Characterization of the VIP receptor from SUP T1 lymphoblasts

Advances in Neuroimmunology Vol. 6, pp. 49-57, 1996 Copyright 0 1996 Elsevier Science Ltd. All rights reserved Printed in Great Britain. 0960-5428/96 $32.00

Pergamon

PII:SO960-5428(96)00006-X

Characterization lymphoblasts Patrick Robberecht”, Michal Svoboda

of the VIP receptor from SUP Tl

Philippe Gourlet, Pascale Vertongen and

Department of Biochemistry and Nutrition, Medical School, UniversitC Libre de Bruxelles, Route de Lennik, B-1070 Brussels, Belgium Keywords-VIP,

receptors,

SUPT. lymphoblasts.

Summary The SUP Tl lymphoblasts

express an original subtype of VIP receptors characterized by a high affinity for the VIP analogue from lizard venom named helodermin, a preference for the neuropeptide PACAPover PACAPand VIP, and an extremely low affinity for secretin. The molecular cloning of that receptor revealed its identity with the VIP, receptor subtype first cloned in rat and mouse tissues. The access to selective probes permits the detection of the mRNA coding for the VIP, receptor by Northern blot, reverse transcriptase-polymerase chain reaction (RT-PCR) and in situ hybridization. These highly selective and sensitive techniques identify the cell types that are equipped to synthesize the receptor but do not prove that the receptor is indeed efficiently expressed at the cell surface. VIP2 mRNA was detected in selected areas of the brain different from that expressing the classical VIP, receptor, in pituitary, in pineal, in pancreatic islets, in testes and ovary. It was also detected in the stomach, in the thymus and in spleen and in T lymphoblastic cell lines. A systematic screening of the immunocompetent cells must still be performed. Copyright 0 1996 Elsevier Science Ltd *Corresponding

B&t. G/E, CP 611, 808

Discovery

of a new class of VIP receptors

in human

SUP Tl lymphoblasts

Candace Pert’s group hypothesized in 1986 that the HIV virus could penetrate into neurons and immunocompetent cells through interaction with the VIP receptor (Pert et al., 1986; Ruff et al., 1987). The rationale was the discovery of a sequence homology between a short peptide of the Gp 120 envelope protein of the virus (ASTlTNYT) and the 4-11 central portion of the VIP molecule (AVFTDNYT). The ‘peptide T’ sequence was reported to inhibit virus penetration (Sacerdote et al., 1988). Shortly after that discovery, we and others searched for a direct interaction of peptide T and analogues with the VIP receptor, but could not find any (Nguyen, 1988; Robberecht et al., 1989~). The experiments were, however, criticized as the models studied (liver cell membranes, intestinal cells) were not, as a rule, targets for the HIV virus. We thus looked for the presence of VIP receptors in the SUP Tl lymphoblast cell line CD,+ that was generally used in the department of virology to measure HIV virus infectivity (Hecht et al., 1984). We discovered that these cells expressed a VIP receptor that recognizes VIP analogues with a selectivity different from that previously described in human cell lines or tissues as for example liver, brain, pancreatic, lung, intestinal cell membranes

author.

49

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(Robberecht er al., 1988b). Peptide T was also unable, even at 10 pM concentrations, to interfere with that receptor (Robberecht ef al., 1989~). A clear difference between the SUP Tl lymphoblast cell line receptor and the ‘classical’ VIP receptor was the high affinity of the peptide named ‘helodermin’ for the SUP Tl receptor. This receptor was therefore named the ‘heloderminpreferring receptor’. Helodetmin is a 35 amino acid peptide isolated from the venom of the Gila monster lizard (Robberecht et al., 1988a). Its peptide sequence is clearly related to that of VIP and secretin and the peptide indeed interacted with both VIP and secretin receptors (Raufman er al., 1982; Vandermeers et al., 1984, 1987; Gillet et al., 1984; Hoshino et al., 1984; Robberecht et al., 1984; Parker et al., 1984). We described large amounts of helodermin-like immunoreactive material in mammalian tissues (Robberecht et al., 1985a,b) but the purification and sequencing of a mammalian peptide failed. Although mammalian helodermin might be present in some endocrine cells (Sundler et al., 1988; Luts et al., 1994) we demonstrated that in most of the tissues studied, helodermin-like immunoreactive material was an artifact, due to the high aflinity of labelled helodermin for calmodulin (Vandermeers et al., 1992) and that its presence in the thyroid cells could be due to a cross-reactivity of the antibody used for its detection with salmon calcitoninlike substance (Tsutsumi et al., 1990). Independently of the existence of a mammalian counterpart of helodermin, the lizard peptide is a valuable tool to classify the VIP/secretin receptors Properties preferring

