RESUMEN
The Golgi is a dynamic organelle whose correct assembly is crucial for cellular homeostasis. Perturbations in Golgi structure are associated with numerous disorders from neurodegeneration to cancer. However, whether and how dispersal of the Golgi apparatus is actively regulated under stress, and the consequences of Golgi dispersal, remain unknown. Here we demonstrate that 26S proteasomes are associated with the cytosolic surface of Golgi membranes to facilitate Golgi Apparatus-Related Degradation (GARD) and degradation of GM130 in response to Golgi stress. The degradation of GM130 is dependent on p97/VCP and 26S proteasomes, and required for Golgi dispersal. Finally, we show that perturbation of Golgi homeostasis induces cell death of multiple myeloma in vitro and in vivo, offering a therapeutic strategy for this malignancy. Taken together, this work reveals a mechanism of Golgi-localized proteasomal degradation, providing a functional link between proteostasis control and Golgi architecture, which may be critical in various secretion-related pathologies.
Asunto(s)
Aparato de Golgi/metabolismo , Ionóforos/uso terapéutico , Mieloma Múltiple/tratamiento farmacológico , Complejo de la Endopetidasa Proteasomal/metabolismo , Proteostasis/fisiología , Animales , Apoptosis/efectos de los fármacos , Autoantígenos/metabolismo , Línea Celular Tumoral/trasplante , Modelos Animales de Enfermedad , Aparato de Golgi/efectos de los fármacos , Células HEK293 , Humanos , Membranas Intracelulares/metabolismo , Ionóforos/farmacología , Proteínas de la Membrana/metabolismo , Ratones , Monensina/farmacología , Monensina/uso terapéutico , Mieloma Múltiple/patología , Proteolisis/efectos de los fármacos , Proteostasis/efectos de los fármacos , Ubiquitinación/efectos de los fármacos , Proteína que Contiene Valosina/metabolismoRESUMEN
We found that a localization artifact can arise from common immunofluorescence methods. Specifically, cell fixation and permeabilization can cause mislocalization of a type II membrane-bound protein, ER mannosidase I, from its native localization in vesicles to the Golgi complex. Live cell microscopy and interestingly also mild cell fixation with paraformaldehyde without membrane permeabilization do not present this artifact.