Mapeamento genético e procura do geneCandidato para a mutação sacudidor de cabeça em camundongos

Abstract

The mutation Sacudidor de Cabeça (Sacc) causes an autosomal dominant disorder in mice and was isolated during a project developed in a partnership between the Laboratory of Animal and Human Genetics - ICB/UFMG and the Department of Immunology - ICB/USP, which aimed to induce different mutations in the genome of mice using the mutagen N-ethyl-N-nitrosourea (ENU). The mutant Sacc presents abnormal movement of the head and neck, up and down. This behavior is observed from the eighth day of life and is constant, being more pronounced under conditions of stress and disappearing during sleep. However, the mutant animals are fertile, develop normally and present normal life span. Previous studies have mapped the Sacc mutation to a region of 9.3 Mb on chromosome 15, delimited by the microsatellite markers D15Mit242 and D15Mit77. This project aimed at identifying and characterizing the mutation responsible for the phenotype Sacudidor de Cabeça. Linkage analysis using microsatellite markers and SNPs reduced the genetic interval that harbors the mutation to 9.1 Mb, delimited by the marker D15Mit242 and the SNP rs8243603. The assessment of transcript levels of five positional candidate genes Lrrk2, Slc38a, Rnd1, Cacnb3, Kif21a was performed between control and mutants animals by Real Time PCR. The amount of Rnd1 transcript was significantly increased in Sacudidor de Cabeça mice. Thus, the gene Rnd1 was selected as a strong candidate for harboring the mutation responsible for the phenotype and was isolated for sequencing. So far, 90% of the coding region and flanking intronic regions of the gene Rnd1 have been sequenced and no nucleotide alteration has been found. Further characterization of the mutation Sacudidor de Cabeça will allow functional studies on the mutated gene and will greatly contribute to understanding the mechanisms underpinning the development of the nervous system. The knowledge obtained from this model may contribute to the understanding and development of new treatments for related neurological human disorders.