of the functional heloderminreceptors from the SUP Tl cells

The ‘helodermin-preferring

receptor’ of the SUP Tl cells is positively coupled to adenylate cyclase (Robberecht et al., 1989~). It is a glycoprotein, but the glycosylation, although necessary for an efficient expression of the receptor to the cell surface, is not required for the recognition of the agonists, nor for adenylate cyclase activation (Gourlet et al., 1991b). The receptor is rapidly

desensitized and internalized after cell exposure to VIP, helodermin and other agonists (Robberecht et al., 1989d). The recovery of the receptor at the cell surface after internalization is almost complete after 8 hours incubation of the cells in the absence of agonist (Robberecht et al., 1989b). Comparison of the ability of VIP and related peptides to occupy the SUP Tl receptor and the classical VIP receptor reveals two different orders of potency: on the SUP Tl receptor, helodermin > VIP = PHI & secretin and GRF; on the classical VIP receptor, VIP > helodermin > PHI > GRF > secretin (Robberecht et al., 1988b). GRF and secretin were virtually unable to recognize the SUP Tl receptor. Furthermore, guinea pig VIP that differs from the common mammalian VIP in positions 5, 9, 19 and 26 (Du et al., 1985) had a lo-fold lower affinity for the classical VIP receptor, but the same affinity as common VIP for the SUP Tl receptor (Cauvin et al., 1991). The two forms of pituitary adenylate cyclase activating polypeptide (Miyata et al., 1989), PACAPand PACAP-38, were also useful to discriminate the SUP Tl receptor from the classical VIP receptor: the decreasing order of potency helodermin > PACAP> PACAPb VIP of the SUP Tl receptor contrasts with PACAP= VIP = PACAP> helodermin observed on the classical VIP receptor (Gourlet et al., 1991a). Both profiles markedly differ from that of the selective high ahinity PACAP receptor, PACAP= PACAP+ helodermin % VIP (Gottschall et al., 1990; Cauvin et al., 1990). Non-natural synthetic analogues of VIP and PACAP also discriminate clearly between the two VIP receptor populations (Robberecht et al., 1988b, 1989~; Gourlet et al., 1991a). For instance, Acetyl-His’-VIP had a higher affinity than VIP for the SUP Tl receptor but not for the classical VIP receptor; [Phe’] VIP and VIP were almost equipotent on the SUP Tl receptors whereas [Phe’] VIP had a reduced potency on the classical VIP receptor; the VIP fragment (10-28) inhibits the VIP stimulated effect on the classical VIP receptor but not on the SUP Tl receptor. Thus, pharmacological evidence supports strongly the existence of two distinct classes of

VIP receptors

from SUP Tl lymphoblasts

VIP receptors that were named the ‘VIP-’ and the ‘helodermin-preferring’ receptors (Robberecht et al., 1990). Identification of ‘helodermin-preferring receptors’ in various cell lines On the basis of in vitro binding studies and/or the presence of a stimulated adenylate cyclase activity exhibiting a higher potency for helodermin than for VIP, the receptors were identified in human THP- 1 monocytes/macrophages (Gespach et al., 1989) in human small cell lung carcinoma (Luis and Sdid, 1990) in murine T cell lymphomas (Robberecht et al., 1989a; Abel10 et al., 1989), in the mouse melanoma cell line B 16 (Damien et al., 1989) and, recently, in the human glioblastoma cell line T98G (unpublished observation). This apparently limited number of cell lines or tissues expressing functional helodermin-like receptors is probably due to the difficulty in identifying them in the presence of classical VIP receptors. Molecular cloning of the VIP receptors Following the molecular cloning of the parathormone (Jtippner et al., 1991), calcitonin (Lin et al., 1991) and the secretin receptors (Ishihara et al., 1991), a new subfamily of the seven transmembrane helices receptors coupled to G proteins was identified and it was possible, on the basis of conserved sequences, to clone relatively rapidly the VIP (Ishihara et al., 1992), glucagon (Jelinek

