Abstract
We have examined the influence of reducing conditions on the activity of group-I or -II metabotropic glutamate receptors. In cultured cerebellar granule cells or in hippocampal slices, the reducing agent dithiothreitol (DTT) inhibited the stimulation of polyphosphoinositide (PPI) hydrolysis elicited by group-I mGlu receptor agonists without affecting responses to norepinephrine or carbamylcholine. Similarly, DTT reduced the increase in intracellular free Ca2+ induced by glutamate in HEK-293 cells expressing mGlu5 receptors. In adult hippocampal slices, the selective group-II mGlu receptor agonist, (2S,1'R,2'R,3'R)-2-(2,3-dicarboxycyclopropyl)glycine (DCG- IV) had no effect per se on PPI hydrolysis, but potentiated the response to quisqualate. Although DTT substantially attenuated the action of quisqualate, it did not affect the potentiation by DCG-IV, suggesting that group-II mGlu receptors are resistant to extracellular reduction. Accordingly, DTT did not affect the inhibition of forskolin-stimulated cAMP formation induced by maximally effective concentrations of group-II mGlu receptor agonists in hippocampal slices or in CHO cells expressing mGlu2 receptors. At structural level, DTT differentially affected the aggregation state of mGlu1a, -2/3 or - 5 receptors. In immunoblots performed under non-reducing conditions, mGlu1a, -2/3 or -5 antibodies labeled exclusively a high-molecular weight band, corresponding to receptor dimers. Under reducing conditions, mGlu1a or -5 receptors were detected as monomers, whereas a large proportion of mGlu2/3 receptors was still present in a dimeric form. We conclude that reducing conditions differentially influence the aggregation state of group-I and -II mGlu receptors and suggest that dimerization affects the functional activity of native mGlu receptors. (C) 2000 Elsevier Science B.V.
| Original language | English |
|---|---|
| Pages (from-to) | 165-172 |
| Number of pages | 8 |
| Journal | Brain Research |
| Volume | 867 |
| Issue number | 1-2 |
| DOIs | |
| Publication status | Published - Jun 9 2000 |
Fingerprint
Keywords
- Dimerization
- Metabotropic glutamate receptor
- Signal transduction
ASJC Scopus subject areas
- Neuroscience(all)
Cite this
Reducing conditions differentially affect the functional and structural properties of group-I and -II metabotropic glutamate receptors. / Copani, A.; Romano, C.; Di Giorgi Gerevini, V.; Nicosia, A.; Casabona, G.; Storto, M.; Mutel, V.; Nicoletti, F.
In: Brain Research, Vol. 867, No. 1-2, 09.06.2000, p. 165-172.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Reducing conditions differentially affect the functional and structural properties of group-I and -II metabotropic glutamate receptors
AU - Copani, A.
AU - Romano, C.
AU - Di Giorgi Gerevini, V.
AU - Nicosia, A.
AU - Casabona, G.
AU - Storto, M.
AU - Mutel, V.
AU - Nicoletti, F.
PY - 2000/6/9
Y1 - 2000/6/9
N2 - We have examined the influence of reducing conditions on the activity of group-I or -II metabotropic glutamate receptors. In cultured cerebellar granule cells or in hippocampal slices, the reducing agent dithiothreitol (DTT) inhibited the stimulation of polyphosphoinositide (PPI) hydrolysis elicited by group-I mGlu receptor agonists without affecting responses to norepinephrine or carbamylcholine. Similarly, DTT reduced the increase in intracellular free Ca2+ induced by glutamate in HEK-293 cells expressing mGlu5 receptors. In adult hippocampal slices, the selective group-II mGlu receptor agonist, (2S,1'R,2'R,3'R)-2-(2,3-dicarboxycyclopropyl)glycine (DCG- IV) had no effect per se on PPI hydrolysis, but potentiated the response to quisqualate. Although DTT substantially attenuated the action of quisqualate, it did not affect the potentiation by DCG-IV, suggesting that group-II mGlu receptors are resistant to extracellular reduction. Accordingly, DTT did not affect the inhibition of forskolin-stimulated cAMP formation induced by maximally effective concentrations of group-II mGlu receptor agonists in hippocampal slices or in CHO cells expressing mGlu2 receptors. At structural level, DTT differentially affected the aggregation state of mGlu1a, -2/3 or - 5 receptors. In immunoblots performed under non-reducing conditions, mGlu1a, -2/3 or -5 antibodies labeled exclusively a high-molecular weight band, corresponding to receptor dimers. Under reducing conditions, mGlu1a or -5 receptors were detected as monomers, whereas a large proportion of mGlu2/3 receptors was still present in a dimeric form. We conclude that reducing conditions differentially influence the aggregation state of group-I and -II mGlu receptors and suggest that dimerization affects the functional activity of native mGlu receptors. (C) 2000 Elsevier Science B.V.
AB - We have examined the influence of reducing conditions on the activity of group-I or -II metabotropic glutamate receptors. In cultured cerebellar granule cells or in hippocampal slices, the reducing agent dithiothreitol (DTT) inhibited the stimulation of polyphosphoinositide (PPI) hydrolysis elicited by group-I mGlu receptor agonists without affecting responses to norepinephrine or carbamylcholine. Similarly, DTT reduced the increase in intracellular free Ca2+ induced by glutamate in HEK-293 cells expressing mGlu5 receptors. In adult hippocampal slices, the selective group-II mGlu receptor agonist, (2S,1'R,2'R,3'R)-2-(2,3-dicarboxycyclopropyl)glycine (DCG- IV) had no effect per se on PPI hydrolysis, but potentiated the response to quisqualate. Although DTT substantially attenuated the action of quisqualate, it did not affect the potentiation by DCG-IV, suggesting that group-II mGlu receptors are resistant to extracellular reduction. Accordingly, DTT did not affect the inhibition of forskolin-stimulated cAMP formation induced by maximally effective concentrations of group-II mGlu receptor agonists in hippocampal slices or in CHO cells expressing mGlu2 receptors. At structural level, DTT differentially affected the aggregation state of mGlu1a, -2/3 or - 5 receptors. In immunoblots performed under non-reducing conditions, mGlu1a, -2/3 or -5 antibodies labeled exclusively a high-molecular weight band, corresponding to receptor dimers. Under reducing conditions, mGlu1a or -5 receptors were detected as monomers, whereas a large proportion of mGlu2/3 receptors was still present in a dimeric form. We conclude that reducing conditions differentially influence the aggregation state of group-I and -II mGlu receptors and suggest that dimerization affects the functional activity of native mGlu receptors. (C) 2000 Elsevier Science B.V.
KW - Dimerization
KW - Metabotropic glutamate receptor
KW - Signal transduction
UR - http://www.scopus.com/inward/record.url?scp=0034625738&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0034625738&partnerID=8YFLogxK
U2 - 10.1016/S0006-8993(00)02293-9
DO - 10.1016/S0006-8993(00)02293-9
M3 - Article
C2 - 10837810
AN - SCOPUS:0034625738
VL - 867
SP - 165
EP - 172
JO - Brain Research
JF - Brain Research
SN - 0006-8993
IS - 1-2
ER -