scholarly journals Vasoactive intestinal peptide receptors in rat liver after partial hepatectomy

1992 ◽  
Vol 285 (2) ◽  
pp. 515-520 ◽  
Author(s):  
L G Guijarro ◽  
A Couvineau ◽  
M S Rodriguez-Pena ◽  
M G Juarranz ◽  
N Rodriguez-Henche ◽  
...  
Keyword(s):  
Adenylate Cyclase ◽  
Vasoactive Intestinal Peptide ◽  
Structural Changes ◽  
Binding Capacity ◽  
Regenerating Liver ◽  
Vip Receptors ◽  
Receptor Complexes ◽  
Binding Data ◽  
The Status ◽  
Affinity Labelling

We describe the status of vasoactive intestinal peptide (VIP) receptors in regenerating liver. VIP-stimulated adenylate cyclase activity was markedly decreased in proliferating liver 3 days after partial (70%) hepatectomy. This was associated with a reduced efficacy of VIP (53% compared with controls), with no change in the potency of the peptide (ED50 0.8 nM). In contrast, forskolin- and guanosine 5′-[beta gamma-imido]triphosphate (Gpp[NH]p)-stimulated enzyme activities were not decreased after hepatectomy. The expression of Gs protein subunits (alpha and beta) was studied by cholera toxin-catalysed ADP ribosylation of alpha s and by immunoblotting of alpha s and beta subunits. Both subunits were increased in regenerating liver, further suggesting that the decreased response to VIP was not related to a decreased expression of Gs proteins. In fact, the reduced adenylate cyclase response to VIP in regenerating liver was associated with quantitative and structural changes in VIP receptors. Equilibrium binding data obtained with 125I-VIP indicated the presence of two classes of binding sites, the Kds of which were not altered after hepatectomy. In contrast, changes in binding capacity (Bmax.) were as follows: 0.11 +/- 0.01 and 0.05 +/- 0.01 pmol/mg of protein for high-affinity sites in control and hepatectomized rats respectively; and 2.3 +/- 0.2 and 0.65 +/- 0.03 pmol/mg of protein for low-affinity sites in control and hepatectomized rats respectively. Moreover, affinity labelling experiments showed that the M(r) value of 125I-VIP-receptor complexes was higher in regenerating liver than in quiescent hepatocytes, e.g. 58,000 and 53,000 respectively. It is concluded that VIP receptors are altered in regenerating liver, resulting in a decreased response of adenylate cyclase to the neuropeptide.

scholarly journals Evidence that non-covalent forces, thiol and disulphide groups affect the structure and binding properties of the prolactin receptor on hepatocytes from pregnant rats

1985 ◽  
Vol 228 (2) ◽  
pp. 383-390 ◽  
Author(s):  
K Yamada ◽  
D B Donner
Keyword(s):  
Growth Hormone ◽  
Binding Capacity ◽  
Prolactin Receptor ◽  
Sodium Dodecyl ◽  
Specific Effect ◽  
Scatchard Analysis ◽  
Pregnant Rats ◽  
Receptor Complexes ◽  
Affinity Labelling ◽  
Triton X

Incubation of hepatocytes from pregnant rats with dithiothreitol decreased specific 125I-prolactin (125I-prl) binding to such cells by about 20% relative to control. This was not due to a non-specific effect of dithiothreitol on the cell membrane, since reduction also altered the binding of prl to solubilized partially purified receptor. Exposure of hepatocytes to N-ethylmaleimide (6 mM) for periods as brief as 1 min decreased the subsequent specific binding of 125I-prl by more than 50%. N-Ethylmaleimide was less effective as an inhibitor of binding when applied after hepatocytes had been exposed to 125I-prl, binding being decreased by about 15%. Scatchard analysis demonstrated that the effect of N-ethylmaleimide resulted from loss of receptor-binding capacity without any substantial effect on the affinity of the prl receptor for hormone. Dithiothreitol diminished the affinity of lactogenic sites for prolactin without altering cellular binding capacity. These observations suggest that thiol and disulphide groups are present in the prl receptor and that these functional moieties regulate the formation and properties of prl receptor complexes. The species to which 125I-prl had bound were identified by affinity labelling. 125I-prl was covalently coupled into saturable complexes of Mr 65000 and 50000. 125I-human growth hormone (125I-hGH) was covalently incorporated into complexes of Mr 300 000, 220 000, 130 000, 65 000 and 50 000. Bovine growth hormone (bGH), but not prl, competed for 125I-hGH uptake into the 300 000-, 220 000- and 130 000-Mr complexes, indicating that these species were somatogenic. Prl, but not bGH, inhibited 125I-hGH uptake into 65 000- and 50 000-Mr complexes. This demonstrated that 125I-hGH in the presence of bGH could affinity-label lactogenic receptors. 125I-prl aggregates in Triton X-100, whereas 125I-hGH does not. Therefore lactogenic complexes to which 125I-hGH was bound in the presence of excess bGH were solubilized in Triton X-100 and characterized sequentially by gel filtration and affinity labelling. Prl receptors were eluted from columns of Sepharose 6B as a species of Mr380 000. Fractionation of the 380 000-Mr species on sodium dodecyl sulphate polyacrylamide gels resulted in the isolation of complexes of Mr 65 000 and 50 000. Thus non-covalent forces stabilize aggregates of the monomeric prolactin receptor.