51

et al., 1993; Svoboda et al., 1993a), GRF (Mayo,

1992) glucagon-like peptide I (Thorens, 1992), and PACAP receptors (Pisegna and Wank, 1993; Svoboda et al., 1993b; Spengler et al., 1993). The VIP receptor cloned by Ishihara et al., (1992) from a rat lung cDNA library had the expected properties of the classical VIP receptor (Ishihara et al., 1992; Ciccarelli et al., 1994) from lung, pancreas, liver and intestinal cell membranes. The corresponding human receptor was cloned from normal and cancerous human intestinal cells (Sreedharan et al., 1993; Couvineau et al., 1994). More recently, a second VIP receptor has been cloned from a rat olfactory bulb cDNA library (Lutz et ul., 1993) and was named the VIP, receptor. The relative potency of the agonists suggested that this receptor was indeed different from the classical VIP receptor, presently named the VIP, receptor, and close to the ‘heloderminpreferring’ receptor. The mouse counterpart of the VIP, receptor was a clone from a mouse insulin-secreting l&cell line cDNA library (Inagaki et al., 1994) but called PACAP III receptor. The receptor we have cloned from a SUP Tl cell library (Svoboda et al., 1994) is the human counterpart of the VIP, receptor. The translated amino acid sequences of the rat, mouse and human VIP, receptors as well as that of the VIP, human receptor are given in Table 1. The human 438 amino acid sequences had 85.6% identity (92.7% similarity) with both the rat 437 amino acids and the mouse 437 amino acid sequences. The human 457 amino acid VIP, receptor sequence

Table I. Alignment of the sequence of human (VIPrh2), rat (VIPrr2) and mouse (VIPrm2) II, VIP, receptors and human (VIPrhl) PACAP type II VIP, receptor

PACAP type

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. VIPrh2)

-TMTM-

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I

I

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:

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I : I I I I I.

I I I

I I I I I .I

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1 j I

IIIPrhZ) Gwrr2) VIPt-lllZ) VIPrhl)

VIPrhl)

“IFWZ) ViFm?) VIPrhl)

S 3. S R D Y R V C G S S S S~NGS2GbLQ......FWHASRAQSF~QTgTS"I* : I I I I I I III1 Ill

I

:

:

:

:

PGSRDYRLHS7SMS~NGSES_LG......IHRG .:I]!/]: :_ !. I : i I I ! : I ! I R G s RDYRLHSWSMSRNGS~S~LQ......IHRGSRTQSF~PSETS”I:_: : _I : ;:__._ I

II : I I. III I I. SRTQSFLQSZTSYI’ : I I : I I I ! III. :-I

I

: I

I I I I I ill !

I/ i :

:

"LGWNeKYRHPSGGS~G~TCs~*"~,,=~~"~~~~~~~~s~*~=~sL".

Identical amino acids are indicated by vertical bars, and conserved amino acids, by dashed vertical symbols. Putative transmembrance regions are indicated by lines above the sequence and the three glycosylable aspargine residues are indicated by black circles.

I

VIP receptors

from SUP Tl lymphoblasts

had only 49.2% identity and 68.2% similarity with the VIP, sequence. The following arguments strongly suggest that the VIP, receptor was indeed the heloderminpreferring receptor of the SUP Tl cells: (a) during molecular cloning of the VIP2 receptor from the SUP Tl cDNA library, we did not obtain any evidence for the presence of a further related receptor mRNA; (b) the functional data obtained on Chinese hamster ovary (CHO) cells transfected with the receptor DNA and expressing stably the protein were similar, if not identical to those of the SUP Tl receptors: helodetmin and PACAPwere more potent than PACAPand VIP (Svoboda et al., 1994). However, the multiple analogues that were used to characterize the SUP Tl receptors have not yet been tested on the recombinant receptors. Cellular and tissular VIP, receptor

