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- The polyglutamine protein ATXN2: from its molecular functions to its involvement in diseasePublication . Costa, Rafael Gomes da; Vieira da Conceição, André Filipe; Albuquerque Andrade de Matos, Carlos Adriano; Nóbrega, ClévioA CAG repeat sequence in the ATXN2 gene encodes a polyglutamine (polyQ) tract within the ataxin-2 (ATXN2) protein, showcasing a complex landscape of functions that have been progressively unveiled over recent decades. Despite significant progresses in the field, a comprehensive overview of the mechanisms governed by ATXN2 remains elusive. This multifaceted protein emerges as a key player in RNA metabolism, stress granules dynamics, endocytosis, calcium signaling, and the regulation of the circadian rhythm. The CAG overexpansion within the ATXN2 gene produces a protein with an extended poly(Q) tract, inducing consequential alterations in conformational dynamics which confer a toxic gain and/or partial loss of function. Although overexpanded ATXN2 is predominantly linked to spinocerebellar ataxia type 2 (SCA2), intermediate expansions are also implicated in amyotrophic lateral sclerosis (ALS) and parkinsonism. While the molecular intricacies await full elucidation, SCA2 presents ATXN2-associated pathological features, encompassing autophagy impairment, RNA-mediated toxicity, heightened oxidative stress, and disruption of calcium homeostasis. Presently, SCA2 remains incurable, with patients reliant on symptomatic and supportive treatments. In the pursuit of therapeutic solutions, various studies have explored avenues ranging from pharmacological drugs to advanced therapies, including cell or gene-based approaches. These endeavours aim to address the root causes or counteract distinct pathological features of SCA2. This review is intended to provide an updated compendium of ATXN2 functions, delineate the associated pathological mechanisms, and present current perspectives on the development of innovative therapeutic strategies.
- Molecular hallmarks of neurodegeneration in polyglutamine spinocerebellar ataxiasPublication . Nóbrega, Clévio; Marcelo, Adriana; Vieira da Conceição, André Filipe; Encarnação Estevam, Bernardo Alexandre; Rajado, Ana Teresa; Albuquerque Andrade de Matos, Carlos Adriano; Vilhena Catarino Brito, David; Torquato Afonso, Inês; Antunes Codêsso, José Miguel; Koppenol, Rebekah; Costa, Rafael Gomes da; Afonso Reis, Ricardo António; Paulino, Rodrigo; Gomes, TiagoPolyglutamine spinocerebellar ataxias (PolyQ SCAs) comprise a group of six inherited rare neurodegenerative diseases. They are caused by abnormal mutation of a CAG tract in six otherwise unrelated genes, leading to a complex cascade of molecular events that culminate in neuronal death. Based on decades of research in these diseases, this review identifies and categorizes the distinctive hallmarks involved in the molecular pathogenesis of PolyQ SCAs. We organized these molecular signatures into three groups: (i) primary hallmarks, which directly refer to the transcription and translation of the abnormally expanded gene and protein, respectively; (ii) secondary hallmarks, which include alterations in pathways and organelles that are implicated in the disease pathogenesis; and iii) end-stage hallmarks, which highlight the final events of the pathogenesis cascade in PolyQ SCAs. This framework is expected to provide a platform for understanding the complex network of molecular mechanisms involved in these diseases and to guide current and future efforts in developing therapies.