Establishment and characterization of a brain cell culture model system of myotonic dystrophy type 1

Proyecto de Graduación (Bachillerato en Ingeniería en Biotecnología) Instituto Tecnológico de Costa Rica, Escuela de Biología, 2011 ; Myotonic dystrophy type 1 (DM1) is an autosomal dominant genetic disease caused by the expansion of an unstable CTG repeat in the 3’UTR of the dystrophia myotonica-protein kinase (DMPK) gene. DM1 is the most common form of adult muscular dystrophy. It was initially considered as a muscle disease, but today it is known that DM1 is a multisystemic disease that affects many tissues and organs, including the central nervous system (CNS). Indeed, DM1 patients present debilitating neurological manifestations, such as hypersomnia, cognitive and learning impairment. Congenital DM1 shows severe mental retardation. The unsteady CTG sequence in DM1 tends to expand in size when it is transmitted vertically from one generation to the next. Intergenerational trinucleotide repeat instability serves as the molecular explanation of the phenomenon of anticipation, meaning the increasing severity and decreasing age of onset in successive generations of a DM1 families The repeat is also unstable in somatic tissues, continuing to expand throughout the patient´s life. Important symptoms of DM1 are explained by the nuclear accumulation of toxic, expanded DMPK transcripts and subsequent deregulation of RNA-binding proteins, which leads to missplicing in multiple tissues, including brain. However the molecular pathways contributing to DM1 neuropsychological dysfunction are still unknown. To investigate the disease pathogenesis, DMSXL transgenic mice, carrying large CTG expansions (>1000 repeats) within the human DM1 locus, were generated and studied. In the CNS, these animals show RNA missplicing, as well as Tau hyperphosphorylation, recreating, to a certain extent, the spliceopathy and tauopathy described in humans. A global proteomic approach and the study of candidate genes on DMSXL brains revealed molecular abnormalities in proteins involved in the regulation of calcium metabolism. These findings ...