Department of Anatomy and Neurobiology, Wakayama Medical University, 811-1 Kimiidera, Wakayama 641-8509, Japan.
Neuroscience. 2010 Mar 17;166(2):551-63. doi: 10.1016/j.neuroscience.2009.12.055. Epub 2009 Dec 28.
Foxp1 and Foxp2, which belong to the forkhead transcription factor family, are expressed in the developing and adult mouse brain, including the striatum, thalamus, and cerebral cortex. Recent reports suggest that FOXP1 and FOXP2 are involved in the development of speech and language in humans. Although both Foxp1 and Foxp2 are expressed in the neural circuits that mediate speech and language, including the corticostriatal circuit, the functions of Foxp1 and Foxp2 in the cerebral cortex remain unclear. To gain insight into the functions of Foxp1 and Foxp2 in the cerebral cortex, we characterized Foxp1- and Foxp2-expressing cells in postnatal and adult mice using immunohistochemistry. In adult mice, Foxp1 was expressed in neurons of layers III-VIa in the neocortex, whereas the expression of Foxp2 was restricted to dopamine and cyclic adenosine 3',5'-monophosphate-regulated phosphoprotein, 32 kDa (DARPP-32)(+) neurons of layer VI. In addition, Foxp2 was weakly expressed in the neurons of layer V of the motor cortex and hindlimb and forelimb regions of the primary somatosensory cortex. Both Foxp1 and Foxp2 were expressed in the ionotropic glutamate receptor (GluR) 2/3(+) neurons, and colocalized with none of GluR1, gamma-aminobutyric acid, calbindin, and parvalbumin, indicating that expression of Foxp1 and Foxp2 is restricted to projection neurons. During the postnatal stages, Foxp1 was predominantly expressed in Satb2(+)/Ctip2(-) corticocortical projection neurons of layers III-V and in Tbr1(+) corticothalamic projection neurons of layer VIa. Although Foxp2 was also expressed in Tbr1(+) corticothalamic projection neurons of layer VI, no colocalization of Foxp1 with Foxp2 was observed from postnatal day (P) 0 to P7. These findings suggest that Foxp1 and Foxp2 may be involved in the development of different cortical projection neurons during the early postnatal stages in addition to the establishment and maintenance of different cortical circuits from the late postnatal stage to adulthood.
叉头框蛋白 1（Foxp1）和叉头框蛋白 2（Foxp2）属于叉头转录因子家族，在发育中和成年小鼠的大脑中表达，包括纹状体、丘脑和大脑皮层。最近的报告表明，FOXP1 和 FOXP2 参与了人类言语和语言的发育。尽管 Foxp1 和 Foxp2 都在介导言语和语言的神经回路中表达，包括皮质纹状体回路，但 Foxp1 和 Foxp2 在大脑皮层中的功能仍不清楚。为了深入了解 Foxp1 和 Foxp2 在大脑皮层中的功能，我们使用免疫组织化学方法对出生后和成年小鼠的 Foxp1 和 Foxp2 表达细胞进行了特征描述。在成年小鼠中，Foxp1 表达在新皮层的 III-VIa 层的神经元中，而 Foxp2 的表达则局限于多巴胺和环腺苷酸 3'，5'-单磷酸调节磷蛋白 32kDa（DARPP-32）（+）神经元的 VI 层。此外，Foxp2 在运动皮层和初级体感皮层的后肢和前肢区域的 V 层神经元中也有微弱表达。Foxp1 和 Foxp2 均表达在离子型谷氨酸受体（GluR）2/3（+）神经元中，并且与 GluR1、γ-氨基丁酸、钙结合蛋白和 parvalbumin 均不共定位，表明 Foxp1 和 Foxp2 的表达仅限于投射神经元。在出生后的阶段，Foxp1 主要表达在 III-V 层的 Satb2（+）/Ctip2（-）皮质皮质投射神经元和 VIa 层的 Tbr1（+）皮质丘脑投射神经元中。尽管 Foxp2 也在 VI 层的 Tbr1（+）皮质丘脑投射神经元中表达，但在出生后 0 天（P）至 7 天（P）期间未观察到 Foxp1 与 Foxp2 的共定位。这些发现表明，Foxp1 和 Foxp2 可能除了在出生后晚期到成年期建立和维持不同的皮质回路外，还可能参与早期出生后阶段不同皮质投射神经元的发育。
