In vivo and in vitro functional study of AMMECR1 gene and clinical follow up of a patient without functional copies of this gene

Abstract

In her master's thesis, the student Mariana Moyses Oliveira described a female patient with a balanced translocation t(X;9)(q23,q12) that caused AMMECR1 gene disruption in the X chromosome breakpoint, leading to the absence of functional copies of this gene. AMMECR1 gene function has not been described yet, however it is known that, under normal conditions, its expression is ubiquitous and occurs primarily in the placenta, fetal liver, cardiomyocytes and osteoblasts. These organs and cell types were affected during the patient's development. AMMECR1 protein is highly conserved throughout evolution, presents a nuclear localization, several phosphorylation sites and a similar conformation to proteins that interact with nucleic acid, suggesting a regulatory role.This patient may represent a unique model of the phenotypic consequences of the AMMECR1 functional impairment in the human organism. Thus, her clinical follow up should point at which organs and tissues AMMECR1 gene plays important roles. Ammecr1 gene expression levels will be investigated during mouse development in order to verify if the embryonic tissues that give rise to organs affected in the patient present higher expression levels of this gene. This in vivo study will provide supporting evidences for the correlation between the patient's phenotypic alterations and AMMECR1 loss of function.In vitro studies will be performed in cell strains in which AMMECR1 gene is highly expressed in order to determine its protein sublocalization and its possible function in cellular context. Further in vitro functional studies will be conducted in different experimental cellular models: patient-derived lymphoblastoid cell line, normal lymphoblastoid and mesenchymal stem cell lines with, and without, AMMECR1gene silencing. In these studies, biological responses resulting from AMMECR1 functional impairment, such as cellular proliferation, cell cycle, apoptosis, and signaling pathways possibly modulated by this gene will be assessed.Thus, the AMMECR1 role elucidation can lead to the recognition of pathways that drive primary processes in the cellular context, improving the understanding of mechanisms that regulate replication, transcription and DNA repair. The association of the in vitro studies results with detailed patient's follow up and in vivo studies in mice should reveal in which organs and tissues the action of signaling pathways revealed is important.