The Co-chaperone BAG2 Mediates Cold-Induced Accumulation of Phosphorylated Tau in SH-SY5Y Cells

Autor(es)

Dias de Paula, Cesar Augusto ^[1] ; Santiago, Fernando Enrique ^[1] ; Alves de Oliveira, Adriele Silva ^[1] ; Oliveira, Fernando Augusto ^{[1, 2]} ; Almeida, Maria Camila ^{[1, 3]} ; Carrettiero, Daniel Carneiro ^{[1, 3]}

Afiliação do(s) autor(es)

^[1] Univ Fed ABC, Sao Paulo - Brazil

^[2] Univ Fed ABC, Ctr Matemat Comp & Cognicao, Sao Paulo - Brazil

^[3] Univ Fed ABC, Ctr Ciencias Nat & Humanas, Sao Paulo - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Cellular and Molecular Neurobiology; v. 36, n. 4, p. 593-602, MAY 2016.
• Citações Web of Science: 6

Resumo

Inclusions of phosphorylated tau (p-tau) are a hallmark of many neurodegenerative disorders classified as ``tauopathy,{''} of which Alzheimer's disease is the most prevalent form. Dysregulation of tau phosphorylation disrupts neuron structure and function, and hyperphosphorylated tau aggregates to form neurotoxic inclusions. The abundance of ubiquitin in tau inclusions suggests a defect in ubiquitin-mediated tau protein degradation by the proteasome. Under the temperature of 37 A degrees C, the co-chaperone BAG2 protein targets phosphorylated tau for degradation via by a more-efficient, ubiquitin-independent pathway. In both in vivo and in vitro studies, cold exposure induces the accumulation of phosphorylated tau protein. The SH-SY5Y cell line differentiates into neuron-like cells on treatment with retinoic acid and is an established model for research on the effects of cold on tau phosphorylation. The aim of the present study was to investigate whether BAG2 mediates the cold-induced accumulation of phosphorylated tau protein. Our findings show that cold exposure causes a decrease in BAG2 expression in undifferentiated cells. Conversely, BAG2 expression is increased in differentiated cells exposed to cold. Further, undifferentiated cells exposed to cold had an increased proportion of p-tau to total tau, suggesting an accumulation of p-tau that is consistent with decreased levels of BAG2. Overexpression of BAG2 in cold-exposed undifferentiated cells restored levels of p-tau to those of 37 A degrees C undifferentiated control. Interestingly, although BAG2 expression increased in differentiated cells, this increase was not accompanied by a decrease in the proportion of p-tau to total tau. Further, overexpression of BAG2 in cold exposed differentiated cells showed no significant difference in p-tau levels compared to 37 A degrees C controls. Taken together, these data show that expression of BAG2 is differently regulated in a differentiation-dependent context. Our results suggest that repression of BAG2 expression or BAG2 activity by cold-sensitive pathways, as modeled in undifferentiated and differentiated cells, respectively, may be a causal factor in the accumulation of cytotoxic hyperphosphorylated tau protein via restriction of BAG2-mediated clearance of cellular p-tau. (AU)

• Processo FAPESP: 12/50336-2 - Interação entre hipometabolismo, dinâmica do cálcio e excitabilidade neuronal: implicações no processo degenerativo da doença de Alzheimer
• Beneficiário: Fernando Augusto de Oliveira Ribeiro
• Modalidade de apoio: Auxílio à Pesquisa - Jovens Pesquisadores
• Processo FAPESP: 11/06528-1 - Participação dos canais TRPV4 na termorregulação
• Beneficiário: Maria Camila Almeida
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 09/11446-4 - Um estudo sobre a relação dos receptores nicotínicos com a degradação de isoformas tóxicas de Tau na Doença de Alzheimer: envolvimento da co-chaperona BAG2?
• Beneficiário: Daniel Carneiro Carrettiero
• Modalidade de apoio: Auxílio à Pesquisa - Regular