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| Author(s): |
Danielle Ayub de Barros Guerrieri Pinheiro
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Instituto de Biociências (IBIOC/SB) |
| Defense date: | 2013-04-24 |
| Examining board members: |
Mariz Vainzof;
Juliana Gurgel Giannetti;
Luciana Amaral Haddad;
Celia Priszkulnik Koiffmann;
Acary Souza Bulle Oliveira
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| Advisor: | Mariz Vainzof |
| Abstract | |
Muscular Dystrophies (MD) are a heterogeneous group of genetic diseases characterized by progressive and irreversible degeneration of skeletal muscle. Recently, defects in α-DG glycosylation have been associated with different types of severe forms of muscular dystrophies. Therefore, alteration in this mechanism has been considered an important pathogenetic cause of muscle degeneration, opening new avenues for therapies. The main objective of this study is to evaluate the expression cascade of genes involved in the glycosylation of α-DG in murine models and in patients with different molecular defects causing MD. We found that both normal and dystrophic mice express the glycosyltransferases genes in the following quantitative order: Pomgnt1>Large>Fkrp>Pomt1, in all ages and in all studied strains, suggesting a constant mechanism of gene regulation, independent of growth, aging or dystrophic process. We also observed that this pattern of expression is not related to the degeneration/regeneration process, since there was no concordance between the animals with the most degenerated muscles (Largemyd and Lama2dy2J/J) or the less degenerated muscles (Dmdmdx and SJL/J). Additionally, both gastrocnemius (less degenerated in Dmdmdx) and diaphragm (more degenerated in Dmdmdx) presented the same pattern of expression. In newborn animals, a significant increased expression was observed in Dmdmdx and Largemyd and a decrease in Lama2dy2J/J and SJL/J. In adult animals, the expression profile of Pomt1, Pomgnt1 and Fkrp was similar in normal and affected mice, while Large showed a decreased expression in almost all affected animals. In human muscle, the quantitative order of expression of the 4 genes was: POMT1>POMGnT1>FKRP>LARGE, different from the mice. DMD patients showed an increased expression of all the studied genes, in a pattern similar as the observed in the newborns group of the murine Dmdmdx model, suggesting an association with the lack of protein dystrophin. LGMD 2I patients showed no significant reduction in FKRP expression, indicating a normal transcriptional process. In CMD 1A patients, there was a reduction in POMT1 and FKRP expression, in spite of a normal α-DG glycosylation observed in this disease, suggesting that the deficiency of these enzymes may not alter this process. At the protein level, we did not observe a direct correlation between protein quantities of glicosiltrasferases and gene expression, suggesting that enzymes regulation functions differently as compared with structural proteins. Interestingly, antibodies for POMT1 and FKRP detected, in newborn mice, additional bands of higher molecular weight, suggesting that these enzymes are linked to each other or with other proteins in the early stages of muscle development (AU) | |