Figure 9. Loss of ZDHHC14 increases excitability of hippocampal neurons.

(A, B) Hippocampal neurons were transduced with AAV to express GFP alone (A) or GFP plus Zdhhc14 shRNA#1 (B) and GFP-positive cells were subjected to whole-cell patch-clamp. Representative traces showing the development of outward currents following voltage steps from −80 to +100 mV (Δ15 mV). (C) Summary graph of outward current density following steps of the indicated voltages for neurons infected with control AAV (gray circles) or Zdhhc14 sh#1 AAV (green squares). Zdhhc14 knockdown reduces outward current density (C) Repeated Measures ANOVA, Virus p=0.18 [F(1)=2.06], membrane potential p<0.0001 [F(12)=73.14], **interaction p=0.0027 [F(12)=2.68]; (N = 7). There was also a significant difference (p<0.0001 [F(4)=8.46]) between conditions when the two curves were fitted with a Boltzmann equation. (D, E) Membrane potential was kept at −60 to −65 mV mV by injecting a small DC current through the recording pipette and voltage responses to the indicated current injection steps were measured. Representative traces from control (D) and Zdhhc14 shRNA#1 (E) transduced neurons in response to the indicated current injection steps are shown. (F, G) Summary graphs of number of action potentials fired (F) and latency to first action potential (AP, G) following injection of the indicated currents for neurons infected with control AAV (gray circles) or Zdhhc14 sh#1 AAV (green squares). Zdhhc14 knockdown increases AP firing (F: Repeated Measures ANOVA, *Virus p=0.020 [F(1)=5.84], injected current p<0.0001 [F(9)=49.31], interaction p=0.0002 [F(9)=3.64]; N = 23) and decreases latency to first AP (G: mixed effects model analysis, ****Virus p<0.0001 [F(1,43)=19.99], injected current p<0.0001 [F(3.35, 116.70)=15.18], interaction p<0.0001 [F(6, 209)=6.30]; N = 23).