Expression of novel-transposon-containing mRNAs in human T cells.
The HERV-H family of endogenous retrovirus like elements is the largest such human family known. Using an HERV-H LTR probe, 6 and 4.5 kb transcripts were detected by Northern blot analysis which were induced in normal peripheral T cells after treatment with phytohaemaglutinin (PHA). Expression was not evident 30 min after treatment with phorbol ester, was increased within 3-4 h after treatment, reached a maximum after 8 h and then declined to low levels 24 h after treatment. Expression was inhibited totally by cycloheximide (10 micromolar) and by the immunosuppressant cyclosporin A (1 microgram/ml). Using probes specific for the U3 and U5 regions of the HERV-H LTR, in combination with internal HERV-H probes, evidence was obtained that the 6 and 4.5 kb transcripts are polyadenylated from an HERV-H LTR. A cDNA library was constructed from T cells which had been treated with PHA for 8 h and a 1.7 kb clone was isolated using the HERV-H LTR probe. The insert contained a novel tandem array of an Alu, a LINE-1 element, two endogenous retroviral LTRs and an A-T-rich sequence. The A-T-rich sequence contained multiple copies of AUUUA mRNA regulatory motifs. Because of its high expression level, defined transcription kinetics, novel cassette-like composition and the presence of conserved mRNA stabilization sequences, we hypothesize that the transcript may play a biological role during T cell activation.
Kelleher
C A
CA
Department of Pediatrics, National Jewish Center for Immunology and Respiratory Medicine, Denver, CO 80206, USA.
Wilkinson
D A
DA
Freeman
J D
JD
Mager
D L
DL
Gelfand
E W
EW
D001483:Base Sequence; D015152:Blotting, Northern; D003001:Cloning, Molecular; D006801:Humans; D008213:Lymphocyte Activation; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization; D012333:RNA, Messenger / Q000032:analysis*; D018626:Retroelements; D012190:Retroviridae / Q000235:genetics*; D013601:T-Lymphocytes / Q000821:virology*
D012333:RNA, Messenger; D018626:Retroelements