The HERC2 ubiquitin ligase is essential for embryonic development and regulates motor coordination

// Monica Cubillos-Rojas 1 , Taiane Schneider 1 , Ouadah Hadjebi 1 , Leonardo Pedrazza 1,2 , Jarbas Rodrigues de Oliveira 2 , Francina Langa 3 , Jean-Louis Guenet 3 , Joan Duran 4 , Josep Maria de Anta 4 , Soledad Alcantara 4 , Rocio Ruiz 5,6 , Eva Maria Perez-Villegas 6 , Francisco J. Aguilar-Montilla 6 , Angel M. Carrion 6 , Jose Angel Armengol 6 , Emma Baple 7 , Andrew H. Crosby 7 , Ramon Bartrons 1 , Francesc Ventura 1 and Jose Luis Rosa 1 1 Departament de Ciencies Fisiologiques, IDIBELL, Campus de Bellvitge, Universitat de Barcelona, L’Hospitalet de Llobregat, Barcelona, Spain 2 Laboratorio de Pesquisa em Biofisica Celular e Inflamacao, Pontificia Universidade Catolica do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil 3 Departement de Biologie du Developpement, Institut Pasteur, Paris, France 4 Departament de Patologia i Terapeutica Experimental, Campus de Bellvitge, Universitat de Barcelona, L’Hospitalet de Llobregat, Barcelona, Spain 5 Departamento de Bioquimica y Biologia Molecular, Facultad de Farmacia, Universidad de Sevilla, Sevilla, Spain 6 Departamento de Fisiologia, Anatomia y Biologia Celular, Universidad Pablo de Olavide, Sevilla, Spain 7 Institute of Biomedical and Clinical Science, University of Exeter Medical School, RILD Wellcome Wolfson Centre, Exeter, UK Correspondence to: Jose Luis Rosa, email: // Keywords : ubiquitin, p53, Angelman syndrome, Purkinje cells, behavioural analysis, Pathology Section Received : June 07, 2016 Accepted : August 01, 2016 Published : August 12, 2016 Abstract A mutation in the HERC2 gene has been linked to a severe neurodevelopmental disorder with similarities to the Angelman syndrome. This gene codifies a protein with ubiquitin ligase activity that regulates the activity of tumor protein p53 and is involved in important cellular processes such as DNA repair, cell cycle, cancer, and iron metabolism. Despite the critical role of HERC2 in these physiological and pathological processes, little is known about its relevance in vivo . Here, we described a mouse with targeted inactivation of the Herc2 gene. Homozygous mice were not viable. Distinct from other ubiquitin ligases that interact with p53, such as MDM2 or MDM4, p53 depletion did not rescue the lethality of homozygous mice. The HERC2 protein levels were reduced by approximately one-half in heterozygous mice. Consequently, HERC2 activities, including ubiquitin ligase and stimulation of p53 activity, were lower in heterozygous mice. A decrease in HERC2 activities was also observed in human skin fibroblasts from individuals with an Angelman-like syndrome that express an unstable mutant protein of HERC2. Behavioural analysis of heterozygous mice identified an impaired motor synchronization with normal neuromuscular function. This effect was not observed in p53 knockout mice, indicating that a mechanism independent of p53 activity is involved. Morphological analysis showed the presence of HERC2 in Purkinje cells and a specific loss of these neurons in the cerebella of heterozygous mice. In these animals, an increase of autophagosomes and lysosomes was observed. Our findings establish a crucial role of HERC2 in embryonic development and motor coordination.