TABLE 3.
Functional and pharmacological characteristics in the FMP assay of EAAT2wt and EAAT2b, and co-transfections of different ratios of EAAT2wt (or EAAT2b) and EAAT2 exon-skipping splice variants, expressed in HEK293 cell lines
| Ratio | Glutamate |
DHK |
|||
|---|---|---|---|---|---|
| EC50a | Hill slope | IC50 | Hill slope | ||
| μm | μm | ||||
| EAAT2wt | 23.5 ± 1.2 | 1.3 ± 0.2 | 286.1 ± 1.1 | 1.4 ± 0.2 | |
| EAAT2wt:ΕΑΑΤ2Δ7 | |||||
| 1:5 | 188.2 ± 31.9b | 0.5 ± 0.2 | 679.6 ± 4.7 | 0.5 ± 0.2 | |
| 1:10 | 259.6 ± 34.7b | 0.4 ± 0.1 | 1546.0 ± 9.3 | 0.5 ± 0.2 | |
| EAAT2wt:ΕΑΑΤ2Δ9 | |||||
| 1:5 | 27.1 ± 0.7 | 1.4 ± 0.1 | NDc | ND | |
| 1:10 | 108.6 ± 19.5b | 1.1 ± 0.4 | 629.6 ± 1.9 | 0.9 ± 0.3 | |
| 1:20 | 275.5 ± 37.7b | 0.4 ± 0.1 | 1084.0 ± 8.8 | 0.4 ± 0.2 | |
| EAAT2b | 32.9 ± 2.0 | 1.0 ± 0.1 | 104.6 ± 1.2 | 1.3 ± 0.2 | |
| EAAT2b:ΕΑΑΤ2Δ7 | |||||
| 1:5 | 70.3 ± 13.9b | 0.7 ± 0.2 | 686.8 ± 4.4 | 0.6 ± 0.3 | |
| 1:10 | 237.6 ± 48.2b | 0.9 ± 0.3 | 1183.0 ± 48.0 | 0.5 ± 0.3 | |
| EAAT2b:ΕΑΑΤ2Δ9 | |||||
| 1:5 | 41.4 ± 11.4 | 0.7 ± 0.3 | 433.3 ± 1.3 | 1.2 ± 0.3 | |
| 1:10 | 99.8 ± 21.2b | 0.6 ± 0.1 | 466.9 ± 1.5 | 1.0 ± 0.2 | |
| 1:20 | 161.3 ± 37.8b | 0.6 ± 0.2 | 728.9 ± 10.2 | 0.5 ± 0.3 | |
a EC50/IC50 values represent the average of at least three independent experiments performed in triplicate; values are mean ± S.E. Non-linear regression was carried out as described under “Results.” The inhibitor DHK was tested at 300 μm glutamate concentration.
b Indicates significance relative to EAAT2wt/EAAT2b by unpaired Student's t test (p < 0.01).
c ND, not determined.