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Biochim Biophys Acta Mol Cell Res ; 1866(2): 225-239, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30389374

RESUMO

GM2-gangliosidosis, a subgroup of lysosomal storage disorders, is caused by deficiency of hexosaminidase activity, and comprises the closely related Tay-Sachs and Sandhoff diseases. The enzyme deficiency prevents normal metabolization of ganglioside GM2, usually resulting in progressive neurodegenerative disease. The molecular mechanisms whereby GM2 accumulation in neurons triggers neurodegeneration remain unclear. In vitro experiments, using microsomes from Sandhoff mouse model brain, showed that increase of GM2 content negatively modulates sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) (Pelled et al., 2003). Furthermore, Ca2+ depletion in endoplasmic reticulum (ER) triggers Unfolded Protein Response (UPR), which tends to restore homeostasis in the ER; however, if cellular damage persists, an apoptotic response is initiated. We found that ER GM2 accumulation in cultured neurons induces luminal Ca2+ depletion, which in turn activates PERK (protein kinase RNA [PKR]-like ER kinase), one of three UPR sensors. PERK signaling displayed biphasic activation; i.e., early upregulation of cytoprotective calcineurin (CN) and, under prolonged ER stress, enhanced expression of pro-apoptotic transcription factor C/EBP homologous protein (CHOP). Moreover, GM2 accumulation in neuronal cells induced neurite atrophy and apoptosis. Both processes were effectively modulated by treatment with the selective PERK inhibitor GSK2606414, by CN knockdown, and by CHOP knockdown. Overall, our findings demonstrate the essential role of PERK signaling pathway contributing to neurodegeneration in a model of GM2-gangliosidosis.


Assuntos
Gangliosidoses GM2/metabolismo , Neuritos/fisiologia , eIF-2 Quinase/metabolismo , Adenina/análogos & derivados , Adenina/farmacologia , Animais , Apoptose/efeitos dos fármacos , Apoptose/genética , Atrofia/metabolismo , Linhagem Celular Tumoral , Retículo Endoplasmático/metabolismo , Estresse do Retículo Endoplasmático/fisiologia , Gangliosídeo G(M2)/metabolismo , Gangliosídeo G(M2)/fisiologia , Gangliosidoses GM2/genética , Indóis/farmacologia , Camundongos , Neuritos/metabolismo , Doenças Neurodegenerativas/metabolismo , Neurônios/metabolismo , Transdução de Sinais/genética , Fator de Transcrição CHOP/metabolismo , Resposta a Proteínas não Dobradas/fisiologia , eIF-2 Quinase/fisiologia
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