distribution

of the

In the absence of highly selective molecules (agonists or antagonists) able to discriminate unambiguously functional VIP, from VIP, receptors, it is extremely difficult to identify the presence of the VIP, receptor in tissues expressing the VIP, receptor. However, it is easy to select mRNA sequences which are highly selective for each receptor subtype mRNA and to demonstrate the expression of both receptor subtypes by techniques such as Northern blot, reverse transcriptase-polymerase chain reaction (RTPCR), RNAse protection assays, or in situ hybridization. However, even if these techniques may quantify the relative amounts of the mRNA, they do not indicate whether the receptor protein is effectively present at the cell surface, nor the relative number of each subtype protein. The VIP, receptor was expressed in the brain and, at variance with the VIP, receptor, predominated in the olfactory bulb, the thalamus, the suprachiasmatic nucleus, and in the anterior pituitary (Harmar and Lutz, 1994; Usdin et al., 1994). VIP, mRNA was heavily expressed in human skeletal muscle (Adamou et al., 1995), but the cell type involved has not been determined.

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The presence of the VIP, receptor in the pineal gland, in pancreatic islets, in testes and the ovary suggests that it may be the neuroendocrine VIP receptor (Usdin et al., 1994; Inagaki et al., 1994). However, we did not detect VIP, mRNA in the RIN-SF cells (unpublished results) and in the 6/23 cell line of a rat thyroid medullary carcinoma (Vertongen et al., 1994). The VIP, mRNA is also expressed in the germinal centre of white pulp and in both cortex and medulla of the thymus (Usdin et al., 1994). We investigated via the RT-PCR technique human tumour specimens and selected transformed cell lines. In 22 neuroblastoma specimens of various grades, three expressed only the VIP, mRNA, two the VIP,, and eight expressed both mRNAs (Vertongen et al., 1996). Thirteen of 22 gliomas samples expressed VIP receptor mRNA: two expressed the VIP,, three the VIP, and eight both of the receptors’ mRNA. Four ependymomas and two oligodendrogliomas expressed both VIP, and VIP, receptor mRNA. Fifteen of 19 pituitary adenomas expressed low amounts of VIP receptor mRNA but surprisingly the VIP, receptor was identified in only three samples, while the VIP, receptor was detected in 12 samples. Two teratomas also expressed VIP, and VIP, receptor mRNA. The only neuroendocrine tumour of the pancreas studied expressed the VIP,? receptor mRNA only, but the three carcinoid tumours of the lung studied expressed VIP, receptor only. The human cell lines we studied are presented in Table 2: epithelial colonic cell lines expressed the VIP, receptor mRNA; VIP, mRNA was present in the T lymphoblastic cell line but not in the B cell lines.

Conclusion The VIP receptor was initially identified in SUP Tl cells on the basis of the relative efficacy of VIP analogues, and was recently cloned and is presently named the VIP, receptor. The VIP, receptor is expressed in the central nervous system

54 Table 2. Identification

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of the mRNA coding for the VIP, and VIP, receptor by RT-PCR

Tumour code number

Cell type

SW 480 SW 620 HT 1080 u 373 T 98G SUP Tl MOLT 4 KT 1 Nall 1 H33HJ-JAI RAJ 1 Nemalwa DAUDI K 562

Colon Colon Fibrosarcoma Glioblastoma Glioblastoma T lymphoblasts T lymphoblasts T lymphoblasts T lymphoblasts T lymphoma B lymphoblasts B lymphoblasts B lymphoblasts Chronic myeloid leukemia

VIP, mRNA

VIP, mRNA

++ ++ -

++ -I-++

-

++

-

+++

-

+++ -

+ -

-

+

-

The primers used have been described in Vertongen et al. (1996). The relative intensity of the PCR product was judged by eye after electrophoresis on a 1.2% agarose gel stained with ethidium bromide and visualization under U.V. light.

and in the endocrine

glands

and its distribution

differs from that of the VIP, receptor. Blood cells and immunocompetent cells have not yet been extensively studied, but analysis of selected cell lines suggests a predominant expression of the VIP, receptor in the cells of the T lineage.

Acknowledgements We are grateful to the ‘Fonds de la Recherche Scientifique Medicale’ (Belgium), to the I.R.S.I.A. (Belgium), TELEVIE (Belgium), The ‘Minis&e de la RCgion Wallonne de Belgique’, the ‘Fonds Solvay’ and the ‘Fonds Alice et Jean Van Buuren’ for their continuous experimental work presented

support to the in this review.

