Sumoylation of FOXP2 Regulates Motor Function and Vocal Communication Through Purkinje Cell Development

Abstract

Background Mutations in the gene encoding the transcription factor forkhead box P2, FOXP2, result in brain developmental abnormalities including reduced gray matter in both human patients and rodent models, and speech and language deficits. However, neither the region-specific function of FOXP2 in the brain, in particular the cerebellum, nor the effects of any post-translational modifications of FOXP2 in the brain and disorders have been explored. Methods We characterized sumoylation of FOXP2 biochemically, and analyzed the region-specific function and sumoylation of FOXP2 in the developing mouse cerebellum. Using in utero electroporation to manipulate the sumoylation-state of Foxp2 as well as Foxp2 expression levels in Purkinje cells (PCs) of the cerebellum in vivo, we reduced Foxp2 expression approximately 40% in the mouse cerebellum. Such a reduction approximates the haploinsufficiency observed in human patients who demonstrate speech and language impairments. Results We identified sumoylation of FOXP2 at K674 (K673 in mouse) in the cerebellum of neonates. In vitro co-immunoprecipitation and in vivo colocalization experiments suggest that PIAS3 acts as the SUMO E3 ligase for FOXP2 sumoylation. This sumoylation modifies transcriptional regulation by FOXP2. We demonstrate that Foxp2 sumoylation is required for regulation of cerebellar motor function and vocal communication, likely through dendritic outgrowth and arborization of PCs in the mouse cerebellum. Conclusions Sumoylation of Foxp2 in neonatal mouse cerebellum regulates PC development as well as motor functions and vocal communication, demonstrating evidence for sumoylation in regulating mammalian behaviors.

Characterization of an enhancer element that regulates FOXP2 expression in human cerebellum

“…FOXP2 is expressed in mouse and human developing cerebellum and it has been previously implicated in speech and language disorders (31,32). It might be crucial for Purkinje cell development, as it is specifically expressed in those cells, and thus play a relevant role in vocal communication (28)(29)(30). Our searches in recent neurodevelopmental expression databases confirmed that FOXP2 expression in developing human brain is highest in cerebellum, around 12 pcw.…”

Functional characterization of rare FOXP2 variants in neurodevelopmental disorder

“…In addition, CTBPs may play a role in the post-translational modification of FOXP2. We and other groups have recently demonstrated that FOXP2 is post-translationally modified by SUMOylation [21, 60, 61]. The essential SUMOylation enzyme UBC9 is a core component of the protein complex containing CTBP1, and CTBP1 has been suggested to function as a platform for protein SUMOylation [62].…”

Cortical Foxp2 supports behavioral flexibility and developmental dopamine D1 receptor expression

“…Neonatal isolation USVs were also largely unaffected by loss of cortical Foxp2, contrasting with the USV reductions in pups with cortical Foxp1 deletion or cerebellar Foxp2 knockdown (Usui et al 2017a;Usui et al 2017b). Whereas Foxp2 is expressed in CThPNs, Foxp1 is likely expressed in callosal and corticostriatal neurons based on its coexpression with Satb2 (Hisaoka et al 2010;Sohur et al 2014;Sorensen et al 2015).…”

“…Castellucci et al 2016;Chabout et al 2016;Gaub et al 2016), which have been attributed to its functions in the striatum(Chen et al 2016), cerebellum (Fujita-Jimbo and Momoi 2014;Usui et al 2017b), and laryngeal cartilage(Xu et al 2018). Cortical…”