Figure 5. KCC2 expression is necessary and sufficient for the inhibition of cortical interneuron migration.
(A) Wild-type embryonic cortical slices (300 microns thick) were injected in the MGE with either control EGFP constructs or EGFP-IRES-KCC2* expressing constructs and subsequently electroporated. Inset shows early EGFP expression restricted to the MGE after 1div.
(B–C) While EGFP controls (B) show robust migration of interneurons from the striatum into the dorsal telencephalon, precocious expression of KCC2* in slices reduces migration to the cortex by approximately 2-fold.
(D) Significant decrease (p<0.0001) in the percentage of MGE-derived interneurons migrating into the cortex in KCC2-expressing interneurons compared to control.
(E–G) MGEs electroporated with either (E) control plasmid, (F) shKCC2 or (G) shKCC2+KCC2* were explanted on wild-type cortical dissociated cultures for 7div and time-lapsed for 6 hours. Pictures show initial frame (t=0) in red and frame captured 3 hours later in green. Yellow labeled cells indicates sedentary interneurons.
(H) Box plots show change in pausing frequency of cortical interneuron populations expressing the indicated constructs, before and after the indicated drug treatment Light-grey shading shows middle 50th percent range of appropriate control population. Quantification shows a significant decrease in the pausing frequency of interneurons expressing shKCC2 (p<0.0001) and a significant rescue with KCC2* (p<0.0001). See also Movies S9–11 for representative examples.