Table Of ContentGIT Receptor
Dass S. Vinay1 and Byoung S. Kwon2,3,*
1Department of General Surgery, University of Michigan Medical School, 1516 MSRB I,
1150 West Medical Center Drive, Ann Arbor, MI 48109, USA
2The Immunomodulation Research Center, University of Ulsan, Ulsan, Korea
3Department of Ophthalmology, LSUMC, 2020 Gravier Street Suite B, New Orleans, LA 70112, USA
*corresponding author tel: 504-412-1200 ex 1379, fax: 504-412-1315, e-mail: [email protected]
DOI: 10.1006/rwcy.2000.16015.
SUMMARY BACKGROUND
The TNF and TNF receptor gene superfamilies con- Optimal induction of T cell activation is incomplete
trol a variety of distinct physiological functions such without the cognate interaction between T cells and
as cell proliferation, differentiation, and survival, etc. antigen presenting cell (APC)-derived cell surface
A newly emerging member this family with strong molecules(Schwarz,1990).AnumberofAPC-derived
role in T cell homeostasis is GITR (glucocorticoid- cell surface determinants have been shown to possess
induced tumor necrosis factor receptor) (Nocentini the ability to potentiate/desensitize T cell effector
et al., 1998). A majority of glucocorticoid hormones functions. Although it is considered that B7/CD28 is
are known to induce apoptosis (Nocentini et al., central to this pathway, studies of CD28-deficient
1998). It is surprising to note that these hormones mice(Shahnianetal.,1993)haveshownthatthismay
also protect the cells from undergoing apoptosis not be the limiting factor in immune regulation.
undertheinfluenceofdiscreetstimuli(Riccardietal., Recent studies indicate that several ligand/receptor
1999). These events are thought to involve the pairs, beyond the B7/CD28 pathway, also have the
participationofGITRandGILZgenesbycontrolling ability to initiate and propel the ongoing immune
eventslikeactivationofNF(cid:20)BandexpressionofFas/ reaction. Among these are three members of the
FasL molecules (Riccardi et al., 1999). Recently, a expanding TNFR family: 4-1BB, Ox40, and GITR.
human homolog of murine GITR was discovered
(Kwon et al., 1999; Gurney et al., 1999). The human
Discovery
receptor was called AITR (activation-induced TNFR
member) (Kwon et al., 1999) and hGITR (Gurney
et al., 1999). Its ligand was cloned and called AITRL The glucocorticoid-induced tumor necrosis factor
(Kwon et al., 1999) and hGITRL (Gurney et al., receptor (GITR) family-related gene was cloned first
1999). Within the cytoplasmic domain, the AITR from dexamethasone-treated murine T cell hybri-
shares a striking homology with 4-1BB and CD27 doma (3DO) cells by differential display technique.
(Kwon et al., 1999). AITR associates with TRAF1
(TNF receptor-associated factor 1), TRAF2, and
Alternative names
TRAF3, and induces NF(cid:20)B activation via TRAF2
(Kwon et al., 1999). AITRL was expressed in endo-
thelial cells (Kwon et al., 1999). Expression of GITR Published data from our laboratory provide evidence
appears to be activation dependent as stimulation of that a novel 25kDa protein named activation-
Tlymphocytesbyanti-CD3mAb,ConA,orphorbol inducible protein of the TNF receptor (AITR) is the
12-myristate 13-acetate plus Ca-ionophore treat- human homolog of the murine GITR (Kwon et al.,
ment readily upregulates its levels (Nocentini et al., 1999). The AITR has 55% identity with murine
1997). GITR at the amino acid level. It is shown to activate
1756 Dass S. Vinay and Byoung S. Kwon
by transducing signals through TRAF2-mediated PROTEIN
mechanism. The expression of AITR is inducible by
PMA and ionomycin, anti-CD3 plus anti-CD28 Sequence
monoclonal antibodies. It is detected as a 1.25kb
mRNA in lymph nodes, PBLs and weakly in the
See Figure 1.
spleen and colorectal adenocarcinoma cell line (SW
480) (Kwon et al., 1999).
Description of protein
Structure
The molecule putatively encoded by the GITR
GITR is a 228 amino acid type I transmembrane mRNA is a cysteine-rich protein of 228 amino acids.
protein characterized by three cysteine pseudorepeats The two hydrophobic regions are present, probably
in the extracellular domain. It is similar to 4-1BB in representing the signal peptide and the transmem-
the intracellular domain. The full-length GITR brane domain. A cleavage site for the signal peptide
cDNA revealed a 1005bp long sequence. Northern can be found between GLY (at position (cid:255)1) and Gln
blot analysis suggested that GITR mRNA is about (atposition1),despitetheunusualpresenceofAspat
1.1kb long. position (cid:255)3. The transmembrane domain is located
between positions 135 and 157 of the mature protein.
