Instability of endogenous MRP/proliferin transcripts in the nucleus of mouse embryo fibroblasts contrasts with their stability when produced during transient transfections.
The mitogen regulated protein/proliferin (MRP/PLF) gene is transcribed in primary mouse embryo fibroblasts (MEFs), but the pre-mRNA is not properly converted into a stable cytoplasmic mRNA and instead is rapidly degraded, apparently in the nucleus [Malyankar et al. (1994): Proc Natl Acad Sci USA 91:335-359]. In 3T3 cells derived from the MEFs by the standard 3T3 immortalization protocol, stable MRP/PLF mRNA is produced. We show here that the processing of intron sequences is similar in the two cell types and that some of the MRP/PLF transcripts are polyadenylated in the MEFs. We also document the production of stable MRP/PLF mRNA generated by transcription of various plasmid constructs containing different portions of the MRP/PLF3 gene after calcium phosphate-mediated transfection into the MEFs. We conclude that the inability of the MRP/PLF mRNA to accumulate in the MEFs is unlikely to result solely from a single localized sequence in the primary transcript (or the mRNA) that causes it to be subject to rapid breakdown; possibly export of the mRNA from the MEF nucleus is defective or some aspect of the transcriptional process marks the transcript for degradation.
Malyankar
U M
UM
Department of Biological Sciences, Rutgers University, Piscataway, New Jersey 08807, USA.
Rittling
S R
SR
Denhardt
D T
DT
D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002467:Cell Nucleus / Q000378:metabolism*; D004622:Embryo, Mammalian / Q000502:physiology*; D006023:Glycoproteins / Q000235:genetics*; D006133:Growth Substances / Q000235:genetics*; D036341:Intercellular Signaling Peptides and Proteins; D007438:Introns; D051379:Mice; D008969:Molecular Sequence Data; D010957:Plasmids; D016133:Polymerase Chain Reaction / Q000379:methods; D011388:Prolactin; D012333:RNA, Messenger / Q000378:metabolism*; D013997:Time Factors; D014158:Transcription, Genetic; D014162:Transfection
D006023:Glycoproteins; D006133:Growth Substances; D036341:Intercellular Signaling Peptides and Proteins; C000634106:Prl2c2 protein, mouse; D012333:RNA, Messenger; D011388:Prolactin