J. Biol. Chem., Vol. 261, Issue 12, 5467-5472, Apr, 1986
Autoantibodies specific for U1 RNA and initiator methionine tRNA
J Wilusz and JD Keene
Autoantibodies reactive with specific nuclear and cytoplasmic small RNAs
were identified by immunoprecipitation of HeLa cell RNA. Approximately 30%
of antisera examined from patients with autoimmune disorders contained
anti-RNA antibodies. Two previously undescribed specificities--anti U1 RNA
and anti-initiator methionine tRNA--were identified. Anti-RNA antibodies
were reactive with gel-purified species as well as with RNA synthesized in
vitro using the SP-6 transcription system. Antigenic mapping using two sera
specific for the human initiator methionine tRNA revealed separate
epitopes, one of which is conserved in formyl-methionine initiator tRNA
from Escherichia coli. RNA fragmentation studies further suggested that
secondary or tertiary tRNA structure is required for antibody recognition.
The mammalian U1 RNA specific antibodies did not precipitate small RNAs of
yeast but were highly reactive with yeast ribosomal RNA, thus indicating a
possible relationship between these RNA species. Results obtained with
these antisera are discussed in terms of higher order structure of small
RNA molecules as well as the role of nucleic acid antibodies in the
autoimmune phenomenon.