Given this, GITR can be categorized as a type I
Main activities and
membrane protein. The molecular weight of the
pathophysiological roles predictednativeproteinis25,334,consistentwiththat
obtained by in vitro translation of the cloned cDNA.
Thepredictedmolecularweightoftheputativemature
Evidence accumulated thus far suggests that GITR
proteinbeforefurtherposttranslationalmodifications
expression confers resistance to TCR/CD3-induced
is 23,321.
apoptosis of transfected T cells. This resistance is
independent of Fas triggering. However, modulation
of GITR expression does not seem to modify the
sensitivity to apoptotic stimuli other than TCR Relevant homologies and
triggering (Nocentini et al., 1997). species differences
The GITR amino acid sequence exhibits marked
GENE
homologies with 4-1BB, a member of the TNF/
NGFR family. The GITR cytoplasmic domain spans
Accession numbers
amino acids 158–209 of the mature protein. It has a
striking homology with the cytoplasmic domains of
GenBank: murine and human 4-1BB and CD27 (Figure 1) but
Murine GITR: U82534 does not show any significant homology with other
membersoftheTNF/NGFRfamily(Gravesteinetal.,
1993).Thissimilaritydefinesanewintracellularmotif
Sequence
that could identify a subfamily of the TNF/NGFR
family, including GITR, 4-1BB, and CD27.
Full cDNA from a T lymphocyte cDNA library
revealed a 1005bp long sequence. Northern analysis
of GITR mRNA was found to be 1.1kb long. Cell types and tissues expressing
Nucleotide sequencing of the three cDNA clones
the receptor
showed the presence of a single 684bp ORF begin-
ning at nucleotide position 46 and extending to a
TGAterminationcodonatposition730.Theputative GITR is not detectable in freshly derived lymphoid
initiation codon at position 46 is surrounded by a tissues(includingthymocytes,spleen,andlymphnode
sequence (AGCACTATGG). The termination codon Tcells),liver,kidney,andbrainandTcellhybridoma
is followed by a 30 UTR of 276bp. A canonical 3D0. However, low levels of GITR mRNA were
polyadenylylation signal is present from 18bp 50 to detected by competitive RT-PCR in T cell hybri-
the poly (A) tail. doma, thymocytes, spleen, and lymph node T cells.
GIT Receptor 1757
Figure1 (a)DeducedaminoacidsequenceofAITR.Thepotentialsignalsequenceisindicatedas
bold characters and the transmembrane region is indicated in boxes. (b) Comparison of the amino
acid sequence of AITR with the murine GITR. Bold Cs within three cysteine pseudorepeat motifs
indicate cysteine residues found in the extracellular domain of the TNFR superfamily members.
Conserved acidic amino acid clusters of the cytoplasmic domain are indicated in boxes.
A
1 MAQHGAMGAFRALCGLALLCALSLGQRPTGGPGCGPGRLLLGTGTDARCCRVHTTRCCRD
61 YPGEECCSEWDCMCVQPEFHCGDPCCTTCRHHPCPPGQGVQSQGKFSFGFQCIDCASGTF
121 SGGHEGHCKPWTDCTQFGFLTVFPGNKTHVAVCVPGSPPAEPLGWLTVVLLAVAACVLLL
181 TSAQLGLHIWQLRKTQLLLEVPPSTEDARSCQFPEEERGERSAEEKGRLGDLWV
B
(cid:239)
cysteine pseudorepeat #1
AITR MAQHGAMGAFRALCGLALLCALSLGQRPT-GGPGCGPGRLLLGTGTDARCCRVHTTRCCRD 60
GITR M------GAWAMLYGVSMLCVLDLGQPSVVEEPGCGPGKVQNGSGNNTRCCSLYA------ 48
(cid:239) (cid:239) (cid:239) (cid:239)
(cid:239) cysteine pseudorepeat #2 (cid:239)
AITR YPGEECCSEWDCMCVQPEFHCGDPCCTTCRHHPCPPGQGVQSQGKFSFGFQCIDCASGTF 120
GITR -PGKEDCPKERCICVTPEYHCGDPQCKICKHYPCQPGQRVESQGDIVFGFRCVACAMGTF 109
cysteine pseudorepeat #3 (cid:239) (cid:239)
AITR SGGHEGHCKPWTDCTQFGFLTVFPGNKTHVAVCVPGSPPAEPLGWLTVVLLAVAACVLLL 180
GITR SAGRDGHCRLWTNCSQFGFLTMFPGNKTHNAVCIPEPLPTEQYGHLTVIFLVMAACIFFL 169
AITR TSAQLGLHIWQLRKTQL-------LLEVPPSTEDARSCQFPEEERGERSAEEKGRLGDLWV 234
GITR TTVQLGLHIWQLRRQHMCPRETQPFAEVQLSAEDACSFQFREEERGEQT-EEKCHLGGRWP 229
Regulation of receptor expression apoptosis appears to be specific, as other apoptotic
signals (Fas triggering, dexamethasone treatment,
and UV irradiation) were not modulated by GITR
GITR expression in T cells was found to increase
transfection, indicating that GITR is a new member
4- to 8-fold upon treatment with immobilized anti-
of TNF/NGFR family involved in the regulation of
CD3, Con A, PMA+ Ca2(cid:135) ionophore. However, the
TCR-mediated cell death.
