was also present in the developing somites. High expression was detected in branchial arches and limb bud mesenchyme. At later stages, fascin-1 was expressed in different muscles of the face, skeletal muscles of the body, and in smooth muscle layers of several organs. Limb tendons appeared strongly positive. There was weak expression in heart ventricles. These results show that fascin-1 is principally expressed in neural and mesenchymal derivatives during embryonic development.     

Expression of the homeobox gene,Hox 2.1, during mouse embryogenesis

This article reviews recent studies on the expression of the homeobox gene, Hox 2.1, during mouse embryogenesis, using the technique of in situ hybridization. Differential hybridization of radiolabelled antisense versus sense strand RNA is first clearly detected in sections of 8.5 day post coitum (p.c.) early somite embryos. At 12.5 days p.c., higher levels of Hox 2.1 expression are seen in the spinal cord, extending into the base of the hind brain. Hybridization of antisense Hox 2.1 RNA is also seen in the spinal ganglia, in the nodose ganglia of the Xth cranial nerve (which contains derivatives of the neural crest arising from the posterior hind brain), and in the myenteric plexus. Mesodermal cells of certain visceral organs also express Hox 2.1 RNA, in particular the mesoderm of the lung, stomach and meso- and meta-nephric kidney. Comparison of the spatial domains of expression of mouse homeobox genes reveals a pattern consistent with the idea that they play a role in anteroposterior positional specification during embryogenesis.     

Expression of p53 during mouse embryogenesis.

By in situ hybridisation we have examined the expression of p53 during mouse embryogenesis from day 8.5 to day 18.5 post coitum (p.c.). High levels of p53 mRNA were detected in all cells of the day 8.5 p.c. and 10.5 p.c. mouse embryo. However, at later stages of development, expression became more pronounced during differentiation of specific tissues e.g. of the brain, liver, lung, thymus, intestine, salivary gland and kidney. In cells undergoing terminal differentiation, the level of p53 mRNA declined strongly. In the brain, hybridisation signals were also observed in postmitotic but not yet terminally differentiated cells. Therefore, gene expression of p53 does not appear to be linked with cellular proliferation in this organ. A proposed role for p53 in cellular differentiation is discussed.     

Expression of acute and late-stage inflammatory antigens, c-fms, CSF-1, and human monocytic serine esterase 1, in tumor-associated macrophages of renal cell carcinomas

Purpose: Tumor cells influence the differentiation of infiltrating macrophages. In the present study, the differentiation of macrophages in renal cell carcinomas was investigated with special regard to their possible role in tumor growth and spread. Methods: Macrophages were characterized by means of immunohistochemistry of the Ki-M1P, 25F9, MRP8, MRP14, and MRP8/14 antigens and by means of in situ hybridization of CSF-1, its c-fms-coded corresponding receptor, and human monocytic serine esterase-1 (HMSE-1) mRNA. Macrophage subgroups were quantified within central tumor tissue, the corresponding tumor host interface, and tumor-free tissue and correlated with tumor necrosis, fibrosis, and tumor stage and grade. Results: Macrophage density was much higher within tumor tissue and the tumor/host interface than in tumor-free tissue. Well-differentiated carcinomas showed a lower degree of macrophage density than less-differentiated carcinomas. Tumor-associated macrophages could be divided into an active inflammatory type (MRP14⁺, MRP8/14⁺) and into a late-phase inflammatory type (25F9⁺, MRP8⁺). Necrosis was seen in less-differentiated carcinomas and associated with a significantly increased density of MRP14⁺ macrophages, which, however, did not correlate with the extent of necrosis. The density of 25F9⁺ macrophages was correlated with an extensive connective tissue formation and an advanced tumor stage. c-fms, CSF-1, and HMSE-1 mRNA expression did not discriminate between the macrophage subgroups. Conclusions: Tumor-associated macrophages of the late-stage inflammatory type potentially support the spread of renal cell cancer. CSF-1 derived from tumor cells and macrophages acts as a monocyte attractant and induces macrophage differentiation able to modulate the extracellular matrix rather than to exert cytotoxicity. Received: 25 May 2000 / Accepted: 29 June 2000     

Expression of Deltex1 during mouse embryogenesis: comparison with Notch1, 2 and 3 expression.

The Notch signalling pathway defines a phylogenetically conserved cell-cell communication process that enables cell-fate specification in multicellular organisms. Deltex is a component of the Notch signalling network that physically interacts with the ankyrin repeats of Notch. Here, we report on the expression pattern of the Deltex1 gene during mouse embryonic development and, furthermore, we compare its expression with that of the Notch1, 2 and 3 genes. Complementary and combinatorial expression patterns between Deltex1 and the three Notch genes were observed throughout embryogenesis since Deltex1 expression was related either to cytodifferentiation (i.e. neuronal tissues) or to cell proliferation events (i.e. eye, vascular structures, hematopoiesis).     

Synthesis of membrane-bound colony-stimulating factor 1 (CSF-1) and downmodulation of CSF-1 receptors in NIH 3T3 cells transformed by cotransfection of the human CSF-1 and c-fms (CSF-1 receptor) genes.