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lnagaki, N., Yoshida, H., Mizuta, M., Mizuno, N., Fujii, Y., Gonoi, T., Miyazaki, J. -1. and Seino, S. (1994). Cloning and functional characterization of a third pituitary adenylate cyclase-activating polypeptide receptor subtype expressed in insulin-secreting cells. Proc. Nat1 Acad. Sci. USA 91~2679-2683. Ishihara, T., Nakamura, S., Kaziro, Y., Takahashi, T., Takahashi, K. and Nagata, S. (1991). Molecular cloning and expression of a cDNA encoding the secretin receptor. EMBO J. 10: 1635-1641. Ishihara, T., Shigemoto, R., Mori, K., Takahashi, K., and Nagata, S. (1992). Functional expression and tissue distribution of a novel receptor for vasoactive intestinal polypeptide. Neuron 8:811-819. Jelinek, L. J., Lok, S., Rosenberg, G. B., Smith, R. A., Grant, F. J., Biggs, S., Bensch, P. A., Kuijper, J. L., Sheppard, P. O., Sprecher, C. A., O’Hara, P. J., Foster, D., Walker, K. M., Chen, L. H. J., McKernan, P. A. and Kindsvogel, W. (1993). Expression cloning and signaling properties of the rat glucagon receptor. Science 259:1614-1616. Jiippner, H., Abou-Samra, A. -B., Freeman, M., Kong, X. F., Schipani, E., Richards, J., Kolakowski, L. F. Jr., Hock, J., Potts, J. T. Jr., Kronenberg, H. M. and Segre, G. V. (1991). A G protein-linked receptor for parathyroid hormone and parathyroid hormonerelated peptide. Science 254:1024-1026. Lin, H. Y., Harris, T. L., Flannery, M. S., Aruffo, A., Kaji, E. H., Corn, A., Kolakowski, L. F. Jr., Lodish, H. F. and Goldring, S. R. (1991). Expression cloning of an adenylate cyclase-coupled calcitonon receptor. Science 254: 1022- 1024. Luis, J. and Sai’d, S. I. (1990).Characterization of VIPand helodennin-preferring receptors on human small cell lines. Peptides cell lung carcinoma 11:1239-1244. Luts, A., Uddman, R., Hakanson, R. and Sundler, F. (1994). Calcitonin, CGRP and helodermin in endocrine cells of the developing rat lung. Regul. Pept. 51:121-129. Lutz, E. M., Sheward, W. J., West, K. M., Morrow, J. A., Fink, G. and Harmar, A. J. (1993). The VIP, receptor: molecular characterisation of a cDNA encoding a novel receptor for vasoactive intestinal peptide. FEBS Lett. 334:3-8. Mayo, K. E. (1992). Molecular cloning and expression for pituitary-specific receptor for growth hormone-releasing hormone. Mol. Endocrinol. 6:1737-174-k Miyata, A., Arimura, A., Dahl, R. R., Minamino, N., Uehara, A., Jiang, L., Culler, M. D. and Coy, D.

