Phenotypic characterization and central nervous system analysis of mutant mice EQU...
| Grant number: | 17/21103-3 |
| Support type: | Regular Research Grants |
| Duration: | February 01, 2018 - May 31, 2020 |
| Field of knowledge: | Agronomical Sciences - Veterinary Medicine - Animal Pathology |
| Principal Investigator: | Claudia Madalena Cabrera Mori |
| Grantee: | Claudia Madalena Cabrera Mori |
| Home Institution: | Faculdade de Medicina Veterinária e Zootecnia (FMVZ). Universidade de São Paulo (USP). São Paulo , SP, Brazil |
| Assoc. researchers: | Enio Mori ; Maria Martha Bernardi ; Sandra Regina Alexandre-Ribeiro ; Silvia Maria Gomes Massironi |
Abstract
Analysis of mutations in murine models may reveal new functions for known genes, identify genes underlying orthologous human diseases - in which the causal gene has not yet been identified - as well as provide the investigation of new relevant phenotypes. The spontaneous mutation tremor (tr), autosomal recessive, was identified in the colony of Swiss mice of the laboratory animal facility of the Department of Pathology of FMVZ/USP. The mutants presented tremors, ataxia and audiogenic seizures as the main phenotypic characteristics. The mutation was transferred to the C57BL/6 congenic strain by backcrosses (N10), and the genetic mapping was performed with microsatellite markers indicating that it was on chromosome 14, between 33.21 and 38.21 cM. The Egr3 gene, one of the transcription factors of the zinc-finger family, involved in the innervation and formation of the mitotic spindle, was identified as a possible candidate for the mutation. The recessive mutant mouse cruza pernas (crup), so named due to the position of the hind limbs when the animal is suspended by the tail, was originated from chemical mutagenesis induced by ENU. Initially this mutation was mapped by microsatellites on chromosome 11 and, later, the exoma sequencing was performed, resulting in several candidate genes already confirmed by the Sanger method. Exclusive mutations of crup mice were found in the Taf15, Car4, Slfn 1 and 9, Apoh and Heatr6 genes. After analyzing these genes function, the Taf15 was identified as main candidate, which acts mainly on motor neurons in the central nervous system. Previous results showed that crup and tr mutant mice presented motor and sensorial impairments that may be related with neurodegenerative diseases. The present project aims to characterize the phenotype of crup and tr mutant mice by means of behavioral analysis, evaluation of neurogenesis and gene expression. The behavioral tests will be performed by direct observation of the animals ordered by evaluated parameter, in the following sequence: 1) general activity and sensorial system, 2) psychomotor tests, 3) evaluation of the central and autonomic nervous system. Motor coordination in the balance beam, spatial memory in the T maze, anxiety in the plus maze, and depressive-like behavior by tail suspension and forced swim tests will also be evaluated. In addition, functional tests will be performed to verify possible changes in neurogenesis, especially in the hippocampus, of the mutant mice by the in vivo BrdU (5-bromo-2'-deoxyuridine) cell proliferation test and neuronal nuclei protein expression (NeuN), as well to determine the expression of mRNA to Taf15 and Egr3 genes in the CNS. Also, Sanger sequencing of the Egr3 gene will be performed, aiming to identify the causal gene for the tr mutation. (AU)