NIH 3T3 cells cotransfected with the human c-fms proto-oncogene together with a 1.6-kilobase cDNA clone encoding a 256-amino-acid precursor of the human mononuclear phagocyte colony-stimulating factor CSF-1 (M-CSF) undergo transformation by an autocrine mechanism. The number of CSF-1 receptors on the surface of transformed cells was regulated by ligand-induced receptor degradation and was inversely proportional to the quantity of CSF-1 produced. A tyrosine-to-phenylalanine mutation at position 969 near the receptor carboxyl terminus potentiated its transforming efficiency in cells cotransfected by the CSF-1 gene but did not affect receptor downmodulation. CSF-1 was synthesized as an integral transmembrane glycoprotein that was rapidly dimerized through disulfide bonds. The homodimer was externalized at the cell surface, where it underwent proteolysis to yield the soluble growth factor. Trypsin treatment of viable cells cleaved the plasma membrane form of CSF-1 to molecules of a size indistinguishable from that of the extracellular growth factor, suggesting that trypsinlike proteases regulate the rate of CSF-1 release from transformed cells. The data raise the possibility that this form of membrane-bound CSF-1 might stimulate receptors on adjacent cells through direct cell-cell interactions.     

Tandem linkage of human CSF-1 receptor (c-fms) and PDGF receptor genes

A 5' untranslated exon of the human CSF-1 receptor gene (c-fms) is separated by a 26 kb intron from the 32 kb receptor coding sequences. Nucleotide sequence analysis of cloned genomic DNA revealed that the 3' end of the PDGF receptor gene is located less than 0.5 kb upstream from this exon. Similarities in chromosomal localization, organization, and encoded amino acid sequences suggest that the genes encoding the CSF-1 and PDGF receptors arose through duplication. The as yet unidentified c-fms promoter/enhancer sequences may be confined to the nucleotides separating the two genes or could potentially lie within the PDGF receptor gene itself.     

Expression of the c-fos proto-oncogene in bone, cartilage and tooth forming tissues during mouse development

The c-fos proto-oncogene is the cellular homologue of v-fos identified as the bone transforming gene of the FBJ and the FBR murine osteosarcoma viruses. We show here, using a sensitive in situ hybridization method, that the c-fos proto-oncogene is expressed in the cartilage, bone and tooth forming tissues during mouse development. This result suggests that the tumors observed after infection by the FBJ viral complex and c-fos overexpression in transgenic mice occur in those tissues in which c-fos is expressed during development.     

Expression of creatine kinase isoenzyme during oogenesis and embryogenesis in the mouse

Creatine kinase activity was discovered in the growing mouse oocyte and in the preimplantation embryo. Changes in the enzyme activity during the growth and maturation of the egg and during the development of the embryo up to the blastocyst stage were determined. Close similarity of the protein to the brain-type isoenzyme of creatine kinase was established immunochemically. The kinetic parameters of the brain-type isoenzyme (M. R. Iyengar, C. E. Fluellen, and C. W. L. Iyengar, 1982, J. Muscle Cell Motil. 3, 231–246) and the pattern of development-associated changes in activity suggest a possible role for creatine kinase in maintaining the reported high ATP/ADP ratio (L. Ginsberg and N. Hillman, 1975, J. Reprod. Fertil. 43, 83–90), which is essential for the biosynthetic activities of the embryo.     

Expression of the Lingo/LERN gene family during mouse embryogenesis

We have analysed the expression during mouse development of the four member Lingo/LERN gene family which encodes type 1 transmembrane proteins containing 12 extracellular leucine rich repeats, an immunoglobulin C2 domain and a short intracellular tail. Each family member has a distinct pattern of expression in the mouse embryo as is the case for the related NLRR, FLRT and LRRTM gene families. Lingo1/LERN1 is expressed in the developing trigeminal, facio-acoustic and dorsal root ganglia. An interesting expression pattern is also observed in the somites with expression localising to the inner surface of the dermomyotome in the ventro-caudal lip. Further expression is seen in lateral cells of the hindbrain and midbrain, lateral cells in the motor horn of the neural tube, the otic vesicle epithelium and epithelium associated with the developing gut. Lingo3/LERN2 is expressed in a broad but specific pattern in many tissues across the embryo. Lingo2/LERN3 is seen in a population of cells lying adjacent to the epithelial lining of the olfactory pit while Lingo4/LERN4 is expressed in the neural tube in a subset of progenitors adjacent to the motor neurons. Expression of all Lingo/LERN genes increases as the embryo develops but is low in the adult with only Lingo1/LERN1 and Lingo2/LERN3 being detectable in adult brain.     

Expression of the human c-fms proto-oncogene in hematopoietic cells and its deletion in the 5q- syndrome

The c-fms proto-oncogene was shown to be expressed in human bone marrow and in differentiated blood mononuclear cells, suggesting that its gene product plays a role in hematopoietic maturation. The c-fms mRNA was not detected in HL-60 cells, an established promyelocytic line, whereas c-fms expression appeared 48 hr after induction when most cells had differentiated into macrophages. An acquired deletion of chromosome 5 (5q-) in bone marrow cells is associated with abnormalities in blood cell production. The normal 5 and 5q- chromosomes were segregated by construction of cell hybrids between bone marrow and rodent cells. A selective system was used that requires retention of the structural gene for dihydrofolate reductase, located on human chromosome 5. Analysis of DNA from individual hybrid clones revealed that the 5q- deletion had removed the c-fms gene. We postulate that hemizygosity at the c-fms locus leads to abnormalities in hematopoietic maturation.     

Expression of estrogen receptor alpha and beta during mouse embryogenesis.

In adult mammals numerous target tissues and organs for estrogens exist. Little is known about possible target organs during embryogenesis other than the reproductive tract and the gonads. This is the first report on the expression of estrogen receptor beta (ERbeta) in comparison with ERalpha mRNA during mouse embryogenesis. We found expression of estrogen receptor mRNA in the reproductive tract, but also in the atrial wall, brain, kidney, urethra, bladder neck, mammary gland primordium, midgut, cartilage primordia and perichondria.