Identification of proliferin mRNA and protein in mouse placenta.
Proliferin is a recently described, prolactin-related protein whose mRNA appears in several murine cell lines during active growth. We have surveyed a number of mouse organs or tissues for the presence of mRNAs that hybridize to cloned proliferin cDNA. Of the tissues tested, only the placenta yielded proliferin-related mRNA. This placental RNA is about 1 kilobase in length, increases sharply between days 8 and 10 of pregnancy, and then gradually declines through day 18. It is more abundant in RNA extracted from the fetal, compared to the maternal, part of the placenta. From a cDNA plasmid library prepared from poly(A)+ placental RNA, two types of proliferin-related clones were isolated, differing in intensity of hybridization to proliferin cDNA. By nucleotide sequence analysis, a strongly hybridizing clone was found to be nearly identical to the proliferin cDNA clone isolated from a library prepared from mRNA of a growing mouse fibroblastic cell line. Using an antiserum prepared against a synthetic proliferin fusion protein, we show that proliferin is secreted as a glycoprotein by minced placental tissue and that it differs from mouse placental lactogen. We conclude that proliferin is a placental hormone that is synthesized in certain mouse cell lines during active growth. Its function during pregnancy and during the growth of cultured cells is presently unknown.
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D004247:DNA / Q000032:analysis; D005260:Female; D005786:Gene Expression Regulation; D006023:Glycoproteins; D036341:Intercellular Signaling Peptides and Proteins; D051379:Mice; D008807:Mice, Inbred BALB C; D010920:Placenta / Q000032:analysis*; D010928:Placental Lactogen / Q000032:analysis*; D011247:Pregnancy; D011388:Prolactin / Q000032:analysis; D011506:Proteins / Q000235:genetics*; D012333:RNA, Messenger / Q000032:analysis*; D014018:Tissue Distribution
D006023:Glycoproteins; D036341:Intercellular Signaling Peptides and Proteins; C000634106:Prl2c2 protein, mouse; D011506:Proteins; D012333:RNA, Messenger; D011388:Prolactin; D004247:DNA; D010928:Placental Lactogen