Figure 5. The expression of CELF4 protein is greatly reduced in Celf4^flox/flox mice with Emx1-cre.

a–d: Sagittal sections from B6J adult mice with either wildtype Celf4 and Emx1-cre expression, floxed Celf4 expression (flox/flox) without Cre, or floxed Celf4 and Emx1-cre expression were examined for CELF4 protein expression by immunohistochemistry with α-CELF4 antibody. Confocal imaging showed that expression of either Emx1-Cre or floxed Celf4 alone did not affect the high levels of CELF4 expression observed in the highly glutamatergic CA3 region of hippocampus (a), dentate gyrus (b), or cerebral cortex (c) nor the sparse expression of CELF4 observed in the highly GABAergic striatum (d). However, expression of floxed Celf4 in conjunction with Emx1-cre greatly reduces CELF4 protein expression specifically in excitatory neurons in hippocampus and cerebral cortex (a–c), but does not affect CELF4 expression in inhibitory neurons, such as those seen in abundance in the striatum. This result was predicted from the known expression pattern of the excitatory-neuron specific Emx1 promoter, and shows that the seizure phenotype of Celf4^flox/flox, Emx1-cre⁺ mice is indeed correlated with specific deletion of CELF4 from excitatory neurons. Scale bars: 50 µm.