p27 Kip1 regulates alpha-synuclein expression

// Edurne Gallastegui 1 , Carla Domuro 1 , Joan Serratosa 2 , Alejandra Larrieux 1 , Laura Sin 1 , Jonatan Martinez 1 , Arnaud Besson 3 , Jose Manuel Morante-Redolat 4 , Serena Orlando 1 , Rosa Aligue 1 , Isabel Farinas 4 , Maria Jesus Pujol 1 and Oriol Bachs 1 1 Department of Biomedical Sciences, (CIBERONC), University of Barcelona, Barcelona, Spain 2 Department of Cerebral Ischemia and Neurodegeneration, Institut d’Investigacions Biomediques de Barcelona-Consejo Superior de Investigaciones Cientificas, Barcelona, Spain 3 Cancer Research Center of Toulouse, Universite Toulouse III Paul Sabatier, Toulouse, France 4 Departamento de Biologia Celular, Biologia Funcional y Antropologia Fisica, ERI de Biotecnologia y Biomedicina, (CIBERNED), Universidad de Valencia, Valencia, Spain Correspondence to: Oriol Bachs, email: obachs@ub.edu Keywords: p27Kip1; p21Cip1; E2F4; alpha synuclein; transcription Received: September 27, 2017      Accepted: February 27, 2018      Published: March 27, 2018 ABSTRACT Alpha-synuclein (α-SYN) is the main component of anomalous protein aggregates (Lewy bodies) that play a crucial role in several neurodegenerative diseases (synucleinopathies) like Parkinson’s disease and multiple system atrophy. However, the mechanisms involved in its transcriptional regulation are poorly understood. We investigated here the role of the cyclin-dependent kinase (Cdk) inhibitor and transcriptional regulator p27 Kip1 (p27) in the regulation of α-SYN expression. We observed that selective deletion of p27 by CRISPR/Cas9 technology in neural cells resulted in increased levels of α-SYN. Knock-down of the member of the same family p21 Cip1 (p21) also led to increased α-SYN levels, indicating that p27 and p21 collaborate in the repression of α-SYN transcription. We demonstrated that this repression is mediated by the transcription factor E2F4 and the member of the retinoblastoma protein family p130 and that it is dependent of Cdk activity. Chromatin immunoprecipitation analysis revealed specific binding sites for p27, p21 and E2F4 in the proximal α-SYN gene promoter. Finally, luciferase assays revealed a direct action of p27, p21 and E2F4 in α-SYN gene expression. Our findings reveal for the first time a negative regulatory mechanism of α-SYN expression, suggesting a putative role for cell cycle regulators in the etiology of synucleinopathies.