Observations on the binding and interaction of radioiodinated colony- stimulating factor with murine bone marrow cells in vitro

Journal Article · Mon Feb 01 04:00:00 EST 1982 · Blood; (United States)

OSTI ID:5658648

Pigoli, G; Waheed, A; Shadduck, R K

Radioiodinated L-cell-derived colony-stimulating factor (CSF) was used to characterize the binding reaction to murine bone marrow cells. The major increment in cell-associated radioactivity occurred over 24 hr incubation at 37/sup 0/C, but virtually no binding was observed at 4/sup 0/C. The reaction was saturable with approximately 1 ng/ml of purified CSF. Unlabeled CSF prevented the binding, whereas a number of other hormones and proteins did not complete for CSF uptake. Further specificity studies showed virtually no binding to human bone marrow, which is unresponsive to this form of murine CSF. Minimal CSF uptake was noted with murine peritoneal macrophages, but virtually no binding was detected with thymic, lymph node, liver, or kidney cells. The marrow cell interaction with tracer appeared to require new protein synthesis, as the binding was prevented by cycloheximide or puromycin. Preincubation of marrow cells in medium devoid of CSF increased the degree of binding after 1 hr exposure to the tracer. This suggests that CSF binding sites may be occupied or perhaps decreased in response to ambient levels of CSF in vivo. Approximately 70% of the bound radioactivity was detected in the cytoplasm at 24 hr. This material was partially degraded as judged by a decrease in molecular weight from approx.62,000 to 2 peaks of approx.32,000 and approx.49,000 but 72% of the binding activity was retained. After plateau binding was achieved, greater than 80% of the radioactivity released into the medium was degraded to biologically inactive peptides with molecular weights less than 10,000. These findings suggest that the interaction of CSF with marrow cells is characterized by binding with subsequent internalization and metabolic degradation into portions of the molecule that are devoid of biologic activity.

• Research Organization: University of Pittsburgh School of Medicine, PA
• OSTI ID: 5658648
• Journal Information: Blood; (United States), Journal Name: Blood; (United States) Vol. 59:2; ISSN BLOOA
• Country of Publication: United States
• Language: English

Related Subjects

551001* -- Physiological Systems-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ANIMAL CELLS
ANIMALS
BETA DECAY RADIOISOTOPES
BINDING ENERGY
BONE MARROW CELLS
COLONY FORMATION
CONNECTIVE TISSUE CELLS
DAYS LIVING RADIOISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
ENERGY
IN VITRO
INTERACTIONS
INTERMEDIATE MASS NUCLEI
IODINE 125
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
LABELLED COMPOUNDS
MAMMALS
MICE
NUCLEI
ODD-EVEN NUCLEI
RADIOISOTOPES
RODENTS
SOMATIC CELLS
STIMULATION
TRACER TECHNIQUES
VERTEBRATES