ITA, a vertebrate homologue of IAP that is expressed in T lymphocytes.
Apoptosis plays a crucial role in both the development and the control of the immune system. During T lymphocyte development, thymocytes undergo apoptosis as part of the process of elimination of self-reactive clones. Mature T cells also undergo apoptosis following antigen-stimulated proliferation as part of a mechanism that controls the immune response. Apoptosis also provides a defense mechanism against viruses whereby the rapid death of virus-infected cells reduces virus spread. Viruses, on the other hand, often express proteins that inhibit apoptosis of their host cells, thereby enhancing their infectivity. We have isolated a novel gene, ita (inhibitor of T cell apoptosis), which is a vertebrate homologue of the viral apoptosis inhibitor IAP. Expression of ita appears to be restricted to cells of the T lymphocyte lineage, and high levels of ita mRNA are induced within 4-8 hr of T cell activation. Immunohistologic studies show that medullary and cortical thymocytes express detectable levels of ITA. ITA is a 69 kDa protein that contains a C-terminal ring-finger motif that is found in several oncogenic proteins and N-terminal repeat elements that have only been reported in other apoptosis inhibitors. These findings suggest that ITA may play a role in controlling apoptosis in T cells.
Digby
M R
MR
CSIRO Division of Animal Health, Geelong, Vic., Australia.
Kimpton
W G
WG
York
J J
JJ
Connick
T E
TE
Lowenthal
J W
JW
D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins; D030161:Avian Proteins; D001483:Base Sequence; D002460:Cell Line; D002645:Chickens; D003001:Cloning, Molecular; D017124:Conserved Sequence; D017931:DNA Primers; D051034:Inhibitor of Apoptosis Proteins; D007700:Kinetics; D008213:Lymphocyte Activation; D008969:Molecular Sequence Data; D009928:Organ Specificity; D016133:Polymerase Chain Reaction; D014176:Protein Biosynthesis; D011506:Proteins / Q000737:chemistry*; D012091:Repetitive Sequences, Nucleic Acid; D017386:Sequence Homology, Amino Acid; D013601:T-Lymphocytes / Q000276:immunology / Q000502:physiology*; D014714:Vertebrates; D014764:Viral Proteins / Q000737:chemistry*; D018406:Virus Physiological Phenomena
D051017:Apoptosis Regulatory Proteins; D030161:Avian Proteins; D017931:DNA Primers; D051034:Inhibitor of Apoptosis Proteins; D011506:Proteins; D014764:Viral Proteins; C086430:inhibitor of apoptosis, Nucleopolyhedrovirus; C103270:ita protein, chicken