Vasoactive intestinal peptide (VIP) receptors positively coupled with adenylate cyclase activity in the human placenta: Vascular localization

Placenta ◽  
1992 ◽  
Vol 13 ◽  
pp. 319-334
Author(s):  
André Malassiné ◽  
Françoise Mondon ◽  
Jacqueline Besson ◽  
Micheline Vial ◽  
Gisèle Tanguy ◽  
...  
Keyword(s):  
Adenylate Cyclase ◽  
Vasoactive Intestinal Peptide ◽  
Human Placenta ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Vip Receptors

Expression, pharmacological, and functional evidence for PACAP/VIP receptors in human lung

1999 ◽  
Vol 277 (1) ◽  
pp. L42-L48 ◽  
Author(s):  
Rebeca Busto ◽  
Isabel Carrero ◽  
Luis G. Guijarro ◽  
Rosa M. Solano ◽  
José Zapatero ◽  
...  
Keyword(s):  
Adenylate Cyclase ◽  
Human Lung ◽  
Dissociation Constants ◽  
Binding Capacity ◽  
Rt Pcr ◽  
Vip Receptors ◽  
Pituitary Adenylate Cyclase ◽  
Maximum Binding Capacity ◽  
Specific Receptors

Pituitary adenylate cyclase-activating peptide (PACAP) type 1 (PAC1) and common PACAP/vasoactive intestinal peptide (VIP) type 1 and 2 (VPAC1 and VPAC2, respectively) receptors were detected in the human lung by RT-PCR. The proteins were identified by immunoblotting at 72, 67, and 68 kDa, respectively. One class of PACAP receptors was defined from125I-labeled PACAP-27 binding experiments (dissociation constant = 5.2 nM; maximum binding capacity = 5.2 pmol/mg protein) with a specificity: PACAP-27 ≈ VIP > helodermin ≈ peptide histidine-methionine (PHM) ≫ secretin. Two classes of VIP receptors were established with 125I-VIP (dissociation constants of 5.4 and 197 nM) with a specificity: VIP ≈ helodermin ≈ PACAP-27 ≫ PHM ≫ secretin. PACAP-27 and VIP were equipotent on adenylyl cyclase stimulation (EC50 = 1.6 nM), whereas other peptides showed lower potency (helodermin > PHM ≫ secretin). PACAP/VIP antagonists supported that PACAP-27 acts in the human lung through either specific receptors or common PACAP/VIP receptors. The present results are the first demonstration of the presence of PAC1 receptors and extend our knowledge of common PACAP/VIP receptors in the human lung.

Interaction of thymic peptide thymosin α1 with vasoactive intestinal peptide (VIP) receptors

1986 ◽  
Vol 6 (8) ◽  
pp. 727-733 ◽  
Author(s):  
J. R. Calvo ◽  
R. Goberna ◽  
J. M. Guerrero
Keyword(s):  
Adenylate Cyclase ◽  
Vasoactive Intestinal Peptide ◽  
Plasma Membranes ◽  
Mononuclear Cells ◽  
Specific Binding ◽  
Thymosin Α1 ◽  
Vip Receptors ◽  
Liver Plasma Membranes ◽  
Blood Mononuclear Cells ◽  
Thymic Peptide

Thymic peptide thymosin α1 (10−9 to 3 × 1010−7 M) is shown to inhibit the specific binding of [125I]VIP to rat blood mononuclear cells and liver plasma membranes. Thymosin α1 was 160 and 6250 times less potent that VIP at inhibiting [125I]VIP binding to blood mononuclear cells and liver plasma membranes, respectively. Thymosin α1 (10−10 to 1010−7 M) was weak in stimulating adenylate cyclase activity. Its efficacy is about 25 % and 27 % that of native VIP in blood mononuclear cells and liver plasma membranes, respectively. Thymosin α1 may behave as a partial VIP agonist in rat.

Lung cancer VIP receptors are coupled to adenylate cyclase

1989 ◽  
Vol 26 (2) ◽  
pp. 170
Author(s):  
T.W. Moody ◽  
M. Lee ◽  
R.T. Jensen ◽  
G. Bepler ◽  
L.Y. Korman
Keyword(s):  
Lung Cancer ◽  
Adenylate Cyclase ◽  
Vip Receptors

Expression of vasoactive intestinal peptide (VIP) receptors in human uterus

Peptides ◽  
2000 ◽  
Vol 21 (9) ◽  
pp. 1383-1388 ◽  
Author(s):  
Ana M Bajo ◽  
Marı́a G Juarranz ◽  
Pedro Valenzuela ◽  
Pilar Martı́nez ◽  
Juan C Prieto ◽  
...  
Keyword(s):  
Vasoactive Intestinal Peptide ◽  
Human Uterus ◽  
Vip Receptors
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