induction kinetics was slow (no increase before 6
hours) (Nocentini et al., 1997).
References
BIOLOGICAL CONSEQUENCES
Gravestein,L. A.,Blom, B.,Nolten,L.A., deVries,E.,van der
OF ACTIVATING OR Horst, G., Ossendorp, F., Borst, J., and Loenen, W. A. M.
(1993). Cloning and expression of murine CD27: comparison
INHIBITING RECEPTOR AND with 4-1BB, another lymphocyte-specific member of the nerve
growthfactorreceptorfamily.Eur.J.Immunol.23,943–950.
PATHOPHYSIOLOGY
Gurney,A.L.,Marsters,S.A.,Huang,R.M.,Pitti,R.M.,Mark,
D.T.,Baldwin,D.T.,Gray,A.M.,Dowd,A.D.,Brush,A.D.,
Unique biological effects of Heldens, A.D., Schow,A.D., Goddard,A.D.,Wood, W.I.,
Baker, K. P., Godowski, P. J., and Ashkenazi, A. (1999).
activating the receptors
Identification of a new member of the tumor necrosis factor
family and its receptor, a human ortholog of mouse GITR.
Curr.Biol.9,215–218.
To date, known GITR-induced biological effects are
Kwon, B., Yu, K. Y., Ni, J., Yu, G. L., Jang, I.-K., Kim, Y.-J.,
restricted tooffering resistanceto TCR/CD3-induced
Xing, L., Lium D., Wang, S. X., and Kwon, B. S. (1999).
apoptosis. The protection toward TCR/CD3-induced Identification of a novel activation-inducible protein of the
1758 Dass S. Vinay and Byoung S. Kwon
tumor necrosis factor receptor superfamily and its ligand. Shahnian,A.,Pieffer,K.,Lee,K.P.,Kundig,T.M.,Kishihara,K.,
J.Biol.Chem.274,6056–6061. Wakeham,A.,Kawai,K.,Ohashi,P.M.,Thompson,C.B.,and
Nocentini, G., Giunchi, L., Ronchetti, S., Krausz, L. T., Mak,T.W.(1993).DifferentialTcellcostimulatoryrequirements
Bartoli, A., Moaca, R., Migliorati, G., and Riccardi, C. inCD28-deficientmice.Science261,609–612.
(1997). A new member of the tumor necrosis factor/nerve
growth factor receptor family inhibits T cell receptor-induced
apoptosis.Proc.NatlAcad.Sci.USA94,6216–6221. ACKNOWLEDGEMENTS
Nocentini,G.,Giunchi,L.,Ronchetti,S.,Bartoli,A.,Migliorati,G.,
and Riccardi, C. (1998). Glucocorticoids: regulation of
geneexpressionandapoptosis.J.Chemother.10,187–191. Authors are grateful to Dr Byoung Suk Kwon for
Riccardi, C., Cifone, M. G., and Migliorati, G. (1999). Gluco- sharing certain unpublished research data on the
corticoidhormone-inducedmodulationofgeneexpressionand human homolog of murine GITR, the AITR.
regulationofT-celldeath:roleofGITRandGILZ,twodexa-
SRC funds to IRC from the Korean Ministry of
methasone-inducedgenes.CellDeathDiffer.6,1182–1189.
Science and Technology and NIH Grants (AI28125
Schwarz, R. H. (1990). A cell culture model for T lymphocyte
clonalanergy.Science248,1349–1356. and DE12156) are greatly appreciated.
