Fezf2 expression in layer 5 projection neurons of mature mouse motor cortex.
The mature cerebral cortex contains a wide diversity of neuron phenotypes. This diversity is specified during development by neuron-specific expression of key transcription factors, some of which are retained for the life of the animal. One of these key developmental transcription factors that is also retained in the adult is Fezf2, but the neuron types expressing it in the mature cortex are unknown. With a validated Fezf2-Gfp reporter mouse, whole-cell electrophysiology with morphology reconstruction, cluster analysis, in vivo retrograde labeling, and immunohistochemistry, we identify a heterogeneous population of Fezf2(+) neurons in both layer 5A and layer 5B of the mature motor cortex. Functional electrophysiology identified two distinct subtypes of Fezf2(+) neurons that resembled pyramidal tract projection neurons (PT-PNs) and intratelencephalic projection neurons (IT-PNs). Retrograde labeling confirmed the former type to include corticospinal projection neurons (CSpPNs) and corticothalamic projection neurons (CThPNs), whereas the latter type included crossed corticostriatal projection neurons (cCStrPNs) and crossed-corticocortical projection neurons (cCCPNs). The two Fezf2(+) subtypes expressed either CTIP2 or SATB2 to distinguish their physiological identity and confirmed that specific expression combinations of key transcription factors persist in the mature motor cortex. Our findings indicate a wider role for Fezf2 within gene expression networks that underpin the diversity of layer 5 cortical projection neurons.
['Tantirigama|Malinda L S|ML|', 'Oswald|Manfred J|MJ|', 'Clare|Alison J|AJ|', 'Wicky|Hollie E|HE|', 'Day|Robert C|RC|', 'Hughes|Stephanie M|SM|', 'Empson|Ruth M|RM|']
D000818:Animals D004268:DNA-Binding Proteins D049452:Green Fluorescent Proteins D057809:HEK293 Cells D006801:Humans D007150:Immunohistochemistry D017404:In Situ Hybridization, Fluorescence D008297:Male D036961:Matrix Attachment Region Binding Proteins D008822:Mice, Transgenic D009044:Motor Cortex D009419:Nerve Tissue Proteins D056347:Neuroanatomical Tract-Tracing Techniques D009474:Neurons D016133:Polymerase Chain Reaction D011712:Pyramidal Tracts D012097:Repressor Proteins D046509:Tissue Culture Techniques D014157:Transcription Factors D014162:Transfection D025521:Tumor Suppressor Proteins
Fezf2 layer 5 cortex transcription factors electrophysiology IT type PT type RRID:AB_10561696 RRID:AB_2064130 RRID:AB_882455 RRID:nif-0000-30467