Identification and cellular localization of unique interferon mRNA from human placenta.
Although constitutive expression of trophoblast or pregnancy-associated interferon (IFN) has long been recognized, their cDNA sequences have been determined for only ruminant ungulates. Here we show a human trophoblast IFN (htIFN) cDNA whose nucleotide sequence is very similar (85% identity) to that of ovine and bovine trophoblast IFNs, IFN tau s. Like ruminant IFN tau s, htIFN cDNAs contain an open reading frame of 195 codons including a signal sequence of 23 amino acids, resulting in a mature polypeptide of 172 amino acids. The deduced amino acid sequence of htIFN shares 73, 62, and 56% identities with ovine IFN tau, human IFN alpha II, and human IFN alpha I, respectively. However, the expression of htIFN is not limited to a specific period of pregnancy because transcripts of htIFN genes are detected in human lymphocytes, cells obtained by amniocentesis (amniocytes), first trimester, and term placentas. Human trophoblast IFN mRNA is localized mainly in extravillous trophoblasts cells of placental villi, particularly in the migrating cytotrophoblasts cells, which eventually replace maternal endothelial cells in spiral arteries of the decidua. Both sense and antisense mRNAs for human IFN alpha II are localized in the outer layer of villous structures. Coexistence of these mRNAs at the placental villi throughout pregnancy suggests that, in addition to a role in placental cell growth and differentiation, IFNs may play a role protecting the fetus in viral environments.
Whaley
A E
AE
Department of Obstetrics and Gynecology, University of Kansas School of Medicine, Wichita 67214-4716.
Meka
C S
CS
Harbison
L A
LA
Hunt
J S
JS
Imakawa
K
K
D000595:Amino Acid Sequence; D001483:Base Sequence; D018076:DNA, Complementary; D005260:Female; D006801:Humans; D007372:Interferons / Q000235:genetics*; D008969:Molecular Sequence Data; D010920:Placenta / Q000378:metabolism*; D011247:Pregnancy; D012333:RNA, Messenger / Q000032:analysis*; D017386:Sequence Homology, Amino Acid
D018076:DNA, Complementary; D012333:RNA, Messenger; D007372:Interferons