Foxp1 regulates the development of glutamatergic synaptic input onto spiny projection neurons expressing Drd2 [snRNA-seq]. Foxp1 regulates the development of glutamatergic synaptic input onto spiny projection neurons expressing Drd2 [snRNA-seq]

Long-range glutamatergic inputs from the cortex and thalamus provide important motor and cognitive information to the striatum where they are integrated for learning and action planning. Genetic programs and transcription factors that orchestrate the development of these inputs are relatively unknown. The transcription factor, FOXP1, is crucial for the development of spiny projection neurons (SPNs) in the striatum. We investigated the cell-specific role of Foxp1 in the formation of glutamatergic inputs – including corticostriatal inputs. Embryonic Foxp1 deletion in dopamine receptor 2-expressing SPNs (D2 Foxp1cKO) leads to reduced transmission of corticostriatal excitatory inputs and decreased synaptically driven excitability. Postnatal deletion of Foxp1 also resulted in decreased glutamatergic inputs onto D2 SPNs. Single nuclei RNA sequencing of D2 Foxp1cKO striatum identified downregulated postsynaptic genes, consistent with the synaptic phenotype. Reinstating Foxp1 postnatally rescued electrophysiological deficits and expression of a subset of genes that were altered by embryonic deletion in D2 SPNs. Postnatal Foxp1 reinstatement could also rescue behavioral phenotypes. In summary, we demonstrate that FOXP1 regulates the development of corticostriatal circuitry. Further, changes at multiple levels of brain function resulting from loss of Foxp1 are rescued with postnatal Foxp1 reinstatement, indicating a therapeutic approach for individuals with FOXP1 syndrome. Overall design: We used single nuclei RNA sequencing (snRNA-Seq) in juvenile (P18) mouse striatum to test the effects of loss of Foxp1 in D2 SPNs and study gene expression changes with postnatal reinstatment of Foxp1 in striatum.

来自皮层与丘脑的长程谷氨酸能输入向纹状体传递关键的运动与认知信息，此类信息会在纹状体中整合，用于学习与动作规划。目前，调控此类输入发育的遗传程序与转录因子仍知之甚少。转录因子FOXP1对纹状体棘突投射神经元（spiny projection neurons, SPNs）的发育至关重要。本研究探讨了Foxp1在谷氨酸能输入（包括皮层纹状体输入）形成过程中的细胞特异性作用。在表达多巴胺受体2的SPNs中进行胚胎期Foxp1条件性敲除（D2 Foxp1cKO），会导致皮层纹状体兴奋性输入的传递效率下降，同时突触驱动的兴奋性降低。出生后Foxp1敲除同样会导致D2型SPNs接收的谷氨酸能输入减少。对D2 Foxp1cKO小鼠纹状体进行单细胞核RNA测序（single nuclei RNA sequencing, snRNA-Seq），结果鉴定出一批下调的突触后基因，这与突触表型相一致。出生后重建Foxp1表达可挽救电生理缺陷，并恢复D2 SPNs中因胚胎期敲除而改变的部分基因的表达。出生后重建Foxp1表达同样可挽救行为表型缺陷。综上，本研究证实FOXP1可调控皮层纹状体环路的发育。此外，Foxp1缺失所导致的多层面脑功能改变，可通过出生后重建Foxp1表达得到挽救，这为FOXP1综合征患者提供了潜在的治疗策略。实验设计：本研究使用幼年（出生后第18天，P18）小鼠纹状体的单细胞核RNA测序（snRNA-Seq）技术，探究D2 SPNs中Foxp1缺失的影响，并研究出生后重建纹状体Foxp1表达后的基因表达变化。