Fig. 4. Teneurin-2 attenuates the transcriptional activity of zic. (A) Expression of teneurin-2 I could be induced by addition of increasing concentrations of ponasterone in EcR-293 cells stably transfected with the teneurin-2 construct I, and the addition of ALLN resulted in the stabilization of the teneurin-2 I protein. (B) Transcriptional activity of zic was studied by transfecting pXP2- APOE189 alone (- zic) or together with a zic-expressing construct (+ zic) into the teneurin-2 I stable transfectant EcR-293-I cells in the absence or presence of proteasome inhibitor ALLN (-/+ ALLN). Luciferase activity was dependent on the presence of zic, and induction of teneurin-2 I by ponasterone resulted in decreased luciferase expression, which was even more pronounced in the presence of ALLN, which is known to stabilize teneurin-2 I. (C) Transcriptional activity of zic after transfecting pXP2-APOE189 alone (- zic) or together with a zic expressing construct (+ zic) into EcR-control cells. Addition of ponasterone had no effect on the resulting luciferase activity measured.