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Spinocerebellar ataxia type 7 (SCA7) is a neurodegenerative disorder characterized by cerebellar ataxia and retinopathy. SCA7 is caused by a CAG expansion in the ATXN7 gene, which results in an extended polyglutamine (polyQ) tract in the encoded protein, the ataxin-7. PolyQ expanded ataxin-7 elicits neurodegeneration in cerebellar Purkinje cells, however, its impact on the SCA7-associated retinopathy remains to be addressed. Since Müller glial cells play an essential role in retinal homeostasis, we generate an inducible model for SCA7, based on the glial Müller MIO-M1 cell line. The SCA7 pathogenesis has been explained by a protein gain-of-function mechanism, however, the contribution of the mutant RNA to the disease cannot be excluded. In this direction, we found nuclear and cytoplasmic foci containing mutant RNA accompanied by subtle alternative splicing defects in MIO-M1 cells. RNA foci were also observed in cells from different lineages, including peripheral mononuclear leukocytes derived from SCA7 patient, suggesting that this molecular mark could be used as a blood biomarker for SCA7. Collectively, our data showed that our glial cell model exhibits the molecular features of SCA7, which makes it a suitable model to study the RNA toxicity mechanisms, as well as to explore therapeutic strategies aiming to alleviate glial dysfunction. [ABSTRACT FROM AUTHOR]

The polymorphisms rs3758391 and rs1800470 located in SIRT1 and TGF‐β1 have been associated with type 2 diabetes in different populations but its functional effect is not clear. In this study, we evaluated their effect on the expression of SIRT1 and TGF‐β1 in peripheral blood as well as their participation in the formation of DNA–protein complexes in a pancreas‐derived cell line. It has been described that SIRT1 and TGF‐β1 participate in cell growth and regulation of production and secretion of insulin in the pancreas. Anthropometric and biochemical profiles of 127 adults were measured. Genotypes for rs3758391 and rs1800470 were determined using TaqMan assays. Expression analysis of SIRT1 and TGF‐β1 were performed using real‐time PCR. Gene expression of these genes increased 1.8 ± 0.6‐ and 1.3 ± 0.6‐fold in patients carrying the TT genotype of rs3758391 and rs1800470 when compared to carriers of the CC genotype. Then, we tested whether these single‐nucleotide polymorphisms (SNPs) (and rs932658, which is in linkage disequilibrium with rs3758391) are located in regulatory DNA‐protein binding sites by electrophoretic mobility shift assays using nuclear extract from the pancreas‐derived cell line BxPC‐3. The electrophoretic mobility shift assay showed no binding of nuclear proteins to DNA. In conclusion, the genotypes of rs3758391 and rs1800470 are associated with modifications in the expression of the genes SIRT1 and TGF‐β1, respectively, but none of the tested SNPs are located in regulatory DNA‐protein binding sites. [ABSTRACT FROM AUTHOR]

To maintain the continuity of an injured blood vessel, platelets change shape, secrete granule contents, adhere, aggregate, and retract in a haemostatic plug. Ordered arrays of microtubules, microfilaments, and associated proteins are responsible for these platelet responses. In full-spread platelets, microfilament bundles in association with other cytoskeleton proteins are anchored in focal contacts. Recent studies in migrating cells suggest that co-ordination and direct physical interaction of microtubules and actin network modulate adhesion development. In platelets, we have proposed a feasible association between these two cytoskeletal systems, as well as the participation of the dystrophin-associated protein complex, as part of the focal adhesion complex. The present study analysed the participation of microtubules and actin during the platelet adhesion process. Confocal microscopy, fluorescence resonance transfer energy and immunoprecipitation assays were used to provide evidence of a cross-talk between these two cytoskeletal systems. Interestingly, beta-dystroglycan was found to act as an interplay protein between actin and microtubules and an additional communication between these two cytoskeleton networks was maintained through proteins of focal adhesion complex. Altogether our data are indicative of a dynamic co-participation of actin filaments and microtubules in modulating focal contacts to achieve platelet function.