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- Enzyme Replacement Therapies for Lysosomal Storage DiseasesPublication . Coutinho, Maria FranciscaLysosomal Storage Disorders (LSDs): Genetic; Rare; Autosomal recessive (majority). Portugal - 1/4000; Almost 70!. The concept of enzyme replacement as a potential therapeutic approach to ameliorate lysosomal storage disorders (LSDs) is virtually as old as the concept of LSD itself. In fact, both concepts were established right after the first enzymatic deficiency underlying an LSD was described, and enzyme replacement therapy (ERT) remained the golden standard for LSD treatment for years. Nevertheless, its ineffectiveness to correct brain pathology, together with its high cost and lifelong dependence prompted the search for additional therapeutic approaches, which are currently being investigated: chaperone therapy; gene enhancement and gene therapy. Still, no matter how effective the treatment or cutting-edge the technology used in any of these cases, the underlying rationale is virtually the same: an attempt to provide or enhance the activity of the missing enzyme.
- SCARB2 mutations as modifiers in Gaucher disease: the wrong enzyme at the wrong place?Publication . Coutinho, Maria Francisca; Lacerda, L.; Gaspar, A.; Pinto, E.; Ribeiro, I.; Laranjeira, F.; Ribeiro, H.; Silva, E.; Ferreira, C.; Prata, M.J.; Alves, S.Unlike most lysosomal proteins, β-glucocerebrosidase (GCase), the hydrolase defective in Gaucher disease (GD), is delivered to lysosomes through its interaction with the transmembrane protein LIMP2. A few years ago, mutations in its coding gene, SCARB2, were reported to modify the severity of GD phenotype. The existence of a great variety of GD phenotypes is well-known, with numerous patients who carry identical genotypes presenting remarkable phenotypic variability. Over the years, that variability has been attributed to other genetic, epigenetic and/or environmental factors. Still, there is still much to learn on this subject. Recently, an association between Parkinson's disease (PD) and the presence of mutations in the GBA gene has been demonstrated. Moreover, there are also studies suggesting that genetic variants in the SCARB2 gene may also be risk factors for PD. We analysed the SCARB2 gene in the Portuguese cohort of 91 GD patients, having identified 3 different SCARB2 coding variants. Of those, 2 were known polymorphisms with high prevalence in the normal population (p.M159V and p.V396I) and the third was a novel coding variant, p.T398M, present in heterozigousity in a single patient. Our study demonstrated that, at least for the Portuguese population, genetic variability at SCARB2 does not account much to the GD phenotypic spectrum. Nevertheless, in vitro analyses of the novel p.T398M are envisaged, in order to further characterize the effect of this variant on the levels and sub-cellular location of GCase. The clinical presentation of the patient harbouring this coding variant will also be discussed.
- Terapias inovadoras nas Doenças Lisossomais de Sobrecarga: as possibilidades (ilimitadas) da InvestigaçãoPublication . Coutinho, Maria FranciscaAs possibilidades (ilimitadas) da investigação relativamente às Terapias inovadoras nas Doenças Lisossomais de Sobrecarga.
- Genetically Modulated Substrate Reduction Therapy for Sanfilippo Syndrome: Proof of PrinciplePublication . Santos, Juliana Inês; Coutinho, Maria Francisca; Gaspar, Paulo; Alves, SandraAbout proof of principle in genetically modulated substrate reduction therapy for Sanfilippo syndrome.
- Genetically Modulated Substrate Reduction Therapy for Sanfilippo syndrome – proof of principlePublication . Santos, J.I.; Coutinho, Maria Francisca; Gaspar, P.; Alves, S.Introduction: Mucopolysaccharidosis type III (MPS III) refers to a group of five autosomal recessive neurodegenerative lysosomal storage disorders caused by the incomplete lysosomal degradation of the heparan sulphate (HS) that accumulates in patient cells and triggers disease. The main characteristic of this disease is the degeneration of the central nervous system, resulting in mental retardation and hyperactivity. Currently, there is no effective therapy available, with treatment limited to clinical management of neurological symptoms. Methods: Taking advantage of the RNA interference (RNAi) technology potential, we have designed and assayed a specific siRNA targeting an early stage of the HS biosynthetic cascade (XYLT1) in order to promote an effective reduction of the accumulating substrate. Fibroblasts from MPS III patients were transfected with the designed siRNA. Total RNA was extracted and target mRNA levels evaluated through real-time PCR. The effect on GAGs accumulation was quantified over time using a modified 1,9-dimethylmethylene blue assay. Results: Proof of principle on the effect of siRNA targeting XYLT1 was achieved for two independent control cell lines, with 8-12 fold decreases on the target mRNA levels, after 24h of incubation with concentrations of 20nM of each siRNA. Subsequent analysis on the effect of the same siRNA on MPS III cell lines resulted in significant lower expression of XYLT1 in types A, B and C, after 24-48h of siRNA incubation. Studies on type B are also ongoing. For types C and D, we have already assessed the treatment effect on storage and observed a significant reduction (50-70%) on the total GAGs levels. Conclusions: The effect of siRNA targeting XYLT1 was achieved, resulting in significant lower levels of XYLT1 mRNA. Studies on MPS IIIB are ongoing. Moreover, a significant reduction on GAGs’ accumulation was observed, and we are currently addressing this storage in the remaining MPS III cell lines.