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H. (1989). Isolation of a novel 38 residue hypothalamic polypeptide which stimulates adenylate cyclase in pituitary cells. Biochem. Biophys. Rex Commun. 164:567-574. Ngyuen, T. D. (1988). Peptide T from human immunodeficiency virus envelope does not interact with hepatic, intestinal and colonic vasoactive intestinal (VIP) receptors. Peptides 9:425-428. Parker, D. S., Raufman, J. -P., O’Donohue, T. L., Bledsoe, M., Yoshida, H. and Pisano, J. J. (1984). Amino acid sequences of helospectins, new members of the glucagon superfamily, found in Gila monster venom. J. Biol. Chem. 259: 11751-11755. Pert, C. B., Hill, J. M., Ruff, M. R., Berman, R. M., Robey, W. G., Arthur, L. O., Ruscetti, F. W. and Farrar, W. L. (1986). Octapeptides deduced from the neuropeptide receptor-like pattern of antigen T4 in brain potently inhibit human immunodeficiency virus receptor binding and T-cell infectivity. Proc. Nat1 Acad. Sci. USA 83:9254-9258. Pisegna, J. R. and Wank, S. A. (1993). Molecular cloning and functional expression of the pituitary adenylate cyclase-activating polypeptide type I receptor. Proc. Nat1 Acad. Sci. USA 90:6345-6349. Raufman, J.-P., Jensen, R. T., Sutliff, V. E., Pisano, J. J. and Gardner, J. D. (1982). Actions of Gila monster venom on dispersed acini from guinea pig pancreas. Am. J. Physiol. 242:G47O-G474. Robberecht, P., Abello, J., Damien, C., De Neef, P., Vervisch, E., Hooghe, R. and Christophe, J. (1989a). Variable stimulation of adenylate cyclase activity by vasoactive intestinal-like peptides and R-adrenergic agonists in murine T cell lymphomas of immature, helper, and cytotoxic types. Immunobiology 179:422-43 1. Robberecht, P., Cauvin, A., Gourlet, P. and Christophe, J. (1990). Heterogeneity of VIP receptors. Pauwels, R., Lefebvre, R. A., and Herman, A. G., eds Second Workshop on Nonadrenergic Noncholinergic Mechanisms, Arch Int. Pharmacodyn. Ther. Vol. 303, 90:~~. 51-66. Robberecht, P., De Graef, J., Woussen, M.-C., Vandermeers-Piret, M.-C., Vandermeers, A., De Neef, P., Cauvin, A., Yanaihara, C., Yanaihara, N., and Christophe, J. (1985a). Immunoreactive helodermin-like peptides in rat: a new class of mammalian neuropeptides related to secretin and VIP. Biochem. Biophys. Res. Commun. 130:333-342. Robberecht, P., De Neef, l?, Abello, J., Damien, C., Coussaert, E. and Christophe, J. (1989b). Recovery of VIP/helodermin-and prostaglandin E,-stimulated

adenylate cyclase activities in desensitized SUP-T, human lymphoblasts. Peptides 10:1027-1031. Robberecht, P., De Neef, P, Gourlet, P., Cauvin, A., Coy, D. H. and Christophe, J. (1989~). Pharmacological characterization of the novel helodermin/ VIP receptor present in human SUP-T1 lymphoma cell membranes. Regul. Pept. 26:117-126. Robberecht, P., De Neef, P., Vandermeers, A., Vandermeers-Piret, M. -C., Svoboda, M., Meuris, S., De Graef, J., Woussen-Colle, M. -C., Yanaihara, C., Yanaihara, N. and Christophe, J. (1985b). Presence of helodermin-like peptides of the VIPsecretin family in mammalian salivary glands and saliva. FEBS Lett. 190:142-146. Robberecht, I?, De Neef, P., Waelbroeck, M., Tastenoy, M. and Christophe, J. (1989d) VIP and related peptides induce rapid homologous desensitization in the human lymphoma SUP Tl cell line. Peptides 10:4414I6. Robberecht, P., Vandermeers, A., Vandermeers-Piret, M. C., Gourlet, G., Cauvin, A., De Neef, P. and Christophe, J. (1988a). Helodermin-like peptides. In: Vasoactive Intestinal Peptide and Related Peptides (eds) Said, S. I. and Mutt, V. Ann. NY Acad. Sci. pp. 186-203. Robberecht, I?, Waelbroeck, M., Dehaye, J. P., Winand, J., Vandermeers, A., Vandermeers-Piret, M. C. and Christophe, J. (1984). Evidence that helodermin, a newly extracted peptide from Gila monster venom, is a member of the secretin/VIP/PHI family of peptides with an original pattern of biological properties. FEBS Lett. 166:277-282. Robberecht, P., Waelbroeck, M., De Neef, P., Tastenoy, M., Gourlet, P., Cogniaux, J. and Christophe, J. (1988b). A new type of functional VIP receptor has an affinity for helodermin in human SUP-T1 lymphoblasts. FEBS Lett. 228:351-355. Ruff, M. R., Martin, B. M., Ginns, E. I., Farrar, W. L. and Pert, C. B. (1987). CD4 receptor binding peptides that block HIV infectivity cause human monocyte chemotaxis. FEBS Lett. 211:17-22. Sacerdote, P., Ruff, M. R. and Pert, C. B. (1988). VIP,-,, is a ligand for the CD,/human immunodeficiency virus receptor. Ann. NY Acad. Sci. 527:574-578. Spengler, D., Waeber, C., Pantaloni, C., Holsboer, F., Bockaert, J., Seeburg, I? H. and Joumot, L. (1993). Differential signal transduction by five splice variants of the PACAP receptor. Nature 365:17&175. Sreedharan, S. P., Patel, D. R., Huang, J. -X., and

