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A human B-lymphoblastoid cell line produces prolactin
G E DiMattia1, B Gellersen, H G Bohnet
1Department of Physiology, Faculty of Medicine, University of Manitoba, Winnipeg, Canada.
Endocrinology
|June 1, 1988
Summary
Researchers discovered ectopic human prolactin (PRL) production in a B-lymphoblast cell line. This PRL is biologically active and differs in mRNA size due to untranslated regions, offering a model for studying ectopic gene expression.
Area of Science:
- Molecular Endocrinology
- Cell Biology
- Genetics
Background:
- Prolactin (PRL) is a hormone primarily produced by the pituitary gland.
- Ectopic gene expression, the expression of a gene in a tissue or cell type where it is not normally found, is a complex phenomenon.
- Understanding the mechanisms of ectopic PRL expression can provide insights into gene regulation and disease.
Purpose of the Study:
- To investigate the expression of prolactin (PRL) and PRL-related messenger RNAs (mRNAs) in various cell lines.
- To characterize the nature and biological activity of PRL produced by a human B-lymphoblast cell line.
- To establish a cellular model for analyzing the molecular mechanisms underlying ectopic human PRL expression.
Main Methods:
- Northern blot hybridization was used to detect PRL and PRL-related mRNAs in cell lines.
- Immunoaffinity purification and SDS-PAGE were employed to isolate and characterize PRL from conditioned medium.
- Biological activity was assessed using the rat Nb2 lymphoma mitogenic assay.
- Ribonuclease-H digestion and genomic Southern blot analysis were performed to investigate mRNA structure and gene integrity.
Main Results:
- A human B-lymphoblast cell line (IM-9-P) was found to express a PRL mRNA that hybridized to human PRL cDNA.
- The lymphoblast-derived PRL mRNA was approximately 150 bases longer than pituitary PRL mRNA, not due to poly(A) tail length.
- Purified IM-9-P PRL exhibited identical molecular weight and biological activity to pituitary PRL.
- Genomic analysis revealed no major rearrangements of the PRL gene in IM-9-P cells, suggesting altered untranslated regions (UTRs) in the mRNA.
- Cloned cell lines (IM-9-P3 and IM-9-P6) were established, providing a system to study ectopic PRL expression.
Conclusions:
- Ectopic expression of biologically active human prolactin occurs in a B-lymphoblast cell line.
- The size difference in PRL mRNA between pituitary and lymphoblast cells is likely due to alterations in the 5' and/or 3' untranslated regions.
- The established cell line system offers a valuable tool for dissecting the molecular mechanisms of ectopic PRL gene expression.