Study of the effect of mutations in ubiquitination sites on the content of the 'Transcription Factor 4' protein.

• Grant number: 22/13085-3
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: December 01, 2022
• End date: November 30, 2023
• Field of knowledge: Biological Sciences - Genetics - Human and Medical Genetics
• Principal Investigator: Fabio Papes
• Grantee: Manuella Munuera Hoff
• Host Institution: Instituto de Biologia (IB). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil

Abstract

Pitt-Hopkins Syndrome (PTHS) is a rare genetic disorder, belonging to the group of autism spectrum disorders (ASD), caused by mutations in the TCF4 gene. This encodes the protein 'Transcription Factor 4', whose role is to coordinate cell proliferation and differentiation of neural progenitor cells. The different de novo mutations that occur in PTHS patients result in haploinsufficiency of TCF4, i.e. expression of only one copy of the gene, causing the syndrome. The disease is characterized by motor delay, lack of motor coordination, absence of language, intellectual disability, and stereotyped, repetitive movements. Besides PTHS, polymorphisms in the TCF4 gene have been associated with other neuropsychiatric disorders, including schizophrenia, bipolar affective disorder, post-traumatic stress, and depression. Although associated with numerous pathologies, little is known about the biology of the TCF4 protein and there are no specific therapeutic strategies for PTHS. Given that it is caused by insufficient expression of TCF4 protein, increasing the total functional amount of TCF4 protein in cells becomes a possible therapeutic strategy. Since the process of protein degradation by the ubiquitin-proteasome system is one of the main mechanisms of protein quantity reduction in cells, the study of TCF4 degradation mechanisms by this system becomes extremely relevant for advances in the understanding of this transcription factor and for the development of specific therapies. In the present project, we seek to investigate the relationship between two predicted ubiquitination sites on TCF4 and the degradation of this protein component by the ubiquitin-proteasome pathway. To this end, we will conduct protein quantification assays in neural progenitor cells overexpressing TCF4 proteins carrying site-directed mutations in these ubiquitination sites, followed by the evaluation of the impact of the mutations on TCF4 content and subcellular localization, allowing us to infer whether these sites control the degradation of this protein by the proteasome.