VIP receptors

from

Goetzl, E. J. (1993).Cloning and functional expression of a human neuroendocrine vasoactive intestinal peptide receptor. Biochem. Biophys. Res. Commun. 193546-553. Sundler, F., Christophe, J., Robberecht, P., Yanaihara, N., Yanaihara, C., Grunditz, T. and H&anson, R. (1988). Is helodermin produced by medullary thyroid carcinoma cells and normal C cells? Immunocytochemical evidence. Regul. Pept. 20:83-89. Svoboda, M., Ciccarelli, E., Tastenoy, M., Cauvin, A., Stievenart, M. and Christophe, J. (1993a). Small introns in a hepatic cDNA encoding a new glucagonlike peptide l-type receptor. Biochem. Biophys. Rex Commun. 191:479-486. Svoboda, M., Tastenoy, M., Ciccarelli, E., StiCvenart, M. and Christophe, J. (1993b).Cloning of a splice variant of the pituitary adenylate cyclaseactivating polypeptide (PACAP) type I receptor. Biochem. Biophys. Res. Commun. 195881-888. Svoboda, M., Tastenoy, M., Van Rampelbergh, J., Goossens, J. -F., De Neef, P, Waelbroeck, M. and Robberecht, P. (1994). Molecular cloning and functional characterization of a human VIP receptor from SUP-T1 lymphoblasts. Biochem. Biophys. Res. Commun. 205:1617-1624. Thorens, B. (1992). Expression cloning of the pancreatic I3 cell receptor for the gluco-incretin hormone glucagon-like peptide 1. Proc. Nat1 Acad. Sci. USA 89:8641-8645. Tsutsumi, Y., Kamoshida, S., Iguchi, K., Mochizuki, T. and Yanaihara, N. (1990). Is helodermin-like immunoreactivity in human thyroid C cells due to a salmon calcitonin-like substance? Regul. Pept. 31:11-21. Usdin, T. B., Bonner, T. I. and Mezey, E. (1994). Two receptors for vasoactive intestinal polypeptide with

SUP Tl lymphoblasts

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similar specificity and complementary distributions. Endocrinology 135:2662-2680. Vandermeers, A., Bounjoua, Y., Vandermeers-Piret, M. -C., Robberecht, P. and Christophe, J. (1992). Helodermin-like immunoreactivity is artefactually increased in bovine brain by the presence of calmodulin. 5th International Symposium on VIP and Related Peptides, Biomed. Res. 13:361-366. Vandermeers, A., Gourlet, P., Vandermeers-Piret, M. -C., Cauvin, A., De Neef, P., RathC, J., Svoboda, M., Robberecht, P. and Christophe, J. (1987). Chemical, immunological and biological properties of peptides like vasoactive-intestinal-peptide and peptide-histidine-isoleucinamide extracted from the venom of two lizards (Heloderma harrtdum and Heloderma suspectum). Eur. J. Biochem. 164:321-327. Vandermeers, A., Vandermeers-Piret, M. -C., Robberecht, P., Waelbroeck, M., Dehaye, J. -P., Winand, J. and Christophe, J. (1984). Purification of a novel pancreatic secretory factor (PSF) and a novel peptide with VIP-and secretin-like properties (helodermin) from Gila monster venom. FEES Lett. 166:273-276. Vertongen, P., Ciccarelli, E., Woussen-Colle, M.-C., De Neef, P., Robberecht, l? and Cauvin, A. (1994). Pituitary adenylate cyclase-activating polypeptide receptors of types I and II and glucagon-like peptide- receptors are expressed in the rat medullary carcinoma of the thyroid cell line 6/23. Endocrinology 135: 1537-l 542. Vertongen, P, De Valck, C., Sariban, E., De Laet, M.H., Martelli, H., Paraf, F., Helardot, I? and Robberecht, P. (1996). Pituitary adenylate cyclase activating peptide and its receptors are expressed in human neuroblastomas. J. Cell Physiol. in press.