Related Experiment Videos
Expression of eosinophil-granule major basic protein messenger ribonucleic acid in placental X cells
M Bonno1, G M Kephart, C M Carlson
1Department of Immunology, Mayo Clinic, Rochester, Minnesota.
Background:
The human eosinophil-granule major basic protein (MBP) is a 13.8-kilodalton cationic polypeptide constituting the core of the eosinophil granule. MBP is cytotoxic to parasites and numerous mammalian cells and is a potent secretagogue for platelets, basophils, mast cells, and neutrophils. Concentrations of a molecule immunochemically similar to eosinophil granule MBP are present in maternal plasma, and MBP has been localized by immunofluorescence to placental X cells.
Experimental Design:
To determine whether X cells produce MBP, the expression of MBP messenger RNA (mRNA) was investigated in placentas by Northern blot analyses and by in situ hybridization with 35S-labeled RNA probes.
Results:
Northern blot analyses of RNA from placental septa and villi showed the existence of a 1.0-kb RNA band that hybridized with the MBP anti-sense probe; no MBP mRNA was detected in whole blood of normal or pregnant women or in cord blood. Analyses of placentas by in situ hybridization showed MBP mRNA in X cells of placental septa and anchoring villi, but not in other cellular elements such as syncytiotrophoblasts, cytotrophoblasts, villous stromal cells, and fetal endothelial cells. RNase pretreatment abolished X-cell hybridization signals; treatment of sections with an excess of nonradiolabeled anti-sense RNA also blocked binding of the 35S-labeled anti-sense RNA probe. Additional evidence supporting the production of MBP by X cells was obtained using a combination of in situ hybridization and immunofluorescence, which showed colocalization of MBP and its mRNA.
Conclusions:
The presence of MBP mRNA and MBP protein in placental X cells indicates that X cells synthesize this biologically active molecule.
Insights
Human placental X cells synthesize major basic protein (MBP), a cytotoxic and secretagogue molecule. This study confirms MBP production by X cells using molecular and immunofluorescence techniques.
Area of Science:
- Immunology
- Cell Biology
- Reproductive Biology
Background:
- Human eosinophil-granule major basic protein (MBP) is a cytotoxic cationic polypeptide.
- MBP acts as a secretagogue for various immune cells.
- MBP is found in maternal plasma and localized to placental X cells.
Purpose of the Study:
- To determine if placental X cells produce MBP.
- Investigate the expression of MBP messenger RNA (mRNA) in the placenta.
Main Methods:
- Northern blot analysis of placental RNA.
- In situ hybridization using 35S-labeled RNA probes.
- Combined in situ hybridization and immunofluorescence.
Main Results:
- MBP mRNA detected in placental X cells, but not in blood or other placental cell types.
- Hybridization signals confirmed MBP mRNA localization to X cells.
- Colocalization of MBP and its mRNA in X cells provided evidence of synthesis.
Conclusions:
- Placental X cells synthesize major basic protein (MBP).
- MBP is biologically active and produced by placental X cells.