Date of Award


Degree Type


Degree Name

Doctor of Philosophy


Mitogen-regulated protein/proliferin (MRP/PLF), a member of the prolactin-growth hormone family that occurs in the mouse, is expressed in a number of immortal cell lines including 3T3 and BNL. Neither MRP/PLF protein nor mRNA is detected in the mouse embryo fibroblasts (MEFs) from which the 3T3s are derived. One aim of this work was to identify the level at which this regulation of MRP/PLF expression is occurring. Differences were not observed in the MRP/PLF gene copy number, DNase I hypersensitive sites or methylation patterns of immortal cell lines compared to MEFs. RNA transcriptional mapping did not detect MRP/PLF hybridizing transcripts in either the nucleus or cytoplasm of the MEFs. These results, coupled with previous results that MRP/PLF is transcribed to an equal extent in both MEF and 3T3 cells, led to the conclusion that the MRP/PLF transcripts are highly unstable in MEF cells.;MRP/PLF expression in 3T3 and BNL cells is induced by a variety of growth factors but little is known about how the growth factors bring about changes in MRP/PLF expression.;An MRP/PLF gene was isolated from a mouse genomic library. Sequencing and Southern blot analysis allowed the determination of the intron/exon structure. S1 mapping identified the transcriptional start site and 1.1-Kbp of the promoter region was sequenced. Potentially important regions were identified by comparison with reported regulatory sequences. Transient expression assays revealed that the promoter is weak but functional, and likely contains a negative regulatory element in a defined 65-bp region. Northern blotting showed that MRP/PLF cytoplasmic RNA levels are negatively regulated by dexamethasone and positively regulated by TGF-{dollar}\alpha{dollar}, estrogen and to a small extent, vitamin D3. Suitable clones were generated so that transient expression assays can be used to further define the potentially important regulatory regions.



To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.